Re: [CAD_CAM_EDM_DRO] How important is ballscrew alignment?

Hi Abby,

Does it feel the same over the whole travel? If it gets stiffer towards
one end then it would be a good idea to do something about it. If you
loosen the nut mounting onto the saddle does it get easier? If so you do
really need to sort it out. If it is the nut mounting that is the
problem here is one bodger's method of getting accurate alignment:

Assuming the nut fits in some sort of block that is then bolted to the Y
axis, make sure there is a small gap between the block and the Y axis
with the bolts loose. If you need to machine the block down a bit then
do so. You don't need much of a gap as long as there is one. Now fill
the gap with epoxy paste such as 'chemical metal' or 'metalset'. Make
sure none gets in the bolt holes. Grease the bolts and lightly screw
them in but don't tighten them up. Assemble everything and leave it to
set overnight. Now tighten the bolts up. Plenty of machinists will
cringe but this technique does work!

Les

Abby Katt wrote:

>I've installed a ballscrew for my X-axis on my 3/1 mill and it's a great
>improvement!
>I've just used it for testing and one small profiling run so far, and it
>seems good.. No backlash, deadly-fast speed (so much so I turned it down
>because it scares me)
>
>But now I am getting paranoid - it was very difficult to align the
>mounting which sits on the Y-saddle with the ballnut, especially in
>ensuring that the angle is 90 degrees exactly. It all moves and works
>quite nicely, perhaps just a little stiffer than I had imagined it to
>be, and this is what worries me. How fatal is it to have this every so
>slightly out of alignment? Will my ballnut/screw fail in 100 hours? Or
>is it OK to have it not absoloutely perfect? Remember this is a Chinese
>drill/mill thing, so it's not exactly a precision instrument to start
>with..... so I expect some play in the system. (I have angular contact
>bearings, if that helps! :P)
>
>I guess my question is, if this alignment is out, will it just result in
>loss of efficiency or mechanical-tragedy?
>Thanks!
>Abby
>
>
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