UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Hints, Tips and Solutions (Do NOT post requests for help here)

Notices

Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

Closed Thread
 
Thread Tools
Old 11th Aug 2013, 2:37 am   #1
QQVO6/40
Hexode
 
Join Date: May 2009
Location: Newcastle, Australia
Posts: 316
Default Cleaning and Polishing Smaller Parts

For cleaning and polishing smaller parts such as knobs, screws, stand off bushes and the sort of little bits and pieces used in vintage radios I use a gemstone tumbler.
This is a simple machine consisting of 2 parallel metal shafts mounted on pillow block bearings. Both shafts are belt driven from a small fractional horsepower electric motor. You obtain a sturdy parallel sided plastic jar with a wide mouth that will sit sideways on the 2 parallel metal shafts so that when the motor is running, the plastic jar will just rotate about it's cylindrical axis at a slow rate.
Place a small number of objects to be polished in the jar, not too many, and also put in some clean saw dust to act as the polishing agent. best results are obtained when the jar is not more than a third full. The whole idea is to get a tumbling action going within the jar. Place the jar on the shafts, switch on the motor and go and do something else for a few hours. If you do not get a good tumbling action in the jar, you might have to roughen the inside of the jar or get some small plastic strips and securely glue them to the inside of the jar. It needs to get a tumbling action going. If the mix just slides around inside the jar it will not give the desired result.
If you have quite a few bits to polish, do not overfill the jar as you will find that the bits will collide with each other and get damaged. Be patient. If you know you will have lots to polish then make the metal shafts longer and use 2 or 3 plastic jars at the same time.
If you have a valuable item then just put it by itself in the plastic jar.
This system is really good on Bakelite knobs.
Vary the type of sawdust to get different grades of polishing going. Hardwood, softwood, different sizes of wood chip from very fine sawdust right up to wood shavings from a hand plane. All worth a try. I use wood shavings to put a magic gloss on small Bakelite parts.

If you want a stronger cut you can add things such as diatomaceous earth to the sawdust. Just a little.

Only thing is that you have to use a small screwdriver to pick the sawdust out of holes and cavities after the cleaning job is done.

Yes, there are small drawbacks such as it struggles with polishing into tight corners but overall, the method is very gentle but just takes time. I have to stress, just be patient.

I hate polishing little bits. It is so time consuming and hard on the fingers. I have a friend who is into telephones and he was polishing a Bakelite casing from a phone on a rotating cotton buff wheel. The wheel caught the edge of the case and ripped it from his hands, downwards at a 45deg angle at high velocity to smash into a thousand pieces on the concrete floor. Such a waste.
As a result of this I made him a larger polisher and he has successfully polished whole telephone Bakelite cases in it.

I also made one for another friend who is into old rifle and pistol cartridge cases. It is magic for this type of thing. It brings up brass to a beautiful shine.

You can cheat and buy one of these from a lapidary supply shop but making one is more fun.

Cheers, Robert.


Please mods. This is sort of related to the topic. If you think it should have it’s own thread then please would you? Thanks.

Last edited by AC/HL; 11th Aug 2013 at 12:01 pm. Reason: As suggested, given a life of it's own
QQVO6/40 is offline  
Old 11th Aug 2013, 3:27 pm   #2
Guest
Guest
 
Posts: n/a
Default Re: Cleaning and Polishing Smaller Parts

Some commercial 'tumblers' use a rubber container round on the outside and hexagonal on the inside to promote tumbling. Perhaps a 'pretty' jam jar could be used with rings attached.

I was at an arms fair where one stand had lovely polished shells (up to 5" or so) on display, they were made in India. I asked the stand holder how they were so shiny, he said (in a wonderful Indian accent) "we have been polishing them all night in the hotel", glad they were dummies!

Last edited by Mike Phelan; 12th Aug 2013 at 8:34 am. Reason: Typos.
 
Old 12th Aug 2013, 8:38 am   #3
Mike Phelan
Dekatron
 
Mike Phelan's Avatar
 
Join Date: Nov 2003
Location: Near Leeds, West Yorkshire, UK
Posts: 4,609
Default Re: Cleaning and Polishing Smaller Parts

I did make one of these devices years ago when my better half used to polish semi-precious stones. The main part was a plain cylindrical jam jar with ex-inner tube rings at each end and a shaded-pole motor from a scrap record player.
__________________
Mike.
Mike Phelan is offline  
Old 13th Aug 2013, 5:51 am   #4
QQVO6/40
Hexode
 
Join Date: May 2009
Location: Newcastle, Australia
Posts: 316
Default Re: Cleaning and Polishing Smaller Parts

I spent my early childhood with my parents who had a small business making cast phenolic resin components. Phenolic resin type plastics are a thermo-setting type of plastic that is quite different to today's modern plastic. It is a lot like "Bakelite" except that it is a viscous liquid and is poured into a mould and then heated gently to make it set.
This type of plastic takes to polish very well and it is reasonably easy to bring up a good lustre.
In our small factory we did all of the polishing ourselves. We had a setup with 4 barrels rotating simultaneously.
The first one in the process had a medium grade of sawdust with some diatomaceous earth in it and it was used for the main polish barrel.
The second barrel was just clean medium grade sawdust and it was used to remove the diatomaceous earth from the plastic components basically used as a cleaner.
The third barrel had a polish component in with the medium grade sawdust. I think, and this is testing my memory, the polish had stearic acid in it. Last time I saw it in operation was over 50 years ago and i have seen and done a lot since then.
The 4th and final barrel had just a coarse grade of sawdust and nothing else and was used to give the plastic items a final buff up.

Do not put too much stuff into a jar. Probably no more than one third full. The contents of the jar must tumble over do be able to do the job. If the stuff just slides around inside the jar then it will not do the job.

Be patient. This takes time to do.
Do not try to put too many components into the jar at any one time.
Please experiment. It is good to try out different polishing mixtures.
I have a friend that cleans and polishes knob sized plastic components and he swears by peanut shells. Says he gets a very fine glass like polish on his bits.


Enough of my blather.

Cheers, Robert.
QQVO6/40 is offline  
Old 13th Aug 2013, 11:38 am   #5
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
Default Re: Cleaning and Polishing Smaller Parts

I've heard of finely crushed eggshells being used as a polishing material in tumblers: guess it helps if you take the egg out first!
G6Tanuki is offline  
Old 13th Aug 2013, 12:49 pm   #6
Dave757
Heptode
 
Join Date: Apr 2009
Location: Scratby, Norfolk, UK.
Posts: 648
Default Re: Cleaning and Polishing Smaller Parts

Quote:
Originally Posted by G6Tanuki View Post
I've heard of finely crushed eggshells being used as a polishing material in tumblers: guess it helps if you take the egg out first!
Hi,

I have heard that crushed walnut shells is another polishing medium

Kind regards

Dave
Dave757 is offline  
Old 11th Oct 2013, 10:21 am   #7
FrankB
Heptode
 
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 663
Default Re: Cleaning and Polishing Smaller Parts

If you reload shells, your shell casing tumbler/ polisher works well too.
Glass beads do a nice job, and we get them here from an automotive body supply
Company.
Walnut shells are great too.
The S.O. uses them at her job to clean and polish up aircraft parts when doing mods
and repairs.
FrankB is offline  
Old 6th Nov 2013, 6:13 am   #8
FrankB
Heptode
 
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 663
Default Re: Cleaning and Polishing Smaller Parts

I have discovered that walnut shell and baking soda work well too.
FrankB is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 12:08 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.