Making a Lathe Pully

[jdrichard]

Anyone have any experience in making a replacement pulley for a Watchmakers lathe.

 

 

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[jdrichard]

Phase 1, bandsaw cut chunk of material


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[vinn3]

a lathe is the only machine that repair itself;  coined before the internet.  the specifications for turning can be found in "the machinest's hand book".  good luck  vin

[jdrichard]

Phase 2 - Drill a hole
Phase 3 - Put in 3 Jaw Chuck
Phase 4 - Grave Pulley Slots

Phase 5 - Install



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[jdrichard]

a lathe is the only machine that repair itself;  coined before the internet.  the specifications for turning can be found in "the machinest's hand book".  good luck  vin

Thanks Vinn3


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[vinn3]

    the proper name for the "good book" - as i remember is Machinery hand book. it weighs about 5 pounds and has been used in aprentiships for years.  vin

[nickelsilver]

You might find that the belt slips with that groove shape, generally for pulleys used with round belts the angle should be between 35 and 60 degrees, more towards the smaller angle. Most I've actually measured have been between 40 and 50. The smaller angle makes the belt wedge into the groove, so you don't need excessive belt tension.

[jdm]

2 hours ago, nickelsilver said:

You might find that the belt slips with that groove shape

I was to make the same comment but I didn't, as jdrichard is an able machinist and will figure out, without the need for any book. 

However it seems to me that the original pulley have radius concave grooves, but the pics don't show clearly. I suppose that turning Acetal that can be easily achieved by grinding a round nose tool.

Please excuse if I'm talking without sound experience, I still have to resume my machinist self-learning with the new steel bars that I just bought for an hefty price to me. 

[nickelsilver]

Pulleys for high-confidence applications with wire rope (cable) are often round looking in cross section but there's a fair bit of engineering in the actual shape. All pulleys wear over time, I can see a round-ish wear pattern on many of my old machines and motors. I don't recall any watchmaking equipment that came with round grooves though.

[jdrichard]

You might find that the belt slips with that groove shape, generally for pulleys used with round belts the angle should be between 35 and 60 degrees, more towards the smaller angle. Most I've actually measured have been between 40 and 50. The smaller angle makes the belt wedge into the groove, so you don't need excessive belt tension.

Great tip, thanks.


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[jdrichard]

I was to make the same comment but I didn't, as jdrichard is an able machinist and will figure out, without the need for any book. 
However it seems to me that the original pulley have radius concave grooves, but the pics don't show clearly. I suppose that turning Acetal that can be easily achieved by grinding a round nose tool.
Please excuse if I'm talking without sound experience, I still have to resume my machinist self-learning with the new steel bars that I just bought for an hefty price to me. 

Thanks. I take ALL advice and tips. The belts I have made so far are great and do not slip: so far.


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[vinn3]

11 hours ago, nickelsilver said:

You might find that the belt slips with that groove shape, generally for pulleys used with round belts the angle should be between 35 and 60 degrees, more towards the smaller angle. Most I've actually measured have been between 40 and 50. The smaller angle makes the belt wedge into the groove, so you don't need excessive belt tension.

    on a v belt,   the shape is not as importand as useing a type of grease on the belt, often AND; dos  not   need excessive tighting.  cheers,     vin

[jdrichard]

    on a v belt,   the shape is not as importand as useing a type of grease on the belt, often AND; dos  not   need excessive tighting.  cheers,     vin

What grease would I use on the belt to make it grip better?


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[vinn3]

1 hour ago, jdrichard said:

What grease would I use on the belt to make it grip better?


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   "belt grip spray", i have used it but dont remember the name.  and a couple solid  rods.  but;  here is the secret --- bar soap.  an old flat belt leather trick.  good  on old auto v belts.  im shure they still sell that spray and less chance of loseing a finger.    vin   

[nickelsilver]

I know it sounds crazy, but for round belting like us guys use beeswax is fantastic. Seems like it'd promote more slipping but it doesn't.

[vinn3]

3 minutes ago, nickelsilver said:

I know it sounds crazy, but for round belting like us guys use beeswax is fantastic. Seems like it'd promote more slipping but it doesn't.

    leather or rubber belts?      there use to be round leather for sowing machines.    vin

[jdrichard]

The leather I use is boot lace and it is square, but the lathe doesn’t know it:) It’s diameter is good enough to provide grip and I have not needed any grip spray or treatment of any type. I get no slip when cutting a part. You can get it from Amazon for 8 bucks and sew it together with fishing line: like on my YouTube video.


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[vinn3]

5 minutes ago, jdrichard said:

The leather I use is boot lace and it is square, but the lathe doesn’t know it:) It’s diameter is good enough to provide grip and I have not needed any grip spray or treatment of any type. I get no slip when cutting a part. You can get it from Amazon for 8 bucks and sew it together with fishing line: like on my YouTube video.


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   good show !