Lathe change gears vs gearbox

I’m looking at buying either a Myford 7, Boxford Model A,B or C or maybe a Colchester bantam. I’m trying to decide whether the gear box options are worth the extra. The lathe with be used for vintage sewing machine parts so quite a few different thread types but all as one offs rather than production. Any thoughts? Change gears or gearbox?

Hi Nick,

Welcome to the forum. My small lathe is without a gearbox but I don't cut threads that often so it is not a problem for me to set up the correct change wheels for the few threads I cut. If you often cut threads with different pitches a gearbox is very handy and it will also be easy to set different feedrates. If you can find a Boxford Model A or a Bantam in good condition and at a reasonable price you will get a good lathe.

Thor

Gearbox for me, not only for pitch change ease but also for feed rate as well

Welcome to the forum, Nick.

A lathe with a leadscrew benefits from more than just threading operations, the finer thread pitch settings are useful for simple turning giving a power feed for the saddle (carriage) in both directions. The lathe that I use can cut threads down to 76tpi and 152tpi if the change gears are selected to halve the leadscrew speed. That is down to 0.013" and 0.007" per turn of the spindle. This particular lathe also has a feed screw which will allow power facing and turning down to 0.001" per turn, but that feature is normally confined to the more sophisticated and expensive types.

For your particular size of work, the Myford range would be ideal.

Depends on how often you change pitch and/or threads.

Not often in my case, so the change gears can be left in fine pitch most of the time.

Vital though it is when needed, I rarely lathe cut threads because all the smaller thread sizes are done with taps and dies. The lathe is only used to thread large diameters and specials.

Having said that, resetting change gears is slow and messy. If I had to do it more than once a day, I'd vote gearbox!

Dave

Gearbox for me also, much more convenient also able to vary feed rates easily.

Tony

You could also consider an electronic leadscrew conversion that gives the convenience of a gearbox with the wider variety of thread pitches that change gears would offer. I use a gearbox lathe at work and a change gear lathe and am happy with either as I only cut different threads on the lathe a few times a year, I more often use thread milling on a CNC mill.

Andrew.

Edited By Andrew Entwistle on 20/01/2022 20:46:12

Edited By Andrew Entwistle on 20/01/2022 20:48:43

I got used to a Colchester Triumph 2000 at work for my motorcycle tinkering, great range on the gearbox suited me. On retirement I sold my old Southbend "Heavy Ten" And bought a 14" x 40" Exel lathe, a good machine but a real faff some days with the change gears. Sometimes cutting 20/24/26 TPI the change gears can be left alone and the gearbox used, throw in a few other pitches and metric it becomes tedious. I don't mind the actual changing over of gears but the faff to get them meshed quietly sometimes annoys me. So a gearbox gets my vote if it will cover the range you require.

With vintage sewing machines, the threads were quite often proprietry, so you had to buy genuine spares, so matching thread pitches would be inexact. Of course a near match would probably be ok, after all sewing machines don't need airworthyness certificates. Some of the old Singer screws looked like they had been hand filed by an apprentice.

All the lathes you mentioned also require the changewheels to be moved around for metric threads or imperial if the other version, even those with a QCGB.

Better to spend the extra and be wrong than not spend it and be wrong....

Nick, see if you can find a good Bantam, aside from the gearbox loads of additional good features. I saw a nice one advertised recently but cannot remember where.

Chris Gunn

Thanks for the welcome and thank you all for your thoughts on this. I can begin to see the sense in going with the gearbox.

@oldmart you are right about the threads on sewing machines. I have all sorts of machines with all sorts of threads.

looks like the gearbox route is better for all the reasons mentioned.

my budget is max £2k. Fingers crossed.

Gearbox wouldn't be top of my list because maybe the money is better spent on something else, like a lathe that's in better condition.

Remember it's a not a gearbox, it's a SECOND-HAND gearbox, history unknown. Make sure it's in reasonable condition, because missing teeth, knackered bearings, bent shifters, broken shear pins and oil leaks can turn a nice-to-have into a basket-of-pain.

Likewise, when buying a second-hand gearbox-less lathe, make sure all the change-gears and banjo parts are present and correct. Much easier to correct than a trashed gearbox, but finding or adapting change gears for old lathes isn't painless.

I'd much rather spend £2000 on a basic lathe in good condition than an iffy machine with all the bells and whistles.

Jon Lawes said 'Better to spend the extra and be wrong than not spend it and be wrong..' Dubious advice I fear, because buying second-hand is risky, like betting on horses. You shouldn't bet the farm on a nag just because the winnings will be maximised if it comes home, and if it should happen to win you'll regret not going all out. The odds and amount of money spent make no difference, what really matters is the state of the horse. Ditto old lathes.

Dave

The first thing you need is a list of the thread TPI or pitches you will need to cut and find out if it rules out any of your options. It should make it easier to narrow down the best option for you if there are some threads that can only be done with a lathe and some lathes can't do them.

martin C

Where would I find such a list? I'm not sure how useful it would actually be, as one of the main reasons for screw cutting is when you have to make a one-off part with a thread you don't have a die for. Or one that is too big for your tools, like the M20 threads I had to cut on a clapper bolt

I have a Boxford AUD with gearbox but it is also possible to add change wheels to increase the number of pitches available.

Brian

Have a look at this site for information:

**LINK**

If its sewing m/c parts mainly, you will be needing some peculiar thread pitches, some metric, some imperial and some (like Ba not simple multiples). Do you need a lathe as big as a Boxford etc, and just a small precision lathe. Gearbox lathes can by use of additional gears cut just about any thread form different from the standard gearbox set. Again, do you want an imperial or metric lathe.

From the net, I found that :

Singer used fraction of inch and normal TPI pitches, Nähnorm 100 also, Practical Machinist indicated that most machines used imperial measurements (But was that for older machines ??).

If you have decided on Myford or Boxford, then there is only one choice. BOXFORD with a gearbox - Ha Ha, I am biased though.

Couldn't be faffed with all those gearbox levers, look up charts, change wheels.

Fitted a Clough42 Electronic Leadscrew to my Myford. Heaven.

Yes, an ELS is a distinct possibility for me.