hone: is it worth it?

[neric]

I've honed 3 air compression chambers using a 3 stone brake cylinder hone with the far ends of the stones ground off so as not to scar the end of the chamber with the steel part.  I used a light weight oil, on a slow drill, stroking in and out to get the cross hatch effect, final cleaning with aerosol carb cleaner,  compressed air dry, light coat of RWS air chamber oil.  2 out of the three there has been no gain at all.   One had a gain of 14 fps.

IZH 61 gained 14 fps. with the same average deviation.
RWS 92 gained nothing at all.
RWS 54 I actually lost 6 fps and worsened my deviation by 12 fps.

Only the 54 looked like it needed honing because it was pretty dirty from black carbon build up on the wall - and it came out looking real nice,,,,but it had the worse effect.  The other two didn't change the appearance much at all.

On these three I did not change the seal,,,only a hone and lube job.

Based on these observations of my experiences I'm thinking a hone job is probably superfluous,,,although it was fun to do and I felt like I was accomplishing something.  And I'm thinking it may be like cleaning barrels,,,,just don't do it.  I've cleaned a several of barrels and in the long run wished I hadn't - lost velocity and accuracy.

Any opinions,,,experiences?

[pappa]

The grit of the stones can have a detrimental effect on the smoothness of the chamber. If it is too course, it will cause excess drag on the piston and wear the seal out in a big hurry. Also, if the only lubrication you gave the chamber was the light coat of chamber oil, this is NOT a good lubricant for a springer's compression chamber. You have to use a coating of moly grease (at least 60% molybdenum disulfide) that is thick enough to not only form a super slick and protective coating on the chamber walls but ease the glide path for the compression seal.

If the honing is overdone, especially with a too coarse set of stones, you are setting yourself up for disaster, especially if the wrong lubricant is used. The reason rifle manufacturers recommend using chamber oil is because they put together a rifle with polished chamber walls that will not retain a well mixed moly grease very well, if at all.

[CharlieDaTuna]

I've done over three thousand tunes and honed over three thousand compression chambers and one of the most important things is proper honing the compression chamber. But... unless done properly using the right tools, the right lubes and parts, you really cannot expect to see much in results. It's like rebuilding an engine and reassembling it putting it back together using the old parts with and wrong lubes.

How you do things, where and why makes a tremendous difference in the final results. If I was you, I wouldn't be too disappointed in your results or expected anything different and I wouldn't expect much better in the results either.

And the reason that they sell chamber oil is because people will buy it even though it is probably the worse thing that you can use in a springer. Just another way for them to make a buck.

CDT

[K_sqrd]

I've been curious about this topic for quite a while and have done several searches on various forums looking for info.
Your data are the first real numbers that I've seen that shows what effect, if any, cross hatching can have on performance.

Question for CDT - what sort of data can one expect to see for a proper cross hatch and lube job? ie. 5%, 10%
increase in FPS or ? 

I use the term "cross hatch" because I believe that honing is for actually "truing" a compression chamber and is
different than just cross hatching and requires very special equipment. Hope that's correct.

Thanks.

[neric]

Thanks for all the feedback.

I am going follow thru with 400 paper to finish the hone, then use SuperLube with PTFE on the chamber wall with wiping excess off - as suggested in the Library notes on "All About Lubes" as I have a synthetic seal.  The notes also suggest using the Moly paste in the compression chamber - wiping off the excess.  I do have some Moly from Maccari.

Is one better than another? (Moly paste vs Super Lube grease with PTFE)

Final question then:  With this lubing strategy for the compression chamber (forgetting about RWS Air Chamber Lube) - is the compression chamber ever lubed again?

[thekid]

Next time you need to change parts.

