Stell frame cnc 1500X1000. Adjustable table your opinion please

[Boyan Silyavski]

Dean thanks for your good words
As more than a year has passed since my last attemp of rails intalation, today i go on
I had some questions that i wrote 1,5 year ago (30-11-2014 #171).
I repeat them in order to understand what level of accuracy i have to achieve

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#1 ( very important to know what I am trying for )
When you measure the flatness of a beam ( or epoxy surface) against a straight edge, what is the acceptable tolerance-gap ( so we assume the surface is straight) . I use light to understand whether my top beams attach the straight edge. The touching points can be easily seen. But at other points althought i can see that there is no touch ( light passes through) , the 0,02mm Gap Filler cant pass through the gap. So what is the critical gap ? the light passing test ( that is less than 0,02mm ) or the 0,02mm gap filler test?

#2
When someone use the solution with the adjustable top beams ( without epoxy) or the shimming method how does he succeed to have the top rails in the same plane. How does he know when the two rails ( left and right ) are in the same plane?

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Hiwin maual (among others) has this table that says ( if i read right the table) that the height H of a rail has a range +- 0.1 mm for normal accuracy rails



Thanks for your time
Vagelis

#1
For me its very simple. Depends on table size. For under 1m everything more than 0.05 anywhere is unacceptable. For bigger tables 0.1 deviation on height is the limit. So hiwin is right.
Now i want to tell you that it took me a week to mount my 2 long rails . I mounted them and dismounted them 5 times, not counting the 3 pours of epoxy. So at thend depends what you will use the machine for.

My standard is very simple. if i can notice a gap with naked eye, its unacceptable. Be it 1m or 10 meters table.


#2
yeah, thats why i dont like this method. Ask Dean. But it should be possible if you of course have straight edge that can lay on top of both of them at the same time. i doubt though you could achieve same precision as with epoxy