pinions

[dinnie hoekstraParticipant @dinniehoekstra63856]

I made some clock pinions module 0.4 in silver steel ; leaves number from 12 to 32 .

I have hardened en tempered them . it appeared that they were more or less not true anymore .

does anyone know how to solve this problem ? I did it my way by making for each pinion head a special holder in brass and then let the holder run true in a four jaw chuck followed by true grinding the ends of the pinions , but this was very time consuming and not perfect ( plm. 0,05 mm out of round )

dinnie

[dinnie hoekstraParticipant @dinniehoekstra63856]

truing a pinion

[speelwerkParticipant @speelwerk]

This is perhaps worthwhile buying, they try of course to sell there products but it gives also useful information. Niko.

**LINK**

[Bob StevensonParticipant @bobstevenson13909]

There are lots of imponderables and variants in this (and your post)

 

Probably the simplest way to cut pinions is to make up a holder for the silver steel stock which you have already turned or aquired to the finished diameter of the pinion…….you can use a boring bar holder in the tool post of the lathe to hold the stock and index it by fitting a lathe change wheel to the rear end of the stock….now pass the tool post/holder against either a fly cutter or commercial multi-toothed cutter held in the lathe spindle or chuck etc.

 

You can also make pinions by planing using the top slide of the lathe.

 

Be aware that the tooth (leaf) profile for a pinion is NOT the same as for a wheel tooth……

 

You have previously centre bored the stock to the diameter of the arbour……..

 

Polish the pinion leaves by holding against a small disc of hardboard on a mandrel in the lathe chuck….charge this with some rouge or 'T-Cut' etc

 

Harden the pionion by wrapping in soft iron wire until completely covered and leave a small twisted 'tail' for easy handling……….heat to red heat and then, using the tail, hold under running cold tap…..remove wire, place pinion on bed of brass filings and heat underneath to required temper colour…….drop in oil.

 

 

Edited By Bob Stevenson on 08/03/2017 23:44:19

Edited By Bob Stevenson on 08/03/2017 23:47:33

[Brian HParticipant @brianh50089]

Is it worth hardening ( and tempering) clock pinions? Clocks from hundreds of years ago were probably not fitted with hardened pinions and yet still continue to run without problems.

If hardening is considered to be necessary, would case hardening be better?

[not done it yetParticipant @notdoneityet]

Agree with Brian.

Problem of 'more or less' truth after hardening and tempering may be any stress within the original material (so anneal carefully when material is close to final machining size) and the hardening conditions not being entirely equal (likely quenching unevenly).

[Michael Smith 15Participant @michaelsmith15]

I make mine in EN 24 T which is hardened and tempered but is machinable and requires no further treatment

Edited By Michael Smith 15 on 09/03/2017 08:52:19

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