Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Polishing metal capstans in the field

Hello all,

I have a quick question here.

When I am at the workbench, polishing metal capstans is a simple matter. I just use a buffing wheel and some white rouge. It's a quick and easy way to bring them up to a mirror finish.

When I need to polish capstans at a customer's home, it seems impossible to get the same results... especially so quickly and easily.

The way I was taught back in the late 70's was to use 4/0 steel wool. It does an OK job. It has always (for me anyhow) eliminated any squeaks caused by burrs and/or pits on the capstan rubbing against the felt on the bottom of the whippen. And, the capstans do look better. But, the steel wool inevitably leaves fine scratches and leaves a less attractive look than what I can achieve with a buffing wheel.

I thought of using something like Brasso, but I am afraid of contaminating the felt with any residue. Plus, there is the risk of a disastrous spill.

I'm curious if anyone out there has any alternative approaches to polishing the capstans at the customer's home that give good results.

Thanks,
-Joe

You can get buffing wheels that you can fit to a cordless drill. If your drill is fast enough, it should work ok. You can also get them for a Dremel tool.

Wow... That was fast! Thanks, Ando

When you do this, do you find it necessary to cover the strings, sides, etc. to protect them from the rouge flying coming off the wheel. Or, have you found that this is not a problem? Or, do you use some other compound?

I only ask because I have found that when buffing at the bench using a wheel, I need to cover the rest of the key to protect if from the rouge coming off the wheel.

Thanks,
-Joe

In the shop or the field:

Flitz metal polish, applied by hand with rag, followed by two coats of McLube 444. I use the same procedure for key pins.

Thank you, beethoven986

I Googled Flitz metal polish and did a little quick reading. It seems like very good stuff. I like that it can be used to use it to hand-polish brass. (http://www.flitzpolish.com/category_s/18.htm So, I could steel wool and then Flitz by hand in a very controlled fashion in the customer's home.

Usually, I don't use a clear coat on the capstan; I just try to make it as clean and dry as possible. I usually use either Teflon powder or talc on the felt. But because of your post, I am re-examining this and considering coating like you do with McLube.

Thanks for the great tip
-Joe

I'm not a piano tech actually, but have experience with many hands on projects. You don't necessarily get fling off with a spinning disc - especially a small diameter one with a dense liquid based polishing compound. Just use a small amount and it should polish anything up with minimal mess. Probably just need to practice on a few bits and pieces before using it in the field.

Honestly, I wouldn't even bother with steel wool (Let's be honest, it's much more fun to just light it on fire, so why waste it on polishing, right?). Flitz and a rag will remove anything nasty from the capstan, and the McLube will take care of the rest. I only use Teflon on the knuckles (after spraying them with TFL-50). Realistically, the capstan is much lower on the food chain than the knuckle or shank/flange centers, or the key pins, so don't spend too much time on them.

Since we're on the topic of polishing stuff, if you hate polishing key pins, Coleman tools has a nifty polisher that fits into a power drill... I bought one recently and can't wait to try it out!

Joe:

I've only ever used the likes of Brasso on capstans when I'm doing a service. Only ever resorting to using a buff wheel of some kind when I find someone previously has used fine sandpaper or wirewool.

I want the surfaces to be like mirrors ( oh the thought of seeing 88 images of me )

A nice piece of clean white cloth impregnated with brasso, and a steady hand, result in a great job. If you're worried about getting any on the woodwork, just mask it off.

I too, let it dry completely, wipe off, and apply a coat of Protek .... I'm pretty sure it's the same as Mclube 444.

The finish is infinately better than leaving a scratched surface by using wirewool.

I've used a woollen mini buffing weel on my Dremel tool to polish the damper spoons on my upright (while the dampers were out of the action anyway). The wheel left the spoons with a near-mirror finish, and because of the high speed wheel doing most of the work, there was hardly need for polishing compound. The wheel did, however, make some fine, white dust. A quick once-over with the vacuum took care of that. IMHO, if you have a Dremel, I'd recommend this over hand-polishing because it's so easy and runs no risk of staining any parts with polish.

Is there any who hasn't tried lighting steel wool on fire? LOL!

I realize that the capstans are far less important than the knuckles when it comes to friction. But, I have found the capstans to be the source of squeaks occasionally. When the pitting or burrs are buffed out or polished out so there is an absolutely smooth surface, the squeak disappears.

Also, I often see a lot of felt crumbs where the capstans are pitted or have burrs. (Also, when the spoons are pitted on a vertical.) The additional friction seems to cause the felt to wear faster.

Thank you for the tip about Flitz polish. I will look into this. We have a number of auto parts stores nearby, so I will see if I can find it locally.

