Plywood camper fabrication questions (thinking of idaSho)

[Alloy]

I'm essentially working out of my garage that's been converted into a woodworking shop, so true open floor space is basically 0. If I frame this thing up it can be done outside, in the driveway, or on the truck itself and not take up any valuable garage space. I live in San Diego so weather is not much of an issue.

I have a great table saw station and the plan would be to run everything through that - Just get a dado stack, hook up the vacuum to the saw and run a lot of foam through it. Admittedly I've never cut XPS like this so if it is a nightmare I'd look into other options. I was dissuaded from the PVC foam by the cost but if it make my life easier I'm not opposed to it.. When I start diving into this I'll likely make a lot of prototypes, if anything just to nail down the process before I try it on the actual rig.

Corner framing is flexible, I'd probably use something more like a typical CA corner used in home framing. I think the point I wanted to get across was using the pw studs. It is similar to what TC does, and it gives you the option to glue interior parts on while using screws to hold them in place while the glue dries. Or in the case of small things, ie coat hooks, paper towel holders, etc, you could simply screw them on and know they've got more than 1/8" of purchase in wood.

Also, This build will likely be years in the making, and I want to be able to use it in the meantime. It likely won't be as nice and integrated as a lot of campers you'd see here because I want it to be usable once the shell is complete. The plywood studs provide some flexibility with tweaks to interior layout.

Static electricity makes the foam stick to everything so cleaning the dust collection takes forever. After the dust collector is empty then you spend 1/2 an hour cleaning the foam that spread everywhere else.

 

[IdaSHO]

I have a great table saw station and the plan would be to run everything through that - Just get a dado stack, hook up the vacuum to the saw and run a lot of foam through it. Admittedly I've never cut XPS like this so if it is a nightmare I'd look into other options.

Its a nightmare.

Regardless of the amount of shop vac suction...

Think a shop full of static cling powdered sugar.

Its that bad.

 

[Alloy]

I still don’t think I’d want to cut channels out of it. That sounds like a nightmare!

I hot knife channels with a bent 1/32" welding rod and guide.

 

[Alloy]

FYI on cutting essentially any ridged foam...

A band saw with a fence on it makes quick work with near zero mess.

Also, if you dont have the option of a band saw, a fresh blade on a utility knife does very good,
but doesnt get all the way thru, and snapping it may create an undercut. Finish the cut with a bread knife.

What blade? Probably a better than I have. I was using a 1/2" - 12 tooth raker blade on a 24" bandsaw. The flywheels picked the foam up and filled everthing with foam particles including the open face motor which wasn't good.

 

[IdaSHO]

Blade that was on it at the time.... most likely a 3/8 6-tpi wood blade that I normally use.
Bandsaw is a small but mighty 3-wheeled Inca 710 stationary. 20" throat capacity as I recall.

Nothing special about it really, but it cut foam great without the issues you speak of.

What speed is yours running at? Maybe its too fast? Mine runs pretty slow.

 

[rruff]

Also, if you dont have the option of a band saw, a fresh blade on a utility knife does very good,
but doesnt get all the way thru, and snapping it may create an undercut. Finish the cut with a bread knife.

I used the long bladed knifes with the snap off blades.

My first try was a jigsaw with knife blades. Maybe I did something wrong, but I had no luck with that...

 

[ReluctantTraveler]

I hot knife channels with a bent 1/32" welding rod and guide.

clever!

 

[renglekirk]

Its a nightmare.

Regardless of the amount of shop vac suction...

Think a shop full of static cling powdered sugar.

Its that bad.

Lol maybe I'll reconsider this method..I have a pretty decent dust collection set up but the static electricity throws a wrench in things.

 

[1000arms]

With regards to plywood framing, I considered it but its screw/nail holding capability on end grain is terrible.
And unless you are paying good money for boil proof, void free ply, IMO you are asking for trouble.
The issues with voids and delamination in todays plywood is terrible. Ive been finding voids in baltiv birch lately.
Well, almost lately... I snagged a unit of both 1/2" and 3/4" 5x5 months ago in hopes of weathering the Russia debacle.

Framing I used is "1x2" 3/4"x1-1/2" vertical grain Fir. Tough, stable, and lightweight.

There are a lot of boats made from plywood that are strong, light, and long-lasting when done well, and boats are expected to float in water rather than just shed rain.

I'm not saying that @ReluctantTraveler should make a plywood frame for his camper, but that he could make a plywood fame from overlapping strips of plywood that would be very strong. Just thinking about how to do so might help him continue his understanding of just how effective the right adhesives can be.

I also wish plywood was consistently made much better than it often is today.

 

[renglekirk]

but that he could make a plywood fame from overlapping strips of plywood that would be very strong.

Agree, I make a lot of projects out of glued up plywood and find that glue penetrates the end grain of plywood really well and often time makes a much stronger connection than solid lumber would. You can get more blowout if you're not careful, but a well constructed plywood stick or connection can be incredibly strong. Plus you're not limited to the lumber sizes you can find at your local lumber yard. This assumes you're buying quality plywood and baltic birch (what I use) in particular is not easy to source or cheap atm.

 

[ReluctantTraveler]

That's all great, but I think presumes a greater level of builder skill and expertise than I likely possess.

Which is to say: you may not be wrong, but it might not be the right advice for the current audience (as in, me).

 

[1000arms]

That's all great, but I think presumes a greater level of builder skill and expertise than I likely possess.

Which is to say: you may not be wrong, but it might not be the right advice for the current audience (as in, me).

... Well, you seem pretty interested making a camper from wood, plywood, foam, PL Premium Construction Adhesive, epoxy, and fiberglass. ... You seem to have become much more comfortable with the thought of using adhesives to hold things together. ... I'm just suggesting that in addition to the cutting and gluing that you would need to do to use IdaSHO's, method, you could do more cutting and gluing for an even stronger frame, if you think you need to. ...

Respectfully, if you have the skills to build an IdaSHO style camper (or will develop them along the way), you have (or will have) the skills to do the additional cutting and gluing.

That being said, I don't think that you need to make your frame from strips of plywood. I know that you were concerned about frame strength, and I mentioned the layered plywood frame as a way that you could increase frame strength.

 

[1000arms]

I'd advise making lots of samples and test pieces and destruction testing them, if you have questions about your design.

I need to burn this into my brain. Every custom camper is an experiment, and the more R&D you do beforehand, the better!

I'll suggest buying some popsicle sticks, wood glue, and construction paper. Build a frame, skin it with the construction paper, then reinforce the construction paper with wood glue. Follow this with some destructive testing. A cheap, fun, and informative way to burn it in to your brain, and possibly a family activity.

 

[ReluctantTraveler]

I know that you were concerned about frame strength, and I mentioned the layered plywood frame as way that you could increase frame strength.

Nod nod, that all makes sense!

The use of structural foam over cheap XPS alleviates a lot of those concerns, I think.

 

[1000arms]

Nod nod, that all makes sense!

The use of structural foam over cheap XPS alleviates a lot of those concerns, I think.

Good!

... I'm pretty sure that you are comfortable with using adhesives rather than mechanical fasteners now that you are thinking about using structural foam. ...