Thanks Peter. After reading some of the comments there are obviously some people who cannot set a negative Z value in the controller (eg LinuxCNC). I think the workaround is to zero the Z axis with the tool on the spoil board, then MANUALLY MOVE Z UP BY THE THICKNESS OF THE STOCK or DEPTH OF CUT THAT YOU SPECIFY IN THE CAM program, then ZERO THE Z AXIS AGAIN, then move the tool up out of the way while you lay down the stock. So to cut out the part (not a pocket), the CAM job will go down to the bottom of the specified stock depth but will never go any lower into your spoil board. Example: your stock measures approximately 12.2 mm so in your CAD software you set the stock thickness or max cut depth to 12 and because your Z zero is exactly 12 mm ABOVE the spoil board, you are ignoring the variations in the actual thickness of the stock and the tool will cut to Z-12 and just touch the spoil board. Of course you will also need to set your Z clearance height to allow for the highest peaks in the stock. For accurate pocketing you should reset the Z zero to the exact top surface of the stock and, assuming that the stock is flat, the pocket depth will be whatever you specified in the CAM package. I've recently started using the excellent Estlcam for toolpaths and usually add a few small holding tabs when cutting out very small parts. It's annoying when you've spent thirty minutes engraving something, only to see it chewed up and flying across the room. Thanks again for the tips.
I have found a way that guarantees not spoiling your board. My SB is 3mm thick, MDF material. I have a vacuum bed also. I place a 6mm mdf same size as SB. Using the software, not the cnc own surfacing method, I hatch fill the entire board 1mm leaving 5mm as a result. Leave this board on the machine as it is now your SB. Say my next cut job is 3mm. In the software I input 8mm thickness and input my thru cut as 3mm (like normal inputting). As a result, 5mm is left at the bottom. That 5mm is actually what has been surfaced so my cutting is thru perfectly and not even scratching the new SB. The trick is to ALWAYS add 5mm to your stock but input as usual. My cnc when cutting displays what is left at the bottom, so it will always show 5mm and I know the cut is thru. Your vacuum has to be in good order too to have success. Good luck, all.
Thank you for sharing your work methods. I installed a new spoilboard and did my first project zeroing on the spoilboard then setting the Z to minus my stock thickness in the CAD software and voilà A perfectly cut through project with an unspoiled spoilboard. Very happy!
WOW!! Which I would had seen this video many a spoiler boards ago. What a great "common sense" idea. Implemented your approach and there were no cuts on the spoiler board after milling. THANKS, Mike
I don't use Mach3 but I do work off the top of my spoilboard, I set Z0 (zero) on top of my spoilboard as follows I place a sheet of paper on my spoilboard then lower the bit till it touches the paper (use the paper as a feeler gauge). Once I am at the correct height I tell my CAM software Z0, so like you I never cut into my spoilboard. Keep up the great work
Nice, I never thought about setting to the top of the spoil board, I always did what most do, just cut a little extra to make sure it goes thru. BTW, Here is another tip.. use a thin piece of paper between the cutter bit and the spoil-board surface. When the paper is stuck and can't be moved then the cutter is too deep, I raise the cutter bit very slightly until I feel the paper can be moved again but is not too loose. This will essentially make the space of your spoil-board and cutter space only the thickness of the paper.
@@cncnutz could you please do a revisit to episode 51,how not to spoil your spoilboard please. Been seven years and not sure if you can still do the same. Maybe just me. Love your videos. Tim
Thanks Klaus, If you take a look at episodes 202 to 205 I expand on the concept and add a custom touch off plate macro that makes it even easier. Cheers Peter
Now I get it for the top pockets... thanks Peter. i was always worried about precise depth of my pockets but now setting the toolpath as a seperate tool I can get it right every time with a seperate tool change..
Great tip. I have been doing as you say "cut deeper". Looks like you may also have the advantage of not needing to add holding tabs. Looking forward to trying this. Cheers - BillT
Hi Bill, If you set the cutter fractionally above the table top when you are setting the Z, it will leave a thin skin of material and hold the pieces in place. In the video I cut all the way through but I am using an down cutting spiral bit which packs the cut with chips and holds everything in place. You need to pick and choose carefully what items you don't use holding tabs with. Small items will generally move and will be damaged if not held properly. Cheers Peter
***** I know I said thanks already, but I just used this for the first time. Made a new jig for a large order, and the final cut left not a touch on the fresh cut spoilboard!!
I have been using your method for a few months now and in the that time havn't added any new marks to my spoilboard. It's become second nature to me now. This is why today I decided to resurface my spoilboard. I saw the Dave Gatton video today where they touched on this subject, and I am a fan of your method. The way I see it, the only sure thing on the CNC machine is the level bed. The material on the bed can vary enough that you either don't cut all the way through or you hit the spoilboard. This way you will always go all the way through and never hurt the spoilboard. Top Tip
+John Revill Thanks John. That's the was I see it as well. Also you have the choice of Zeroing the cutter to the stock surface if you need the pocket to an accurate depth as well. You get the best of both worlds. Cheers Peter
i dont really have a easily replaceable spoil board. my entire machine is attached to it so i have to treat it well. I've never cut into it. and its good practice not too for any machine.
