Thrifty Alternatives ..Building Foam Campers

[HandyAtLeast]

Anyone thought of or tried using 3Mâ„¢ FoamFast 74 Spray Adhesive? I've used Super77 and it works great. Seems like one can would do it for a TD.

[GPW]

DON'T PANIC !!! The sanded surface adheres much better (the tooth) , and Now I'm trying the full strength T2 instead of the 50/50... and remember the household iron is your friend ... I went back on some suspect areas , and ironed them @ 275F and now they are darn near impossible to remove... so any lifting can be quickly taken care of with the iron ... I believe the extra heat actually slightly melts the fabric/glue into the foam ...
For joining foam to foam with the fabric in between, I plan to perforate the cloth with a pounce wheel which will create little glue "nails" through the fabric and foam (gorilla glue) ... Should be plenty strong ...
' Cars , the 1/2" will bend easily on large radius bends , like a TD , better with a little heat ...
HAL... That would probably work great too... just we haven't tried that .... as yet ... Many glues yet to be tried ... Who'll be first ?

[GPW]

All Done ... inside anyway ...

[HandyAtLeast]

Thoght I'd throw in some thoghts on bending foam sheets with kerfs. With a little math you can figure out the number and size of kerfs to cut in foam to get a desired radius.

Example:



Lets say you have a sheet of foam that is 1 inch thick and you want to make a 90 degree bend with a 6.4 inch radius. This is a very tight bend for this kind of foam, but with some kerfs cut in it, you can do it.



First some math. Illustrated above you see a 90 degree bend in 1 inch foam with a radius of 6.4 inches. We need to find out the arc length of the outside and inside curves of the foam. This will help use figure out how wide the kerfs need to be.

The formula for finding the arc length is:

arc length = (angle of bend / 360) x 2 ( pie x radius)

so we have:

10 inches = (90 degrees / 360) x 2 (3.14 x 6.4 inches)

The arc length of the outside curve is 10 inches. Then with the same formula we find that the arc length of the inside curve is 8.4 inches.

When we subtract the two we have a difference of 1.6 inches. This is how much material we need to remove from the inside curve with kerfs.



So, if we decide to make 5 kerfs on the inside of the foam, they will have a spacing of about 2 inches apart and 1 inch from the end.



Divide the 1.6 inches by 5 and you get 0.32 inches. This is how wide each kerf needs to be. The kerfs should be cut to a depth of about 75% of the 1 inch foam thickness in a triangular shape. the widest part of the kerf will be 0.32 inches. This can be done with a straight edge and a sharp utility knife.

OR if you want to make the kerfs with a circular saw and more kerfs, then you would divide the 1.6 inches by the thickness of the saw blade (also called the kerf of the blade.) With a 1/8 inch thick blade you would need to make about 13 kerf cuts spaced evenly apart. ( 1.6 / 0.125 = 12.8 )



Apply some glue inside the kerf cuts and bend the foam to the needed radius. It should hold its shape fairly well on its own after the glue dries.

[GPW]

HAL, That's BRILLIANT!!! ...

[CARS]

HandyAtLeast .... your screen name is the understatement of the year!!

That my friends should be a sticky (because there is no way I am going to remember the equations )

[HandyAtLeast]

Thanks GPW and CARS! I have yet to really put it up to the test of real world use, but I'm going through the mental exercises. I find that if you can figure out as many ways to do something, it opens up the design possiblities.

[swampjeep]

question on these kerfs, once you have them cut, and you know the foam will bend to the desired rad. would you dab a line of glue in the kerf so it strengthens the faom and locks in this rad? or is this not needed? or possibly even mess it up somehow?

[CARS]

question on these kerfs, once you have them cut, and you know the foam will bend to the desired rad. would you dab a line of glue in the kerf so it strengthens the faom and locks in this rad? or is this not needed? or possibly even mess it up somehow?

Handy said "Apply some glue inside the kerf cuts and bend the foam to the needed radius. It should hold its shape fairly well on its own after the glue dries."

It's on the very last line under the last pic.

[HandyAtLeast]

I think if you used the appropriate glue, it would hold fairly well. If you are just wrapping the top around the TD shaped walls, then it may not be necessary. It would help to strengthen it though, if the kerfs were glued.
Gorilla glue expands, so taping/strapping/clamping somehow would be necessary.

[Ratkity]

DON'T PANIC !!! The sanded surface adheres much better (the tooth) , and Now I'm trying the full strength T2 instead of the 50/50... and remember the household iron is your friend ... I went back on some suspect areas , and ironed them @ 275F and now they are darn near impossible to remove... so any lifting can be quickly taken care of with the iron ... I believe the extra heat actually slightly melts the fabric/glue into the foam ...
For joining foam to foam with the fabric in between, I plan to perforate the cloth with a pounce wheel which will create little glue "nails" through the fabric and foam (gorilla glue) ... Should be plenty strong ...
' Cars , the 1/2" will bend easily on large radius bends , like a TD , better with a little heat ...
HAL... That would probably work great too... just we haven't tried that .... as yet ... Many glues yet to be tried ... Who'll be first ?

Eagle and I had no problem with the canvas even thinking about coming off with the full strength T2 glue and also with the copious amounts that were used. The glue permeated the canvas. We also wrapped it under the wood floor and had it stretched smooth and attached it with a staple gun. I think full strength T2 is the key. That stuff is going nowhere.

Hugs,
Ratkity

[Conestoga]

... I think full strength T2 is the key. That stuff is going nowhere.

Hugs,
Ratkity

i reckon if T2 worked just as well watered down, they would surely sell it watered down.

[GPW]

Although I've used the watered down glue in the past for various projects , I think Rat's (and Eagle) right about this ... I was just trying to be Thrifty ... Penny wise and Glue foolish .. Full strength T2 from now on ... and I will be prepping the surface too .... Just trying to get the Best results , mainly for everybody else who tries this ... After all , none of us wants any troubles down the road ...

[eaglesdare]

DON'T PANIC !!! The sanded surface adheres much better (the tooth) , and Now I'm trying the full strength T2 instead of the 50/50... and remember the household iron is your friend ... I went back on some suspect areas , and ironed them @ 275F and now they are darn near impossible to remove... so any lifting can be quickly taken care of with the iron ... I believe the extra heat actually slightly melts the fabric/glue into the foam ...
For joining foam to foam with the fabric in between, I plan to perforate the cloth with a pounce wheel which will create little glue "nails" through the fabric and foam (gorilla glue) ... Should be plenty strong ...
' Cars , the 1/2" will bend easily on large radius bends , like a TD , better with a little heat ...
HAL... That would probably work great too... just we haven't tried that .... as yet ... Many glues yet to be tried ... Who'll be first ?

Eagle and I had no problem with the canvas even thinking about coming off with the full strength T2 glue and also with the copious amounts that were used. The glue permeated the canvas. We also wrapped it under the wood floor and had it stretched smooth and attached it with a staple gun. I think full strength T2 is the key. That stuff is going nowhere.

Hugs,
Ratkity

i did not have that shiny smooth sided foam though. so our t2 with canvas worked fine. i did wonder about that smooth sided stuff.

[GPW]

Eagle , I went back and looked at your foam... Marked Loew's ... Mine's Dow ... Noticed the surface of yours was much rougher than mine ... That apparently is a "Good Thing" ...!! I wonder how the Pink stuff is surfaced ...???

Now since I plan on rounding out my edges any way , the plan was/is to put some 36 grit on my palm sander and have at the whole shiny surface , before covering ... Shouldn't take long ... just another step on my slick foam ...
I have to check at Loew's again , see what they have ... Keep thinking about that second one ...