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View Full Version : Advice on ballscrew mounts for epoxy granite rebuild


Nealieboyee
29-06-2021, 08:42 PM
Hi All,
I'm rebuilding my ali extrusion moving gantry cnc router and planning to cast a solid epoxy granite base and gantry for it. The only stumbling block I've hit is the mounts for the y-axis ball screws.

As you can see in the images, the best method I can think of is to cast a plate into the epoxy granite wall on each end of the ballscrew so that I can attach the BK12 blocks. However, after casting, I would have to flatten these somehow, making sure they are parallel to the linear rails and level to each other.


Can you think of a better way?
Also, what are your thoughts on the ballscrew nut mounting. Too far below the linear rail?

Thanks
Neal
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Voicecoil
29-06-2021, 09:07 PM
An alternative could be to fix thick (>25mm) blocks of ali to the ends of the raised sides and screw your BK's into the edges of these? - that way you could have some adjustment. If you already have a working machine making them square shouldn't be too difficult.
Nealieboyee
29-06-2021, 09:38 PM
An alternative could be to fix thick (>25mm) blocks of ali to the ends of the raised sides and screw your BK's into the edges of these? - that way you could have some adjustment. If you already have a working machine making them square shouldn't be too difficult.

Interesting idea. Problem is the ballscrew isn't long enough to allow the bearing blocks to reach each end of the raised sides...
Nealieboyee
29-06-2021, 09:53 PM
What about something like this? Keep the embedded plates in the epoxy, but screw "angled" plates to it. Not just any old angled aluminium, but thick plates bolted together to create angled mounts.

Another way would be after I epoxy level the linear rail mounts, I could flip the base on its side and epoxy level the plates too?

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Voicecoil
29-06-2021, 11:42 PM
Interesting idea. Problem is the ballscrew isn't long enough to allow the bearing blocks to reach each end of the raised sides...
Could you not alter your mould to reduce the length of the raised sides relative to the base?
Nealieboyee
30-06-2021, 07:06 AM
I could, but my linear rails run the full length of the raised sides. I'd have to shorten them and reduce my cutting area along Y axis.