I do not know but I have a sensor and after measuring the tool, the machine knows how high it is above the spoiler board (always the same and much more accurately) instead of measuring it you just enter this height in the material position, why combine so much. As I assume the top height of the sensor I have in the program higher in this way, the spoiler board is planning at Z 0 and I am sure that the height of the sensor is guessed as a fraction of mm. As you wrote the program on the values - Z is assuming that the tool, after measuring, approaches 100mm height so that it is easy to add in the 12mm plate junction, the position of the material is 112mm. The very idea of measuring the machine from Z0 is good but I achieve it with 3 mouse clicks and without looking, aiming etc. and I think that the feel is more accurate than the eye, although after years of work I see parts of mm ...
I always measure my material and use that figure in my design programme. I set my through cut depth a fraction of a millimetre more than that, then with a sheet of cardboard between the work and the spoil board, nothing hits. Working from the top surface of the material makes everything that isn't a through cut much more accurate. And of course every tool change uses the probe finder.
That’s sort of what Peter is doing. If your material measured 12.15mm, you’d type in Z= -12.15. That way any pockets you do will be an accurate depth from the surface but you’d have to set your cut out depth to 12.15mm. He’s just trying to say that is more accurate then going off the top surface that could potentially have a different height due to irregular thickness or clamping. If you wanted to have super accurate pocket depths, you’d have to face the top surface. Most jobs you’d get away with Peters method. The paper idea in someone else’s comment works well, quick and accurate.
Nice. I am going to try that on my next project. But question. If you enter z zero as negative nominal stock thickness what happens to the difference? In your case the 0.4mm ? Sorry I am not getting it. I am using Picsender
Great tip. I think the real answer is to change the control software so that you set both the material surface AND spoil board surface depths with the electronic "puck". The software would then know both (material and spoil board) Z values. Using this method, regardless of your depth of cut, the software would not allow the tool to go deeper than the spoil board surface. Thoughts?
As I see it, Peter is creating a workaround to fool the software when it's really not necessary if you set things up correctly from the get-go. I'm using Vectric software, but I think other cam software programs allow you to choose either the material surface or the machine bed surface. If you simply choose the machine bed for through cuts and the material surface for V carvings or pocket cuts, this workaround should not be necessary. As Peter pointed out you can put a tool change in to prompt you to change Z zero, when you change bits. I write separate g-code files, myself. As to using an electronic puck to set the work surface Z zero or the material for Z0, this is going to affect the depth of your cut. Say for example you shift from a 12 mm to a 18mm work piece, but don't change the number of passes in the g code. Now you're cutting a greater depth per cut in the thicker material, which is probably not what you want. The software manufactures allow us to customize g-code without having to do workarounds. I for example like to set ramp cuts, and do my final pass as a climb cut using .001 for the best finish. Just use the machine bed for through cuts, and the material surface for pocket cuts, v-bits or engravings. You're not using the same bit for both, so easy enough to re-zero when the time comes. As I mentioned in my original post, I think Peter is creating a workaround for something that is unnecessary. Just change your set-up from the start.
Peter: I just found this video and it seems like a solution for me. I just have a couple of questions: After barely making contact with the spoil board and entering the nominal thickness of the material , do you then zero out? After entering the nominal thickness, do you position the cutter on top of the material before starting the run?
+Stephen Romanski Having set the cutter on the spoilboard and entering the negative of the nominal thickness you just then need to lift the cutter above the material surface to ensure you don't crash it into the side of the material when the machine takes off. Once you have done it a couple of times you will get the hang of it. If you have any questions don't hesitate to ask. Cheers Peter
that is great, now I cannot do what you are doing in 4:36 , where you input that distance and it stays... i try doing that , but in changes back to whatever value was there... I don't know what I am doing wrong...??
I suppose this is ok and more ok if you have sufficient height during non cutting moves. Otherwise, if there is a bow the, bit will scrape the top of the material when traversing between cuts. 5mm is probably sufficient. If you have stock that has 5mm tolerance, you should probably find a better supplier.
I'm using cut2d, I picked z zero to bottom of material on the material set up page. on the tool path side what would I put in for start depth and cut depth. Thanks
Sorry I haven't tried that method so don't know. You will have problems when it comes to setting the cutter to the top for accurate pockets depths. You will need to know the exact thickness of the stock when you make the file or you will need to do a bit of maths at the table when setting cutter to the stock surface to take into account the difference between real and nominal thickness. Personally I like to keep things simple and the method I use is the best I can come up with. Cheers Peter
Peter I'm thinking that if you used the probe to set the top of the spoilboard height (for speed) and set the starting point of the cut at the bottom of the material in the cam software then it would achieve the same result??? I've not tried it yet. Any thoughts.
Setting the zero point to the bottom of the stock only transfers the problem from the bottom to the top of the material. Please watch episodes 202 to 205 and it will explain and introduce a new script that will sort everything for you if you use Mach3 or UCCNC ua-cam.com/video/1MHyDKkRN0Q/v-deo.html Cheers Peter
Nice explanation. So actually when we level the roughing, the pocketing and the finishing we need to level the Z to the top of the material and to give it a 0 value while the only time we need to level it to the machine bed and to give it a minus Z value is when we cut the masterpiece we've just made. Correct?
It depends. If you want your pocket to leave a specific thickness with respect to the bottom then you would use the table as the reference and call it negative. If you want a particular depth of pocket then you zero to the top. Likewise all VCarving and engraving is zeroed to the top. You have the basic idea. I did more video on the subject. Checkout episodes 202 & 203 Cheers Peter
Just click on the DRO and type your new value. Press enter and you are done. If the DRO reverts to the previous value you are still in estop. Cheers Peter
I have a question to clear this up in my mind. After setting the bit at the spoil board do I zero it out the add my thickness of material in a negative number. And then run my profile cut? For example my material is .75. Would my starting xyz be 0,0.-75?
