RDWorks Learning Lab 242 Beam Setting The 4th Corner Problem Revisited
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- Опубліковано 24 лис 2024
- The "4th Corner Problem" is an issue that almost everyone will encounter when they set their beam. Very few have fully understood the cause and even less have fixed it by logic . Mitigating the problem with screw twiddling is the normal approach. It took me a long time to decode but like everthing else that's difficult to fathom, a simple exagerated diagram helped keep conflicting intuitive ideas at bay and revealed the simple logical facts creatingh the problem . When you understand the problem the sol ution jumps out at you.
Hey Russ, thanks for yet another quality video!
With that in mind, I would like to point out that for DIY machines, it can definitely, 110% be axis that are not co-planar, and shims are in fact the answer. I had been fooling around with the issue for more than a year, and no matter what I tried, including some of your previous videos, there was nothing I could do to get the 4th corner to align.
The solution? A $60 360 degree line laser. Aligning that with the first 3 corners, I could then clearly and undeniably see that the 4th corner was out of the plane by several millimeters. Shimming that axis brought the 4th corner into the same plane as the other 3, and I was able to align the whole system in less than 5 minutes.
For manufactured machines it's unlikely for there to be such a mechanical error like you say, but I wanted to make sure folks don't dismiss it entirely seeing as there's a sizable crowd building their own machines. As I believe most of that crowd to be viewers of your excellent videos, I thought a heads-up wouldn't be out of order.
Once again, thanks for your continued efforts in the laser scene, it's really helpful!
Hi
I appreciate the reminder that not all folks just buy a factory built lase and that significant variations form a flat mechanical plane MAY have an effect. I say MAY because logically it shouldn't. If you consider the mechanics of the problem you will see that because mirror 2 and the head are pernanatly aligned to each other, (via the gantry) , if you push the head fully right, it will follow the ups and downs of your skewed rail. As the head moves up and down it will cause the gantry to rise and fall at the right end also, but at ALL times mirror 2 will reflect onto the head with no change because the mirror tips with the gantry..
However, I agree with your laser method to set your base frame pretty true before you start alighning the beam because if you are working with skewed Y rails there will be a "hill" in the middle of your mechanical plane and that means it will be almost impossible to set your nozzle to a uniform gap at all points on your table. The advantage of a factrory built machine is the rigid welded fame and case with box sides that prevent twist. DIY machines tend to be bolted together aluminium sections.. That method provides a simple manufacturing technique but in relation to a welded steel frame its a piece of jelly that can be inflenced by external features like floor flatness. So if you are building such a frame, either add diagonal braces to each square frame in the structure , or bolt on panels that will achieve the same sort of cross bracing rigidity to the frame.
Thanks again for the comment because self builder may overlook these detail structual issues.
Best wishes
Russ
@@SarbarMultimedia thanks for the reply!
While I agree that the second mirror should tilt with a rise and fall of the gantry, and thus keep the beam spot-on on the head, that can only be true if the fulcrum of the gantry exactly coincides with the spot where the beam hits the second mirror. If this is not the case, tilting the gantry would lever the second mirror out of position, and also change the relative angle to #1, would it not? And while it may not deviate by much, the mechanica shift, along with the change in angle can be enough to cause a detrimental defect over a longer span, like the relatively long x-axis.
So, while one may luck out and have the second mirror accidentally correct for the gantry not being coplanar, I would not rely on that, considering all the frustrations it can cause when the thing doesn't line up. I've spent countless hours trying to align the damn thing before finally purchasing the 360 laser and getting the head mechanically coplanar in the four corners. That fixed years of struggling and frustrations. Hoping these comments can spare others the same misery :)
Once again, thank you for your contributions to the laser scene. It's always intriguing to be pushed to think more thoroughly about issues like these!
I had this problem for so long! Thank you! I can finally understand what I did wrong!
