I am embarking on an upgrade to my MPCNC Burly. I was going to just convert it to a Primo, but decided an LR3 would be better or at least fun to try (and more appropriate for my re-build size).
I am currently getting close to putting the final skin on a 38x68x4.5 torsion table and am looking for advice on any “features” I should add before I button it up. I was originally going to put a window in like Jeffe, but decided against it. I also considered perforating a section and connecting it to to a vacuum plenum for either a hold-down or a sanding area. While this is not impossible yet, I mostly decided against the complexity.
However, I am still open to considering some reinforced areas or internal wiring channels.
Any wisdom on these considerations, or advice on something else I might be missing?
My first one was open so I could put stuff inside, also helps with hold down bolts. My new one is solid, haven’t used it yet, so not sure about that mode yet.
Made a 1/2 solid, 1/2 open box. Rests on 2x4s, isn’t fastened to the legs even, my thinking was to let the torsion box find a plane it wants to rest on regardless of where I roll the table on our lumpy/uneven floor. I can clamp the ‘loose’ corner to stop torsion box pivoting/moving/twisting. Hope that makes sense? No idea if this is good sense. I don’t care if the box is true level or not, I mainly want all four corners to be on the same plane.
Should’ve made surface large enough for laptop, beverage and a few tools could be spread out while CNC is working away. Ended up a making removable shelf to precariously place the laptop…
Space is tight/premium for me, so it’s nice having the Vac, CNC tools, some small stock pieces all on the same rolling table.
My “Burly” was on the big side, sized for using a needle cutter to cut 20"x30" foam board. I haven’t had any trouble cutting through stock, but my current table is so uneven that 3D or even V carving has been only marginally successful. I occasionally tram the surface of the spoil board if I need to, but the flex of my larger-than-recommended MPCNC using 3/4 EMT limits the practicality of that too.
I ended up with a 38"x64" top to get a 24"x48" working area. That left me enough cutoffs from 48x96" sheets to make a 3" thick core. I could have gone a little thicker, but my dado only cuts 1.5" deep and I notched the internal core stringers half way. I was able to generate a 6.5 - 7.0" grid with a few strips to spare.
I spent more time than I’d like to admit hemming and hawing about MDF or plywood and ended up with ACX plywood because it was within a couple of bucks and I prefer to work with it. It had some warp to it, but I think the construction technique will pull that all out. I have about 1mm of free state flatness variation right now, but it still easy to flex. The final skin should take that out and lock it down.
Don’t laugh at my 5 color remnant filament Burly and associated mess in the background - it has given me about 4 years of faithful awesomeness! I plan to put the new top on the same base. Not sure If I am going to let it float or clamp it down - It will probably depend on how much it looks like its going to want to move…
Wow Doug!. I did see a thread about two torsion boxes put together to make a big one - that was probably you. I kind of looked passed it because I don’t have the space, or need for something that big at this time, but your beast is super impressive.
I like the idea of cut-outs around the perimeter; I’ve seen that as a suggestion by others, but mine ended up small enough that I’m not sure how useful they would be (yours seem plenty big). I figure I can always cut them out if I mark where the internal grid is, but it would be easier now for sure though, so maybe I’ll do at least some of them - like Aza B2C.
I guess I should have asked sooner - I’m starting to think I should gone modular with the ability to have one or two tables. Technically I could have gone wider in my shop, but I didn’t want to be committed to the space full time.
Is it plausible to bolt and unbolt the two periodically?
If so I would consider running the split or gantry the “other way” so I could shorten or lengthen the table rather than changing the width. Perhaps a way to hinge it?
The concept of a fold away LowRider has been discussed in various places and has been implemented by various makers. The most common way, I think, is to use the quick disconnect on the belts, and simply remove the gantry from the table, and store it separately, and then as far as getting the torsion box table out of the way, if it is simply resting on either saw horses or fold away legs, like a Paulk workbench torsion box concept, then it is easy.
Ron Paulk used and recommends plywood, and MDF can probably also serve. I actually could only get OSB in the size I needed, so I made mine out of OSB! I would not recommend it, but it’s doing the job decently. I was also hindered by the fact I had no truly flat surface on which to build them. It was a struggle.
I built my new one with osb because it was cheaper. Plywood prices got stupid the last couple years. I’ve not even bothered to price out baltic birch, which is what he builds his tables with, or the lightweight version of it.
