The original lathe bed is like the cross section of a hollow tube, but they've cut away one side (ie the bottom). By bolting it to something solid, you've replaced the bottom side of the (virtual) hollow section. Clearly effective.
Today I tried using my parting tool and it was horrid and sent me on a quest for more rigidity. i knew my 36 year old Taiwanese mini lathe needed better mounting but to what end i knew not. Thanks for quantifying one of the issues. I went straight out and measured .004" twist in it and have a plan of attack for tomorrow.
Your tool is not set up correctly and or the spindle speed is wrong. I use a cut off tool al the time on my mini lathe without a problem. If you machine is properly mounted and leveled with a precision level then your issues will be minimized.
Have now set my lathe on a substantial lump on channel and cut the deflection in half or better. My slowest chuck speed is 100rpm. With a parting tool 2mm wide I should be able to part mild steel unless tool rigidity comes into it. My 1/8" still chatters like crazy.
After many years of procrastination, I finally got around to mounting an older lathe of this design to a heavy piece of of structural "C" channel steel of about 10mm wall thickness and added shims. The section weighs more than the lathe itself. It is now a two-man lift to move it so it is now on a trolley-table. As I only do the occasional job on it making a few lens mounts, parallel accuracy was never really critical. I now wish I had pulled my finger out and improved it years ago. It was never much good for working with mild steel or salvaged alloy from aircraft propellor blades which machines like mild steel. That has changed since.
Great option if you don't have a massive enough bench to bolt your lathe directly to or if you don't have enough space to leave your lathe bolted to a bench when not in use. 👍👍
Back in the day when I used to build machine for testing the Trent jet engines we had some very large fabrications where it wasn’t possible to machine them completely flat. We used some of the engineering epoxy between machined surfaces of parts . It worked incredibly well but I’m not show if it’s affordable in small quantities.
Hi! Yes, that would be a good idea. I may well have used that method if I was aware of it at the time. When I built my small CNC, I used (ordinary) metal filled epoxy as a 'liquid shim' between the gantry and the base - set everything up straight and square and then, once the epoxy had cured, tightened the bolts up. I basically copied the method in the video by Steffan Gotteswinter where he uses the real stuff to align his milling machine ua-cam.com/video/U7Qs-J2swIc/v-deo.html Thanks for taking the trouble to comment 🙂
@@Mister_G I should have said it was used as a shim in my post. Did the metal filled epoxy you used work ok. I have a small model Lathe that needs the same.
@@allthegearnoidea6752 - Yes, it worked extremely well. Actually, I think I ended up using JB Weld in the end as I couldn't find a real metal loaded epoxy with a slow cure at a reasonable price. I did try metal loaded epoxy putty, but it cured far too quickly. I have never tried dismantling it, but one side of the joint was waxed, so it *should* come apart OK. I used the same method to prepare the beds for the linear rails on my CNC (have a look under 'metalwork -> Desktop CNC' on my website for some photos of the process if you are interested)
Great idea I'm probably going to do the same thing only I'm going to weld together a bunch of small square tubes so that it doesn't sit so high and I like how you tested it by parting some steel mild steel is a dream if you really want to put it to the test do some mystery steel like an old cheap weight bar now that gave my mini lathe hell
Ha Ha! - Yes, mystery metal! I got a length of old crowbar about 30mm diameter that defies any attempt at getting a decent finish on it. Thanks for watching! :)
I'm a woodworker with a mini metal lathe (coz why not) and was amazed at the difference putting my 7 X 14 lathe on two large 450mm by 450mm concrete 'stepping stones' made. The instant dampening effect was really noticeable when I made a similar cut to yours at the end, so a nice heavy chunk of steel like you used would certainly notice it, too. I'm about to build a custom stand for the lathe and intend to make a concrete top for it. Thanks for taking the time to upload your video. Stay safe and all the best. Doc from Australia
Wonder how well it would work combine the ideas, and embed studs in a block of concrete at the spacing for the bolt holes, and bolt the thing right down to the concrete.
@@auxchar Thanks for commenting - My view is that I would be reluctant to bolt the lathe to concrete as I would be worried about the effects of temperature fluctuations on the straighness of the metal bed (steel/iron changes length much more than concrete as the temperature changes). Ultimately, it would depend on how important (say) vibration damping is vs thermal stability to the owner of the machine in question.