Ill try this one tomorrow, but at the same time I can attest to the fact that machine currently in my hands, which I've been asked to fix - the base/gantry is not square in any shape or form, and part of the problem is still fixed by shims. Sometimes the metal is too thin and even bows out. Sometimes it's a problem with Y axis rod, where you do not shim the rod, but loosen and move your rod a little and then tighten it. Sometimes its the dragchain pushing on the 2nd mirror bracket when its sitting in a corner (but then this misalighnment is not linear) .
This machine I'm currently having problems with - it's gantry is bolted to the base not in the corners but more to the middle, so shimmiying that is almost unhelpful, unless you drill new holes to fix gantry to the base in the exact corners.
I really hope this new method helps, because I'm dead tired of this cheapo machine, and I cannot give it back in it's current state.
Hi Oleg
Putting this problem into words and diagrams,( up to now it's been an image in my brain) has made me realize there may be a simpler way to set a machine that integrates the 4th corner as part of the process.. see video 244
If you are still stuck after watching and testing video 244 then contact ee privately with this link and we can speak by email and you can send me some pictures.
forms.zohopublic.eu/ndeavorlimited/form/K40XtreeemLaserCutterContactRussSadler/formperma/k2Cn0QN5ChpazfTMAUw25lZ-FKpjZa96TQWHjv3ntOg
Best wishes
Russ
Lol. I had been meaning to message you on this. Upper right corner is always low. Suspected it is the tube alignment slightly off.
Your diagram is helpful.
Laser alignment is one of them things.. you either get lucky and still don't understand it or you are able to understand it.
I always feel sorry for new owners that are told to twist this and adjust that. By someone that can't see the full story.
I do wonder though.. how do the laser manufactures set up the mirrors. They have to have a quick method.
Thank you russ for another video.
Well on my K40, when it arrived the mirrors were so far out of alignment that on my first check it burned a hole in the wall on the other side of the workshop! (good thing I was standing behind the machine and no one else was in the room at the time)
@@zebo-the-fat
Yup I done that. Burns the paint on the inside of machine. :(
Nice, I only had a small error at the 4th corner (about 2mm) couldn't fix it by adjusting mirror 2 (as far as I could see mirror 1 was correct) this makes sense though, so I'm off to play with it again!
OK, you win! adjusted mirror 1 a tiny fraction, now everything is perfect! Thanks for the information
Thanks for this video, however; I haven't found your first video on setting up the mirrors for proper alignment, or did you make one? I've done one in the past 4 months, but I still would like to see yours.
Hi Phillip
Yes I did a videoo that explains the iteration process of setting mirrors . It can never be a single adjustment process as many videos would have you believe. have spent many years setting and unsetting the beam on my machines. Practice makes perfect and I have developed several modifications to my machine that allows perfect beam alignment. See this video.
ua-cam.com/video/6aNwKhTRnd8/v-deo.html.
Bedst wishes
Russ
@@SarbarMultimedia Thanks Russ. I'll check it out tomorrow. Love the videos BTW.
Hi Russ. The issue I’m having is that adjusting M1 in the far upper right makes the bottom right drift then inline it up and go back to upper right and it’s off again. I’m not understanding how to dial it in
You can think of this method as getting an extra X axis length of distance to see any deviation. That means you can see a smaller error angle in mirror 1. Could this be applied to mirror 2? After doing a rough alignment, would it help to make your burn marks on paper in your lens 3 alignment jig? You would get an extra 4-6" of length to see error; and you can align mirror 2, mirror 3, and center the beam down the lens without changing jigs. You could even make a longer lens 3 jig for more precision of both lens 2 & 3. Just a thought, it might not be worth it.
Yes, there is some strange logic here that would probably work BUT to get to the mirror 3 jig, the beam has to be set aprox correct for Y and X so that the beam hits mirror 3. anyway. In which case why bother . Just adopt the 2 step correction procedure I describe. . In fact thinking further about this you have possibly stimulated my thinking juices to create a whole new beam setting strategy which involves setting Xand Y accurately before starting to calibrate the Z axis....... Watch this space for future videos.