It sounds like you have it right. Set your X0, Y0 as per notmal. Take your cutter down to the table surface and enter the negative of the materials nominal thickness. If your file calls for 0.75" stock then when the cutter is on the surface of the table it will be -0.75" It is important to note that it is the thickness you tell your CAM software that determines what value you enter when the cutter is on the surface of the table and not the actual thickness of the stock you are using. For more info on this check out my other video on this subject which should show it more clearly ua-cam.com/video/ZX3DYbkqZko/v-deo.html Cheers Peter
I'm curious, what happens if in the designing program such as Vectric Aspire (what i use), you choose to work off the machine bed instead of the material surface for Z zero? In your final tool paths you set the thickness of the material, plus whatever distance you want above that for clearance. You're also setting the thickness of the material from the get-go in Aspire. This is not going to work for pocket cuts, but for through cuts it seems like it should work fine. I ran through some previews when setting things up this way and it appears to work fine. I guess I was taught, like so many other people, that you zero off the material and not the machine bed. It seems to me you're just compensating for setting things up (in this example) to the material surface, when that's not what you want. Why not just set the program up to do what you want from the get go, instead of creating a workaround for what seems to me like setting things up incorrectly from the start? What am I missing?
As you said, if you set the origin to the tabletop instead of the material surface you won't get accurate pocket depth and VCarving will not work. To get around this you would need to measure every piece of material you use and enter the thickness into Aspire then everything will work as you want but the next time you cut the same thing you will need to remeasure thickness and generate a new file. With the method I use I don't need to worry about material thickness and can still get accurate surface and through cuts with up to 1/8" variance in material thickness. Using the same file. See episodes 125 and 202 - 205 for more information. Cheers Peter
@@cncnutz With the method you show in the video you can't get accurate engravings/pockets, right? As you don't account for material thickness. Setting the top of the spoil board to G54 Z-12 or directly to G54 Z0 does not make a difference in terms of accurate pockets/engravings. In my humble opinion it is best practice to set the spoil board top to G54Z0 and leave it at that for all jobs. No need to change reference for a different file/material thickness.
@@Shu--- You can get accurate pocket depths and engravings because when you are doing these operations you set you cutter to the surface of the material. If you are using the same tool for both operations then you give the tool a different number when you need to change the zero point. this way you get the best of both worlds. This video demonstrated the principle ua-cam.com/video/ZX3DYbkqZko/v-deo.html Cheers Peter
@@cncnutz Peter, thanks for the clarification. That makes sense. I use G92Z0 set to the top of the material if I machine pockets and engravings. That way the spoil board home position is never lost. G92.1 resets the temporary offset.
+Cesar Rullier The Z height is the nominal thickness of the stock. You don't enter the value into CAM as such. The principle is that when cutting through 1" stock your cutter would descend to -1". If you put the cutter on the table top and set it to - 1" then when the cutter is cutting through the stock the cutter will skim the surface. If you checkout episode 125 - CNC Magic it demonstrates the principle on which it is based. Cheers Peter
Couldn't you loosen the collet, let the bit drop to the surface, and then tighten the collet to set the height of the tool at the surface of the table (to save the spoilboard) or work piece (for pockets)? Are there any potential problems with this method? It seems like it would be a quick and accurate method.
+Mark Cole I've done this but some of my bits have collets to set the stickout of the bit at a specific height, which also effects feeds and speeds to some degree. Also even when you can do this trick of dropping it to the surface it is going to be touching the spoil board. From what I can see, I will try this later today, his technique has the bit just a fraction of a hair above the surface, literally just enough to see the light pass between the blade and board which is higher than if it were just dropped onto the board, at least that is my experience.
This idea works an absolute treat. I have been using it for years. Most collet chucks will draw the bit up a half a though or so as you tighten them up. This gives you a perfect Z height to either the table surface or the top of the part being cut if you wish to use that as your datum.
The track is screwed to the bottom board and then a layer the same height is put beside them. The next layer covers the track edges up to the slots so as to make pulling them out impossible.
+CNCnutz (Peter Passuello) yes, i understand that, but the top board , is it screwed to the second board? i don't see any screws on the top, how did u attach the top board?
+Manny Yabar the top board is glued in place. The layer directly on top of the T slots is screwed down but all layers above are glued down. Once the layer is to thin I surface it and glue a new layer on. See my 2 videos on table maintenance for repair techniques. They show the table top repair in preparation for a new surface. Cheer Peter
I am facing a new long term project. I bought 100 board feet of Poplar wood which is over 1 inches tall. Each piece varies in height. I want to place a single board onto the table and plain off one surface so it is flat and will sit with a final height of 1 inch. I figure setting the zero at the table. Next I add my wood but now how do I tell the software to machine off the top of the work and come down to the 1 inch mark? I want my finished piece to be 1 inch thick planed on one side and raw on the other side.
