XS60C PCP Repeater project

[moorepower]

I have used the green on spun bearings in hubs, and it holds up amazingly well. On an air rifle it would last nearly forever.

[stalwart]

About 0.010" max.... basically they touch.... Remember I asked you if you wanted enough for a 9 oz. CO2 and you declined.... I like it up snug, it can't stress anything if you drop/fall on the gun....

Bob

Perfect.

[RHytonen]

Here are the test results for the Loctite 638....

......cured for 24 hours at room temperature....

 .........cured at 100*F, and then post-cured for 3 hours at 175*F .... However, I think that even with a room temperature cure, that the Loctite 638 would work just fine for this purpose....

Bob

The work left for a few weeks to cure indoors, would be as strong as that cured in an oven
- just not ready to use as soon, right?

Good news - I didn't know where I would find an oven for a 43" barrel

What's the offgassing like at room temp.?

Rod

[rsterne]

Yes, I think if you left it for a week at room temp. you wouldn't notice any difference.... the warmer the better, of course.... If you are metal to metal, you should have 100% cure in 24 - 48 hours depending on temp.... the post cure was for plastic/composite on one side....

I couldn't smell anything.... It is, after all, an Anerobic cure.... There was a slight smell while I was cleaning up the excess, but once I threw the paper towel away, nothing....

I plan to weigh the bottle before and after I do my barrel.... that should give a good indication how much I used (and wasted!)....

Bob

[rsterne]

I machined the barrel today.... cut the threads at the muzzle, chambered it using a reamer from Sean Pero, cut the three O-ring grooves, cut the CF sleeve to length, determined which way the curve was (it will be installed with the muzzle "up"), sanded and cleaned the parts, and glued the sleeve on with Loctite 638.... It's hanging to dry, I'll take photos in the morning.... I weighed the bottle of Loctite before and after, and I used 3.25 grams (about 3 ml), so you could probably do three barrels with a 10 ml bottle.... Yeah, I paid over $60 for a 50 ml, the good news is I've heard it stores well (Sean has had his 10 years).... 

The sleeve was a snugish slide fit when I started.... I sanded the OD of the barrel and the ID of the sleeve with 100 grit in a spiral pattern to give it some "tooth" and a fresh surface.... I then cleaned the inside of the tube with a cleaning rod, with patches soaked in Acetone until clean and blew it out with compressed air.... I also wiped the barrel OD 3 times with Acetone after building up a collar of tape as a stop at the breech end and plugging the muzzle with a driven in piece of (snug) wooden dowel.... The fit was now loose enough that the barrel would slide out from it's own weight if you held the assembly vertical by the shroud, but the shroud would not slide off if you held it vertically by the barrel.... I think that is an excellent criteria to remember for the fit if you're using Loctite 638, at least it certainly worked well for me....

I squeezed some Loctite into one end of the sleeve and swabbed it down the inside of the tube with a patch saturated in 638, the did the same thing from the other end.... I then put three longitudinal lines of 638 (about 1/16" wide, equally spaced) the entire length of the barrel.... I then put a "collar" of Loctite around the barrel and inside the tube at the leading ends (first parts to go together) and slide them together, twisting as I went to wipe the lines of 638 around the barrel for full coverage.... The sleeve pushed a collar of 638 ahead of it, and by the time I got to the end (where the tape stop was) it was about 1/8" high and dripping off onto the floor (so don't do this where it matters).... The amount of effort it took to slide it together increased as the overlap increased, so I didn't dare stop.... It probably took 3-4 lbs. force by the end, but there was certainly no problem getting it together.... I mopped up the excess Loctite with paper towels and then hung the barrel by the threads at the muzzle from a string, it will stay there, at room temperature, for 18 hours until tomorrow morning.... At that time I will do a 3 hr post cure at 175*F....

I am VERY pleased with how this assembly went together.... Although this particular sleeve isn't that thick, it will add some stiffness, and it looks killer....

Bob

[RHytonen]

I machined the barrel today.... cut the threads at the muzzle, chambered it using a reamer from Sean Pero, cut the three O-ring grooves, cut the CF sleeve to length, determined which way the curve was (it will be installed with the muzzle "up"), sanded and cleaned the parts, and glued the sleeve on with Loctite 638.... It's hanging to dry, I'll take photos in the morning.... I weighed the bottle of Loctite before and after, and I used 3.25 grams (about 3 ml), so you could probably do three barrels with a 10 ml bottle.... Yeah, I paid over $60 for a 50 ml, the good news is I've heard it stores well (Sean has had his 10 years).... 

