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Reducing diameter cylinder bobs

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Chris TickTock26/10/2020 10:48:09
605 forum posts
43 photos

Hi Guys,

One of the ways of finishing pallets on escapements suggested the use of hard felt cylinder bobs.

Can these be reduced on the lathe to get a reduced felt diameter?

I would be aiming for 3/32 Dia. Even if i can get that diameter I would still be interested if using a lathe the diameter can be reduced.

Regards

Chris

Michael Gilligan26/10/2020 10:55:07
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16611 forum posts
723 photos
Posted by Chris TickTock on 26/10/2020 10:48:09:

Hi Guys,

One of the ways of finishing pallets on escapements suggested the use of hard felt cylinder bobs.

[…]

.

dont know

Seems very likely to round various edges, and generally ruin the geometry.

... There’s a difference between ‘shiny’ and ‘accurate’

MichaelG.

Emgee26/10/2020 11:54:49
1763 forum posts
237 photos

You may be able to buy some rubber cylinders impregnated with polishing grit and mounted on 1/8" shanks, as the rubber extends past the end of the shank you could turn down a short length to your chosen diameter.

From memory colours are brown, green and blue which identify the different grades of abrasive.

Emgee

Chris TickTock26/10/2020 12:12:30
605 forum posts
43 photos
Posted by Michael Gilligan on 26/10/2020 10:55:07:
Posted by Chris TickTock on 26/10/2020 10:48:09:

Hi Guys,

One of the ways of finishing pallets on escapements suggested the use of hard felt cylinder bobs.

[…]

.

dont know

Seems very likely to round various edges, and generally ruin the geometry.

... There’s a difference between ‘shiny’ and ‘accurate’

MichaelG.

The reason that I ask is that I found online an article a clockmaker who does it using the same zero top rake round nose cutter he uses for brass. Felt being softer than metal the zero rake makes sense but as I have no hard felt cylinder bobs yet I have no idea. if it cuts evenly fine and of course the quality of the bob may prove to be all important.

Chris

Michael Gilligan26/10/2020 12:23:38
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16611 forum posts
723 photos
Posted by Chris TickTock on 26/10/2020 12:12:30:

The reason that I ask is that I found online an article a clockmaker who does it using the same zero top rake round nose cutter he uses for brass. […]

.

Perhaps you could share a link to that article, Chris

... Then we might be able to comment on his materials, tools, and technique.

MichaelG.

Chris TickTock26/10/2020 12:27:58
605 forum posts
43 photos
Posted by Michael Gilligan on 26/10/2020 12:23:38:
Posted by Chris TickTock on 26/10/2020 12:12:30:

The reason that I ask is that I found online an article a clockmaker who does it using the same zero top rake round nose cutter he uses for brass. […]

.

Perhaps you could share a link to that article, Chris

... Then we might be able to comment on his materials, tools, and technique.

MichaelG.

The only details given are as I have stated Michael. I suppose I will wait till I have some and if needed have a go, providing the bob stays true it will work.

Chris

Michael Gilligan26/10/2020 12:45:24
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16611 forum posts
723 photos

So your sources are secret dont know

... I’ve suddenly lost interest

MichaelG.

Baz26/10/2020 12:48:32
487 forum posts

Chris, you say you have found online an article, can you please share the link with us.

John Haine26/10/2020 12:55:42
3422 forum posts
184 photos
Posted by Chris TickTock on 26/10/2020 12:12:30:
Felt being softer than metal the zero rake makes sense but as I have no hard felt cylinder bobs yet I have no idea. if it cuts evenly fine and of course the quality of the bob may prove to be all important.

Chris

Actually that doesn't make sense. Zero rake is used for brass because it grabs (though actually I use my Diamond tool on hard brass and have never has a problem). Felt is fibrous and soft and you would need to cut through the wool fibres so need a very sharp tool. Anyway the whole idea seems silly to me for the reason that Michael gives. You need to polish the sliding surface but keep sharp and crisp edges. I think a soft metao like zinc is usually used so a suitable abrasive embeds into the surface. Aluminium would probably do the job as well.

Chris TickTock26/10/2020 13:34:16
605 forum posts
43 photos
Posted by Michael Gilligan on 26/10/2020 12:45:24:

So your sources are secret dont know

... I’ve suddenly lost interest

MichaelG.

No not secret at all the article I found online is in the public domain and I downloaded a file so it may take time finding it and that is something I am short of. I will try and find it later on (though why you cannot take some one's word on it is beyond me) again though as i say it does not say anything more in relation to him reducing the hard felt cylinder bobs than he used his round nose cutter with no top rake that he uses for brass. The reason for my post was i too like John wondered about the plausibility of cutting it on a lathe. I believe him just is a different material than I would think you usually cut on a lathe. I am also contacting him for further information. Nothing wrong with a new way of doing something..if it works.

Chris

Chris TickTock26/10/2020 13:39:37
605 forum posts
43 photos
Posted by Baz on 26/10/2020 12:48:32:

Chris, you say you have found online an article, can you please share the link with us.

If you type into google Levers David Morrow grinding oldtymesclockrepair

it should take you to a pdf link

Chris

Edited By Chris TickTock on 26/10/2020 13:42:01

Edited By Chris TickTock on 26/10/2020 13:45:20

Edited By Chris TickTock on 26/10/2020 13:46:28

Michael Gilligan26/10/2020 13:59:12
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16611 forum posts
723 photos
Posted by Chris TickTock on 26/10/2020 13:39:37:
Posted by Baz on 26/10/2020 12:48:32:

Chris, you say you have found online an article, can you please share the link with us.