Hi Scott, Here is what I would do. I am assuming you want to will flatten both sides on the CNC. Machine the first side of the board with a pocket to flatten it. Create a pocket file with a depth of cut of 0 Set the cutter to the lowest point on the surface of the board and call that point Z =+ 0.02" or whatever amount you want to skim off the surface. This will flatten the first side and now you can flip the board over. You will use the same pocket file to machine both sides. This time you set the cutter to the surface of the table and tell the machine that this is Z = -1" When the pocket runs again the cutter will rise 1" above the table and flatten the material. Important things to note is that when you thickness the board the cut is not too aggressive. Eg if the board is 1.5" and you flatten it to 1" in a single cut that would be a bit much to do in 1 pass. In this case I would take 1/8th off when I flattened the first side and then the last 1/8th on the 2nd side. In this case the first side Z would be set to z = +0.125" when set on the surface of stock and for the 2nd side set the cutter to the tabletop and set Z to Z = -1" to remove the last 1/8th. Let me know if you have any questions and I can make a video on it. Cheers Peter
+CNCnutz (Peter Passuello) By the way Scott. Make sure you understand what I am saying in my reply or you could duce your cutter 1" through your spoilboard before you know what you have done or could even hope to stop it. Practice with a non spinning cutter on an air cut. Another possibility is depending on the software you are making the toolpath with you can set some of them to have the table top as the zero point and I think you set the pocket depth to 1". I haven't tried this and will have to test it to confirm. I personally prefer my method for uniformity and then I know where I an at all times. Cheers Peter
a much easier way than this is to use ,say ,an known height; 1" (or whatever) block, jog below 1" and then just slow jog up until the block slides under. set the tool height to 1" at that point. No squinting,no guessing. PLUS no danger of plunging into the spoil board. OR the block, because you are never plunging toward a solid object.
Good trick, i coincidentally started doing this myself a couple weeks ago after getting sick of doing larger through cuts to compensate for material thickness difference, bowing, etc. Only question I have is why you don't use the auto zero for z when setting to the table height... that seems a better way to go.
+blah I haven't installed an auto zero tool setter on my machine and am happy doing it manually. I am also trying to show others how to use these tricks and assume that they don't all have these add-ons. If they do and they understand the method then they can use it in conjunction with their auto zero . If I simply make a video showing I push this button and it all works by magic then people don't learn and ignore the message. This is why I use the minimum of tech on my machine and I find I don't really need it. Don't know if that is really an excuse but I will use it. 😁 Thanks for watching blah. Cheers Peter
Yeah for the video that all makes sense, I think your comment that you haven't used the auto-zero in months is what struck me as odd, since the combination of using the bed z-depth plus auto zero seems like the best option. It seems that you're saying it's better not to use the auto-z and instead eyeball it.
Hi Peter Excellent video and I really like the idea of setting the z axis to the spoil board. Trouble is, I can’t get it to work, when I set the z to say -12 I am then unable to lift the z up so that it clears the work piece. Am I missing something? (A brain perhaps🧠 )
Hi Steve If you mean that when you set it to -12mm and then lift the cutter to 0, the cutter is still below the material surface, it means that the material is thicker than 12mm. Cheers Peter
Why not just set all your tool heights to 0 out on the spoilboard and then the cam software having the origin on the spoilboard rather than the top of the plywood? same result, right?
If you do that Brian then you have the same problem but this time it will be at the top of the board. For a better explaination have a look at this videos. Cheers Peter
complacently disagree, the bottom edge of the parts in the video has poor quality. Cut through your part a few thousand into your spoil board. Resurface your spoil-board weekly takes me about 15 minutes on my 5'x12' table, replace it monthly, for $35 per 4x8. Save a lot of time in cleaning up edges of your parts. Well that how pros do it maybe not for hobbyist. Yes do reference your tool of your table. Its called a spoil board for a reason, and it made out of cheep materiel for a reason
Thanks Denny In a commercial environment where time is money if cutting into the spoilboard a few thou saves time with clean up then it makes sense. Maybe the use of a compression bit would improve the bottom of my cut. I tend to use downcut these days so the bottom will be worse than the top. I also get my moneys worth out of my cutters so it might be a little dull. I have the time to spend on clean of up as well if needed. Cheers Peter
Thanks Peter. After reading some of the comments there are obviously some people who cannot set a negative Z value in the controller (eg LinuxCNC). I think the workaround is to zero the Z axis with the tool on the spoil board, then MANUALLY MOVE Z UP BY THE THICKNESS OF THE STOCK or DEPTH OF CUT THAT YOU SPECIFY IN THE CAM program, then ZERO THE Z AXIS AGAIN, then move the tool up out of the way while you lay down the stock.
So to cut out the part (not a pocket), the CAM job will go down to the bottom of the specified stock depth but will never go any lower into your spoil board. Example: your stock measures approximately 12.2 mm so in your CAD software you set the stock thickness or max cut depth to 12 and because your Z zero is exactly 12 mm ABOVE the spoil board, you are ignoring the variations in the actual thickness of the stock and the tool will cut to Z-12 and just touch the spoil board. Of course you will also need to set your Z clearance height to allow for the highest peaks in the stock.
For accurate pocketing you should reset the Z zero to the exact top surface of the stock and, assuming that the stock is flat, the pocket depth will be whatever you specified in the CAM package.
I've recently started using the excellent Estlcam for toolpaths and usually add a few small holding tabs when cutting out very small parts. It's annoying when you've spent thirty minutes engraving something, only to see it chewed up and flying across the room. Thanks again for the tips.