The sleeve was a snugish slide fit when I started.... I sanded the OD of the barrel and the ID of the sleeve with 100 grit in a spiral pattern to give it some "tooth" and a fresh surface.... I then cleaned the inside of the tube with a cleaning rod, with patches soaked in Acetone until clean and blew it out with compressed air.... I also wiped the barrel OD 3 times with Acetone after building up a collar of tape as a stop at the breech end and plugging the muzzle with a driven in piece of (snug) wooden dowel.... The fit was now loose enough that the barrel would slide out from it's own weight if you held the assembly vertical by the shroud, but the shroud would not slide off if you held it vertically by the barrel.... I think that is an excellent criteria to remember for the fit if you're using Loctite 638, at least it certainly worked well for me....

I squeezed some Loctite into one end of the sleeve and swabbed it down the inside of the tube with a patch saturated in 638, the did the same thing from the other end.... I then put three longitudinal lines of 638 (about 1/16" wide, equally spaced) the entire length of the barrel.... I then put a "collar" of Loctite around the barrel and inside the tube at the leading ends (first parts to go together) and slide them together, twisting as I went to wipe the lines of 638 around the barrel for full coverage.... The sleeve pushed a collar of 638 ahead of it, and by the time I got to the end (where the tape stop was) it was about 1/8" high and dripping off onto the floor (so don't do this where it matters).... The amount of effort it took to slide it together increased as the overlap increased, so I didn't dare stop.... It probably took 3-4 lbs. force by the end, but there was certainly no problem getting it together.... I mopped up the excess Loctite with paper towels and then hung the barrel by the threads at the muzzle from a string, it will stay there, at room temperature, for 18 hours until tomorrow morning.... At that time I will do a 3 hr post cure at 175*F....

I am VERY pleased with how this assembly went together.... Although this particular sleeve isn't that thick, it will add some stiffness, and it looks killer....

Bob

As always Bob, THANKS for the detail!
(especially the good news on the 10ml being enough!)

It will be very helpful when the time comes.

Rod

[stalwart]

What are the advantages of Loctite over something like Acraglas?

[rsterne]

I only used Acraglas once, many years ago when bedding a rifle, and it was a messy experience.... Of all the epoxies I have used over the years, it is the thinnest (runniest, least viscous), and the only one that I would trust to get into the very tiny gap (0.010" or less on the diameter) between the barrel and the shroud.... Some people have said there is a West Systems product that is thin enough, but it must be one I've never worked with, or they are thinning it with Acetone, and that is really a no-no on epoxy in a closed space.... If the Acetone can't get out of the epoxy before it cures, it remains trapped, the epoxy never cures properly, and that is exactly what should happen in this case....  Like any Epoxy, Acraglas is a 2-part system (resin and hardener) that requires fairly accurate mixing, it is sticky, and requires cleanup using Acetone.... If you DO use epoxy, stick to one that it thin enough to get into the joint on assembly.... Do a test piece like I did, let it cure, destroy it, and see if you had 100% coverage in the joint.... With the Loctite 638, even though it was the thickest of the three Loctite 600s I looked at, I got 100% coverage in the joint....

Loctite make a dozen "Retaining Compounds", mostly in the 600 Series, half of them green in colour.... They are an "Anerobic" material, which means they are a single component (no mixing) that cures in the ABSENCE of air.... The bottle is only half full when you buy it for that reason, the air keeps it from curing.... You can spread it out on a surface in the air and it just sits there, and since it has very little solvent, doesn't set, similar to Crazy Glue, to which it is closely related.... Put it in a narrow gap, sealing it off from the air, and it hardens.... Some are thick, some thin, some high temperature, some fast or slow cure, etc.etc.... The thinnest ones (eg. 609) are for close fitting parts (eg. press fits).... as they get thicker they can stand a bigger gap (slip fit).... The 638 I chose is the thickest of the "normal temperature, fast cure" Loctites (about like syrup), and the strongest.... Post cure on steel it is 4500 psi shear strength, which is superior to most epoxies.... Since it is thick, it is the most suited to "slip fits" with gaps up to 0.010" on the diameter, which I thought sounded perfect for our application.... It has a 4-10 minute assembly time before it gets too thick to move (the closer the fit, the less time) and takes 24 hours to cure (steel to steel) at room temperatures.... Heat accelerates the cure rate, it will fully cure in just 4 hours at 40*C (104*F), which is barely warm to the touch.... It was never designed for gluing plastics or composites, but the manufacturer has a work-around for that, by using a post-cure at elevated temperatures (they recommend 3 hrs. at 175*F) to fully cure the product....