And yep, I DO hate polishing pins. Thanks for the tip re the Coleman polisher.

Thanks,
-Joe

Hi Johnkie!

I've thought about using Brasso, too.

Since you do so much concert work, I get the feeling that you are used to working on a much higher grade of piano than I do most of the time. I will see even new pianos with very noticeable pits on the contact surface of the capstans and burrs around the edges (not to mention any specific brands)

When you do encounter cases in the field where the quality control on the capstans was lacking, how do you deal with it? Would you use then consider 4/0 steel wool followed by Brasso? Or maybe use a buffing wheel on your drill? Or maybe some other solution?

Thanks,
-Joe

Joe:

I suppose I'm pretty blessed by being able to work on really good quality instruments that very rarely have pits or burrs on the capstans. It is normally more a case of "going that extra little bit" to reduce friction after being in service for some time.

Of course I also deal with Horrors, as most professional tuner will, and you are quite right to consider taking much larger steps to ensure a smooth mirror like surface.

Under those circumstances Joe, Yes I would resort to either VERY fine Aluminium Oxide paper to remove any pits or burrs. #4/0 steel wool seems a tad too coarse, and would make achieving a mirror finish a boatload of work. Perhaps in your part of the world, gauges work differently, but over here our fine steel wool is #00, and much less likely to leave deep surface scratches.

In summary then ... If on the road .... first smooth with VERY fine paper or wire-wool, finishing off with Brasso (or similar product) ... but if you carry a dremmal in your car, you might find that easier if used with care.

Best wishes - John

Thanks, Johnkie
-Joe

While on the topic of capstan surfaces, have any of you seen such bad scars/marrs before? (Taken on my own Ibach upright of local production - there are about 5 such capstans throughout the piano.) I suspect the capstans are turned into the keysticks by machine, and in these cases, the machine was not aligned properly by the operator?




Even the undamaged capstans have a burr around the edge.

cotton disks can be impregnated with some artificial tallow, this avoid the dust of the polishing paste.

I use more polishing pastes than liquids, with cottons.

on the brass to clean the residues of liquids it is common to use some white powder (the name escapes me, sort of plaster)

most liquid products for brass leave some residue that react and make stains if not well annihilated, that is why I mostly use pastes;
Renner sells a "Bronze Angelack) that sound like synthetic lacquer, very transparent and flowing nicely. makes the final protecting coat without tarnishing under it (which is the case if unadapted lacquer is employed) cand be used with a brush.

Often brass parts are protected with a lacquer, even some capstans (Yamaha, unless it is a surface treatment that looks like lacquer) I never tried the above product on capstans.

your marred capstans surface could be repaired with some solder (kind for electricity), just to avoid scratching the cloth too much.


I never use steel wool on polished surfaces (damper wire, key pins, etc) too difficult to polish afterthat (but there are nice qualities of "Mirka" similar to scoth Brite but way thinner - 1000-30000

a piece of hammer felt is good for hand rubbing

The tool sold to clean tuning pin can help to cut the burrs of the edges.
Reestablishing a good shape and surface on the cloth side usually lower the friction a lot, and then the edges does not touch the cloth.

Thanks, Isaac. Interesting, I hadn't thought of soldering as an option. I was considering metal-powder-filled epoxy (also called "liquid steel"). For soldering, I would probably have to remove the capstan from the keystick, in order to protect the wood from charring.

I hadn't thought of that. Maybe the lesser pitting on the contact surface I keep seeing is also due to the machine inserting the capstans, rather than the capstans themselves having been incorrectly manufactured.

But, the burrs around the edges are probably not caused by the insertion process. It would seem that this IS a manufacturing defect of the capstan. Or, maybe the burrs are supposed to be polished out at the piano factory before installing in the keystick?

Mark R.

There may be an easier way to correct the gouges on your capstans. Is the piano still under warranty? If so, it might just be best to complain to the manufacturer and ask for new capstans to be shipped to you. This would certainly seem to qualify as a manufacturing defect.

If it's not still under warranty, buying new replacement parts might just be the easiest, fastest, cheapest (when you consider the time involved), and most permanent repair.

-Joe

capstans are inserted with a kind of drill press but they are hold by the perimeter. (I did it with an electrical screwdriver also, being attentive they are straight enough) the defects you have are more due to the lathe in my opinion

the edge burrs are not too difficult to cut by hand.

.

Mark :

Thanks for the photos .... B****y Heck ... That second one is horrendous !!

The manufacturer should be shot for allowing this sort of quality control.

I'd demand replacements and a set of heel felts.

Shocking .... simply shocking.