Aluminium base waste board question

I have the Ohio Diesel 1/2" aluminum spoilboards. I think it is about as good as it gets for a solid base but my XXL does sag in the middle even with the Aluminum board. It needs center supports to level it. I like mine very much though and would purchase it again. If you get one and need the sea of holes spoilboard I designed just let me know I will send the files with toolpaths.

Here is what I use. They work very well but good luck getting the middle ones on haha.

Strap adjustable supports


Yep, what Brian said: HDPE is slippy…against other slippy material, but since I use tape&glue, the point is moot because the sticky side of the tape is not going to slip (not at the amount of lateral force I put on the pieces, and not at the dimensional accuracy I’m usually after)

Tape may not adhere (in the Z direction) as well to HDPE as it would to a more porous surface (MDF), but I have yet to have a case where I had the tape&glue give during the job (AND it was not because I got lazy and did not see that the bottom of my stock was not flat…that, I did)

I went to an HDPE wasteboard because I developed a strong dislike for MDF in general, and how it wears out/tears out quickly when prying pieces off the wasteboard (when using tape&glue, again), and I figured HDPE would also be much more stable over time (compared to MDF which soaks up humidity).

If I am being honest, I never quantified the gain in dimensional stability.


Even with the Aluminium, wow!

I just finished bolting the base of mine down to the table to take sag and flex out.


Too much weight and not enough second moment of inertia! :wink:


I have an aluminum base and typically use a HDPE waste board on top to be surfaced, this was mostly because first, I don’t want to surface my ~$400 base as it would continue to have to be resurfaced when doing maintenance/mods (requiring disassembly) and would just create a pocket in the base, interfering with work holding, secondly at the time I was experimenting with [misting] coolant.

It is, using the gator clamps, they like to slip outward when being clamped down, I end up putting some pieces of paper under the clamp riser to help them to grip the surface better. I also use something like a scotch brite pad to scuff up the surface a little when doing the tape & glue method.


With regards to HDPE’s dimensional stability, I’ve attached a worksheet. I’d suspect in most shop environments, such dimensional changes will likely be imperceptible. But I always take it into account in my installations.


Here’s my overcomplicated setup:

Stock wasteboard, with a MDF wasteboard w/ t-track on top. That gets surfaced square with the machine. I’ll eventually need to replace the MDF here. On top of that I use an aluminum or MDF “tooling board” that has holes for clamps and such in it and is known parallel (as I can make it anyway). When I use the aluminum one, I put HDF shims under work so a mistake doesn’t take another hunk out of my aluminum tooling board. I do lose working height with this setup, but that hasn’t been an issue for the projects I do, and I can easily go to the t-track level if I need some height.

Sort of overly complicated, but evolved over time.


Probably well supported underneath?

Both MDF and Melamine have really uniform thickness - they just need good support underneath.

@LiamN might be on to something. Now that I have had a little bit of time to play with some of the sheets of Valchromat/Forescolor I picked up weeks ago, I am a big fan of it over regular mdf and will be making a new waste board out of it with threaded inserts asap.

Something that would help me out is pictures.

I have received all of the boxes for my Shapeoko XL, and I have a pile of Amazon boxes from the various things you guys have suggested (dust collection etc). But I’m not letting myself build the Shapeoko it until I finish a work project, and I finish building an enclosure for the Shapeoko.

I think I understand the engineering behind building a firm/stable/flat base under the Shapeoko and how you just can’t take the feet off and let the Shapeoko lay directly on MDF due to the “layout cross straps” not having a flat bottom. And while I “think” I am following some of your solutions what I really need is to see what you did so cross straps are fully supporting the weight and are flat. And (I assume) the corners (now without feet) are still supported?

What I am picturing is custom surface that isn’t flat, but rather has grooves cut for the cross straps? This is where my mental image starts to go fuzzy.

Thanks in advance

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I just finished bolting my XXL down to the torsion box it sits on, which was flat enough for me to say “flat reference”. I used some spacers under the steel cross straps, but it did involve drilling some holes in the steel cross straps which would void a warranty…

I’ll grab some pics and screenshots of the CAD model tomorrow if that helps.

Edit - Should also add, this isn’t something you need to stop building your machine for, there’s plenty to do and learn before small movements in the wasteboard become a problem for you, getting it built, learning to use it, tram it etc. There’s plenty of time later to decide what aspects you want to improve and do that.


Hmm now this statement counters my argument for doing it in the first place, this thread and your feedback has given me much food for thought. Particularly my thinking on fire and forget when getting the new base, clearly I need to re visit this with a view to supporting the underside of the aluminium base… very interesting indeed

The Ohio Diesel aluminum plate is a 2 piece and relies on the Shapeoko straps (3ea) for rigidity. The Shapeoko straps will not support the heavy aluminum plate and you will suffer from sagging.

In my case, I removed the Shapeoko straps and used 2020 aluminum for the base in order to support the aluminum plate.

The Ohio Diesel plate is half inch thick whereas the Shapeoko design uses a 3/4 mdf board. To keep the Z distance the same, I used a 1/4" spacer to make up the difference.

If I were to redo it, I would out source a 1 piece aluminum plate, remove the straps, bolt the bed frame to the aluminum plate, use 20/20 cross beams to support the aluminum plate. Ditch the leveling feet. Add a mdf waste board and bolt it to the aluminum plate.



Here’s what I ended up doing to my XXL.