The criteria for gluing a CF (or steel) sleeve to a barrel are pretty simple, really.... It has to fill the gap completely and cure to a reasonable strength.... It has to give you long enough to assemble and position the parts, and then cure within a reasonable length of time.... If the product you use meets those criteria, it should work just fine.... I chose Loctite 638 because it would fill the largest gap, and it had the highest shear strength.... I think that 609 or the new 648 (both designed for a 0.006" diametrical gap) would work as well, the 609 is the thinnest and slowest curing, and would therefore be the easiest to use, but it is only half the strength (still fine, though, at 2300 psi minimum).... I have never used the newer 648, which is in between in viscosity, the fastest set (3 min.), and nearly as strong as the 638.... There is also 640, nearly identical to the 648 in properties, but it is a slow cure product, with a 1 hr. assembly time, but it is only designed for a 0.004" gap, which may be too tight for easy assembly over the long length of a barrel, IMO....

Bob

[stalwart]

It looks like I'll need 620... I'll need the high heat resistance for powder coating aluminum sleeves.

I don't mind making a mess, but for 1 barrel at a time? Zoro.com has the 600s for $12.21 (10ml).

[RMM]

I've done more whittlin.   



I decided to epoxy the reverse tank bottle holder to the receiver as I couldn't figure out a mechanical fastener.  I voided the idea of epoxying the bottle retention assembly into the stock as I felt that would have been a fatal flaw for the stock if dropping the gun.  I roughed up the angle and receiver with 80 grit, cleaned with a stainless steel brush and acetone (no degassing) then air dried,  once dry (a minute max) I immediately buttered with JB Weld so flash oxidation wouldn't spoil the bond.  As far as shear strength I'm not sure but we'll find out here shortly plus she aint' aesthetically pretty but then again all will be hidden by wood.

The plenum/tube is chromoly which I single pointed threads on both ends, after much much practicing as this is my first.  Although the threads have a much better engagement than the FDPCP plenum/tube threads I resign to keep the Bobcat a 1.5K shooter, the reason being I should have paid closer attention to details afforded me by the wisdom of this group and should not have used a sharp V threading tool.  Live and learn.

I've already pressure tested @ 1.5K with no leaks so I felt I was close enough to completion I ordered Cerakote to make my whittlin pretty. 

I have to poke a hole (whittlin talk) in the stock for fore stock retention and I still think I'll use the backing block as it will have deeper threads.  As far as staining and or painting the stock I've talked with stalwart about bedliner and bedliner it will be. 

As always constructive critique is always welcome. 

More to come.

[rsterne]

620 is pretty thick, about the consistency of honey.... but the good thing is it's slow enough to let you pull it apart and inspect it for 100% coverage and then reassemble.... Otherwise the specs look similar.... I'd check into the Activators, there may be one that will eliminate the need for the post cure?.... I have no idea what the temperature capability of Acraglas is.... If you get the CF sleeve too hot, the resin may come unglued (literally) anyway, something else to look at....

Bob

[QVTom]

It looks like I'll need 620... I'll need the high heat resistance for powder coating aluminum sleeves.

I don't mind making a mess, but for 1 barrel at a time? Zoro.com has the 600s for $12.21 (10ml).

I've used the RC620 for years.  I never considered steel to CF before.  Sometimes I room temp cure but for high temp apps I go for 25*F higher than the expected operating temp.

Tom

[stalwart]

The 620 needs a cure at 356*F, to activate it's 450* max working temp. .015 gap max.

I'll find out if the 10mins at 400* (coating cure) works. It'll only see heat once... maybe twice

Per barrel, considering the cost of many other adhesives (my head hurts...lol) and the time to clean them up, it is dirt cheap. 50ml only costs $33 and change.

Tom, I'm looking into aluminum sleeves, powder coated... so they can be beaten, and re-coated if needed. Thanks, your info is quite reassuring... 

[stalwart]

I've done more whittlin.   

As always constructive critique is always welcome. 

