Thread dial indicators on mini lathes

[Mark CoplandParticipant @markcopland55477]

Imperial and metric

[Mark CoplandParticipant @markcopland55477]

I have just bought the basic amadeal? I am looking for advise on thread cutting. If I get a dial indicator will it be good for both imperial and metric? If only one I would plump for metric as I have a large Colchester which I can use also.

Next question is where would I source one?

[Thor 🇳🇴Participant @thor]

Hi Mark,

For a MiniLathe with metric leadscrew you need a metric Thread Dial indicator – and more than one wormwheel to cover the most usual pitches. Have you read this? It explains how Thread Dial Indicators work on metric MiniLathes. If Amadeal stocks an imperial version, I assume you could use that and make new wormwheels.

Thor

[Neil WyattModerator @neilwyatt]

Welcome Mark,

The simple answer is no, buy a mini-lathe with a leadscrew that suits the sort of threads you want to cut.

Neil

[Mark CoplandParticipant @markcopland55477]

OK thanks fella. Just watching a you tube seig review he had one. Guess I will just have to work around it.

Mark

[AjohnwParticipant @ajohnw51620]

I think some of the metric mini lathes come with 2, Amadeal (harry something or the other on ebay or his web site) or a name something like that. It seems many don't come with one.

It's good to see a site that explains how they work. Another way of putting it is that the indicator marks give repeat distances of the lead screw that are exactly divisible by the pitch being cut.

John

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Edited By John W1 on 08/11/2015 23:42:40

[HopperParticipant @hopper]

Best book on screwcutting I have seen is Martin Cleeves' "Screwcutting in the the Lathe". IT is well worth buying a copy if you want to learn the secret tricks of the art.

Once you are familiar with how the thread chaser dial works, you can make one up yourself using brass gears you can cut in the lathe by using a slotting technique and change gears for indexing. Several of the older books such as "the Amateurs Lathe" by LH Sparey have details of making a dial for older British lathes that coiuld be scaled down to suit the mini jobs.

[Danny M2ZParticipant @dannym2z]

G'day Mark – when I purchased my (metric) C3 minilathe, a spare (imperial) leadscrew was also purchased. It came with the appropriate thread chaser dial, a thread cutting chart and a set of headstock gears. (<$120 Au)

It's quite easy to change the leadscrew if required for single-point threading, but for 99% of work I just leave it in metric mode (or whatever the last mode was – with a fridge magnet pointer on the appropriate threading chart).

The last time I used the imperial set-up was to cut a 40TPI thread for a Cox 0.049 model engine cylinder.

It's handy to have, but for most jobs not involving threading it does not really matter and a tailstock die holder can simplify small threading projects. As Neil said, it all depends what units you wish to work with.

* Danny M *

[AjohnwParticipant @ajohnw51620]

This is the company I mentioned, it looks like their mini lathe does come with a metric indicator. I think they all should but more gears are needed for metric lathes as the earlier link explains. Just need one with imperial but in practice in the wider world the capabilities of those has varied on larger lathes.

**LINK**

He's also on ebay, harry something and enjoys the same sort of reputation as Arceuro has with a number of people. He even usually has stocks of 5% cobalt HSS toolbits.

John

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[BazyleParticipant @bazyle]

On a minilathe make a mandrel handle as you will want one for screwcutting anyway and leave the half nuts engaged for both cutting and run back. Then you don't need a thread indicator. It is actually quicker by handle most of the time anyway rather than waiting for the motor to stop etc and gives precise stopping at a shoulder with less tool breakage.

[Mark CoplandParticipant @markcopland55477]

Thanks for all the responses folks. Bit of reading to get through now huh.

Best regards

Mark

[AjohnwParticipant @ajohnw51620]

Posted by Bazyle on 09/11/2015 12:49:47:

On a minilathe make a mandrel handle as you will want one for screwcutting anyway and leave the half nuts engaged for both cutting and run back. Then you don't need a thread indicator. It is actually quicker by handle most of the time anyway rather than waiting for the motor to stop etc and gives precise stopping at a shoulder with less tool breakage.

There is no need to wait for the motor to stop and etc when an indicator is used. Just disengage, wind back and engage again at the same mark or choice of marks depending on the pitch being cut.

They can also be used to work up to a shoulder when the lathe has to be reversed with the nut engaged when a pitch has to be cut that the indicator can't cope with used in the normal way. That makes it much easier to work up to a shoulder even in this case.

John

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