@@Mister_G actually concrete has almost exactly the same coefficient of thermal expansion than steel and cast iron. (It varies and you can get both concrete that expands more and less than cast iron)
I just bumped into your video, it's a year old, checking how much it can deflect. I'm Keith from Michigan USA. I've been around professional machinery for nearly 44yrs. Turning 65yrs in March, and yes I have been around with metric and I love and it's actually easier to work with. Well anyway, has your mini Lathe doing what you want 😉? Please give me a reply
Hi Keith - Yes, at the moment, my mini lathe is doing me proud - I machined all the parts for my model jet turbine on it, and managed to hold 0.004mm TIR on a 125mm long shaft and machined a couple of bearing journals to within ~0.002mm which is as much as I can ask for. It even turned nckel alloy without too much hassle. It's definitely not in the same league as a "proper" lathe, but then a "proper" lathe wouldn't fit into my shed. For the hobby stuff that I do, you really just need decent measuring equipment and patience 😊. Thanks very much for the comment. 👍
@@Mister_G Welcome for reading your response 😀. I'm impressed with what you accomplished 👍. My last career, 9yrs with a company called Woodward. They do new and overhauled fuel nozzles around the turbine engines. Passengers jets and military. I worked on some tough materials to machine. But my huge career was working on honing, gone to auto manufacturing facilities for the the engine blocks. This is when I learned about microns. I'm happy 😊 that you used your Lathe and hold good tolerances, take care 🙂.
I mounted mine. Problem solved. Simple. All these vids about cheap machines and how imperfect they are. Hilarious. Buy a Bridgeport. All of these mini machines need to be mounted to add to the rigidity. I bought a Grizzly G0752 and absolutely love it! It is a beast and does more than I need it to. I have modded it quite a bit. One thing I dont do is complain about it. Make chips!
Surely if you want rigidity increasing across the plain of the bed, then you need to go 90 degrees to the bed. For example 2 x channel or heavy box section cut to the width (F2B) of the drip tray. And perhaps bolt the ends down whilst shimming there?
Thanks for commenting - I didn't wan't to bolt the bed to a wooden bench because the wood moves with humidity change and would mean that the alignment of the lathe changed with the weather. The biggest thing I had to bolt it to was that metal channel.
@@Mister_G who mentioned wood? Going in the direction of play with a brace lowers the direction of play, yet your brace follows the play. It's like putting a corner on a wall, it becomes stronger. Plus, oversizing a hole through wood would deal with most movement also...
@@carlraymond5418 Sorry! - I misread your original comment as adding 2X cross-wise pieces and bolting them to the bench (don't know why). Yes, you are right, the bigger the "cross section" (actually 2nd moment of area) of the part linking the two ends, the stiffer it will be. One must appreciate though, that a chain is only as strong (or stiff!) as its weakest link. I don't pretend that what I did is in any way optimal, but I think it's enough to mean that torsional stiffness of the bed is no longer the 'weakest link'. Thanks for the reply.
@@Mister_G The shining in such cross members to get the ways level along its course also becomes easier in this way as a shim can be moved in or out to achieve optimum adjustment. Where as if you needed to shim it would be under the casting, not the support.
In your parting operation, I don't think it was finding the right feed rate. You've simply loaded some of the springiness in three system. At least that was my experience with a similar lathe. Replace the compound with a solid tool post with an anti rotation feature and I bet you'll see even more improvement. Also, bell mouth chuck jaws can cause chatter. Thanks for quantifying the stiffness before and after.
Hi, thanks for the comment :) I've got less timid with parting off since this video, and now use an insert parting blade and it works just fine. I wouldn't want to lose my compound slide as I use it too often. As delivered, the top/compound slide was horribly flexible (the gib strip wasn't working properly and the slide was lifting as the gib was tightened - seems to be quite common). After sorting this out, it is much better (but it's still the weakest link, I think). Thanks again.
