Re Chrome a sleeve
 

Anyone know if it is possible to re chrome a sleeve ? I am going to call a chrome place tomorrow-but has anyone heard of it being done for model size engines ?

Thanks,Jackjet

It's the fitting..
 

of the piston that is the hard part. When you get new chrome in the sleeve, it has to be honed to a perfect fit, and not too many people have what it takes to do this.

This was passed on to me by George Aldrich, who used to re-chrome engines. I have a buddy with a chrome shop, and asked the same question to George. Maybe he just wanted me to send my sleeves to him <G>

I never took it any farther than that since I sure don't have the tooling to do it...maybe someone will come along that knows how to hone cylinders.

Re Chrome a sleeve
 

Yes know of it being done quite frequently. Usually by after market engine reworkers. The original manufacturers do not get involved. The process involves stripping the old chrome off, re-chroming and then honing. It will have to be honed to suit the existing piston.

By the time you have found people to do all this and paid their rates it is probably cheaper to buy a new piston and liner.

Ed S

Re Chrome OS.91 DF Sleeve
 

[QUOTE]Originally posted by Ed Smith
Yes know of it being done quite frequently. Usually by after market engine reworkers. The original manufacturers do not get involved. The process involves stripping the old chrome off, re-chroming and then honing. It will have to be honed to suit the existing piston.

By the time you have found people to do all this and paid their rates it is probably cheaper to buy a new piston and liner.

Ed S [/QUOTE

Ed and Chuck,
you pilots are probably right about the price-but I got to try right ? Plus I can go to the NAPA auto parts store and buy a small brake cylinder hone.............


Jackjet

Re Chrome a sleeve
 

If it was as easy as using a brake cylinder hone then everybody would be doing it. Does not a brake cylinder piston have an 'O' ring fitted. So a little bore inaccuracy will not matter. However. if you are an experimenter and have to scratch an itch go to it. If your engine is an ABC engine with a tapered bore save your money on the hone, it will not do it.

Ed S

Re Chrome a sleeve
 

I think Ed is correct as the whole process is more involved than it looks. Its really too bad GoergeAldrich passed away last year as he would do most ABC jobs for $50 and the quality of work was reported to be better than factory specs. Good Old American Chrome Plating is hard to beat.

Is there anyone now who is doing this kind of work? I see that Just Engines has a line of true ABC piston/liner sets for the 46SF and FX and their prices seem a bit lower than Performance Specialties ABC piston/liner sets.

Re Chrome a sleeve
 

The hone used for cylendars is know as a Sunnen digital hone. It is capable of honing a taper with an accuracy of .0005 inches. When I was a machinest for Rockwell there were two in the shop. Even the stones have to be trued for every job and sometimes more than once. Somehow I don't think you'll get that kind of accuracy with a wheel cyl hone, But I don't see anything wrong with trying.

Re Chrome a sleeve
 

I have been rechroming sleeves and lapped pistons since I was in early high school - it is not all that difficult, and the hard chroming equipment only costs a few dollars, although it takes a bit of learning, by practicing on scrap pieces first to get the current and bath temperature right. I have only seen one hard chroming article in model mags, by the venerable C.O. Wright, and it only covers iron pistons, not sleeves, but the principle involved with sleeves is not all that much different. I used to buy worn out, junk engines, and hard chrome them to better than new performance. For doing cylinder sleeves, it is handy to have a lathe available for making up tapered laps, since lapping and honing is essential after chroming, which leaves substantial buildup around port edges, etc. You might get by with a simple brake cylinder hone if you are careful, though. You don't have to strip the old chrome; just clean and acid etch it, and start plating.
The bath is simply chromium trioxide, about 32 ounces per gallon, and about 0.32 ounces concentrated sulphuric acid, in distilled water. You do need a fairly high current DC supply at about 5 or 6 volts, but C or D size nicads will do for small parts, and the bath has to be heated to around 120 to 130 degrees F. The bath is not corrosive - chromium trioxide is a very mild acid, but it will stain your hands and release an aerosol that is not terribly healthy, so good ventilation is necessary.

Re Chrome a sleeve
 

RotaryPhile,

This sounds too cool. Any resources available online?

Thanks!

E

Re Chrome a sleeve
 

Hey, Rotaryphile, would you be willing to write up a complete How-To article so I can post it?