[Bryan Heimann]

The whole point of honing, as I undersgand it, is so that the moly can coat the chamber walls in a microscopic layer and basically do it's job.  With polished walls and shnthetic seals, the moly is mostly wipdd away while other, thinner lubes like superlube just get burned off in the compression chamber.  A hone doesn't help without moly.  Moly still helps without a hone, but with a hond it's much better

[uncle paulie]

As I understand it, the honing and moly is not primarily to increase fps. Its primary function is to insure there is a uniformly repeatable amount of dieseling which will reduce the spread variations and remain in place for a very long time. The less viscous oils do provide the fuel for dieseling as well, but as it is wiped/burned off the result is inconsistent and short lived. This is why the manufacturers recommend adding a drop every 100 rounds while JM's moly will last for thousands of rounds.

pv

[s10gto]

I use the term "cross hatch" because I believe that honing is for actually "truing" a compression chamber and is
different than just cross hatching and requires very special equipment. Hope that's correct.

Thanks.

Thats correct. A brake hone will not true the chamber but follow every inaccuracy. I use a fixed hone.

[s10gto]

neric   If you like send me that 54 chamber and I will true it up for you. 

Dustin

A pic of the Sunnen hone.
 

[neric]

Here is my final formula:  2 phase hone (220 then 400 grit)  +  JM Moly on the compression chamber wall  +  Vortek PG2 kit (spring and new seal) and I come up with

5 shot string (last 5 shots of 15 string):   avg 841 fps     dev 13  (CPHPs)

This is better than I had when new, which was :  avg 800 fps   dev 9  (CPHPS)  I'm betting the deviation will become better than 13 over time plus I will change the breech seal when it comes.

Turns out that Uncle Paulie's explanation of hone plus moly lube is exactly what I saw.  Using the RWS Air Chamber Oil (with the single stage hone of only 220 stones) I got a 15 string average of:  854 fps (14 fps faster than Moly)  but with a deviation of :  34 fps.

I'll take the more even deviation any day with the Moly lube.

I questioned this honing operation because my old seal looked like it was still in perfect shape,,,spring looked good too.   The new seal gave me 80 fps increase,,,obviously the old seal wasn't perfect.  Curiosity got the better of me and I had to know,,,so I put the old seal back in and found I had actually lost 6 fps and worsened my deviation by 12.  I was thinking it would have been better to just drop in the new Vortek without honing.

But with the evidence of more even deviation with Moly and the promise of lasting longer without having to oil the chamber,,,,my answer to:  Is it worth honing?  is yes.

The combination I have right now of hone plus Moly lube isn't better than my deviation before the hone.  Before honing my deviation was 11,,,,now it is 13.  Almost the same in my book.  I'm still betting it will be better when I get the new breech seal in place

I'd rather not have to lube for a long time,,,as infrequently as I shoot these days.  I don't keep track like I used to.

But anyhow,,,this 54, now,,is in my opinion just like a single-stroke-pneumatic because with this new Vortek kit,,,there is NO recoil at all now,,,there was very little before hand.  Plus this 54, now is only 10 fps less than my Hyper Max Tuned 850 Magnum from Roald pcp rifle (both are .22) and it has better deviation than my 850.  This 54 rocks.  The Vortek kit rocks,,,it is better than new now.  This 54 is completely stock on the exterior,,not going to include a pic.

Thanks for all feed back, it guided my final outcome,,,,with which I am VERY pleased.

Thanks again.

[Bryan Heimann]

I don't think the purpose of the moly is to diesel- rather, it's to lubricate without dieseling very much. I know that the dieseling effect is technically supposed to be a part of a spring gun's shot cycle- depending on who you ask- but I for one don't buy into that.  The less dieseling you have, the better- and if you can find a good lube that won't diesel at all and still gets the job done then you've found gold.

[PakProtector]

hey-Hey!!!,
The cross-hatch it a break-in thing used when both the cylinder and seals are to wear a bit and mate to this new wear pattern. In the case with AG piston seals, you've got a situation where the seal will just keep wearing. Like nitriding a honed cylinder, the rings will keep on seating until they're completely sat.

There is no magic here, rounder is better, and a surface that doesn't wear out the seal or induce piston-wall galling is all. The lubes available can support this well. High pressure/low speed calls for moly-fortified grease. Plastic seals on steel tubes will prefer to ride on a thin film of clean oil. On cock there is very little going on with the seal, however the force on the piston is asymetric, and the low-speed/high pressure regime just behind the seal needs attention.