I have found a way that guarantees not spoiling your board. My SB is 3mm thick, MDF material. I have a vacuum bed also. I place a 6mm mdf same size as SB. Using the software, not the cnc own surfacing method, I hatch fill the entire board 1mm leaving 5mm as a result. Leave this board on the machine as it is now your SB. Say my next cut job is 3mm. In the software I input 8mm thickness and input my thru cut as 3mm (like normal inputting). As a result, 5mm is left at the bottom. That 5mm is actually what has been surfaced so my cutting is thru perfectly and not even scratching the new SB. The trick is to ALWAYS add 5mm to your stock but input as usual. My cnc when cutting displays what is left at the bottom, so it will always show 5mm and I know the cut is thru. Your vacuum has to be in good order too to have success. Good luck, all.
Thank you! I was wondering if something like this could be done. And now I know.
Thank you for sharing your work methods. I installed a new spoilboard and did my first project zeroing on the spoilboard then setting the Z to minus my stock thickness in the CAD software and voilà A perfectly cut through project with an unspoiled spoilboard. Very happy!
Excellent. Glad it worked for you.
Cheers
Peter
WOW!! Which I would had seen this video many a spoiler boards ago. What a great "common sense" idea. Implemented your approach and there were no cuts on the spoiler board after milling. THANKS, Mike
+Mike Falkner
Great to hear Mike. Once you start using this method you never go back.
Cheers
Peter
OK, I will have to work on that as well. Lots to learn.
Thanks
Scott
Thanks for the great tip Peter. I sure appreciate you sharing your knowledge.
No worries. Glad you find it useful.
Cheers
Peter
That the best way to save spoilboard as much as you can ..i use this method for more than 7 years ....so happy to watch the video ...
+Osama Mohammed
I couldn't agree more.
I don't use Mach3 but I do work off the top of my spoilboard, I set Z0 (zero) on top of my spoilboard as follows I place a sheet of paper on my spoilboard then lower the bit till it touches the paper (use the paper as a feeler gauge). Once I am at the correct height I tell my CAM software Z0, so like you I never cut into my spoilboard.
Keep up the great work
Nice, I never thought about setting to the top of the spoil board, I always did what most do, just cut a little extra to make sure it goes thru.
BTW, Here is another tip.. use a thin piece of paper between the cutter bit and the spoil-board surface. When the paper is stuck and can't be moved then the cutter is too deep, I raise the cutter bit very slightly until I feel the paper can be moved again but is not too loose. This will essentially make the space of your spoil-board and cutter space only the thickness of the paper.
Peter,
Thanks so much for this info, as always it's clear and informative. Love your channel and all the good info.
Thanks again and God Bless.
Thanks jer428
@@cncnutz could you please do a revisit to episode 51,how not to spoil your spoilboard please. Been seven years and not sure if you can still do the same. Maybe just me.
Love your videos.
Tim
Great that is one of the best Tips I have seen for a looooong time, thanks for that!
Thanks Klaus,
If you take a look at episodes 202 to 205 I expand on the concept and add a custom touch off plate macro that makes it even easier.
Cheers
Peter
ok thanks I will have a look :)
Thanks for the video and logic.
thanks for the video series and keep up the good work. Cheers Gerald
Thanks. I will use this going forward. Tired of replacing my spool board.
Great tip Peter
I use a piece of paper to slide under the cutter as a feeler gauge to know when the cutter has reached the table top.
As always you give us some great tips.
Thanks Dean
Now I get it for the top pockets... thanks Peter. i was always worried about precise depth of my pockets but now setting the toolpath as a seperate tool I can get it right every time with a seperate tool change..
You got it Andre.
I demonstrated it in my CNC magic video.
ua-cam.com/video/ZX3DYbkqZko/v-deo.html
Cheers
Peter
Why didn't I think of that? Brilliant!
Wow, many thanks. It's a very great vidéo and great explanation. Fully clear now.
+JFAirplane
Good one, glad it sorts it out for you. Also see my CNC magic video which shows a little trick you can use with this method.
Cheers
Peter
You sir are a busy man....lol. You do plenty of cutting :D
Great tip. I have been doing as you say "cut deeper". Looks like you may also have the advantage of not needing to add holding tabs. Looking forward to trying this. Cheers - BillT
Hi Bill,
If you set the cutter fractionally above the table top when you are setting the Z, it will leave a thin skin of material and hold the pieces in place. In the video I cut all the way through but I am using an down cutting spiral bit which packs the cut with chips and holds everything in place. You need to pick and choose carefully what items you don't use holding tabs with. Small items will generally move and will be damaged if not held properly.
Cheers
Peter
Such a great idea.
+Mark K
Thanks Mark
Very good tip. Thanks for sharing!!
Glad it helps Rusty.
***** I know I said thanks already, but I just used this for the first time. Made a new jig for a large order, and the final cut left not a touch on the fresh cut spoilboard!!
Excellent, Glad the method worked so well for you. Thanks for the feedback.
Cheers
Peter
I have been using your method for a few months now and in the that time havn't added any new marks to my spoilboard. It's become second nature to me now. This is why today I decided to resurface my spoilboard. I saw the Dave Gatton video today where they touched on this subject, and I am a fan of your method. The way I see it, the only sure thing on the CNC machine is the level bed. The material on the bed can vary enough that you either don't cut all the way through or you hit the spoilboard. This way you will always go all the way through and never hurt the spoilboard. Top Tip
+John Revill
Thanks John. That's the was I see it as well. Also you have the choice of Zeroing the cutter to the stock surface if you need the pocket to an accurate depth as well. You get the best of both worlds.
Cheers
Peter
i dont really have a easily replaceable spoil board. my entire machine is attached to it so i have to treat it well.
I've never cut into it. and its good practice not too for any machine.