Thanks,
Cliff
http://www.rcfaq.com

Re Chrome a sleeve
 

Hi Ladyflyer: I have set up hard chroming rigs in as small as 500 ml. Pyrex beakers, with ordinary hardware store flashing lead for anodes. I hang the anodes on each side of the beaker from the work, for external work, and use several times as much anode area as work area. For internal work, you need a lead anode positioned more of less in the centre of the bore, and about 2/3 to 3/4 the bore diameter, to leave sufficient space for circulation of the bath in the annulus. You also need additional anodes for internal work, since anode area must always be kept larger than work area, or the bath will tend to poison with trivalent chromium. You don't need to worry about calculating current density - just vary the voltage across the work until you get the deposit you want - nice and shiny. Usually takes about 3.5 volts, depending on anode spacing and bath temperature. I don't usually strip previous chromium from ABC or AAC liners; a good acid cleaning, rinsing, and, most importantly, reverse current etch in the bath, should work just fine. Chromium cannot be applied directly over aluminum or its alloys - you have to zincate plate the part first - one reason for not removing existing, worn chromium from AAC liners.

I have never heard of cynanide gas coming from hard chroming process, but it does generate an aerosol of hexavalent chromium, which has been implicated in all sorts of health problems, although to the best of my knowledge, people who worked for years in chromium plating did not appear to have grossly unusual health difficulties, but it is better to be safe, and use adequate ventilation, and if you plan on doing it for a business, be much more careful than if you are doing one or two liners or pistons a year. I keep a lid on the bath while I am plating, and an exhaust fan drawing air from over the bath. There are commercially available additives for the bath that produce a foamy surface that stops aerosols from getting loose.

The bath usually plates about 0.001 inches per hour, so building up a typically worn ABC liner only takes ten minutes or so to get back to the original fit.

Re Chrome a sleeve
 

If anyone is interested, I can email them the text of the old C.O. Wright no-nonsense article on hard chroming pistons. It is too long for posting here.

Re Chrome a sleeve
 

Rotary...Send that chrome plating article to me for posting!

Cliff
[email protected]

http://www.rcfaq.com

Re Chrome OS.91 DF Sleeve
 

Rotaryphile,


PLEASE send me a copy of this-THANK YOU !


Jackjet


[email protected]

How bout ringed engines?
 

I have a ringed engine that a new ring would not fix, the sleeve is worn out and it's no longer available. Would this need special honing equipment? I think not since it is not tapered. Also E-Mail me a copy of that ariticle and er a source of chromium tri-oxide, or whatever.

Re Chrome a sleeve
 

Perhaps it was just this kind of long term exposure to all these chemical fumes that did George Aldrich in?

Rotaryphile - Do you still do this or know of someon who does on a regular basis for a fee?

Re Chrome a sleeve
 

Rotaryphile,Please give us the procedure you use to size and lap the cyl.

Re Chrome a sleeve
 

Can you chrome over the nickel plating that OS uses?

Alan Angus

Re Chrome a sleeve
 

If I recall George Alrich mentioned that he always honed all ABC/ABN liners down to the brass and then recromed the cylinder walls after which he would then hone both the liner and the piston to match.

Re Chrome a sleeve
 

I hope you folks who create your recipes dispose of your chems in a proper manner

Re Chrome a sleeve
 

Hard chromium plates just fine over the hard electroless nickel used by most of the Japanese engine manufacturers, Alan. Just a good cleaning and reverse current etch in the chromium bath should be all you need, unless the existing plating has partially peeled off, which may indicate poorly done plating which should be honed completely off and redone directly over the brass.

Re Chrome OS.91 DF Sleeve
 

Rotaryphile,
I have a piston that looks to be in pretty good shape-but the sleeve has peeled-can you clean it real good and plate directly over the nickel and peeled areas-or should you hone it out and plate directly over the brass ?

Thanks,
Jackjet

Re Chrome a sleeve
 

Hi Jack Jet - If the chrome has peeled, you will have to remove all the remaining chrome, right down to the brass, and rechrome. If the liner is aluminum, you can't rechrome it directly - chromium won't plate directly over aluminum or its alloys. You have to apply a zincate layer first, requiring a special bath, but this is not terribly difficult, once you have the bath, and no electric current is required - just dipping the part in the bath for a minute or two, then stripping the zincate in 50% nitric acid, and re-zincating, to get complete coverage of any area missed the first time. But this is getting a bit too complicated for most modelers - best to start with brass liners - plating them is like falling off a log.

Re Chrome OS.91 DF Sleeve
 

Rotaryphile,
yes, this sleeve is brass-do you recommend a chemical strip to remove the remaining nickel or is using a lathe good enough ?

Many,many thanks for your help !


Jackjet

Re Chrome a sleeve
 

Hi Jack - I would be very worried about trying to machine off the remaining nickel deposit in a lathe, although you could use internal grinding, using a tool post grinder, if you can get the liner really accurately centered and square, using only the lightest possible chuck jaw pressure, since the chuck will tend to distort the liner a lot. I would be inclined to just hone the remaining plate off with a drill press turning the hone, while hand-holding the liner. It might be possible to strip it with 50% nitric acid, but you may get too much attack on the brass. Honing two-stroke engine cylinders is always a problem, since the hone tends to cut too heavily around the ports, but very light honing pressure, and taking your time, helps here.