Excitement

[Doc Sharptail]

...A little too much of.

Finally got set up with a bank that does EMT. Way too much running around setting up accts and passwords.

...Then my +ten year old computer crashes.

Now no e-mail access.

At least I got another order rolling with Eric at scopes and ammo. Much thanks to him for being patient with all the questions- a class act, as usual. Now the wait begins...

Which brings me back onto topic

I've been reading a bit about the 78 series valve stem, and it appears they need replacing with delrin, for what I'm about to subject them to. Anyone know where to source delrin valve stems? Or am I going to be safe for a while with the factory stem, doing a slow work up to hpa performance?

The other concern is an rva. I had it in mind to make one. I don't have access to a lathe, and the drill press I've been using has had me doing the slow burn thing as of late. I'll probably play with shimming the hammer spring a bit first, but I'm likely going to want some measure of adjustable spring control. Wish I could spring for a mill table and lathe...

Life is good, though. I'm looking forward to the next few weeks.

Regards,

Doc Sharptail

[sholo]

I know how you feel Doc, with regards to setting up EMT, crashing computers and no email. I went through the exact same thing last year (in the same order too!). It just plain sucks! Glad you got it all straightened out...

As for the '78 needing delrin valve stems when running HPA, I've heard that too. Like you, I don't have a lathe/mill either so I contacted RVD over at the CAF a few months ago about getting one made up (him and Magnumair are apparently the "guru's" on QB's) but at the time he was out of material for making stems. He may have stock on hand now? Wouldn't hurt to drop him a PM to find out...

Are you going to use a regulated bottle, or an HPA tube @ 3000 psi? Reason I ask is because if using a regulated bottle @ 1500-1600 psi, you may be fine with the stock stem (for now, anyways). FWIW, I've been using the stock stem for about a year now running 1500 psi with no problems or inconsistency's whatsoever after roughly 2500-3000 shots through it. It may (?) fail at some point, but I will keep using it until then. Be interesting to see if/when it does conk out on me...My guess is that if it does fail, it will no doubt be in the middle of an FT match!

If you plan on using an HPA tube @ 3000 psi fill, I don't think the factory stem seal will hold up too long at those pressures as they were never designed to see that kind of force exerted on them. Hopefully someone (a lot smarter than me) will chime in with a more definitive answer for you...

Cheers,
Todd

[SeanMP]

Sounds like a great project Doc.. I wouldn't be concerned about the stock stem not holding up. Both Bob and myself have taken stock stems up to some fairly high Fpe's. I think the main idea behind the Delrin is slightly reduced mass allowing higher operating pressures and slightly smaller OD giving higher flow yields.
But I can report that a certain little birdie talked to a certain Airgun elf this week and these stems will be available soon

[sholo]

But I can report that a certain little birdie talked to a certain Airgun elf this week and these stems will be available soon

[Doc Sharptail]

I'm on one of the Dell re-furbs that XS Cargo had on last year for 99 and change. I got it for just this contigency, and I'm glad I did. I think all the enhanced security features that come with EMT accts scared the crap out of my old machine.

I have one of the hpa tubes Eric had on the site a while back. I can't see myself subjecting it to that 3K psi.
Ideally, I'd like to see it at a lot less than 1600 psi- hopefully somewhere between 1200 and 1500. Bottles and tanks and compressors and shoe boxes can come later. I'm not in that much of a hurry yet. As usual, everything done in small increments, with the learning curve. I've ordered the hill pump, and a few other goodies for the 78's.

Was playing with the MK-1 last night, and it needs a new piercing pin seal. Too bad I haven't won 649 yet- there's so much stuff I want to get.

Regards,

Doc Sharptail

[SeanMP]

Sadly it's hard to find any fasteners that aren't made in China now. Even my beloved Holo-Krome has been bought and a second line called Holo Krome International is being made in China.....Unbelievable!

Fortunately they are still being held to decent ASTM Standards on the branded stuff at least. It's gotten so bad I have to sign a form when I order certain fastaners that I am aware of the anti dumping law and that I am indeed using them in the prescribed way.

Re dickless!

[Doc Sharptail]

I come as close as I could with the Brownell's bits- darn near perfect fit- the head simply crumbled away in little chunks. There were no shavings from the screwdriver bit cutting.

Parts source was open late tonight. Grabbed a roll of 69 cent teflon tape. 850 PSI from zero on the gauge, but I think there was still a little in the tube~ took 31 pumps

I'm pretty happy with the pump now.

Back in a bit with some slightly blurred photo's.

It may be a while before I get to shoot. This flu wants the best of me...

Regards,

Doc Sharptail

[Doc Sharptail]

Picture 001.jpg

photo of grandson Bryan with the D/V tube on the 2078

Picture 002.jpg

Me with the same beast.

Picture 004.jpg

Slightly closer look at the rifle

Picture 003.jpg

Do not enter. Grampa's in here chasing his tail around in circles, pretending to work on air guns. Typical cat owner's shredded bed.

Picture 005.jpg

There's the spring I used for the valve. It got clipped a little on the narrow end for a proper fit. It came out of an old 600 amp Fusematic circuit breaker. Those of you familiar with transfer switches should recognize this...

Regards,

Doc Sharptail

[SeanMP]

Well. this is anecdotal and I'm not suggesting that this is a safe working pressure but my hydro-static pump will go up to 8k. After I machined a similar unit I installed the real threaded plug and a dummy valve and tried to blow it up. The relief valve on the pump popped and the tube was fine.

[Doc Sharptail]

But I can report that a certain little birdie talked to a certain Airgun elf this week and these stems will be available soon

Great! Hope that includes the rva's...



Regards,

Doc Sharptail