Crazy Ideas Vol 1

Hi All

Been busy with my first mill. I decided on a arch type ("fixed Gantry" with moving table) after reading a book on high speed milling and high speed mill design. Working volume is 300x300x300mm. This is no router as I expect to do all metals including superalloys. I got bits and pieces from ebay and is now busy with construction. I also did some FEM analysis for errors etc. (I am a mechanical/production engineer). The drivers and steppers are sorted, now the integration.

First problem I face is leadscrews. I did not buy commercial units, instead settling on normal M10x1.25 thread (cheap). I read on a website (about optical equipment) about lapping these to give an accurate thread. That is now done. Next problem is mounting them. I got a bicycle axis and split this in 2, giving me 2 adjustable angular contact units. I noticed that they did not run very smooth, and after investigation I saw that they have a very rough torque nut. Setting up a Dremel and fitting these units onto bearings, I ground them smooth and accurate (pictures available for those that want to see). They now run extremly smooth even when overtorqued. Next problem is the nut. I have seen various designs on the net for these, but none to my satisfaction. The roller screw nut design in the files section is very interesting and i think i will go for that. Problem is I do no have my lathe yet, so I might have to settle for a Delrin or oil impregnated Nylon nut, tapped long enough to take up any backlash.

Couple of questions:

Anyone have a recommendation for homing switches. They obviously need to be fairly repeatable. (optical, mechanical)

I need an idea for cheap bellows to protect the linear guides and leadscrews

Vol 2 will follow soon with ideas for DRO's

Stephan


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