What is the proper way for using a Cox piston resetting tool

LAST EDITED ON Mar-16-04 AT 09:22 AM (CDT)
 
I was wondering what the proper technique is for using the piston resetting tool. I have only done this once, and at first I used some gentle taps. When this didn't seem to do much, the taps turned into whacks. Eventually I think I succeeded.

However is there some better technique? And what exactly are we trying to achieve? One of my production unrun (Sure Start) Cox 049's has a fair amount of slop in the this joint. How much slop is "ideal"? And should we set this before running, or perhaps just after breakin....?

Thanks

LAST EDITED ON Mar-16-04 AT 11:41 AM (CDT)
 
Alan,

This is how I do it.It takes a pretty good hit like you have noticed to really do anything. I do a hit at 12:00,6:00,3:00 and 9:00 then check my progress. Then I work my way around the full 360 degrees. On the lastest Cox engines I have worked on they NEEDED a reset before I even started to work on them they were that bad! You would be shocked at how many bad running Cox engines could be fixed just by getting their rods reset.Just my 2cents.

Take care,
Tim

I use the same technique as Tim. Once an engine has run for a while, you should aim for zero slop, but no binding. That is where the work up to it and rotate comes in. You want the entire rim of the socket to just touch the ball. No tight spots, no loose spots. Better you give it a whack, and nothing happens, than suddenly it is tight.

Thanks guys! I was going to title this Whacking at my C*x, but thought better of it!

Alan,

I think you've been in Treetown too long. Your sense of humor is getting warped!

Fred

Back when we were using TDs in 1/2A Combat, some of us got to be pretty good at resetting this socket. I even had an aluminum plate which was drilled to accept the top of the piston, bought it from Joe Klause.

Designman, I was told use of this holding fixture, in conjunction with a good reset tool, was required in order to not de-form the piston. Is this correct?

It is indeed adviseable to use a special socket, though concrete will work too if you are very careful not to tilt anything. The sockets are designed to steady the piston while only supporting them in the center where it is needed.

The first reset tool I got, I did the job on a wooden workbench. End of a useable piston.

C*x always sold the tool and socket as a matched pair.

Where can I buy that tool?Is KUSTOM KRAFTSMANSHIP now history?Or did they move from San Diego area . Maybe the area code changed from 760-761-0511 thanks Scott

From the 'There's a hole in my piston' thread

The gentleman's name is Andrew Coholic. He was selling them for $15. Try this email address - "[email protected]".

Andy makes them for all the Cox engines. He also has one heck of neat looking Twin that he made for this years 1/2A project on RCUniverse's 1/2A forum.

15 bucks, if you fly Cox, you need one of these.

Especially on the new Product engines. Yes reseating will provide better performance. Not using it will provide you with a dark, metal mung filled residue that upon teardown of the engine will show you this
[photo not recovered: coxhole.JPG]

Not a performance enhancer.
I had 3 product engines, I went through the other two that only had 5 or ten runs on them, they all had at least 1/16 of an inch of play. This one with the whole has clers to 3/16 no doubt extra slack at the top there where the hole is.

All of the newer engines I've had my hands on have come with the socket WAY loose. It's a shame but what that's just the way it is! Not a problem for guys like us but it has to hurt the newbies that Cox stuff is targeted for.

Hopefully, this is being dealt with at the manufacturing level.

I whacked mine one too many times and the piston mushroomed at the top - a classic case of more is not neccessary better.

I think it may fit a 051 cylinder.

How to use the tool? I usually tap on it, rotate, tap on it, rotate, tap on it and rotate, then check. Usually after checking I throw it in the garbage!

Actually, I've finally gotten the touch on it, you may not think you are doing anything to the piston, but you are. Use a tack hammer. It will take longer, but if you use a 16 ounce framer, you will be looking at the trash can. Use the cap and tool and make sure the cap is sitting on a solid surface. If I put it on my plywood top workbench, the wood takes all the energy and I don't get anywhere. I usually put the whole assembly on the floor. It does take a pretty good whack to do it quickly, but there is not much difference between doing it right and screwing it up. Use the smaller hammer with many cycles of light taps. Moving it a 64th at a time is better than moving it an eigth when you only had a 16th to go anyways.

I've found they need resetting after they break in, and then a couple more times before the socket finally work hardens and keeps the joint tight. You can just about tell it needs resetting by how it's running. Do them on the field all the time.

Tools

Before I located my own tool, I reset the socket with a tiny punch, working my way around the socket very carefully, peening the edge down just a bit. Huge exercise in manual dexterity. Seemed to work alright, definitely better than letting it stay loose.

Actually this is a question regarding the picture of the piston. Why does the piston top look like copper? I noticed my piston had the same coloring.

I don't know why the piston tops are copper. Larry???

Just bring the question back to the top, instead of starting a new thread. Why do Cox piston look like they are part copper??

One explanation I heard was that the piston has copper plating left on it so that the hardening process (case hardening??)is only applied to the piston skirt. Also, one would think that the copper helps to dissipate the combustion heat and would keep the piston cooler.

The entire piston is copper plated (Look at the inside, too), then the outside surface rough ground. Then the pistons are nitride hardened, but it only takes on the unplated outer surface. So, the infamous socket stays ductile enough to get the ball socket swaged down. After the nitriding, the piston is centerless ground to final diameter, and if required, taper ground on a really strange rotary dual wheel grinder.