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PMF on OSB?

PostPosted: Sun Nov 06, 2016 11:39 pm
by martymcfly
I am thinking about building a tongue box for my atv trailer out of some OSB scraps that are left from putting a new roof on my buddies moms house. I am thinking about trying PMF over OSB. Will the TB2 stick to OSB? Is OSB smooth enough to PMF?

Re: PMF on OSB?

PostPosted: Mon Nov 07, 2016 6:20 pm
by rowerwet
thicker fabric for the PMF helps to hide surface imperfections, you might also try building the box then sanding it with a belt sander to get a smoother surface.
I haven't done much with OSB, but it might be a good idea to seal the OSB with THE MIX to help stabilize the surface so you don't get buldges down the road from moisture.

Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 10:13 am
by elcam84
What is PMF. Is it FRP ?

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Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 11:27 am
by MadMango
Poor Man's Fiberglass, which is canvas impregnated with TiteBond II.

Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 2:44 pm
by tony.latham
I am thinking about building a tongue box for my atv trailer out of some OSB scraps


When I built my tongue box, I was amazed at how long it took. Granted, it has a hinged holder inside for the additional solar panels and then there's the aluminum and trim. It seems like it was a two week project.

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I'm in the "I hate OSB camp." The stuff is junk. It gets damp, it swells and never shrinks back down. And it's not TB2 friendly (like bare wood is). It was made to save $700 per house. Do yourself a favor and buy a sheet of 1/2" ACX (the CDX has too many voids). It'll cost you about $25 and will be much more resistant to moisture (but seal the interior with the mix too) plus you'll have that nice smooth surface to lay your PMF on. That kind of an investment for a two-week project is nothing.

Tony

Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 4:42 pm
by MtnDon
A big ditto to what Tony says. OSB has certain uses, all in residential construction. It is miserable stuff once wetted. As Tony says it expands and stays expanded. At that point the wood strands also loose glue adhesion. Plywood with an exterior rating is the way to go. ACX is much better than the CDX

Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 7:51 pm
by elcam84
Advantech doesn't have the moisture issues that regular osb does and has like a 5 day in the rain guarantee but I still wouldn't use it much for campers etc.
Also FYI if you want a water resistant mdf you can use medex

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Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 10:50 pm
by MtnDon
Advatech is great stuff for house sub floors. Thinnest is 19/32... most common is 3/4 or thicker. Sort of more than is needed for a box, IMO

Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 11:50 pm
by Xanthoman
MtnDon wrote:Advatech is great stuff for house sub floors. Thinnest is 19/32... most common is 3/4 or thicker. Sort of more than is needed for a box, IMO
my only experience with advantech was garbage. I have built many custom homes and the worst subfloor weathering I ever saw was done with advantech. I would not recommend it for anything! But for a trailer box I would recommend 3/8 CDx or scrapped packing crate ply (1/4-5/16 even). pmf will make a solid part with the added skin strength and the small size will make it a strong unit in the first place. I know people like to overbuild but I see no need; remember the strength of the whole unit is greater than the sum of its parts!


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Re: PMF on OSB?

PostPosted: Tue Nov 08, 2016 11:59 pm
by Xanthoman
martymcfly wrote:I am thinking about building a tongue box for my atv trailer out of some OSB scraps that are left from putting a new roof on my buddies moms house. I am thinking about trying PMF over OSB. Will the TB2 stick to OSB? Is OSB smooth enough to PMF?
having worked with osb a lot (scraps from my house builds) I would say it is perfectly doable. Like others have noted it does have water issues when left to soak it up, and certain glues are watery enough to set it off. It does glue well though, but I have only seen clamped gluing with it; not open faced surface treatment like this scenario. A decent exterior primer (zinsser bullseye) applied on it then canvas applied and primer again on top with a final coat of exterior should hold fine from my experience with the materials and others with pmf in general. As for using scrap osb see John heisz' osb stool...


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