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Tubegun Project . Start to Finish. The glue-in begins!.
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Tubegun Project Start to Finish
The glue-in begins! Here's Jim Cobb getting ready to do the deed on my poor little MAK/Borden tubegun. Jim is a composite materials and fabrication guru for a major aerospace company and very graciously volunteered to do this job which I think is roughly the equivalent of chewing gum in terms of difficulty compared to his real job. The barreled action is clamped in the vise, the materials are laid out and Jim is ready to begin.
Jim dropped the barreled action out of the vise for this first part which involved filling all holes with modeling clay. This stuff is really sticky, once its in, it wants to stay in. Leaves a nice red color on most anything it touches also!
Here's the bottom of the receiver with the trigger slot and pin holes already clayed.
Jim slid the receiver into the sleeve to check things out, also began to clay up a few holes in the sleeve such as the trigger pin holes there.
Receiver back out of the sleeve, bolt holes have been clayed as well. Jim also put some release agent into the bolt holes with a swab, sorry I didn't get pictures of that.
Here you can see some of the claying going on in the sleeve. The idea was to clay up any holes that could have epoxy running out of them as it would be easier to remove the clay than to clean up a bunch of oozing epoxy.
Next, Jim removed the scope rail and put release agent and wax into the holes and on the screws. Again, if any epoxy is going to ooze into there, it'll be a lot easier to remove this way.
Time to break out the tape. Jim put masking tape on any hole or area that could allow epoxy to escape. Note also the tape on the barrel just ahead of the receiver. Scope mounting holes in the receiver were plugged with 8-40 plugs and a bit of wax over them. Those plugs are in there forever as the holes don't get used with the sleeve, but just in case the receiver comes out one day, it'll make things simpler if the holes are filled.
The taping continues. Don't be stingy with the tape, you can peel it right off as soon as the receiver is in the sleeve and it sure keeps things clean.
MAK instructions say JB Weld will do the job (and it does) but telling Jim to use JB Weld is like telling Tiger Woods to play miniature golf. Jim brought over some Hysol epoxy. I think this can hold the wings on an F16 or something like that. I sure hope I never have to remove the receiver from the sleeve! The consistency of this stuff is just like peanut butter.
Jim begins to lay the epoxy into the sleeve. It's very important to coat both the sleeve and the receiver for maximum adhesion. Doing just one surface will significantly reduce the quality of the bond.
So, you wait a year for a beautiful new custom action, you get one of the first ones made (probably the first lefty), you're all excited about it and some guy smears epoxy all over it. If you ever crashed a new car while leaving the dealership, that's about what it feels like. Oh the pain...
The Borden Alpine has a couple of big scallops cut into it which reduced our surface area for adhesion quite a bit. The front and rear rings give 360 degree coverage and the solid bottom provides plenty of area as well. Adhesion shouldn't be a problem but I sure wish those scallops weren't there.
Here we go. Slide the coated receiver into the coated sleeve. Note the screws in the front of the sleeve; they hold the fore-end on the sleeve, but we put them in to keep epoxy out of the holes (they were wax and release agent coated as well) and to center up the action in the sleeve, although that may not be stricly necessary as there is very little clearance in there anyway.
Once we passed the ejection port, Jim ripped off a strip of tape to make sure we were properly aligned with the bolt handle slot. Things are going to plan, no mess, epoxy is well contained.
No need to rush, the epoxy takes a long time to set up, make sure everything is where its supposed to be.
As soon as it's in, Jim starts attacking all the overflow with swabs wet with denatured alcohol. He went through about 100 swabs (seriously) so be prepared with a lot of them.
The two action screws were run in at this point to keep things aligned. Note the tape bushings Jim made to keep things centered; it worked perfectly. Get all the tape off, get to work on the epoxy. As the epoxy is cleaned out of the trigger slot, the clay is revealed. That'll come out in a minute, for now we're getting epoxy out while it's easy.
There's lots of excess epoxy in the loading port area and with the scallop on the backside of the Alpine, we really have to dig deep to get it all out and leave a clean looking port.
As you can imagine, the tang area picks up a ton of loose epoxy as the receiver is pushed into the sleeve. Lots of cleanup needed there. Jim taped up the inside of the sleeve in this area and that got most of the epoxy, the cleanup with swabs was minor thanks to that pre-planning.
Jim pushed the swabs through the trigger pin holes to knock the clay out, then we went in with a 1/8" drill bit just to get a bit more. Robert Whitely suggested using some string for this which is a great idea but I couldn't find any.
After a night of drying/curing inside, I took the barreled action outside for a few hours this morning. Just leaving it in the sun got the sleeve up to about 150 degrees helping cure the epoxy.
Here you can see the port area, it cleaned up nicely last night, no further work needed. You can see the gap created by the scallop on the back side of the action. Too bad about that, but there's nothing to be done about it.
The breech area cleaned up perfectly and with the tape on the barrel during the slide-in, that stayed perfect. The blue on the barrel is just a reflection.
There was still some clay hiding in the trigger pin holes despite our best efforts last night. Got it our with swabs and then ran the trigger pins through to make sure. Front pin is in the trigger.
As I lowered the trigger to put the rear pin into place I ran into the only real problem of the whole project, the little screw on the side of the Jewell trigger bumped into the sleeve before it got all the way down. A couple of minutes of careful work with a small round Swiss file took care of that.
Bolt handle is perfectly centered in the slot, no contact and smooth operation. Slide the buttstock on, tighten two screws and it's ready to shoot; well, mount sights also!
