Insulating around corners

[mnswamp]

First apologies if this has been asked before, I looked but didn't find...

Is there any reason that using multiple layers of 1/4¨ Foamular instead of kerfing a slab of full thickness insulation won't work? obviously you can't make too tight a corner, but on a 2'+ radius it seems like it should do fine. What am I not thinking about here?

[tony.latham]

I suppose it would work.

I find it easy to cut the kerfs and then press the piece in place and it stays put.





The challenge you may have is holding all those pieces in place. But I suppose there's a way to do it.



Tony

[mnswamp]

Tony,
Believe me, I'm digesting your book cover to cover as I work thru a thousand details on this build.
Ordered Timbren axles last week, sketched up the frame and started figuring out where all the holes need to go, where to put flanges, what gauge tubing,
Of all the petty reasons for wanting to avoid kerfing is that I am doing most of the work in a maker space, and the wood shop boss really frowns on anything non-wood going thru the table saw. (I might have to sneak in at 0600 to do the kerfing!)

[tony.latham]

and the wood shop boss really frowns on anything non-wood going thru the table saw.

That's damn funny.

Tony

[Tom&Shelly]

First apologies if this has been asked before, I looked but didn't find...

Is there any reason that using multiple layers of 1/4¨ Foamular instead of kerfing a slab of full thickness insulation won't work? obviously you can't make too tight a corner, but on a 2'+ radius it seems like it should do fine. What am I not thinking about here?

We did it, it did work out fine. We couldn't find 3/4 inch foam for the walls, so we bought 1" thick foam and made a 6 foot long hot wire cutter to trim them to fit. I later used some of the quarter inch scrap in multiple layers between our 19 inch radius ceiling/roof. Glued the layers together with Titebond III; clamped with scrap wood screwed between the ribs with wedges jammed in where necessary. I also tried kerfing some pieces, but preferred the layering.

Tom

[Tom&Shelly]

and the wood shop boss really frowns on anything non-wood going thru the table saw.

That's damn funny.

Tony

This may only apply to our shop in the woods, but my SOP is to sweep up the saw dust and throw it out for the wind to carry into the forest. The wood dust degrades nicely on its own. When cutting foam however, I have to carefully sweep it up, bag it, and throw it in the trash. Might be some sort of reason like that? Or, maybe he's just a pri...but that does remind me of a curious point I've contemplated occasionally: Out here, it's common to not own the mineral rights to your own property. Legalistically speaking, when I sweep up metal dust and throw it in the woods, it ceases to be mine!

[John61CT]

Even "wood" can include very poisonous materials

but certainly metal dust should not be littered, any more than chemical foam.

[KCStudly]

I ran into issues with water based and air cured adhesives not curing between larger areas of 3/4 thick foam. The foam is not permeable, so it either takes a very long time or never for the middle of a panel to cure. 1/4 thick might be more permeable?

My solution? Shallow kerfs every inch or so to act as air ducts, or chimneys. If you use PL2 or 3 between wood and foam you can use a sparse application of glue and the wood (if unsealed) will pull enough moisture to cure, but it is tricky and won't work with PL300.

For PL300 I used the shallow kerfs (for air) and spread with a small notched trowel (to avoid large beads/blobs).

[Tom&Shelly]

I ran into issues with water based and air cured adhesives not curing between larger areas of 3/4 thick foam. The foam is not permeable, so it either takes a very long time or never for the middle of a panel to cure. 1/4 thick might be more permeable?

Good point! I seem to remember having that as a minor issue. I actually layered a lot of foam in the roof, including larger thicknesses over the flat parts. But the gluing was only to tack the pieces in place so we could put the roof on, not for any strength on its own. I guess it's possible we still have glue slowly curing in there...

Tom

[Tom&Shelly]

Even "wood" can include very poisonous materials

but certainly metal dust should not be littered, any more than chemical foam.

Yes, I'm a terrible, evil, person!

Tom

[mnswamp]

Y'all hit on a couple of the reasons the table saw is 'wood only' - but here's the biggie for us. This is in a maker space with a couple of hundred members. In any given week, 30-40 different people are likely to use the Delta tablesaw. Of that 30, probably 20 are *very* casual users, and there's always one knucklehead who is planning to trim old painted casings (that may/may not contain lead paint), or do something like cut plexiglass with the general purpose table saw blade - which can ruin the blade, and/or send shards of some sort of brittle plastic all over the shop.
So the boss tries hard to keep people from doing stupid stuff, winning stupid prizes.

[KCStudly]

If you don't have your own table saw, kerfs can be made with a hand held circular saw (using a guide fence... or not) or router. Best to have a shop vac connected for dust collection... and, as always, wear proper PPE.

A small panel saw would be especially handy at this.

[Pmullen503]

First apologies if this has been asked before, I looked but didn't find...

Is there any reason that using multiple layers of 1/4¨ Foamular instead of kerfing a slab of full thickness insulation won't work? obviously you can't make too tight a corner, but on a 2'+ radius it seems like it should do fine. What am I not thinking about here?

What I thought about was using two layers, both kerfed, but gluing them together kerf side to kerf side. Like two 1" layers to equal 2" foam. That would give smooth surfaces to both the inside and outside of the curve without having to clean up a kerfed side.

This would also give air channels for any glue to dry(or expand in the case of Gorilla glue.)

[JasenC]

No reason it wont. One thing you want to keep in mind is you don't want any air gaps between sheets where moisture/condensation can accumulate, so glue everything together well.

[tony.latham]

So the boss tries hard to keep people from doing stupid stuff...

Rules are rules. I'm not sure I'd want his job.

Tony