Fine finish

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Fine finish

This topic has 9 replies, 7 voices, and was last updated 12 August 2011 at 21:17 by John Stevenson 1.

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11 August 2011 at 20:33 #73216
Old Fart UK
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@oldfartuk
Ive just bought a s/h 7×16 minilathe.

Ive got an idea. There several parts Meccano SHOULD have made to make life easier, but never did. One example was a clock escapement. You CAN make one using Meccano parts, but its a pitb and doesnt work very well. If you dont believe me, try getting a Meccano Clock no 1 to run properly. Someone has already spotted this one, and you can now buy laser cut 30 tooth escapement wheels that bolt onto a standard two inch wheel, with a 20 inch pendulum you get one rev per minute.

Ive thought of some others, which im not going to reveal to you yet, but im making a few prototypes in order to test the technique of how to make a pile of them with the minimum number of tool actions.

One question. A lot of the reproduction brass parts parts have a very nice satin finish with no tool marks, how do you get such a fine finish. Ive tried using a Glanze indexable tool with TC tip and a plain HSS but, but you still get tool marks

Edited By Old Fart UK on 11/08/2011 20:34:29

Edited By Old Fart UK on 11/08/2011 20:35:13
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11 August 2011 at 20:33 #5612
Old Fart UK
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@oldfartuk
11 August 2011 at 20:52 #73217
JasonB
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@jasonb
Its quite likely that mass produced items have been placed into some form of machine to deburr them and take off any rough edges and this is wat gives them a satin finish.

Think of a tumble drier or vibrating container will lumps of ceramic material as it all jumps about the ceramic abrades the surface removing sharp edges and giving that satin finish

Jason

PS a Mini Lathe is unlikely to be rigid enough for getting a fine finish with indexable tools but try the non-ferrous tips that Glanze sell rather than the standard ones.
11 August 2011 at 23:04 #73221
Old Fart UK
Participant
@oldfartuk
ah like the thing used to polish stones, they fill with diamond or carborundum dust.

Ive come to the conclusion HSS is better than the TC, its just a case of making a tool of the right shape. Ive concluded the cutting edge has to be level with the centreline (zero rake). If i use a tool as wide as the cut i want to make, there will be no sideways ribbing, thats my theory. Ill try polishing the cutting tip on an oilstone as well.

Edited By Old Fart UK on 11/08/2011 23:05:01
12 August 2011 at 08:19 #73229
Weldsol
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@weldsol
You can get a nice satin finish by polishing with a Scotchbrite pad ( try using the green side of a nylon pot cleaner as that will give you some idea of the finish )

Paul
12 August 2011 at 08:24 #73230
Clive Hartland
Participant
@clivehartland94829
The fine finish on brass and other metals is called ‘Graining’.

Its where the parts are polished with emery sticks whilst they are turning or Grained on the flat in long easy strokes.

Its an old method of making clock parts look nice.

The deep gold finish is done with ‘Dragons Blood’ a mixture of varnish and colouring dye. Some times the parts are heated while the varnish dries.

Clive
12 August 2011 at 09:09 #73231
Old Fart UK
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@oldfartuk
Thanks for the tips. I posted the same problem on the CNC forum and didnt get an answer after 4 days. Some forums ae spot on and some are just a waste of hosting disc space.

Ill try emery. Id love to know how Meccano did it down Binns Road.
12 August 2011 at 09:49 #73235
Chris Trice
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@christrice43267
You might get better results with a more focussed thread title other than “Hi” in answer to specific problems. Most people seeing it will assume it’s just an introductory post by a new member.

I’ve found very fine wet and dry or a scouring pad can impart a nice satin finish to brass parts.

Edited By Chris Trice on 12/08/2011 09:51:11
12 August 2011 at 13:19 #73245
WALLACE
Participant
@wallace
I quite like the finish you get with an orbital sander – lots of small, fine circles – it’s a bit of a ‘poor man’s’ engine turning – but a lot, lot quicker !!

W.
12 August 2011 at 21:17 #73268
John Stevenson 1
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@johnstevenson1
Posted by Old Fart UK on 12/08/2011 09:09:13:

I’d love to know how Meccano did it down Binns Road.

I can answer this one I think as when they packed in we collected 5 of the Escomatic wire feed machine they made the pins and screws with.

When we went to collect after the auction [ I wasn’t at the auction, only machinery collecting ] there were rows of vibro tumblers there and we brought 5 back to Derby as they had been bought by the company that made them for refurb and later resale.

John S.
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