Steel framed fixed gantry draw slide build super cheap

[Zeeflyboy]

Axial force from the plunge is I would say largely irrelevant in the materials you are using and is probably the least of your worries. The weight of the router/mount and travelling parts of the Z-axis are probably higher than the force required from the motor as long as you aren't plunging crazy fast.

Typical max axial rated load for a double bearing nema23 is in the region of 1.5kg-f (e.g. see data sheet here, last page at the bottom specifically) https://www.anaheimautomation.com/ma...ec%20Sheet.pdf

So your biggest problem (in terms of Z-axis axial load, I think Jazz would probably contend that it's not your biggest problem lol) is that unless your screw, nut, router, router mount, and all "hung" mass of the mounting plate is less than 1.5kg, you are already exceeding the axial load before you even start moving.

Let's say you are using a small router that weighs about 3kg, add the weight of the screw, router mount, etc etc and what, maybe 5kg? Simply hanging there before taking into account any dynamic acceleration loads during retracts you are exceeding the rating by over 3 times.

You could bodge your way around it by counterweighting the Z-axis, but you'd still be subjecting it to axial loads when it does actually hit the material by doing it that way, and it would also be more complicated than just giving it a proper bearing setup which would be superior in every way.

edit - actually are you using a nema17 there? in that case it'll be more like 1kg-f axial load rating which would change the equation to being 5 times over load just hanging there.

double edit - I'm not sure why you think a steel framed build like this is innovative or indeed preferable to any of the other extrusion or wood based drawer slide builds? Indeed the only point I can see of doing a drawer slide build is that it's cheap and easy to build without access to any special equipment, which you kind of ruin the point of when you start talking about welding a steel frame. The components you are using don't have the accuracy or rigidity to benefit from the more sturdy steel frame, so it actually seems to be slightly defeating the point of these designs in the first place.

To me it seems like you're wasting what could be quite a nice little steel frame by then going and fitting it with sub-par components. assuming you've done a semi-decent job of alignment on that frame, if you took that same frame and fitted it out with some proper linear motion components (and stopped hoping that radial bearings could take thrust loads) you'd actually have a half decent machine there.