Build #2: Going bigger - How does this torsion box look so far?

I’ll be using the 525-23.5 build, everything printed in PETG this time instead of PLA, with a working area of 2’ by 6’ for sign making. On a 4’x8’ sheet, this gives me about 13 inches in both dimensions for power supply, RAMPS, laptop, tool cases… I finally got real RS bearings instead of those heavy-grease 608-ZZ’s, so I should be able to print in colder weather. I’ll probably support the long spans at three positions, about every 20 inches.

So, to the table: The option of hoisting it to the ceiling to free up space is appealing, so I need a torsion box to keep the surface rigid. Although unfinished, is there enough cross-support here, or should I add another set in the short (4’) direction?

The material is 1/4" OSB, because it’s cheap and so am I, but I will be topping it with a good MDF spoil board.

More questions to come, I bet…

Thanks Ryan and all!


The major problem will be rigidity in the long access. To have a 6’ working area your axis will be close to 7’ long… I am sure the weight of the router will bow the conduit.

I have a large build as well 60" square with a working area of 1200mm the conduit doesnt seem visually to deflect with a dw600 on it at that length. I have perimeter supports at the mid point of each axis to keep the outer rails straight.

I am interested to see how it performs at that length. I want to rebuild mine and make one small like 12x12x3 for most of the stuff I do but then I would like something like your plan for some bigger projects.

I did a rigidity test on some stainless steel at different wall thicknesses, It can handle that length for sure I did the tests at 6’ lengths or 8 can’t remember and hung a 10lb weight. Have a look if you run into issues with conduit SS is the fix.

Thanks Jason! So, at 60" you don’t see much sag in the gantry? That’s good news - I’m hoping having the area narrow and long will allow the Y gantry tube to support the super-long X as it travels. If it sags, I might reduce it to a 18"x72" area. I’m not too worried about the side spans, the supports should do it.

Thanks Ryan, I’ll be reporting back! Good to know about the SS, one piece for the gantry wouldn’t be too much of an investment…

Okay, box is complete, with extra lumber for the feet to screw into. Now to cut pipe…

Edit: Whoops, looks like the forum doesn’t like my pic. Rest assured the earth is in the right spot.

Box looks nice and sturdy!

I am starting to think about replacing my X and Y with stainless… I can leave the perimeter rails as conduit as I have added support mid way on the axis and they are very strong…

Question is… Is there a stainless pipe that will fit the 23.5 Center I just printed. HMMM

That crossed my mind - if you find it, let me know! This, from the Stainless test link above, looks close-ish…

So is this type of torsion box flat enough? Wouldn’t any twist in the 2x4s mess it up? Or does it just end up flat enough, after the ply and MPD toppers?

Lots of people are starting to use cheap doors from the hardware store. Pretty cheap option for a ready made surface. I think it is a slick idea.

A door sounds interesting. Plus it can fit in my car. Might even have one in the garage. Currently building a nice table for my small configuration.

we have a “habitat for humanity re-store” here that sells used building materials. I got a $1 door to use for mine.

I had nice crayon marks all over the door. A little kid must have had a lot of fun and apparently likes orange a lot…