My favorite bedding compound, Pro Bed 2000!

[Ledd Slinger]

I’d also add that Marine Tex seems to have a much longer shelf life than Devcon. And I would much rather deal with initial bedding shrinkage and correct it as needed before tuning a rifle, rather than have it suddenly surprise me later on by shrinking and causing problems at the range. But of course no shrinkage at all is the best outcome and that’s why I’m interested in this thread about the PB 2000 compound

 

[Alex Wheeler]

I’d also add that Marine Tex seems to have a much longer shelf life than Devcon. And I would much rather deal with initial bedding shrinkage and correct it as needed before tuning a rifle, rather than have it suddenly surprise me later on by shrinking and causing problems at the range. But of course no shrinkage at all is the best outcome and that’s why I’m interested in this thread about the PB 2000 compound

I dont doubt your experience, but Id say its very unique. To the point I have never heard of it happening before. You have found a process that works for you and Id stick with that. You talk about tune changing. Thats not something I have seen, even before and after gluing in an action. I have been meaning to run a test I have in mind and went ahead and picked up some of the pb2000. In the past it was too thick, but its much warmer where I am at now. So worth another try.

 

[Greg Y]

I work in hydroelectric generation and there's only two epoxies you'll find in critical applications. Devcon and belzona. They (when mixed by weight properly) are good enough to risk our MASSIVE expense of down time. Both are waaaay more than adequate for bedding.

 

[Edd]

I work in hydroelectric generation and there's only two epoxies you'll find in critical applications. Devcon and belzona. They (when mixed by weight properly) are good enough to risk our MASSIVE expense of down time. Both are waaaay more than adequate for bedding.

Which Devcon and which Belzona? There are a lot of choices.

 

[Greg Y]

Which Devcon and which Belzona? There are a lot of choices.

10110 and 1111 are the two major players here.

 

[WSnyder]

Well I did a small test blob of PB2K with acetone added. It readily took the acetone and didn’t do anything weird as far as mixing it. I pushed it into a nice tight blob and over 10 minutes or so it’s flowed out quite a lot. Probably doubled in surface area. Let’s see how it hardens up.
View attachment 1546314

Update: Hard as a rock. Broke cleanly in two pieces when put in a vise and smacked with a screwdriver handle. I don’t think the acetone had any negatives that I see so far. I’ll see about mixing a cube with acetone added this weekend, machine it flat and see what that does over time.

 

[MClark]

I use different materials for different areas of the bedding.
I make one mix of the epoxy parts, West System split up and add as require. Pot life is hours so I can do all this.
The recoil lug area gets reinforced with 1/8” chopped glass fibers until it is like modeling clay.
Under receiver add Cabosil to thicken to prevent running.
Barrel has tape to leave gap. Any really low areas have micro balloons to reduce weight.
In picture it is a Mannlicher style and has two layers of carbon fiber cloth with just resin. carbon goes all the way to end of receiver.

 

[WSnyder]

Update: Hard as a rock. Broke cleanly in two pieces when put in a vise and smacked with a screwdriver handle. I don’t think the acetone had any negatives that I see so far. I’ll see about mixing a cube with acetone added this weekend, machine it flat and see what that does over time.

So Thursday evening I mixed up a batch and thinned with acetone to what I’d say was a pourable but thick molasses consistency. Friday afternoon the top was setting up but still soft, the bottom was still gooey. Keep in mind this was poured into a piece of PVC at ~.500” thick. As of today (Saturday afternoon) the top is hard (I can’t mark it with a fingernail) but the bottom (I just peeled it off the wax paper) is still soft enough to put a fingernail into. It seems that the acetone has slowed the setup. I’ll leave it standing on edge so both sides are exposed and see if it fully sets up.

 

[Sniperhandle]

So Thursday evening I mixed up a batch and thinned with acetone to what I’d say was a pourable but thick molasses consistency. Friday afternoon the top was setting up but still soft, the bottom was still gooey. Keep in mind this was poured into a piece of PVC at ~.500” thick. As of today (Saturday afternoon) the top is hard (I can’t mark it with a fingernail) but the bottom (I just peeled it off the wax paper) is still soft enough to put a fingernail into. It seems that the acetone has slowed the setup. I’ll leave it standing on edge so both sides are exposed and see if it fully sets up.
View attachment 1548046View attachment 1548047

Thanks for experimenting with it.

 

[Jud96]

This thread is convincing me to test Pro Bed for shrinkage vs Devcon. I haven’t found any real world data on shrinkage but Pro Bed is slow to set up so it makes me think it may shrink less.

 

[WSnyder]

Machined both sides early in the week. Got busy and distracted and forgot about it until yesterday (Friday 26).
Fri 26 rock hard both sides. .4545” thick.
Sat 27 .4545” thick.

 

[Sniperhandle]

Machined both sides early in the week. Got busy and distracted and forgot about it until yesterday (Friday 26).
Fri 26 rock hard both sides. .4545” thick.
Sat 27 .4545” thick.
View attachment 1550171

Looks like acetone should be fine, Just extended cure times.

 

[WSnyder]

Looks like acetone should be fine, Just extended cure times.

For sure. It was so soft on that bottom side at first I was wondering if it would actually harden. Looks like it did.

 

[Edd]

How can the Acetone evaporate from the mixture without causing shrinkage?

 

[Hal]

MClark

Your idea of mixing different bedding compounds for the different areas
of a rifle stock sounds great.
What is a good source for the required material.
West Systems epoxy,chopped glass,micro balloons carbon fiber cloth ?

Hal

 

[WSnyder]

How can the Acetone evaporate from the mixture without causing shrinkage?

Not sure. The first question was if it would tolerate adding acetone to thin it. I couldn’t measure it while it was still soft. I’m measuring it from when it set to see if it changes over time. Next I might bed a test cylinder with the acetone mix and see how the fit does after it sets up.

 

[Phys86]

Not sure. The first question was if it would tolerate adding acetone to thin it. I couldn’t measure it while it was still soft. I’m measuring it from when it set to see if it changes over time. Next I might bed a test cylinder with the acetone mix and see how the fit does after it sets up.

Wouldn't it be pertinent to machine it earlier, so that the amount of shrinkage during curing could be measured?

If it's still soft (firm but leaving a fingernail mark), I don't know how it'd machine. Maybe not possible?

 

[Phys86]

I use different materials for different areas of the bedding.
I make one mix of the epoxy parts, West System split up and add as require. Pot life is hours so I can do all this.
The recoil lug area gets reinforced with 1/8” chopped glass fibers until it is like modeling clay.
Under receiver add Cabosil to thicken to prevent running.
Barrel has tape to leave gap. Any really low areas have micro balloons to reduce weight.
In picture it is a Mannlicher style and has two layers of carbon fiber cloth with just resin. carbon goes all the way to end of receiver.



View attachment 1547510

Very slick. Would you mind showing more pictures of the bedding in that mannlicher?

 

[WSnyder]

Wouldn't it be pertinent to machine it earlier, so that the amount of shrinkage during curing could be measured?

If it's still soft (firm but leaving a fingernail mark), I don't know how it'd machine. Maybe not possible?

I machined it when the bottom could still be indented slightly with a fingernail. With a sharp 1/2" cutter taking my time it did fine.

 

[boltfluter]

Machined both sides early in the week. Got busy and distracted and forgot about it until yesterday (Friday 26).
Fri 26 rock hard both sides. .4545” thick.
Sat 27 .4545” thick.
View attachment 1550171

Thanks for taking one for the team and sharing your results! Very interesting.
Paul