How to fix regulator creep problem without buying a Huma ?

[airgunfans]

My Huben K1 ( version 2 ) has rather sever regulator creep and after reading many posts on this subject, I came to the understanding that it can be fixed by improving the mating between the seat and the piston ( if that is the correct term ) that do the sealing between the high and low pressure end of the regulator.

This is the structure of the seat and the piston inside the regulator of my Huben.

I understand it can be done by lapping but I don't quite know how to do it, e.g. do you apply some lapping compound like Brasso to the mating surface and rub the seat against the piston ? how do you hold the two parts to make sure that they are aligned ? Grateful if someone can share some experience. 

 

[JamesD.]

Just wrap Teflon tape around reg at, JK, don’t do that.

You have a lathe? A drill that has a big enough chuck & spins true? 

If I had your problem I’d send those two parts to Ernest Rowe, Charlie Frear, etc. I like The Huben performance & concept but I’m not jumping on that train or any other until designs are far out of the beta testing era & into the AZ Rapid/RAW legendary era.

I’m not even sure if you can do it as described with that seal. I know you would definitely seat engine valves that way but a engine though ingenious is not as finicky as an air gun. At least we, as owners of both aren’t trying to squeeze more MPG out of our cars the way we do efficiency out of our air guns. Air gunners tend to be dedicated to their guns in their passions. As long as ol Betsy gets em to the match to show off Leyla’s (enter any hot woman’s name) performance & looks, we’re good.

Well, most of us as air gunners as they’re so darn expensive compared to firearms guys who can mop the floor by buying any Savage in any Varmint caliber. 6.5 Creedmoore .

My neighbor does have his own range, Class 3, & a yellow Lamborghini but he’s from Eastern Europe so, we, Americans usually have an 06 & a Pick-up truck.

Man I wish I could help you more but I’m intelligent because I know I know nothing about nothing. I don’t want to tell you to try something I wouldn’t try in fear of making worse. Someone with more experience in air guns is gonna have to take the time I do if send those two parts to a good tuner ain’t helpful enough. Sorry & good luck. I will be watching Huben though as once it’s perfected,  if ever, I would definitely buy one.

 

[nervoustrig]

Firstly I want to say I'm happy to see someone having a go at it. I've fixed several regs this way--cheap paintball regulators, in-tube regulators, etc.--but so far it seems like folks have been reluctant to take my advice.

I can't tell the scale from your photo but it appears to be a fairly large sealing surface...perhaps about 0.3" diameter and a 0.040" (~1mm) bevel. The larger it is, the harder it is to get the surfaces to mate well and prevent the slow seeping of air from the high pressure side to the low pressure side. For example, if the plastic piece had a sharp corner instead of the bevel, it would be less apt to creep...however it would perhaps be subject to damage from either repeated cycling or a big temperature rise (e.g. firing it outside in the cold and then taking it into the warm indoors). So my advice is to try lapping the surfaces at their present geometry before resorting to something else.

Rest assured you can get a successful result without the aid of a lathe. We aren't cutting material, just abrading down the surfaces to remove microscopic scratches. You can just chuck the piston into a handheld drill, however the trick is going to be holding the plastic disc. It needs to be backed up by a good solid flat surface so it doesn't deflect while you're lapping the surfaces together. The way I'd approach it is to drill a hole in a piece of thick stock that's about 0.010 - 0.020" larger than the opening in the disc. Then use a thin piece of transfer tape to bond the disc centered over the hole (transfer tape...think double-sided foam tape without the foam). Whatever stock you use needs to be nicely flat. A piece of aluminum bar stock or even just a piece of hardwood like oak or cherry will work. I would start first by flattening the surface with a piece of sandpaper held against a known flat surface like a thick piece of glass or a marble countertop.

Use a black marker to color the mating surfaces. As you're lapping them together, it will be apparent when you've done enough because the marker will wear away.

Brasso will probably work as a lapping compound. I typically use a slurry of J-B bore paste and shavings from a stick of polishing compound like is used to load the cloth wheel of a benchtop polishing wheel. The J-B is extremely fine and useful for final lapping, but I can mix in a more aggressive compound if the surfaces are especially poor and I need to remove a bit of material. I imagine the Brasso is pretty similar in its fineness to the J-B. For your first go at it, I'd say start with the Brasso and if it seems to be going agonizingly slow, then go get something more coarse. Load fresh abrasive every 30 seconds or so until you see two nice clean rings where the black marker used to be.

When I think I'm nearly done, I usually repeat the application of the marker and do a final polishing run with a light touch, and if the marker abrades away easily, I know my surfaces are good.

Limit how much pressure you apply to perhaps 1-2 lbs and let the abrasive do the work. Go slow so as not to overheat and melt the plastic disc. The metal piece will help wick away heat that is generated where they rub together so I don't want to overstate the risk but if in doubt, go slow. I typically use my handheld drill at no more than perhaps 1/4 of its max speed.

Good luck!

 

[airgunfans]

@ nervoustrig , many thanks for taking time to explain it in such a great detail. I am the kind of person that prefer fixing things if they are within my capability and resources allow. Actually I can afford a Huma but successfully fixing the stock regulator will gives me a much stronger sense of satisfaction. 

 

[BDX]

My only concern would be that the metal side of the mating surfaces will wear considerably less during the lapping process than the Delrin/Teflon side. I would simply be careful to not over do it if you did chuck the piston into a drill. Blackening the two parts surfaces will definitely help give you and idea of what's going on but because of the dissimilar material one side is likely to wear off sooner than the other. I'm almost wondering if buffing the piston first with a very light grit abrasive would get those larger scratches off before its lapped/mated to the seat.

How old is the gun? Does Huben give any indication this will settle in over time? 



George

 

[nervoustrig]

I’m curious if you’ve had an opportunity to try fixing it? Let us know how it goes. 

 

[Motorhead]

BY COLOR ... that Regulator seat appears to be PEEK and not surprised by it's use either being the rapid cyclic the gun operates at.