More to come.

Not much to criticize, Mike... looks like a ton of fun already! You'll love the bedliner, it takes a real beating, and will take paint (camo?) well. Play with distance and ambient temp, and you can do some nice textures. When I use a spraycan, I put it in a 140* water bath (10 mins), and stand back a bit... it shoots spiderwebs that turn into a fine texture... grippy without retaining a lot of crud. Wipes right off.

[QVTom]

The 620 needs a cure at 356*F, to activate it's 450* max working temp. .015 gap max.

I'll find out if the 10mins at 400* (coating cure) works. It'll only see heat once... maybe twice

Per barrel, considering the cost of many other adhesives (my head hurts...lol) and the time to clean them up, it is dirt cheap. 50ml only costs $33 and change.

Tom, I'm looking into aluminum sleeves, powder coated... so they can be beaten, and re-coated if needed. Thanks, your info is quite reassuring... 

I assure you 620 will cure at room temp just fine.  It will be slow and never reach its high temp properties until its post cured at temp though.  Room temp cure and letting the final post cure occur during the powder coat will work just fine.

Tom 

[rsterne]

This morning I post-cured the Loctite 638 that I used to glue the CF sleeve onto the barrel, and while that was baking I did some bluing on the main tube, valve backing block, hammer and spring guide.... After the barrel had baked, I machined the port and the pockets for the set screws, machined the flow-through side port in the bolt, and modified a Hatsan Air Stripper to fit he muzzle and then blued the bolt and the ends of the barrel.... I used Van's Gun Blue, and I'm pretty pleased with the results as you can see in the photo below....



Hatsan Air Stripper and threaded muzzle....



Bolt and Barrel Stub, showing ports.....



Hammer, Valve, Adjuster and Spring Guide....



With a little luck I'll assemble the gun far enough tonight to do a pressure test overnight....

Bob

[QVTom]

Looking good Bob,  I'm amazed at the work you do with a milling attachment on your lathe.  I used to have the exact same Atlas (branded Craftsman Commercial) lathe for years before I bought my first CNC.  From about 1990 to 2013 when I finally gave it away to make room for a 16" Taiwanese Mori known as the Cadillac.  I still miss the Atlas because every thing was so easy to setup and that little machine had nice clearances and travels where nothing would bump into itself during operation.  I did some of my best work on that lathe.  So you see, I get warn and fuzzy when reading about your projects on your Atlas.

Tom

[rsterne]

I'd be lost without that milling attachment, and one thing is does easier/better than a mill is working on an angle to the mill/chuck.... super easy to set up for that....

Ahem!!.... stalwart !!!! .... I have a bone to pick with you !!!!!!!

I ran a pressure test on my regulator today, and promptly blew the 3K burst disc.... Figured it was a dud, so I replaced it and blew that one too !!! .... Remember when you  installed the 3K disc instead of the 7.5K ?.... You were supposed to move the 5K from the output side to the input side where the 7.5K was and install the 3K on the output side.... With it on the input side, it blows as soon as you get the tank to pressure.... FORTUNATELY I only had a 1 CI tank on the regulator, not the 22 CI.... My regulator is set at 1950 psi according to a pretty good gauge, so close enough....

Sooooooooooooooo .... you better check your regulator to make sure you have the 5K on the inlet side and the 3K on the outlet side or you'll do the same thing.... *LOL*.... The output side disc is further from the tank by about 1/8"....

Good news is that the main tube / valve / receiver / tank block is assembled and it's sitting with 3,000 psi in it for an overnight pressure test.... So far, so good....

Bob

[stalwart]

They were supplied with (2) 5ks installed. I have never worked with tanks/regs before.

Sorry.

[rsterne]

Absolutely no problem, buddy.... just giving you a hard time.... If Tim had caught it before he shipped them it wouldn't have been an issue.... and I should have looked when I popped the first disc, after all, this isn't my first Rodeo.... *LOL*.... Ultimately it's Ninja that have stopped using the 3K discs, they only have 1.8K, 5K and 7.5K, which is pretty dumb, IMO....

The gun is holding 3K so far, no drop at all in a few hours, so it looks like it's good to go.... I think I'll tether it at 1800 psi to start, simply because I have a regulator set up for that.... I may also give it a try at 2900 psi to see if we have enough hammer strike to handle that amount of pressure.... With a little luck, tomorrow should be an interesting day....

Bob