I can part off 3/4" (19.05mm) diameter 4150 with a 1/16" HSS parting tool in my 7x12 mini lathe at 500 RPM with no chatter, and no silly chunk of scrap iron bolted to the bottom either. You have other serious issues at hand that you need to sort out if you need to resort to this modification.
Thanks for the comment - Firstly, I didn't have any granite! :). There is also the issue of thermal expansion - granite expands less than steel/iron for a given temperature change. If the lathe was fastened to granite, the bed would bend slightly as the temperature changed. As my shed is unheated, this is something I wanted to avoid. Volume for volume, steel is ~3x heavier than granite in any case (specific gravity ~7.7 vs ~2.7), and about 3X stiffer (Young's modulus ~200GPa vs ~60GPa) - but like I said, it wasn't an option anyway.
@@Mister_G Steel expands at a different rate than cast iron does, especially the junky cast iron the chinese use these days. I also think most times a normal cut off piece of granite is 5cm thick at minimum(good luck finding a 5cm thick plate of steel) so I believe it would have been heavier than that hollow beam. You also forget as well which is a massive factor for going granite rather than steel is that the piece of steel you used is hot rolled angle iron steel which has internal pressures and is very inaccurate compared to a polished granite surface(there is a reason they use granite surface plates) and add to the fact you welded seams along the entire piece and I can bet $100 a piece of polished granite would have been significantly flatter than your welded angle iron steel sections as your beam could have a warp in it from the welding which would also warp your lathe bed when tightening down. To each his own, but speaking from experience a piece of granite works better as I had a steel plate before I went granite. But here comes the kicker. Because of you using hollow section of tubing and it was welded(different steel composition from rod to base material) comparative to a slab of granite your tube would twist far more than a slab of granite, don't believe me? Please put your tube in a strong vise, add an indicator and add a pipe wrench and some leverage and see for yourself how much twist you will get, now go and try the same with a piece of granite and see why I am right and why people use granite epoxy for DIY cnc. Also please read up on resonance and see why steel is a bad material for lathe beds and why granite is better for resonance as well, if you don't know what resonance does to a lathe, think what chatter does when your motor is running and you feel the vibrations through your lathe. Here is something for you to read as I see you don't really understand how thermals actually work in material of granite vs steel and cast iron.(blog.reitz-natursteintechnik.de/en/granite-concrete-vs.-steel-in-mechanical-engineering-five-convincing-properties) This will indicate to you that in fact granite is far superior for a lathe bed material as it does not move because of low internal stresses and it moves far less and far slower in temperature changes, which is exactly what you want your moving cast Iron lathe to be bolted to as the piece of granite will keep it straight instead of twisting with the steel.
@@kazykamakaze131 Granite is a great material for a lathe bed (and any precision machine) - particularly for stability and vibration damping as you say, but my lathe bed was already cast iron :). I wouldn't mix the two, but YMMV. Like I said, I had the steel already, and (as shown in the video) levelled the mounting pads after welding, etc. and checked for bed distortion as I tightened it down. The expansion coefficients of cast iron and steel are near enough the same. I'm very happy with how it worked out. Thanks for the interest :)
I think there's a huge flaw in the design of the lathe bed: the headstock is not supported underneath where the bed has that huge cut away to mount the motor. I consider it an appalling design oversight - the headstock is where the most rigidity in the entire lathe is called for
The original lathe bed is like the cross section of a hollow tube, but they've cut away one side (ie the bottom). By bolting it to something solid, you've replaced the bottom side of the (virtual) hollow section. Clearly effective.
0:40 That first twist you do - wow.
Yep, it surprised me too the first time I measured it. Thanks for taking the time to comment.
Today I tried using my parting tool and it was horrid and sent me on a quest for more rigidity. i knew my 36 year old Taiwanese mini lathe needed better mounting but to what end i knew not. Thanks for quantifying one of the issues. I went straight out and measured .004" twist in it and have a plan of attack for tomorrow.
The very best of luck on your quest! :D
Your tool is not set up correctly and or the spindle speed is wrong. I use a cut off tool al the time on my mini lathe without a problem. If you machine is properly mounted and leveled with a precision level then your issues will be minimized.
Have now set my lathe on a substantial lump on channel and cut the deflection in half or better. My slowest chuck speed is 100rpm. With a parting tool 2mm wide I should be able to part mild steel unless tool rigidity comes into it. My 1/8" still chatters like crazy.
