a Steel Box Section Build with SBR20 & Ballscrews Plus a few questions

[Colin Barron]

A very small drill bit can be used to find the centre spot made with centre punch,(spindle not moving), work should be clamped lightly but adjustable, clamp the work tight when positioned and check again to confirm it has not moved. Drill a small hole to confirm position then full size. A smaller drill bit will not move off centre as much as final size. If you still have problems use a centre finder (point) as shown here. https://www.youtube.com/watch?v=RhtBdar4iVg . I was informed as an apprentice many years ago that using the pointer method an accuracy of 1/64th inch (0.4mm) is achievable.

[Colin Barron]

How do you propose to get the main axis shafts level and parallel with each other? Commercial companies using this style of frame will have accurate jigs to hold the frame in position while they weld it. Special purpose machine makers mount rails onto a flat ground plate, which is mounted onto the frame, to ensure flatness. With the flat plate and one shaft mounted you could check parallelism using a dial indicator to locate the position of the other shaft.

[grain_r]

Hey colin

Sorry for the Delay in replying. I have given myself room to move components for small adjusting of plates which is lucky too because as previously said I just cant get the holes as close as I would like. although I centre punch and then centre drill and then go larger but I think with my newer drill press it has got better. But i have made 6mm holes in the plates that bolt to the m5 tapped holes so that will give me a small amount of movement.

I have a dial indicator to get as close as I can although I need to find a long enough straight edge to trust and then using the Vernier caliper too.

I will then be able to then flatten the spoil board once everything is running so it won't matter if the machine is a small part of a mm out because it will al be parallel with itself and also the work piece.

Well that's the plan anyway. I will be using Epoxy for the rails to get the top rails flat running a channel between the rails and this will then self level.

i think then it will be a lot of fiddling about to chase every last 0.0 of mm

I would be great to have those known flat and precise equipment of the manufacturers have but money would never allow for it sadly.

thanks

Rob

[Colin Barron]

What about using a laser level and laser distance measure. If you are careful you could use a sheet of glass to check for level.

[grain_r]

Great idea I didnt even think about glass I will be keeping my eyes open when I pass any skips from now on.

What about using a laser level and laser distance measure. If you are careful you could use a sheet of glass to check for level.

[Colin Barron]

Best look for old double glased unit the edges are taped and safer, wear gloves and glasses.

[grain_r]

Well still building the frame but also learning as I go about the electronics and everything else.

I am looking at the pulley's to use dean said that a 2:1 gearing ratio is good for a 1605 Ballscrew but does it matter how many teeth are on the pulley as long as it is 2:1 on the otherside of the motor I can't find any threads that show how to work it out.

I am looking at using Nema23 4nm from CNC4You which look to be low inductance and high torque also nothing really shows the torque curves to show if it is usable power through the range.

Has anyone used these motors at all ?

I know that it is best to wait for buying things but my year end accounts are up so trying to make sure I can buy the bits before then.
I have now ordered the 4 Leadshine AM882s because I will be using duel screws on the X.

I'm now ordering the Hiwin rails from Fred because its taking forever to build if I use the supported rails I don't think it would ever get upgraded so do it one do it right.

So its back to cad and make the changes.