Currently just using a disposable spoilboard for now, I’m moving in a month or so so I’ll be making a proper spoil board then and doing this.
Anyone have good thoughts on a single or slats spoil board
I do not know but I have a sensor and after measuring the tool, the machine knows how high it is above the spoiler board (always the same and much more accurately) instead of measuring it you just enter this height in the material position, why combine so much.
As I assume the top height of the sensor I have in the program higher in this way, the spoiler board is planning at Z 0 and I am sure that the height of the sensor is guessed as a fraction of mm.
As you wrote the program on the values - Z is assuming that the tool, after measuring, approaches 100mm height so that it is easy to add in the 12mm plate junction, the position of the material is 112mm.
The very idea of measuring the machine from Z0 is good but I achieve it with 3 mouse clicks and without looking, aiming etc. and I think that the feel is more accurate than the eye, although after years of work I see parts of mm ...
Hi again, it worked! Thanks a lot.... those easter eggs, you sell those?
I always measure my material and use that figure in my design programme. I set my through cut depth a fraction of a millimetre more than that, then with a sheet of cardboard between the work and the spoil board, nothing hits. Working from the top surface of the material makes everything that isn't a through cut much more accurate. And of course every tool change uses the probe finder.
That’s sort of what Peter is doing. If your material measured 12.15mm, you’d type in Z= -12.15. That way any pockets you do will be an accurate depth from the surface but you’d have to set your cut out depth to 12.15mm. He’s just trying to say that is more accurate then going off the top surface that could potentially have a different height due to irregular thickness or clamping. If you wanted to have super accurate pocket depths, you’d have to face the top surface. Most jobs you’d get away with Peters method. The paper idea in someone else’s comment works well, quick and accurate.
Nice. I am going to try that on my next project. But question. If you enter z zero as negative nominal stock thickness what happens to the difference? In your case the 0.4mm ? Sorry I am not getting it. I am using Picsender
Great tip. I think the real answer is to change the control software so that you set both the material surface AND spoil board surface depths with the electronic "puck". The software would then know both (material and spoil board) Z values. Using this method, regardless of your depth of cut, the software would not allow the tool to go deeper than the spoil board surface. Thoughts?
As I see it, Peter is creating a workaround to fool the software when it's really not necessary if you set things up correctly from the get-go.
I'm using Vectric software, but I think other cam software programs allow you to choose either the material surface or the machine bed surface.
If you simply choose the machine bed for through cuts and the material surface for V carvings or pocket cuts, this workaround should not be necessary.
As Peter pointed out you can put a tool change in to prompt you to change Z zero, when you change bits. I write separate g-code files, myself.
As to using an electronic puck to set the work surface Z zero or the material for Z0, this is going to affect the depth of your cut. Say for example you shift from a 12 mm to a 18mm work piece, but don't change the number of passes in the g code. Now you're cutting a greater depth per cut in the thicker material, which is probably not what you want.
The software manufactures allow us to customize g-code without having to do workarounds. I for example like to set ramp cuts, and do my final pass as a climb cut using .001 for the best finish.
Just use the machine bed for through cuts, and the material surface for pocket cuts, v-bits or engravings. You're not using the same bit for both, so easy enough to re-zero when the time comes.
As I mentioned in my original post, I think Peter is creating a workaround for something that is unnecessary. Just change your set-up from the start.
Thanks !!!!
Glad it helps Stephen.
Cheers
Peter
Peter: I just found this video and it seems like a solution for me. I just have a couple of questions:
After barely making contact with the spoil board and entering the nominal thickness of the material , do you then zero out?
After entering the nominal thickness, do you position the cutter on top of the material before starting the run?
+Stephen Romanski
Having set the cutter on the spoilboard and entering the negative of the nominal thickness you just then need to lift the cutter above the material surface to ensure you don't crash it into the side of the material when the machine takes off. Once you have done it a couple of times you will get the hang of it.
If you have any questions don't hesitate to ask.
Cheers
Peter
that is great, now I cannot do what you are doing in 4:36 , where you input that distance and it stays... i try doing that , but in changes back to whatever value was there... I don't know what I am doing wrong...??
hey! Great tip..
but in my case, can i do this with a DSP handle control?
+Mohsen Emad
I don't have one myself but I don't see why not.
I'll give it a go!
thanksss
great advice...woooo hoooo....!
I suppose this is ok and more ok if you have sufficient height during non cutting moves. Otherwise, if there is a bow the, bit will scrape the top of the material when traversing between cuts. 5mm is probably sufficient. If you have stock that has 5mm tolerance, you should probably find a better supplier.
I'm using cut2d, I picked z zero to bottom of material on the material set up page. on the tool path side what would I put in for start depth and cut depth. Thanks
Sorry I haven't tried that method so don't know. You will have problems when it comes to setting the cutter to the top for accurate pockets depths. You will need to know the exact thickness of the stock when you make the file or you will need to do a bit of maths at the table when setting cutter to the stock surface to take into account the difference between real and nominal thickness. Personally I like to keep things simple and the method I use is the best I can come up with.
Cheers
Peter
Peter I'm thinking that if you used the probe to set the top of the spoilboard height (for speed) and set the starting point of the cut at the bottom of the material in the cam software then it would achieve the same result???
I've not tried it yet. Any thoughts.
Setting the zero point to the bottom of the stock only transfers the problem from the bottom to the top of the material.
Please watch episodes 202 to 205 and it will explain and introduce a new script that will sort everything for you if you use Mach3 or UCCNC
ua-cam.com/video/1MHyDKkRN0Q/v-deo.html
Cheers
Peter
OMG This is funny!!!