Then there are special cases; the 54 family is one. Theoben rams are another. Check out DuPont's Krytox, there are lots of detail specs to read, and for a large fraction of available products, they look quite useful for AG bits. Hideously expensive though...which ov course makes them better...
cheers,
Douglas

[Bryan Heimann]

Dude, all I know is that I lightly cross-hatched the tube on my Chinese B-19 with 400 grit paper and a homemade flapper, installed a JM piston seal and spring, lubed with CHEAP moly, and the extreme spread was in the single digits before I cleaned it out and lubed with pure white lithium grease.  I just happen to have some JM moly left over and some JM tar, and soon I'll do her right =D

[pappa]

Dieseling is NOT a normal or desirable part of the shot cycle in a properly operating air gun. It is to be eliminated at all costs if it rears it's ugly head. This is why experienced air gunners try to get rid of it ASAP in a new gun. Dieseling only adds erratic performance and at times, dangerous shot cycles to the gun. There is NOTHING normal, good or desirable about dieseling!!! This is why really experienced tuners recommend only moly lubes for compression chambers. A proper moly lube will never diesel.

My 2 cents...

[neric]

During my process, I did have dieseling with the RWS Air Chamber Oil,,it dieseled twice then I took it apart again and swabbed out all the excess lube at the bottom of the chamber, put it back together and no more dieseling.  It shot in the 850 fps range.

When I finished honing with 400 grit paper with home made flapper, then applied JM Moly evenly thru the tube with a plastic small PVC pipe (fingers won't reach that far in),,,then I used the piston / seal to push the excess Moly down to the bottom where I Q-tipped it out - did that about 3 times;; when I put it back together this time,,,,there was no dieseling - ever,,,it just started shooting in the 840s range.  I was impressed.  All the other times I did any lubing I experienced dieseling.  This is the first time I used JM Moly.  I was impressed - oh wait I already said that,,,,it's worth saying again.

[Bryan Heimann]

Yeah, JM moly is about the best stuff that there is.  A nice light hone with 400 grit paper in a flapper, cleaned properly and lubed with JM moly should give you a perfectly thin layer for the seal to glide on.  I don't even believe that you need to see the cross hatch job that well, either- as long as yo can see the light pattern when you hold it at the right angle to the light, you're good.  You ain't boring it over, but just trying to help the moly "stick".

[shadow]

Any advice that brother Bob offer's treat it as the best advice. There is no great substitute for the proper lubes and lube applying process as well as honing. I learned from Gene and Bob and continue to follow their guidlines for doing tuning. Ed

[uncle paulie]

The first tune I did I used the highly recommended JM Moly. I wiped some in the piston chamber and some on the seal before reassembly. I believe I used too much as the first four shots were every bit as loud as a .22lr. Subsequent tunes have produced only one or no supersonic report( which indicates DETONATION), using far less moly; and are evidently still doing the job as after a couple thousand rounds the fps has held consistently within 10 fps of the original (after break-in). If dieseling were not part of the equation, why would there be a need for oil as the manufacturers recommend? Why lube at all?  Where does the manufacturer recommended "oil" go? Controlled dieseling IS an important component of the shot cycle while Detonation can be very detrimental to the seal, gun and possibly you!

pv 

[pappa]

The first tune I did I used the highly recommended JM Moly. I wiped some in the piston chamber and some on the seal before reassembly. I believe I used too much as the first four shots were every bit as loud as a .22lr. Subsequent tunes have produced only one or no supersonic report( which indicates DETONATION), using far less moly; and are evidently still doing the job as after a couple thousand rounds the fps has held consistently within 10 fps of the original (after break-in). If dieseling were not part of the equation, why would there be a need for oil as the manufacturers recommend? Why lube at all?  Where does the manufacturer recommended "oil" go? Controlled dieseling IS an important component of the shot cycle while Detonation can be very detrimental to the seal, gun and possibly you!

pv 

Detonation IS dieseling! It is NOT controllable! Go back and read the 3rd entry in this posting and check out what CharlieDaTuna said about using manufacturer recommended oils. I have never believed in using oils internally on an air gun and have NEVER had a problem and have been air-gunning since the late 1980s.