Hard Industrial Chroming of Aluminum, Brass or Steel Cylinders

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In the beginning of this topic I failed to explain in detail exactly how aluminum parts were to be physically cleaned before being placed in the three chemical baths used. After very light de-burring of all the cylinder window edges with a very sharp Exacto knife, a brush hone, hot water & full strength Dawn is used to wash the ID of the cylinder. Moving the brush hone up & down as it rotates removes anything that may be loose in the cylinder's ID or at the edges of any window. The cylinders are then throughly washed in hot water with the circular fine hair brush shown.

Jim Allen
 
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Jim Allen said:
In the beginning of this topic I failed to explain in detail exactly how aluminum parts were to be physically cleaned before being placed in the three chemical baths used. After very light de-burring of all the cylinder window edges with a very sharp Exacto knife, a brush hone, hot water & full strength Dawn is used to wash the ID of the cylinder. Moving the brush hone up & down as it rotates removes anything that may be loose in the cylinder's ID or at the edges of any window. The cylinders are then throughly washed in hot water with the circular fine hair brush shown.

Jim Allen
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Hi Jim,

Do you reverse polarity when you first put the cylinders in the solution for a few seconds and then back to normal to begin the plating process? We found this helped to get the last bits of junk out the pores in the material no matter how good our physical and chemical cleaning processes were.

Thanks, John
 
John,

We DO NOT do this on brass or aluminum parts, but the reverse etching process is done on steel parts for a few seconds. Brass parts are washed in a strong alkaline solution & hot water. We are thinking about placing a patent on our aluminum Chroming process because the process has been developed to such a high level. A new bath will chrome plate approximately 200 cylinders before needing to be adjusted or replaced. We do not waste any time adjusting the old bath, we simply start with a new bath. The chrome plating process is very sensitive as to bath temperature, current density, anode size, plating time & any necessary electrical connections.

Someone brought it to my attention that the hone in the picture is called a flex hone.

JA
 
Jim Allen said:
John,

We DO NOT do this on brass or aluminum parts, but the reverse etching process is done on steel parts for a few seconds. Brass parts are washed in a strong alkaline solution & hot water. We are thinking about placing a patent on our aluminum Chroming process because the process has been developed to such a high level. A new bath will chrome plate approximately 200 cylinders before needing to be adjusted or replaced. We do not waste any time adjusting the old bath, we simply start with a new bath. The chrome plating process is very sensitive as to bath temperature, current density, anode size, plating time & any necessary electrical connections.

Someone brought it to my attention that the hone in the picture is called a flex hone.

JA
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Hi Jim,

Yes we were doing steel parts, wonder if that's still a common practice for steel? When the heater unit on my system died I used aquarium heaters for a number of years and then got rid of the lead tank and went with a huge glass battery jar from the chemical supply and set up a smaller system, similar to what I used for gold plating, reduced the size to 1.5 gallon.

Thanks, John
 
John,

Our tanks, which are battery jars, are also approximately 1.5 gallons & we maintain the 120* to 126* F temperature with two adjustable aquarium heaters in each. We pre-heat the tank overnight before the following days use. We also have placed the tank inside a styrofoam container to help stabilize the temperature variations that can take place when removing & replacing fixtures. Tank temperature is checked with a labatory thermometer during operation because the tank itself will develope some heat, in which case we will open the lid of that styrofoam container when necessary.

I think the reverse etching of steel is still done industry wide. I've had very good results doing steel cylinders of gas engines with the reverse etching process.

Jim
 
Just showing how it can be done. I have more than enough work with the Nelson engines & my personal engines.

JA
 
I have received several questions about the honing device shown in post # 81. The honing device shown in post # 81 is a soft nylon deburring brush. The tool is impregnated with 500 grit aluminum oxide & is available from EngineHones.com.

JA
 
I'm also receiving questions about how to hone a tapered cylinder with a Sunnen honing machine, which is used to hone a straight round hole. I'll post photo's & explanations when possible. If you contact Sunnen, they will not discuss the back honing technique we use to get a cylinder with the correct taper amount, that is round within .00005" & has a mirror finish. The mirror finish of the cylinder's Inside wall, the precise roundness of the piston & cylinder, plus the correct taper amount allow a new engine to be fitted in a ready to run condition.

