gear for a thread dial

[martin dustParticipant @martindust87030]

i have just bought a boxford cud 4 1/2 x 18.
it came without a thread dial so looking to make my own.
but looking for a gear to run on the 8tpi lead screw or how to make the gear

[martin dustParticipant @martindust87030]

[Speedy Builder5Participant @speedybuilder5]

One like this ??
**LINK**

[martin dustParticipant @martindust87030]

yes

[HopperParticipant @hopper]

You will need a dividing head and a milling machine to make the gear. Probably easier to buy one if you don't have these already.

It will be a 16 tooth gear and will need to be the right DP so that the circumfrential pitch will match the .125" pitch of the lead screw. Don't have my Machinery's Handbook close by right now but I am sure you can look it up on various gear spec sites on the net.

I think Myford sell the gears at reasonable price, which should fit as they also use an 8tpi Acme leadscrew.

Edited By Hopper on 22/11/2016 23:05:50

[martin dustParticipant @martindust87030]

thank you very much Hopper that the sort of answer i have been looking for.
where i got it from the have a load of myfords and some spares so will go there tomorrow to see what they have.
i have a mill and a rotary table but got to wait till christmas to make any gears.
as my daughter is buying me the plates for it, they will be here next week nut not allowed to use them.

 

Edited By martin dust on 22/11/2016 23:24:23

[John Stevenson 1Participant @johnstevenson1]

Although any gear divisible by 8 will work the one in the link is a 32 tooth gear, not 16 as you can count 15 teeth on the one side

[not done it yetParticipant @notdoneityet]

I know of someone that used a cheap plastic gear for a thread dial as it takes little load and the pukka gear was offered as a 'special' at about ten times the price of the plastic alternative he used.

[HopperParticipant @hopper]

Posted by not done it yet on 22/11/2016 23:46:18:

I know of someone that used a cheap plastic gear for a thread dial as it takes little load and the pukka gear was offered as a 'special' at about ten times the price of the plastic alternative he used.

Yes, I think you don't have to be too fussy about the exact form of the gear teeth as they do not have to mesh fully with the leadscrew in the normal way as when transmitting power etc. The gear teeth on my ancient Drummond's thread dial are worn down to wafer-thin "fins" that have no involute shape left to them at all, yet the dial still functions perfectly. So any 16 (or 32 etc) tooth gear that basically will mesh with the leadscrew should do the job.

[JasonBModerator @jasonb]

If the gear does not have to be super accurate then why not just use the rotary table without plates to get your 32 divisions 11deg 15' is not too hard to do. You can also cut it on the skew like the one in the link rather than use a standard gear.

"So any 16 (or 32 etc) tooth gear that basically will mesh with the leadscrew should do the job"

Although the gear may mesh you also need the diameter to be about right eg a 16T that meshes will be a lot smaller than a 32T that also meshes and the small one will possibly have the casting clashing with the leadscrew.

[Speedy Builder5Participant @speedybuilder5]

Martin, check out your inbox for a PM.
BobH

[martin dustParticipant @martindust87030]

Posted by JasonB on 23/11/2016 07:55:37:

If the gear does not have to be super accurate then why not just use the rotary table without plates to get your 32 divisions 11deg 15' is not too hard to do. You can also cut it on the skew like the one in the link rather than use a standard gear.

"So any 16 (or 32 etc) tooth gear that basically will mesh with the leadscrew should do the job"

Although the gear may mesh you also need the diameter to be about right eg a 16T that meshes will be a lot smaller than a 32T that also meshes and the small one will possibly have the casting clashing with the leadscrew.

that is exactly what i am going to do.
after spending a lump of money out for the lathe i think my balls will no longer be attached to be if i spent more money.

[martin dustParticipant @martindust87030]

Posted by Speedy Builder5 on 23/11/2016 09:57:29:

Martin, check out your inbox for a PM.
BobH

just about to look thanks bob

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