After many years of procrastination, I finally got around to mounting an older lathe of this design to a heavy piece of of structural "C" channel steel of about 10mm wall thickness and added shims. The section weighs more than the lathe itself. It is now a two-man lift to move it so it is now on a trolley-table. As I only do the occasional job on it making a few lens mounts, parallel accuracy was never really critical. I now wish I had pulled my finger out and improved it years ago. It was never much good for working with mild steel or salvaged alloy from aircraft propellor blades which machines like mild steel. That has changed since.
Hi - I was surprised at how much difference it made. Glad it worked for you too, and thanks for watching! 🙂
Great option if you don't have a massive enough bench to bolt your lathe directly to or if you don't have enough space to leave your lathe bolted to a bench when not in use. 👍👍
Absolutely! Thanks for watching 🙂
Awesome job man I’ll be watching your stream
Thank you very much - glad you liked it.
Back in the day when I used to build machine for testing the Trent jet engines we had some very large fabrications where it wasn’t possible to machine them completely flat. We used some of the engineering epoxy between machined surfaces of parts . It worked incredibly well but I’m not show if it’s affordable in small quantities.
Hi! Yes, that would be a good idea. I may well have used that method if I was aware of it at the time. When I built my small CNC, I used (ordinary) metal filled epoxy as a 'liquid shim' between the gantry and the base - set everything up straight and square and then, once the epoxy had cured, tightened the bolts up. I basically copied the method in the video by Steffan Gotteswinter where he uses the real stuff to align his milling machine ua-cam.com/video/U7Qs-J2swIc/v-deo.html
Thanks for taking the trouble to comment 🙂
@@Mister_G I should have said it was used as a shim in my post. Did the metal filled epoxy you used work ok. I have a small model Lathe that needs the same.
@@allthegearnoidea6752 - Yes, it worked extremely well. Actually, I think I ended up using JB Weld in the end as I couldn't find a real metal loaded epoxy with a slow cure at a reasonable price. I did try metal loaded epoxy putty, but it cured far too quickly. I have never tried dismantling it, but one side of the joint was waxed, so it *should* come apart OK. I used the same method to prepare the beds for the linear rails on my CNC (have a look under 'metalwork -> Desktop CNC' on my website for some photos of the process if you are interested)
Great idea I'm probably going to do the same thing only I'm going to weld together a bunch of small square tubes so that it doesn't sit so high and I like how you tested it by parting some steel mild steel is a dream if you really want to put it to the test do some mystery steel like an old cheap weight bar now that gave my mini lathe hell
Ha Ha! - Yes, mystery metal! I got a length of old crowbar about 30mm diameter that defies any attempt at getting a decent finish on it. Thanks for watching! :)
@@Mister_G ,
Please provide the address for this mini lathe dealer/distributor, in *Indonesia* .
I'm a woodworker with a mini metal lathe (coz why not) and was amazed at the difference putting my 7 X 14 lathe on two large 450mm by 450mm concrete 'stepping stones' made.
The instant dampening effect was really noticeable when I made a similar cut to yours at the end, so a nice heavy chunk of steel like you used would certainly notice it, too.
I'm about to build a custom stand for the lathe and intend to make a concrete top for it.
Thanks for taking the time to upload your video.
Stay safe and all the best.
Doc from Australia
Hey! Thanks for watching. Glad you found it of interest. 😊
Wonder how well it would work combine the ideas, and embed studs in a block of concrete at the spacing for the bolt holes, and bolt the thing right down to the concrete.
@@auxchar Thanks for commenting - My view is that I would be reluctant to bolt the lathe to concrete as I would be worried about the effects of temperature fluctuations on the straighness of the metal bed (steel/iron changes length much more than concrete as the temperature changes). Ultimately, it would depend on how important (say) vibration damping is vs thermal stability to the owner of the machine in question.
@@Mister_G actually concrete has almost exactly the same coefficient of thermal expansion than steel and cast iron. (It varies and you can get both concrete that expands more and less than cast iron)
@@MF175mp Every day is a school day - Thanks 😊
Another good video!
