Polishing stanchion tubes

[Suzsmokeyallan]

After Terry had proposed polishing some stanchions, I took a look at some I had that were soon going into newly painted lowers.
Slipping them into my lathe and spinning them up, I used some #600 grit paper, on you guessed it, WD40 as a lube.
The results of some time spent shows they are now a lot better looking than they were originally.
The PO seems to have sanded them along their length, making them dull and full of fine scratches, whereas they should be polished against it.
Now to take out the springs etc and clean up all the small parts before reassembly.
* The photo is shown sideways since turning it upright reduces the overall size for showing the clarity of the tube surfaces *.

[H2RICK]

Allan:
600 grit is too coarse, IMO, to finish stanchions with and expect your fork seals to last any reasonable length of time.
I'd do the next step with some 1000 grit, then some 1500 and finish off with some 2000. You'll end up with a nice mirror finish where the hard chrome is and the rest will look fairly nice too.
A lathe makes this job soooooo easy......and consistent too.....

[wvc]

I've been debating what to do with the fork tubes on my GT500 project. They have some light scratching on the tubes, that I suppose would polish out. But the inch or two right below where the lower triple clamp mounts, there are rust pits coming thru the chrome (they are all high enough, not to affect the sliding / fork seal area). I could polish the rust off, but the little tiny pin holes will still be there. Any ideas? I thought of calling Forks by Frank, and seeing if I could get new ones made, or thought about seeing if mine could be Re-Hard Chromed, but I'm thinking that may be cost prohibitive.
Or another idea I thought of was polishing the tubes up nicely, then using one of those Plug N Plate kits, and replating some chrome into the pitting areas. What do you guys normally do ??

[Suzsmokeyallan]

Rick you would think so at first, but the finish now is actually SMOOTHER than how they were, maybe my #600 grit paper is finer than yours. #1000 grit paper does nothing on the legs other than slide over it, the material is just too hard for it to even leave a polishing impression of any sort.
You have to remember the chrome placed onto fork stanchions is not the same as regular chroming. From what I found out its a hardened chrome process where its applied to the legs for a margin of excess OD diameter, from there its then ground and polished to correct dimensional size.
Comparing these to any sets of forks I have, plus some new ones I got from Franks, these now look identical in smoothness, finish and appearance.

WVC take them off and clean into the pits with a brass brush and apply some thinner to remove any grease. Then apply a tiny blob of JB weld by toothpick to each little pit to just cover it, once it hardens using a very fine file, dress the little heads down almost to the level of the tube. After you have done them all, polish the tubes up by spinning them as I've done and this will clean off the rest of the little heads left from the filing.
If you have most on one side of the tubes turn them around so they are at the back and keep some gun oil wiped on them.
Can this be done on your stanchions? it certainly cant make them any worse than they are now.

[Coyote]

I was involved in the wear prevention industry for 30 years. Basically parts for the petrochemical industry and some for the nuclear power industry. We did our own hard surfacing in house. Occasionally we would get a request for hard chrome. We had to sub this operation out as what we did was spray and fuse coatings, ceramic coatings and tungsten carbide applied HVOC. Over the years I learned lots of things about hard chrome.
We did lots of pump shafts. Some as little as 1/2" in diameter and only a foot long. From there up to 3" in diameter and 26 feet long with detailed close tolerance machining on each end. The long shafts had support bearings in spots along their length. Some customers would require hard chrome in these areas.
So the shaft material (generally 316-L SS) would be purchased oversize. Then it would be centerless ground down to plus .010 from finish. Next it went to the engine lathe and the areas for chrome were undercut .005 under finish. Then to hard chrome and then finish ground to .001 tolerance.
The point I am trying to make here is hard chrome is generally very thin. It takes forever to build up as it only plates a like .0002 (two tenths) per hour. So shaft areas that needed to be oversize for final grind took 3 to 5 days for turn around and half the time there still wasn't enough on them.
Now to the fork tubes. Yes they are hard chromed. My guess is there in no more than .0005 per side or .001 on the diameter. I have seen fork tubes that have worn through the chrome. This generally happens on the rear of the fork leg, just above the seal. I assume this is because the chrome was not concentric with the base material and was ready to break through from the get go. You can see this if you roll the tube on the bench while watching the chrome end line.
Hard chrome and decorative chrome are two entirely different processes. You would be hard pressed to find an outfit that does both under one roof. Hard chrome is 55 to 60 Rockwell C. It has extremely good wear characteristics, particularly in a centrifugal application.

[H2RICK]

Allan:
That's interesting that that's what it takes. Obviously Suzuki raised their quality compared to earlier forks that I've worked on back in the day. Something to keep in mind.

Coyote:
Interesting stuff. I had somewhat of an idea how this was done but thanks for clearing up some of the "murkier" aspects of the whole process.