Nice explanation. So actually when we level the roughing, the pocketing and the finishing we need to level the Z to the top of the material and to give it a 0 value while the only time we need to level it to the machine bed and to give it a minus Z value is when we cut the masterpiece we've just made. Correct?
It depends. If you want your pocket to leave a specific thickness with respect to the bottom then you would use the table as the reference and call it negative. If you want a particular depth of pocket then you zero to the top. Likewise all VCarving and engraving is zeroed to the top. You have the basic idea. I did more video on the subject. Checkout episodes 202 & 203
Cheers Peter
how to do you manually enter the z axis information into mach3?
Just click on the DRO and type your new value. Press enter and you are done. If the DRO reverts to the previous value you are still in estop.
Cheers
Peter
I have a question to clear this up in my mind. After setting the bit at the spoil board do I zero it out the add my thickness of material in a negative number. And then run my profile cut?
For example my material is .75. Would my starting xyz be 0,0.-75?
It sounds like you have it right.
Set your X0, Y0 as per notmal.
Take your cutter down to the table surface and enter the negative of the materials nominal thickness. If your file calls for 0.75" stock then when the cutter is on the surface of the table it will be -0.75"
It is important to note that it is the thickness you tell your CAM software that determines what value you enter when the cutter is on the surface of the table and not the actual thickness of the stock you are using.
For more info on this check out my other video on this subject which should show it more clearly
ua-cam.com/video/ZX3DYbkqZko/v-deo.html
Cheers
Peter
CNCnutz (Peter Passuello) Peter do you set zero to the top of the material or the bottom in V carve pro?
+rchavez 505
I use the top of the material in VCarve Pro
CNCnutz (Peter Passuello) Thanks for the reply Peter. I will have to try it.
I'm curious, what happens if in the designing program such as Vectric Aspire (what i use), you choose to work off the machine bed instead of the material surface for Z zero? In your final tool paths you set the thickness of the material, plus whatever distance you want above that for clearance. You're also setting the thickness of the material from the get-go in Aspire. This is not going to work for pocket cuts, but for through cuts it seems like it should work fine. I ran through some previews when setting things up this way and it appears to work fine.
I guess I was taught, like so many other people, that you zero off the material and not the machine bed.
It seems to me you're just compensating for setting things up (in this example) to the material surface, when that's not what you want. Why not just set the program up to do what you want from the get go, instead of creating a workaround for what seems to me like setting things up incorrectly from the start?
What am I missing?
As you said, if you set the origin to the tabletop instead of the material surface you won't get accurate pocket depth and VCarving will not work. To get around this you would need to measure every piece of material you use and enter the thickness into Aspire then everything will work as you want but the next time you cut the same thing you will need to remeasure thickness and generate a new file. With the method I use I don't need to worry about material thickness and can still get accurate surface and through cuts with up to 1/8" variance in material thickness. Using the same file.
See episodes 125 and 202 - 205 for more information.
Cheers
Peter
@@cncnutz With the method you show in the video you can't get accurate engravings/pockets, right? As you don't account for material thickness. Setting the top of the spoil board to G54 Z-12 or directly to G54 Z0 does not make a difference in terms of accurate pockets/engravings. In my humble opinion it is best practice to set the spoil board top to G54Z0 and leave it at that for all jobs. No need to change reference for a different file/material thickness.
@@Shu--- You can get accurate pocket depths and engravings because when you are doing these operations you set you cutter to the surface of the material.
If you are using the same tool for both operations then you give the tool a different number when you need to change the zero point. this way you get the best of both worlds.
This video demonstrated the principle ua-cam.com/video/ZX3DYbkqZko/v-deo.html
Cheers Peter
@@cncnutz Peter, thanks for the clarification. That makes sense. I use G92Z0 set to the top of the material if I machine pockets and engravings. That way the spoil board home position is never lost. G92.1 resets the temporary offset.
I have a question. With this method, where is you Z height defined from in your CAM software?
+Cesar Rullier
The Z height is the nominal thickness of the stock. You don't enter the value into CAM as such. The principle is that when cutting through 1" stock your cutter would descend to
-1". If you put the cutter on the table top and set it to - 1" then when the cutter is cutting through the stock the cutter will skim the surface.
If you checkout episode 125 - CNC Magic it demonstrates the principle on which it is based.
Cheers
Peter
Thanks, I think I understand the idea.
Couldn't you loosen the collet, let the bit drop to the surface, and then tighten the collet to set the height of the tool at the surface of the table (to save the spoilboard) or work piece (for pockets)? Are there any potential problems with this method? It seems like it would be a quick and accurate method.
+Mark Cole I've done this but some of my bits have collets to set the stickout of the bit at a specific height, which also effects feeds and speeds to some degree. Also even when you can do this trick of dropping it to the surface it is going to be touching the spoil board. From what I can see, I will try this later today, his technique has the bit just a fraction of a hair above the surface, literally just enough to see the light pass between the blade and board which is higher than if it were just dropped onto the board, at least that is my experience.
This idea works an absolute treat. I have been using it for years. Most collet chucks will draw the bit up a half a though or so as you tighten them up. This gives you a perfect Z height to either the table surface or the top of the part being cut if you wish to use that as your datum.
Hey Peter, the 2 boards that are above the bottom board with the t tracks, are screwed to the bottom board?