Thank you very much!
I just bumped into your video, it's a year old, checking how much it can deflect. I'm Keith from Michigan USA. I've been around professional machinery for nearly 44yrs. Turning 65yrs in March, and yes I have been around with metric and I love and it's actually easier to work with. Well anyway, has your mini Lathe doing what you want 😉? Please give me a reply
Hi Keith - Yes, at the moment, my mini lathe is doing me proud - I machined all the parts for my model jet turbine on it, and managed to hold 0.004mm TIR on a 125mm long shaft and machined a couple of bearing journals to within ~0.002mm which is as much as I can ask for. It even turned nckel alloy without too much hassle. It's definitely not in the same league as a "proper" lathe, but then a "proper" lathe wouldn't fit into my shed. For the hobby stuff that I do, you really just need decent measuring equipment and patience 😊.
Thanks very much for the comment. 👍
@@Mister_G Welcome for reading your response 😀. I'm impressed with what you accomplished 👍. My last career, 9yrs with a company called Woodward. They do new and overhauled fuel nozzles around the turbine engines. Passengers jets and military. I worked on some tough materials to machine. But my huge career was working on honing, gone to auto manufacturing facilities for the the engine blocks. This is when I learned about microns. I'm happy 😊 that you used your Lathe and hold good tolerances, take care 🙂.
@@keithmonarch447 Thank you - you too :)
I mounted mine. Problem solved. Simple. All these vids about cheap machines and how imperfect they are. Hilarious. Buy a Bridgeport. All of these mini machines need to be mounted to add to the rigidity. I bought a Grizzly G0752 and absolutely love it! It is a beast and does more than I need it to. I have modded it quite a bit. One thing I dont do is complain about it.
Make chips!
Absolutely! This little lathe is still serving me well and making the odd usefull thing, as well as plenty of chips.
Can't believe it ! And the indicator is not even sitting on the end of the machine bed. Is the headstock attached to the bed properly ?
Hi, yes, everything was done up tight! 😀
It's quite an eye-opener when you start measuring these things.
Thanks for watching!
Surely if you want rigidity increasing across the plain of the bed, then you need to go 90 degrees to the bed.
For example 2 x channel or heavy box section cut to the width (F2B) of the drip tray. And perhaps bolt the ends down whilst shimming there?
Thanks for commenting - I didn't wan't to bolt the bed to a wooden bench because the wood moves with humidity change and would mean that the alignment of the lathe changed with the weather. The biggest thing I had to bolt it to was that metal channel.
@@Mister_G who mentioned wood? Going in the direction of play with a brace lowers the direction of play, yet your brace follows the play. It's like putting a corner on a wall, it becomes stronger. Plus, oversizing a hole through wood would deal with most movement also...
@@carlraymond5418 Sorry! - I misread your original comment as adding 2X cross-wise pieces and bolting them to the bench (don't know why). Yes, you are right, the bigger the "cross section" (actually 2nd moment of area) of the part linking the two ends, the stiffer it will be. One must appreciate though, that a chain is only as strong (or stiff!) as its weakest link. I don't pretend that what I did is in any way optimal, but I think it's enough to mean that torsional stiffness of the bed is no longer the 'weakest link'. Thanks for the reply.
@@Mister_G The shining in such cross members to get the ways level along its course also becomes easier in this way as a shim can be moved in or out to achieve optimum adjustment. Where as if you needed to shim it would be under the casting, not the support.
@@carlraymond5418 True.
Great idea ! Thx
Thanks for watching! :)
Close the pipe up and fill it with sand--stiffness and damping.
But then I couldn't get the bolts in for the feet 😉 - Yes it would be a good idea if you were looking for the ultimate. Thanks for watching.
In your parting operation, I don't think it was finding the right feed rate. You've simply loaded some of the springiness in three system. At least that was my experience with a similar lathe. Replace the compound with a solid tool post with an anti rotation feature and I bet you'll see even more improvement. Also, bell mouth chuck jaws can cause chatter. Thanks for quantifying the stiffness before and after.
