Distance Tube to Mirror and Mirror to Mirror

[Dave Vigness]

I've looked at a number of different extrusion possibilities. When I talked with Matt, he built his with 3030 extrusion, but looking back he would do it with 3060 for the main frame and gantry.

For me it's not necessarily the depth as it is the width for a full sheet. But.... knowing I had the width I would bet I would kick myself if I didn't increase the depth as well. I wonder what the max bed size is for LightBurn's camera system?

[Tim Mellor]

Providing it is supported well 2020 and 4020 is heaps for a Laser build. The Base on mine is part of that thinking the upper section and lower shelf consists of Torsion box construction held together with 140mm Square box section legs. I reckon you could hold a dance party on it

Going with the 4020 Gantry at this stage and the easy 'fix' if it was needed would be to bolt another 20x20 under the main span as a stiffener if needed and it will still clear the job. If I was building from the ground up with Extrusion similar to what Matt had done then the choices need to be different as you are relying on corner fixing bracket for torsional stiffness unless you add diagonal braces on the lower frame.

[Dave Vigness]

I didn't catch it in the videos, or it went right past me, but in our emails, Matt mentioned that his frame was welded. I'm assuming he welded it after it was assembled with the fasteners, but that's just guessing.

I'm a BIG fan of overkill is underrated. It's a whole lot cheaper to over size at the start vs take apart and rebuild.

[Tim Mellor]

It was a while ago I watched his videos so I might be wrong then. I thought it was an Extrusion base but welded is a different matter. The Static frame just needs to be stiff, true and not move in use.

The issue with going overkill on the gantry in the case of a Laser with higher speed moves than some other CNC gear is Kinematic ones. Go to heavy and you need to either slow the acceleration or beef up the drives. Beef up the drives means you need larger or better belts ....... Go the other way you get lighter faster and can bounce out of the end points and likely save a $ too

[Dave Vigness]

He did use extrusion. It has been a while for me since I watched his build video as well. But when I asked him in a recent email about what he would do different, he said that even though it as welded, he would go from 3030 to 3060. Even with it welded the 3030 was a bit light. He may have welded it after the fact to get some stiffness the fasteners couldn't give enough of.