JA
 
I photographed some honing stones that are actually used to hone cylinders. Notice that the 61 & 83 grit stones have become tapered from continued use. Also notice that the stones have been shortened on both ends to allow for honing in a particular area to correct cylinder size or correct cylinder taper amounts. In regards to the size of any cylinder, there is a minimum size that is used according to the Sunnen gauge. No particular size from the minimum size upward is being honed because of the possible selection of pistons finished in .0001" steps. The piston sizes range from .8033" to .8046" in .0001" increnents. The cylinder's taper is always the same, regardless of its ID dimension. Notice the very smooth, polished finish of the cylinders bore. Previous engine builders who though that a cross hatch pattern in the cylinders wall would lubricate the piston as it traveled upward, proved to be incorrect. This would also apply to wedge shapped groves cut into the upper area of the piston's OD. This is why the taper amount & length of the taper on the piston's upper edge is absolutely necessary for prolonged engine, piston to cylinder fit! This cannot be done by hand with such methods as non-embeding lapping compounds or shaping by hand! Also notice the simple PVC cylinder holding fixture, which makes rapid honing of the hard chromed cylinders possible. We are looking for a finished honing time of 5 to 7 minutes per cylinder.

Keep in mind that engine designs that overlook proven methods to maintain cylinder bore roundness at operating temperatures defeat the purpose of what has been described here. The proof that what is written here is valid can be seen in the wear patterns in cylinders & pistons of engines with hundereds of hours of use at 29,000+ RPM's.

Jim Allen
 
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I have been receiving questions about the technique used to fit machined pistons to honed sleeves. I will explain the method used for pylon racing engines & explain how this method could be used for other applications. I'll take photos with explanations when I return to work on 6/21 & 6/22, 2017.

JA
 
I have completed the photos (17) & information about fitting machined pistons to honed sleeves as promised. I have people coming to the shop today & I will post this information latter tonight. Having the ability to machine the necessary parts & finish those parts means nothing if those parts are not fitted properly!

Jim Allen
 
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Jim Allen said:
I have completed the photos (17) & information about fitting machined pistons to honed sleeves as promised. I have people coming to the shop today & I will post this information latter tonight. Having the ability to machine the necessary parts & finish those parts means nothing if those parts are not fitted properly!

Jim Allen
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Looking froward to seeing how you do it!
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The fitting of pistons to cylinders can only be done if the parts are made accurately, with the same finish each & every time. No consistent engine building of any kind can be accomplished without these two things. Since a measurement with a depth micrometer will be used to determine if the piston fits to tight, or to loose, any out of roundness, poor finish, oil, dirt or abrassive materials that may be present, cannot be tolerated!! All of the cylinders seen in the photo are throughly washed & dryed before any test fitting can begin. A 50% solution of Dawn dish washing liquid & super strength Greased Lightning are used to scrub, with a soft brush, both the inside & outside of the cylinders. The pistons are also scrubed in the same fashion. The parts are rinsed in hot water then air dried.

JA
 
There are two basic tools needed when fitting pistons to cylinders. Keep in mind the things previously stated that must be done before any excersize in fitting can be attempted. The photo shows a machined delrin piece used to push the piston into the cylinder from the bottom. A depth micrometer is used to measure from the top of the cylinder to determine how deep the piston is setting after it has been pushed until it cannot move any deeper. A considerable amount of pressure is used when pushing the two parts together between both hands until the piston can move no more. Turning the cylinder flange side up allows the same tool to knock the piston out of the cylinder without any damage. The next step is the fitting of a proper size head. Lose fitting heads will cause the engine to go into detonation when the engine is needled at WOT.

Again, if either of the two parts are out of round, have the wrong tapers, are oily, dirty, have any abrasive materials present or have a poor finish, this will be a total waste of time. I have done this thousands of times. The process is valid & repetable!!

Jim Allen

More to come........................
 
Thanks for sharing all this Jim, this stuff is lost forever unless it's passed on!

Do you just push the piston in as hard as you can until it stops? Or there a certain amount of "feel" involved?

Obviously you look for a certain distance BTD for the piston to stop, how is this distance arrived at?

How much further up the sleeve does a piston travel that's say 0.0001" (one tenth) smaller?

Thanks again!
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Good questions Terry. I have a fellow boater at the shop right now. I'll answer latter.

JA
 
Jim,

Regarding cleaning parts goes, we use an ultrasonic wash system with deionized reverse osmosis water for our final cleaning. Maybe overkill, but we are making dental instruments. We have to conform to certain regulatory requirements. Really works well on things like carbs and other things that have small hard to access orifaces.

Bob
 
Bob,

A customer recently told me that he was cleaning his engines with an ultrasonic cleaner. Good idea but he didn't remove the bearings before cleaning.

Jim
 
Jim,

Yes, bearings and ultrasonics are probably not a good combination. It would probably damage both the balls and the races. We make it a point to not allow parts to touch each other. The parts vibrating together definitely causes damage.

Bob
 

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