Beware - warranty voiding drilling involved…

Carbide3D has a compromise to make between weight, manufacturing cost, shipping cost, difficulty of assembly etc. and outright rigidity. They also need to ship something that is maximally tolerant of being installed in unpredictable conditions. In the case of the XXL and me having a flat surface for installation, I think the compromise is large enough that it’s worth doing something extra as a user, but that’s my personal preference, first, here’s the basic steel and MDF structure of the XXL;

I’m choosing to name the various main parts here;

  1. Front and Rear Steel Support - hold the Aluminium rails
  2. Steel Straps - between the front & rear supports
  3. MDF Baseboard - the supplied MDF base that bolts to the steel
  4. Spoilboard - the extra MDF the customer adds on top of the baseboard

The steel is pretty thick and is folded to give some rigidity, the front and rear steel supports which hold the very stiff aluminium rails have a large fold which goes underneath the base, there are then tied together by a set of steel braces and the supplied MDF baseboard is bolted down to this assembly.

As Carbide has no idea what a customer is going to sit their machine on, they have quite sensibly provided four adjustable feet, one in each corner to allow the frame to be aligned with the rails parallel, and optionally level.

The problem on the XXL is that the sandwich of steel straps and MDF is simply not a very rigid beam, the folds at the edges of the steel straps are quite small and don’t provide much extra support, here’s the horizontal sandwich you end up with, steel strap, baseboard MDF and user spoilboard MDF. It seems OK until you start to notice flex and sag in the middle, the two parts the MDF baseboard is shipped in don’t help here;

There is visible and very measurable flex in the baseboard and therefore your working surface, it’s easy to distort it even if it is level by clamping workpieces to it and it sags over time too. Worse, it can vibrate and move during cutting.

As the underside of the steel straps is folded edges and crinkly powder coat it’s not really a smooth surface to reference the machine from, so I decided to make simple plywood support shims to go the full length of the flat faces of the steel straps, with thin strips of rubber to provide compliance against the rough surface and absorb some vibration energy. To fix this in place I drilled through the MDF baseboard and the steel straps and put threaded inserts in my support table to make a rigid assembly;

It’s worth noting, I already had my machine well squared before committing to where the holes went and bolting things down.

All this got bolted down to the torsion box table I already had, which was sufficiently flat for my purposes to not need any significant adjustment of the machine;

Now that the machine forms it’s own torsion box assembly with the top plate of my table box, it is apparent that I massively over-built the table box and could have got away with something much thinner if I’d realised that I was joining the Shapeoko and the table into a single assembly earlier on.

Certainly for people who want their XXL to be portable, fold up to the wall etc. I’d consider the bolt it down approach.


fantastic info here thank you

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I did similar to this with the cart I made for my XL (I don’t have room to keep it set up all the time, so it needs to be stored vertically and moved around easily). I routed out grooves in my plywood top for the strap edges and countersinks for the nubs on the screw threads (so everything sits flat against the plywood), bought longer M5 screws for the wasteboard hold-downs (attached from below with nuts/washers) and M8 screws for the feet (screwed in from the bottom). Other than using different screws, no changes were needed to the Shapeoko itself. If I were to do it again, or with an XXL (since I didn’t actually learn about the sag issues until after everything was put together), I’d add additional “padding” below. It’s still a nice setup and extremely rigid.

If anyone is interested in this, or just the measurements, the CAD files are in OnShape. There is also a simple take on the XL frame and wasteboard if you just want some measurements.


Thank you @LiamN for taking the time to show me your solution.
I now see that I will need to build my Shapeoko, in order to make the perfect base components so I can then re-build my Shapeoko… which actually sounds fun to me.

Now that your Shapeoko is bolted to the box (via nine bolts through the straps) are the stock Shapeoko feet still installed and just adjusted to the new height, or did you remove those? I see them in your renderings, but wasn’t sure if they remained in reality.

Side Thought: I’ve owned my Nomad 883 for over 5 years now, and the process of researching the “perfect home” for my Shapeoko XL has made me realize just how great a product the Nomad was right out of the box. I enjoy modifying things, but there is something to be said about the fact that an hour after opening the Nomad box my kid and I were watching it make something.

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Happy to help, and as usual there’s been more ideas about how to do similar things different ways too, some involving less warranty voiding vandalism.

A major attraction for me about the Shapeoko and Carbide was the open approach to things, the controllers are based on an open firmware, you can use other gcode sender apps if you want and the forums here openly discuss all sorts of violent surgery, upgrades and replacements that would have most vendors running and hiding under a rock.

Ah, CAD vs. reality :wink:

The feet are still on the base so I don’t lose them, but they’re wound all the way up so they don’t quite touch the table, they’ve not really got much to add now.

You can’t see it very well in the CAD renders but there’s 12 bolts, I used pairs either side of the split between the two MDF baseboards that form the XXL baseboard.

My models are all in Fusion 360, let me know if you want them, I won’t guarantee accuracy but they’re a start.

You don’t need to modify the Shapeoko to get good stuff out of it, I made some pretty big chunks of desk and hundreds of litres of sawdust out of birch ply with only a bodge to make my poor selection of router spindle fit (AMB Kress).

It’s just that if you hang around here for any time you’ll find staff and customers inciting you to ‘upgrade’ your machine, feed rates, parts you make etc. :wink:

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Still needs to be milled square. The whole thing is glued down through a set of spacers to the top of a tool cabinet that weighs a few hundred points. It’s pretty solid, but still needed a little twist taken out.

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