Which leadscrew?

[TigermothParticipant @tigermoth]

After over 30 years of building and flying radio controlled aircraft and helicopters I am looking for a change in direction and intend to purchase a lathe. The plan is to eventually build a diesel engine and then a four stroke glow engine.

This is my first post on this forum and the advice I am looking for is whether to purchase a lathe with a metric or an imperial leadscrew?

Or perhaps it doesn’t matter?

Over to the experts!

Thanks in advance

Bob

[TigermothParticipant @tigermoth]

[IanTParticipant @iant]

Well for most turning operations i don’t think it really matters Bob. It’s not hard to convert from Metric to Imperial (or vice versa) etc if dealing with linear measurements.

 

So the real question is what threads are you most likely to cut (if ever?).

 

If you intend (or might need to) to screwcut a lot of Imperial threads (e.g. if restoring old cars or motorbikes) then buy an Imperial leadscrew. But if you don’t know yet (or you know you intend to cut Metric threads) then the answer is go metric and standardise on it. It is possible to cut Metric threads on an Imperial lathe but why complicate things if you do not need to?

 

I have an old Myford S7 lathe with an Imperial (e.g. 8 tpi) leadscrew by the way but all my newer kit is metric based. I think you will find that going forward life will be easier (and cheaper) if you use the Metric system. I’m not sure how long it’s been the “standard” in the UK now – but my 30 year old sons do not “do” inches – only cm & mm. 

[KWILParticipant @kwil]

It depends upon whether you intend to screwcut threads ,imperial or metric. I have both types of leadscrew and my imperial lathe (Myford Super7) is fitted with a Quickchange imperial gearbox PLUS a permanently installed metric gear train in parallel. You takes your choice.  What units do you expect to work in? Will you fit a DRO? in which case the units on the dials do not matter.

[TigermothParticipant @tigermoth]

This is what I thought (hoped?) to hear and my thanks to both respondents.

My age is such that I was brought up in both systems but my working life was spent most definitely in the metric/SI system.

As an avid DIY’er I use whichever system fits the tape measure more easily although the gauge on my circular saw is metric only.

Time to open negotiations with SWMBO for funds release.

Thank you again.

Bob

[chris stephensParticipant @chrisstephens63393]

Hi Bob,

You say you want to build engines, well if the plans you are going to use are more than a few years old, and you want to follow things exactly because you are a newbie and don’t yet have the confidence to wing it, go for an Imperial lathe. 

In reality it does not matter a fig which system you use, certainly metric screws are easier to buy at the nearest DIY store late on a Saturday evening, but if you plan in advance what you need, buying BA or ME screws and fittings, is not a  problem. 

Oh and welcome to the wonderful world of  swarf makers and allied metal manglers.

chriStephens 

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