Tom & Shelly's build

[Tom&Shelly]

Received the two candidate rubber seals this afternoon:



My initial reaction is that 50% compression, or even 30% is way too much for these.

I was able to compress the one to the left from 1/2" to 1/4" with the vise, but only by tightening hard, and that causes it to squeeze out the sides



Gave the one to the right a similar treatment, but only got to 3/8"



(Both seemed to recover without obvious permanent deformation.)

Difficult to build a jig that will exactly duplicate the conditions, but I'm thinking compressing either of these by much more than 1/16" or so may be a mistake. It's like turning a propane cock too tightly. It wears them out prematurely by eventually permanently deforming the rubber, and you have to keep tightening harder. I'll do some research and see if I can build a jig to test...

Right now I'm thinking of using the D seal for the hatch, and might use the other one for the cap over the battery case, which is open to the bottom of the trailer, and so will need a good dust seal.

Tom

[tony.latham]

My initial reaction is that 50% compression, or even 30% is way too much for these.

That's a good bit of research. I'll for sure buy some seal and test my mockup sometime soon.

I decided on a 3/8" lip on the inner walls:

What plywood? Do you feel you need a wider lip for sealing or for strength?



Tony

[tony.latham]

I just found this recommending a 25% compression for 1/2" Trimlock D-shaped seal. I'm sure that's for a flat surface compressing it.

https://www.trimlok.com/rubber-extrusion/epdm-seal/d-profile/101-series

Tony

[Tom&Shelly]

I decided on a 3/8" lip on the inner walls:

What plywood? Do you feel you need a wider lip for sealing or for strength?



Tony

Hi Tony,

Guess I didn't state that clearly. The lip will be 3/8" tall and 1/4" wide, using the 1/4" Baltic birch. My thinking on the 3/8" tall lip is that I'll have 1/8" gap between the outer wall and hatch side, and this gives 1/4" the water has to go to even see the seal.

Tom

[Tom&Shelly]

I just found this recommending a 25% compression for 1/2" Trimlock D-shaped seal. I'm sure that's for a flat surface compressing it.

https://www.trimlok.com/rubber-extrusion/epdm-seal/d-profile/101-series

Tony

Good! The seals I bought are EDPM, but I don't think they are the sponge rubber (air bubbles inside the rubber), and are harder. (I think McMaster-Carr also sells the sponge rubber D seals.) I may decide to buy sponge rubber in the end.

First though, I think I'll try building a little jig and see how much compression of the seals in hand seem to like with a 1/4" lip pressing on them. I'll report the results.

Tom

[tony.latham]

First though, I think I'll try building a little jig and see how much compression of the seals ....

I ordered some 1/2" x 1/2" this morning and will stick in my mock-up and will let you know what I think.

Tony

[Tom&Shelly]

First though, I think I'll try building a little jig and see how much compression of the seals ....

I ordered some 1/2" x 1/2" this morning and will stick in my mock-up and will let you know what I think.

Tony

Thanks Tony, I'm looking forward to hearing your results.

Hope you didn't buy the entire 500 ft roll! (Didn't see how to buy small amounts from that web page, but didn't look too hard yet.)

Here is what I believe is the McMaster-Carr version of the same stuff (someone cited this page years ago on here somewhere), they call it EDPM foam:

https://www.mcmaster.com/door-weatherstripping

I bought the EDPM hard rubber, which is probably too hard for the hatch seal. I think it should work fine for my battery door seal, and I'm sure I'll find other uses for it.

Tom

[KTM_Guy]

I think you are better with the foam type EDPM (Not open cell foam that will hold water) over the high density foam. I did my hatch a little different than the manual. Instead of using the 1/8" router bit (dangerous in my opinion) I used a 3/8" bit to give me a bigger gap which I use a 1/2" EDPM hard foam gasket on. This gives me another sealing gasket along with the normal one in the Fredricks manual. May main reason is not for water but dust. So far it seems to be working fine, I will at some point change the EDPM to the foam type. We have been having some cold wether (Don't laugh cold for us, I even wore long pants to work two days this week) around 30 degrees and that high density foam was like a rock. Very little compression or spring back.The low density or foam EDPM I had in the garage was much more squishier. Is that a word?

