John's Alu Profile build

**Evengravy** · 07-04-2020

Originally Posted by JAZZCNC

If you are going to do vibration tests then I wouldn't waste time testing individual pieces of profile or steel etc off the machine because all that matters is the tool. Testing at the tool is the only thing that matters IMO. You'd be better investing time on designing a strong Z axis.

Yea, that's a good point. I did a bit more reading around the subject and a guy on CNC zone recommended pea gravel in the non moving parts and nothing in the gantry, for now. I'll try that first and see where it is. I actually have a MIG that I bought years ago but never got around to learning to use the thing, a gas-less 150 from draper (I'm not sure if they're much good). It's been shelved in my dads place for years but maybe it's time to dust it off.

I think the Z axis I have is pretty solid though, it's foundation is milled from stainless. I know the opposite arrangement than most recommend, with the rails on the z plate which seems to be preferred, but it was a simple solution for me. I've tried to keep everything as close to moving bearings and having as little overhang as possible. The Z only has 100mm of travel but after using my other machine for a few years I realised I've never needed to mill anything over a couple of inches thick so the z overhang was really compromising the strength. That plus the momus design is not very good generally. Live and learn. I thought it would be a good idea this time for me to keep the gantry and Z axis as tight to the part as is feasible.

It's a shame about the profile, maybe I'll change it for something heavier but at this stage I might just run with it and see how it does, should be easy enough to swap it out for a heavier profile down the line.

**JAZZCNC** · 07-04-2020

Originally Posted by Evengravy

I think the Z axis I have is pretty solid though, it's foundation is milled from stainless. I know the opposite arrangement than most recommend, with the rails on the z plate which seems to be preferred, but it was a simple solution for me. I've tried to keep everything as close to moving bearings and having as little overhang as possible. The Z only has 100mm of travel but after using my other machine for a few years I realised I've never needed to mill anything over a couple of inches thick so the z overhang was really compromising the strength.

There's nothing wrong with rails on the rear plate, I've built dozens of machines using both methods and neither is better than the other because the difference between them is hardly anything and any advantage one as over the other is mostly dependant on machine design and user needs.
In your case with a short Z-axis, it's the best method because it allows you to make the most out of a short-stroke while allowing you to keep the gantry low and squat giving the best strength.

Edit:

Don't worry about the profile it will be fine. If you using my "L" Gantry design just make sure you bolt it together well.

**Evengravy** · 07-04-2020

Originally Posted by JAZZCNC

There's nothing wrong with rails on the rear plate, I've built dozens of machines using both methods and neither is better than the other because the difference between them is hardly anything and any advantage one as over the other is mostly dependant on machine design and user needs.
In your case with a short Z-axis, it's the best method because it allows you to make the most out of a short-stroke while allowing you to keep the gantry low and squat giving the best strength.

Don't worry about the profile it will be fine.

Ah that's good to hear, I didn't go for the L design you have no, I wish I had of kicked around here before but that does look like a better solution than mine, unfortunately I'm quite a way through the build so at this point I'm just looking to get her done and running. I don't know if you would have any comments on the design as it stands? There's a few places I could reinforce around the gantry connection to the Y axis plates etc. I'm sure I can figure something out there.

I could always beef up the gantry with some steel plate on the back-side too, if that would help. I might just get the base/table done next and see how she does though.

**JAZZCNC** · 07-04-2020

Originally Posted by Evengravy

I could always beef up the gantry with some steel plate on the back-side too, if that would help. I might just get the base/table done next and see how she does though.

I would look to beef up and brace the gantry ends but other than that it's nice and stiff looking.

That Z-axis is spot on for the size and you have half-decent material size. You won't get a much stiffer setup.

NOW just turn it on its side, or stand on its end and bolt to that wall.!!! . . . . You'll love it.