Best wishes
Russ
Поставлю лайк. Дед дело говорит.
I proceeded exactly as in the video and actually hit the same point in all 4 corners. If I move the laser head but at the end of the Y-Axis in the middle of the X-axis, I have a displacement of the spot to the bottom right by about 2mm. How can that be? Kind regards Marco
Hi Marco
That's an illogical issue and not one I have encountered. If all the corners are correct it means you have set your beam to a perfectly flat plane that matches the plane of head travel. Mirror number two is the usual problem mirror because it takes a nice straight beam from mirror 1 and "bends" it in the middle to point it at mirror 3 . By using the extreme corners of the table and setting mirror 2 last removes its sensitivity. . I am racking my brains to visualize how your observation is even possible.. One thought that I have encountered with another correspondents machine (I wont explainat present) Can you test the corners are still coincident but at 50mm away from the back and front ie dont send the Y axis to extreme positions.
Best wishes
Russ
impression almost everyone does their soft in soft soft but record their voice in ProTools. Not sure why. Would like learning how to do
Hello sir,
I am fixing the 4th corner problem, however the 4th corner problem moves to the forward left corner. How should i approach this? By going in circles until i get everything flat? Thanks for the videos. Very helpful 🤝🏼🙏🏼
Ihave demonstarted a completelyy different method to that usually advocated b the Chinese and everyone that speaks of beam alignment, See this more recent video as it should help to solve your problem
ua-cam.com/video/tvNfAg-cOLA/v-deo.html
Best wishes Russ
@@SarbarMultimedia the video doesn’t show which mirror you adjust when checking the front left corner. This is where i am stuck now. I have all corners on point except for front left. With which mirror do i continue here for adjusting?
@@100.t0n did you manage to fix this? I have the same problem. Part of me thinks it has something to do with the frame or gantry not being level.
On my machine I fixed this problem by tensioning Y axis belt.
I am geuinely pleased to hear that you fixed it because it is a very annoying problem but I can only imagine it was luck and not logic. I have never touched my Y belt tension on any of my machines and I still get a 4th corner problem. However, this explanation of the 4th corner problem made me think again about the whole orthodox setting routine we all have been taught/. Is it really that logical? I am planning another video to test my idea. So keep watching........and no Y belts involved.
Best wishes
Russ
ps I admit to trying a lot more than Y belt tension to try fix the problem by trial and error and I never really suceded until I sat down and logically disected the problem. So there is no intended crircism of your lucky fix.
@@SarbarMultimedia My machine is a little bit different than yours (red/black 80w). When I tension y axis belt mirror two moves towards mirror one and that changes beam path. You are right, it was luck but now it is very logical.
@@radionica42
Hi
I also have a machine that is exactly the same design as yourr red and black machine and for months I was fixated that somehow the #2 mirror was being influenced to rotate fractionally between front and back positions. Well, it seemed logical at the time!!!!
When i try this, the problem will move from 4 to corner 1. Can`t figure it out!! ..1610 table..
Hi Jan
After I created this video I realised I has stumbled upon a new method for beam setting which I describe in
ua-cam.com/video/hFlxnjADZDA/v-deo.html
I includes the 4th corner as part of the beam setting process. Perhaps look at this method first.. It's quicker than adding the 4 corner fix to the end of a conventional beam setup.
Best wishes
Russ
@@SarbarMultimedia Ok, Thanks
@@SarbarMultimedia is it possible, you have put in a wrong link?
@@royrohner3573
Hi Roy
Thanks for pointing out the hole between my two remaining grey cells!!!! Yes, I had accidently pasted a lnk and didn't check. It's now been fixed and you can link to #244
Best wishes and thanks.
Russ
@@SarbarMultimedia Russ thanks so much for pointing me in the direction of this video as well. ;) I really appreciate your work on this great channel!