Todd

[Tom&Shelly]

I think you are better with the foam type EDPM (Not open cell foam that will hold water) over the high density foam. I did my hatch a little different than the manual. Instead of using the 1/8" router bit (dangerous in my opinion) I used a 3/8" bit to give me a bigger gap which I use a 1/2" EDPM hard foam gasket on. This gives me another sealing gasket along with the normal one in the Fredricks manual. May main reason is not for water but dust. So far it seems to be working fine, I will at some point change the EDPM to the foam type. We have been having some cold wether (Don't laugh cold for us, I even wore long pants to work two days this week) around 30 degrees and that high density foam was like a rock. Very little compression or spring back.The low density or foam EDPM I had in the garage was much more squishier. Is that a word?

Todd

Nearly the same latitude, about 6200 ft difference in altitude! But I think it was about 30 out when I took the hard rubber seals into my 50 degree shop and let them sit for awhile before the informal testing.

Actually I'm not using an 1/8" router bit. Couldn't find the parts Steve Fredrick used to convert his. I plan to draw two lines 1/8" apart on the wall and cut between them with the jig saw. Then I'll use the two prepared patterns (wall and hatch side) and a template bit to route the cuts neatly.

Your method sounds interesting.

We both know what you mean by squishier, so I think it must be a word.

Tom

[tony.latham]

Nearly the same latitude, about 6200 ft difference in altitude!

Holy, smokes... I'm at 4,000 and 45º

I just received a roll of 1/2" x 1/2" Trim-Lok D-Seal. I think this is what I'll go with



It'll work well with an 1/8" of compression.

Tony

[Tom&Shelly]

Nearly the same latitude, about 6200 ft difference in altitude!

Holy, smokes... I'm at 4,000 and 45º

We're one of the fastest growing mountains in the world! Geologists say that in a million years we'll be higher than Everest. That's why I bought here, property is going up!

I just received a roll of 1/2" x 1/2" Trim-Lok D-Seal. I think this is what I'll go with



It'll work well with an 1/8" of compression.

Tony

Thanks Tony. I ordered some of the Trim-Lok seal tonight.

Tom

[tony.latham]

I used a 3/8" bit to give me a bigger gap...

Todd:

A spiral upcut bit with a bushing and template? Carbide?



Tony

[KTM_Guy]

I used a 3/8" bit to give me a bigger gap...

Todd:

A spiral upcut bit with a bushing and template? Carbide?



Tony

Yes, yes and yes. Did a few passes. I’ve been real happy with the Whiteside bits from Amazon. Been replacing all my old bits with them when I need to replace.

Todd

[tony.latham]

I used a 3/8" bit to give me a bigger gap...

Todd:

A spiral upcut bit with a bushing and template? Carbide?



Tony

Yes, yes and yes. Did a few passes. I’ve been real happy with the Whiteside bits from Amazon. Been replacing all my old bits with them when I need to replace.

Todd

[Tom&Shelly]

So here is what I'm planning:



Did this in Power Point 97 and converted it to a jpeg. There shouldn't be any (unmarked) spaces between the wood (hopefully!)

Think maybe the 1/8" gap between the exterior wall and hatch cover will help water run out/evaporate. Mostly, I'm doing it because it's within my capabilities to cut good enough with the jig saw and square up each side with a router and templates.

I'll keep the inset to 3/8" tall. Think that's tall enough to help prevent water from running up there (or back there for the region along most of the hatch), and hopefully it will be less likely to break in case of accidental contact with a frying pan or anything like that while the hatch is open.

And, as previously stated, I'm leaving the inner skin (1/8" in the cabin) off.

Finished sanding the walls last weekend. Not perfect, probably not good enough for glossy auto paint, but right now it's good enough for hammer finish or bedliner. If we decide to go for a smooth finish, we can always sand more after the walls are erected. We'll have to do that where it joins the roof anyway.

Finally received the Kreg Jig. (FedEx driver couldn't make it back here because the road was muddy! You would think they'd equip them with the proper vehicles for country delivery!) Anyway, when I tried it, I still found the 1/8" Baltic birch splinters too much for my taste. Guess we'll put the toe-screws in from the (fiberglassed) outside and fill them with epoxy/phenolic (or saw dust). More work, particularly on a (then) vertical wall. Maybe we could get away without the toe-screws, but I'd rather build the way others have and not worry about it. We will also put screws up vertically from the floor into the plywood skeleton (probably dipping the screws in PL Premium as we put them in.

Tom