Gunsmithing Curing JB-Weld for scope base bedding?

[jvencius]

I tried bedding my scope base (Seekins base on a SA Rem.700) today following the instructions on 8541Tactical and it didn't go all that well. Since there wasn't much more than a hair's-width of light showing at one edge of the base, I guessed no more than a skim-coat of bedding would be a good idea. I followed the prep instructions carefully, i.e. degreasing the receiver/base, applying a thin coat of neutral shoe polish to the receiver with Play-Doh plugging the rear receiver holes, and then going with the aforementioned trace of JB-Weld for bedding. However, when I removed the two front screws and removed the base, a very thin smear of it stayed on the receiver and it wasn't cured even to a "hard" level vs. being completely solidified. I was able to use a razor blade to very carefully scrape the uncured JB-Weld off the base receiver (the anodizing stayed intact) so things should be fine for re-trying tomorrow.

So, my questions are as follows:

1) I let the JB-Weld cure for 4 hours (didn't touch the rifle at all in that time), so how much longer should I let it sit? I figure it should be fairly well cured in 6 hours but I don't want to go too long and glue the base to the rifle with bedding compound.

2) About how much shoe polish should I use as a release agent? Sure, that's something of a non-quantifiable answer, but I'm wondering if I might not have used too much and that polish interfered with the JB-Weld curing.

3) If I've done things right and used the proper amount of release agent, should any bedding compound remain on the receiver or should it all come off attached to the base?

 

[The Mechanic]

Re: Curing JB-Weld for scope base bedding?

IMHO I think you did not mix the JB Weld well enough. I have used it to repair so many things you would be amazed. It seems the only thing that will do that is not mixing well enough. Sometime you get a thin layer stuck to the bottom of whatever you are mixing it on and when you go to scrape it up to put on what you are glueing you get some unmixed mixture and soft spots.

 

[jvencius]

Re: Curing JB-Weld for scope base bedding?

You may well be right--I mixed it until the material was uniformly gray but stopped as soon as that happened so I'll be more thorough tomorrow on try #2...

 

[hero's machine]

Re: Curing JB-Weld for scope base bedding?

Pay attention to the temp of gun too, extra cold takes extra long. Keep some leftover and when it is set up....you are gtg.

 

[Tripwire]

Re: Curing JB-Weld for scope base bedding?

Mix right, let it sit all night......

 

[jvencius]

Re: Curing JB-Weld for scope base bedding?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tripwire</div><div class="ubbcode-body">Mix right, let it sit all night......</div></div>

The mixing part I understand, but would letting it sit that long "overwhelm" the shoe wax and glue the base to the receiver? This is the first time I've ever had a rifle nice enough to warrant putting this much time into optic mounting so I don't know from experience how long a release agent like shoe polish remains effective.

 

[hero's machine]

Re: Curing JB-Weld for scope base bedding?

Don't sweat the life of the release.

 

[AXEMAN]

Re: Curing JB-Weld for scope base bedding?

when i did mine, i put on a coat of wax, let it dry and buffed it off, then i did it again. i forced wax in the holes and waxed the base and receiver, i think. receiver for sure. then coated the base and set it in place using a qtip to clean the holes which i waxed, and then finger tightened the front and rear screws and cleaned the ooze. let the jb set for an hour so it wont flow out and leave a void. after it cured, i never took it off. the jb that didnt cure for you would have if you had given it time.

 

[Tripwire]

Re: Curing JB-Weld for scope base bedding?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jvencius</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tripwire</div><div class="ubbcode-body">Mix right, let it sit all night......</div></div>

The mixing part I understand, but would letting it sit that long "overwhelm" the shoe wax and glue the base to the receiver? This is the first time I've ever had a rifle nice enough to warrant putting this much time into optic mounting so I don't know from experience how long a release agent like shoe polish remains effective. </div></div>

Dude...I bed my rails with tougher shit than JB weld and just leave 'em on there. Not really sure why you would want to seperate it, then remount it, but whatever. Yeah, I've taken some off over the years to swap out to a different system, and they've always just came right off using some form of car wax as a release agent....and then I rebedded the new shit, and left it on there again.

Here's a clue that will help you sleep a little better at night. Even if you DIDN'T use any release agent, a little bit of heat from a common propane torch to warm the parts up will let the bond loose and voila, it's off of there. Doesn't take much and there's no risk to the parts or the rifle....unless you get stupid with the torch.

Fret more important things if you need to worry about something..........

 

[dinc]

Re: Curing JB-Weld for scope base bedding?

Two hints:

Wipe on a nice even layer of the paste wax. Make sure you get it everywhere you don't want the epoxy to stick. Let it dry and then buff it off, just like you were polishing your shoes or waxing your car. Then do it agian, wipe on the wax to the same area you just polished, dry, buff. Then do it agian. Pro fiberglass people recommend four coats on their molds.
You are creating a nice smooth, thin surface of wax that epoxy won't adhere to.
Where you want the epoxy to stick, don't wax.

Mix, mix, mix epoxy. If I'm using 5 minute epoxy at least 2 minutes are mixing. With JB Weld or longer setting 'normal' epoxy mix 4 or 5 minutes. A good method is to mix it well and then transfer it to a new cup or mixing surface and mix it some more. This ensures there is no little bit of none mixed stuff hiding anywhere.

If your soul is pure your epoxy will always release.

 

[biffj]

Re: Curing JB-Weld for scope base bedding?

In addition to what the others pointed out on release agents remember that heat is your friend. Reactions take place much faster at higher temps so heat up your action with a hair dryer or set it in the sunlight to up the temps a bit. Don't overdo as you don't want to liquify the epoxy and have it run but warm it up. Its hot enough if its too hot to hold on to for more than a couple seconds and too hot if anything smokes. You will get a better and more complete cure with some heat.

Frank

 

[jvencius]

Re: Curing JB-Weld for scope base bedding?

Try #2 went much better today. I did the same prep work but spent much more time (prob 3 minutes or so) mixing the JB-Weld before applying it to the base. The epoxy went on at ~0615 then I went up to Nellis to hit the gym, get a haircut, and do some grocery shopping. When I got back at 1430, I removed the two front screws and with a light tap on the front of the base, it popped right off with no residue left on the receiver. The JB-Weld hadn't completely cured so it was easy to clean up the screw holes and chamfer the edges of the bedding pad so thanks to all of you for your help/advice.

 

[The Mechanic]

Re: Curing JB-Weld for scope base bedding?

Good to see it worked out. I have used JB in all kind of temps and it will only affect cure time but the trick is mixing COMPLETELY.

 

[Nocalphoenix]

Re: Curing JB-Weld for scope base bedding?

+1 on whoever said dont even take the bases off. If I use JB/devcon, I put the bases where I want them to be and let them cure all day. I pull the screws, run a tap through to clean any junk out of the treads and torque it down.