If you type into google Levers David Morrow grinding oldtymesclockrepair

it should take you to a pdf link

Chris

.

Pity you couldn’t have mentioned that earlier

I will search for it when I have some spare time.

MichaelG.

Chris TickTock26/10/2020 14:52:31
605 forum posts
43 photos
Posted by Michael Gilligan on 26/10/2020 13:59:12:
Posted by Chris TickTock on 26/10/2020 13:39:37:
Posted by Baz on 26/10/2020 12:48:32:

Chris, you say you have found online an article, can you please share the link with us.

If you type into google Levers David Morrow grinding oldtymesclockrepair

it should take you to a pdf link

Chris

.

Pity you couldn’t have mentioned that earlier

I will search for it when I have some spare time.

MichaelG.

Michael its very easy to be rude back but no.

Chris

Michael Gilligan26/10/2020 15:47:24
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16611 forum posts
723 photos

Simple statement of two facts ... No rudeness intended

MichaelG.

Michael Gilligan26/10/2020 16:02:43
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16611 forum posts
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From p42 :

Hard Felt Cylinder Bobs:

To polish, the hard felt cylinder bobs illustrated above are used for the two final polishing steps

(1 st brown tripoli and 2nd red rouge). They worked great. […]

....

The turning tool is illustrated on p41, and I admit that I am surprised.

Unfortunately, however, I can find no specification for his ‘hard felt’ so feel unable to comment any further.

 

MichaelG.

.

Ref: for the convenience of others

http://oldetymesclockandpocketwatch.com/assets/LEVERS_with_bent_strip_recoil_Website_Version.pdf

.

Edit: These Questions and Answers may be of interest:

https://www.feltbobs.com/catalog/index.php?main_page=page&id=11

... especially Q2

Edited By Michael Gilligan on 26/10/2020 16:32:15

Steviegtr26/10/2020 16:12:11
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1625 forum posts
196 photos

Its a shame the dremel ones were not small enough.

Steve.

Edited By Steviegtr on 26/10/2020 16:17:23

Chris TickTock26/10/2020 16:34:02
605 forum posts
43 photos
Posted by Michael Gilligan on 26/10/2020 16:02:43:

From p42 :

Hard Felt Cylinder Bobs:

To polish, the hard felt cylinder bobs illustrated above are used for the two final polishing steps

(1 st brown tripoli and 2nd red rouge). They worked great. […]

....

The turning tool is illustrated on p41, and I admit that I am surprised.

Unfortunately, however, I can find no specification for his ‘hard felt’ so feel unable to comment any further.

MichaelG.

.

Ref: for the convenience of others

**LINK**

Edited By Michael Gilligan on 26/10/2020 16:07:04

Thank you Michael,

As you can see adding the site link did not help answering my question as to the cutting the bobs on a lathe, which is why i saw no point adding it. I am told by Jerry Kieffer that David was one of his students a few years ago and is very bright with good ideas, from what i see i agree.

Chris

Chris TickTock26/10/2020 16:35:11
605 forum posts
43 photos
Posted by Steviegtr on 26/10/2020 16:12:11:

Its a shame the dremel ones were not small enough.

Steve.

Edited By Steviegtr on 26/10/2020 16:17:23

Yes Steve, that's my next port of call sourcing the little chaps.

Chris

Michael Gilligan26/10/2020 16:46:11
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16611 forum posts
723 photos
Posted by Chris TickTock on 26/10/2020 16:34:02:
 

Thank you Michael,

As you can see adding the site link did not help answering my question as to the cutting the bobs on a lathe, which is why i saw no point adding it. […]

.

But it did at least let me see that:

  1. He is discussing bent-strip pallets
  2. He only uses the bobs for the two final stages of polishing
  3. The lathe tool, although zero rake, is not round-nosed

So I am a little more relaxed about the idea now !

MichaelG.

.

Edit: If only we had a McMaster-Carr outlet in the UK ...

https://www.mcmaster.com/felt-bobs/

 

 

 

Edited By Michael Gilligan on 26/10/2020 16:47:42

Chris TickTock26/10/2020 16:58:03
605 forum posts
43 photos
Posted by Michael Gilligan on 26/10/2020 16:46:11:
Posted by Chris TickTock on 26/10/2020 16:34:02:

Thank you Michael,

As you can see adding the site link did not help answering my question as to the cutting the bobs on a lathe, which is why i saw no point adding it. […]

.

But it did at least let me see that:

  1. He is discussing bent-strip pallets
  2. He only uses the bobs for the two final stages of polishing
  3. The lathe tool, although zero rake, is not round-nosed

Your not reading the same pages as me Michael, look at page 41 there is a picture with words below;

'Above picture shows the setup where I used the round nose cutting tool that I use for brass i.e. that cutting tool with no rake to machine the 1/4” diameter cylinder bob down to 1/8” diameter. This 1/8” cylinder bob will get inside the Exit Pallet Inside lock surface nicely.'

He is also clearly discussing a deadbeat of anchor design in relation to the cylinder boss.

Shall we just leave it as a don't know and say no more about it?

Chris

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