Hi, thanks for the comment :) I've got less timid with parting off since this video, and now use an insert parting blade and it works just fine. I wouldn't want to lose my compound slide as I use it too often. As delivered, the top/compound slide was horribly flexible (the gib strip wasn't working properly and the slide was lifting as the gib was tightened - seems to be quite common). After sorting this out, it is much better (but it's still the weakest link, I think). Thanks again.
I just bolted mine to the bench. Problem solved
Great stuff! Glad it worked out for you. :)
I can part off 3/4" (19.05mm) diameter 4150 with a 1/16" HSS parting tool in my 7x12 mini lathe at 500 RPM with no chatter, and no silly chunk of scrap iron bolted to the bottom either. You have other serious issues at hand that you need to sort out if you need to resort to this modification.
Whatever dude - thanks for watching :)
Why not just have used a piece of granite? It gives more weight and is more rigid than steel and handles vibrations better as well.
Thanks for the comment - Firstly, I didn't have any granite! :). There is also the issue of thermal expansion - granite expands less than steel/iron for a given temperature change. If the lathe was fastened to granite, the bed would bend slightly as the temperature changed. As my shed is unheated, this is something I wanted to avoid. Volume for volume, steel is ~3x heavier than granite in any case (specific gravity ~7.7 vs ~2.7), and about 3X stiffer (Young's modulus ~200GPa vs ~60GPa) - but like I said, it wasn't an option anyway.
@@Mister_G Steel expands at a different rate than cast iron does, especially the junky cast iron the chinese use these days. I also think most times a normal cut off piece of granite is 5cm thick at minimum(good luck finding a 5cm thick plate of steel) so I believe it would have been heavier than that hollow beam. You also forget as well which is a massive factor for going granite rather than steel is that the piece of steel you used is hot rolled angle iron steel which has internal pressures and is very inaccurate compared to a polished granite surface(there is a reason they use granite surface plates) and add to the fact you welded seams along the entire piece and I can bet $100 a piece of polished granite would have been significantly flatter than your welded angle iron steel sections as your beam could have a warp in it from the welding which would also warp your lathe bed when tightening down. To each his own, but speaking from experience a piece of granite works better as I had a steel plate before I went granite.
But here comes the kicker. Because of you using hollow section of tubing and it was welded(different steel composition from rod to base material) comparative to a slab of granite your tube would twist far more than a slab of granite, don't believe me? Please put your tube in a strong vise, add an indicator and add a pipe wrench and some leverage and see for yourself how much twist you will get, now go and try the same with a piece of granite and see why I am right and why people use granite epoxy for DIY cnc.
Also please read up on resonance and see why steel is a bad material for lathe beds and why granite is better for resonance as well, if you don't know what resonance does to a lathe, think what chatter does when your motor is running and you feel the vibrations through your lathe.
Here is something for you to read as I see you don't really understand how thermals actually work in material of granite vs steel and cast iron.(blog.reitz-natursteintechnik.de/en/granite-concrete-vs.-steel-in-mechanical-engineering-five-convincing-properties)
This will indicate to you that in fact granite is far superior for a lathe bed material as it does not move because of low internal stresses and it moves far less and far slower in temperature changes, which is exactly what you want your moving cast Iron lathe to be bolted to as the piece of granite will keep it straight instead of twisting with the steel.
@@kazykamakaze131 Granite is a great material for a lathe bed (and any precision machine) - particularly for stability and vibration damping as you say, but my lathe bed was already cast iron :). I wouldn't mix the two, but YMMV. Like I said, I had the steel already, and (as shown in the video) levelled the mounting pads after welding, etc. and checked for bed distortion as I tightened it down. The expansion coefficients of cast iron and steel are near enough the same. I'm very happy with how it worked out. Thanks for the interest :)
@@kazykamakaze131 Repeat after me: "we row with the oars we have".
@@BeachsideHank That is not the saying fit for purpose here, since per weight granite is cheaper than steel.
If you weld ends onto the tube, I think that will make it even stiffer.
It would, but then I couldn't get the bolts in! :D (Yes, I know there would be ways around this...) Thanks for watching!
I think there's a huge flaw in the design of the lathe bed: the headstock is not supported underneath where the bed has that huge cut away to mount the motor. I consider it an appalling design oversight - the headstock is where the most rigidity in the entire lathe is called for