Ideas for creating an accurate milling machine. Like any building, the height of the building is determined by the depths of the foundations. In the case of a milling machine, an uneven base will never give great results. Came up with an idea that I thought might be helpful to anyone making a milling machine. Hope its useful!
Using a laser level to make sure that all corners are at exactly the same height and hopefully creating a flat and non wonky base! measuring the height of the laser line from all extents, will give a structure, that is all on the same plane.
Base need to be aligned to 0.1mm or better, imho. It is impossible with laser level.
My lathe aligned with base by 0.05 shims and have accuracy near to +/-0.015mm.
@Rich_Sobocinski that’s the idea, the lasers im using is accurate to within 0.2mm per meter. It does have an auto leveling head. but it doesnt matter if it wasn’t, the aim is just to have a non twisted base which can be skimmed afterwards.
@1111118 the aim here is not to use the level part, but merely to have all four corners in the same plan. Because everything is referenced to the line of the laser, accuracy hopefully will be pretty good!
@Mark_Fuller
Residual stress? Is that what it is called when things warp up after being welded? The coefficient of thermal expansion for steel is pretty high. The only way to avoid it is to bring all of the work up to welding temperature before you weld it. Good luck with that plan I guess?
Welding is a terrible thing to do to a nice alloy. You can still weld the frame, but make it rigid enough that it wont flex much afterwards. Then bolt and shim the guide elements referencing off a real metrology instrument. Those little line lasers are only good enough for rough carpentry or hanging ceilings.
@Henrik_Larsen the water level idea was another idea I was thinking about, I just felt that with the laser line, I can measure every corner in one go. The aim is to use the bottom or the top of the laser line, not the laser line itself. Thanks for the suggestion!
@Wayde_Gutman what do you mean by reinventing the wheel? The current milling machine is made of plywood, not really the same thing at all? Any better ideas of making the base accurate?
@Sam_De_La_Haye
Good luck. Though personally I wouldn’t bet on you. Let me just put it this way, the last bit of “precision welding” I did here I milled the parts, and clamped them up to within 0.001" parallel to each other. After they cooled off they were 0.01" of an inch parallel to each other. At that I was fairly happy with my results. I clamped the living crap out of the parts so they would not move on me either. When metal expands it really doesn’t care about the clamps you have on it. It is going to go where it goes. There is absolutely nothing you can do about it either.
@Sam_De_La_Haye
Just take the time to drill and tap it, then bolt it together. Welding machinery is lazy slob work. Well do what you’re going to do, but that is my opinion about the matter.
If you decide to weld, you should take great care in welding equally on both sides at the same time. One Little weld spot on one side and the same spot on the other side, and gradually build it up. That way you may have a chance to even out residual stress - assuming the steel dimensions are adequate.
measuring the height of the laser line from all extents, will give a structure, that is all on the same plane.