The track is screwed to the bottom board and then a layer the same height is put beside them. The next layer covers the track edges up to the slots so as to make pulling them out impossible.
+CNCnutz (Peter Passuello) yes, i understand that, but the top board , is it screwed to the second board? i don't see any screws on the top, how did u attach the top board?
+Manny Yabar the top board is glued in place. The layer directly on top of the T slots is screwed down but all layers above are glued down. Once the layer is to thin I surface it and glue a new layer on. See my 2 videos on table maintenance for repair techniques. They show the table top repair in preparation for a new surface.
Cheer
Peter
I am facing a new long term project. I bought 100 board feet of Poplar wood which is over 1 inches tall. Each piece varies in height. I want to place a single board onto the table and plain off one surface so it is flat and will sit with a final height of 1 inch. I figure setting the zero at the table. Next I add my wood but now how do I tell the software to machine off the top of the work and come down to the 1 inch mark? I want my finished piece to be 1 inch thick planed on one side and raw on the other side.
Hi Scott,
Here is what I would do. I am assuming you want to will flatten both sides on the CNC.
Machine the first side of the board with a pocket to flatten it. Create a pocket file with a depth of cut of 0
Set the cutter to the lowest point on the surface of the board and call that point Z =+ 0.02" or whatever amount you want to skim off the surface.
This will flatten the first side and now you can flip the board over.
You will use the same pocket file to machine both sides.
This time you set the cutter to the surface of the table and tell the machine that this is Z = -1"
When the pocket runs again the cutter will rise 1" above the table and flatten the material.
Important things to note is that when you thickness the board the cut is not too aggressive. Eg if the board is 1.5" and you flatten it to 1" in a single cut that would be a bit much to do in 1 pass.
In this case I would take 1/8th off when I flattened the first side and then the last 1/8th on the 2nd side.
In this case the first side Z would be set to z = +0.125" when set on the surface of stock and for the 2nd side set the cutter to the tabletop and set Z to Z = -1" to remove the last 1/8th.
Let me know if you have any questions and I can make a video on it.
Cheers
Peter
+CNCnutz (Peter Passuello)
By the way Scott. Make sure you understand what I am saying in my reply or you could duce your cutter 1" through your spoilboard before you know what you have done or could even hope to stop it. Practice with a non spinning cutter on an air cut.
Another possibility is depending on the software you are making the toolpath with you can set some of them to have the table top as the zero point and I think you set the pocket depth to 1". I haven't tried this and will have to test it to confirm. I personally prefer my method for uniformity and then I know where I an at all times.
Cheers
Peter
a much easier way than this is to use ,say ,an known height; 1" (or whatever) block, jog below 1" and then just slow jog up until the block slides under. set the tool height to 1" at that point. No squinting,no guessing. PLUS no danger of plunging into the spoil board. OR the block, because you are never plunging toward a solid object.
I've progressed now to a touch off plate with a custom auto zero script to account for offset. How times have changed.
Cheers
Peter
that's good, I posted so that newbies who might see the original tip, might be made aware of better/safer/easier methods.
Good trick, i coincidentally started doing this myself a couple weeks ago after getting sick of doing larger through cuts to compensate for material thickness difference, bowing, etc.
Only question I have is why you don't use the auto zero for z when setting to the table height... that seems a better way to go.
+blah
I haven't installed an auto zero tool setter on my machine and am happy doing it manually. I am also trying to show others how to use these tricks and assume that they don't all have these add-ons. If they do and they understand the method then they can use it in conjunction with their auto zero . If I simply make a video showing I push this button and it all works by magic then people don't learn and ignore the message. This is why I use the minimum of tech on my machine and I find I don't really need it. Don't know if that is really an excuse but I will use it. 😁
Thanks for watching blah.
Cheers
Peter
Yeah for the video that all makes sense, I think your comment that you haven't used the auto-zero in months is what struck me as odd, since the combination of using the bed z-depth plus auto zero seems like the best option. It seems that you're saying it's better not to use the auto-z and instead eyeball it.
Hi Peter
Excellent video and I really like the idea of setting the z axis to the spoil board. Trouble is, I can’t get it to work, when I set the z to say -12 I am then unable to lift the z up so that it clears the work piece. Am I missing something? (A brain perhaps🧠 )
Hi Steve
If you mean that when you set it to -12mm and then lift the cutter to 0, the cutter is still below the material surface, it means that the material is thicker than 12mm.
Cheers Peter
Why not just set all your tool heights to 0 out on the spoilboard and then the cam software having the origin on the spoilboard rather than the top of the plywood? same result, right?
If you do that Brian then you have the same problem but this time it will be at the top of the board.
For a better explaination have a look at this videos.
Cheers
Peter
complacently disagree, the bottom edge of the parts in the video has poor quality. Cut through your part a few thousand into your spoil board. Resurface your spoil-board weekly takes me about 15 minutes on my 5'x12' table, replace it monthly, for $35 per 4x8. Save a lot of time in cleaning up edges of your parts. Well that how pros do it maybe not for hobbyist. Yes do reference your tool of your table. Its called a spoil board for a reason, and it made out of cheep materiel for a reason
Thanks Denny
In a commercial environment where time is money if cutting into the spoilboard a few thou saves time with clean up then it makes sense. Maybe the use of a compression bit would improve the bottom of my cut. I tend to use downcut these days so the bottom will be worse than the top. I also get my moneys worth out of my cutters so it might be a little dull. I have the time to spend on clean of up as well if needed.
Cheers
Peter