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I'm considering building an 18" drum sander which will be used for hardwoods (making another chess board). I was considering using some 3.5" PVC pipe and gluing some 60 grit sandpaper to it. My concern is whether the heat will warp or distort the PVC, and am wondering if anyone has any experience with that.

For more details -- I plan on attaching the drum to a 3/4" steel rod, and 3D printing some mounting wheels. The mounting wheels would be ABS, and would have angled spokes, that they act as a fans, forcing air through the center of the jig as it turns (hopefully cooling enough). As far as a motor goes, I was going to attach it via a pulley to a grinder at about a 2:1 ratio (so around 100 rpm). I was going to build two drums -- one 60 grit, and one 180 grit.

But PVC has a maximum operating temperature of around 65C, which I'm afraid I'll pass. I'm wondering if anyone has tried this, and what experiences they had.

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  • You could make a quick test jig out of a short piece of pipe with a wooden mounting wheel and see what happens (counter sink a couple of screws for a quick 'n dirty mount of pipe to wheel). Save you the time and material of the 3D print. You might want/need to drill some diagonal holes through your wheel to allow for some cooling effect.
    – FreeMan
    Feb 25, 2022 at 17:30
  • Well experientially PVC does soften enough to distort at temps I would have estimated to be approx upper 50s or low 60s (based on other relevant temperature markers I'm familiar with). But whether this is a temp range your drum will reach in service nobody can say since there are unknowable factors. I would suggest you just make your central cylinder from wood so you can avoid the issue entirely, or, make a slightly smaller cylinder that you can glue inside the PVA pipe to support it. [You don't need a lathe for this.]
    – Graphus
    Feb 25, 2022 at 20:12
  • There are a lot of variables here. How hot do different papers/meshes get? Does the paper or glue backing change anything? And so on. Thermals are hard. This might mean only your experimental evidence might hold. What you are concerned with is the "HDT", which for PVC is probably too low for you to use like this. Maybe ABS is a better choice?
    – user5572
    Feb 25, 2022 at 20:37
  • @jdv, that's some of what I was getting at. But for a fixed paper type, wear on the abrasive and the setting of the roller play a massive role in differences in heat generated. Meaning it's easy to posit a single design that works fine initially and then a problem shows up later..... so bottom line, wood will solve all these issues (in addition to being far, far stiffer). And FWIW almost every DIY sander has a wooden drum, so there's that.
    – Graphus
    Feb 26, 2022 at 5:38
  • @Graphus I think we are in agreement and I just wanted to point out that PVC is, indeed, rather unique in how it handles heat making it the least useful material for this purpose. I've rolled up the hive-mind thoughts into an Answer because why not?
    – user5572
    Feb 26, 2022 at 14:43

2 Answers 2

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I think the consensus involves roughly two notions:

  1. PVC has a rather low HDT, or Heat Deflection Temperature. With plastics it isn't just about at what temperature they go noticeably soft, but at what temperature range are they unable to maintain their shape under sustained load.
  2. Honestly, I don't think anyone here knows how much heat your proposed system will generate, and whether or not it'll get up to ~50C, which is the lower bounds of the the HDT range for PVC.

That being said, I don't think PVC is the right material. It is somewhat unique among plastics for having a very low HDT, and is famous for deforming under pressure and modest heat. It is almost never used for applications above "room temperature", at least not where there aren't litres of water flowing through them to carry away the heat. The fact that PVC is acceptable for high efficiency furnace exhausts speaks to how little waste heat condensing furnaces make. Not to mention that it took years for building code to allow for PVC exhausts (in my locale, anyway) because it wasn't a sure thing that they would hold up to the modest heat and corrosive environment.

If you are going to be watching the thermometer instead of the work then the tool won't be as useful. And if one day you forget you are going to deflect the drum well out of round and it'll be near impossible to make round again.

I would suggest ABS if you are hell-bent on using plastic. I'd skip the fancy 3D printed insert and go for wood circles to drive it, or something equally as rigid.

But, honestly, the traditional material for sanding drums is wood and there is a reason for that.

  • Wood can be resurfaced round again, for years and years
  • Forgiving surface when you push a bit too hard
  • Durable enough that you won't have to be dainty with it, and can get much hotter than any plastic if that happens by mistake

So, while I don't empirically know how this material will work in this application, if I put on my materials sciences hat it doesn't sound like the right material. And if I look to the years of tradition for sanding tools I don't see many (or any?) examples of any sort of plastic being used like this, for either home-made or commercial products.

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I built my own 22" drum sander and I see one main problem with using PVC, and that is that it will be difficult, if not impossible, to make the drum parallel to the bed of the sander.

Here's a link to my sander: https://www.lumberjocks.com/showcase/home-made-22-drum-sander.51692/

What I did was made a bunch of discs out of 3/4" MDF and glued them together over the shaft, and mounted the shaft on pillow blocks. The discs don't have to be perfect.

Then, to make parallel to the bed, I took a piece of very flat plywood and glued 60 grit sandpaper (the same stuff I used for the drum) to the flat plywood. This is my sanding block.

You use this upside-down, so that the block rests on the bed with the paper facing up. Lower the drum (or raise the table, as in my design) so that the drum barely touches the sandpaper, and work your way across the drum truing it up. Then continue lowering the drum or raising the bed until you get a smooth drum across the whole length. Use pencil lines on the drum to see where/if it needs to be sanded more.

I've built this thing in 2006 and never once had to re-tune up the drum.

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