I have a simple die holder I use on the lath it is a hand held job, quite large handled thing. But it has several holding points for split dies so in effect has three screw points.
I screw in to the split firt then the other two screws are used to lock the die.
I put the bar stock in the normal three jaw chuck and rest the die holder against the tail stock barrel. I have one of the handles resting on the top saddle with some scrap steel between.
I set the lathe turning at relitivly slow revs say 150 the use pressure by wining in the tail stock barrel to start the thread. I always keep pressure on from the tail stock to keep the die square.
Basically once the thread is started it pulls it self in. No it can not be done with keep dies and holders but reasonable quality.
The maximum size I have used this on is 16 mm x 2 mm pitch something like
20 pieces for a small job with lentgh of thread around 30 mm. 10 tie bars for someone elses project.
If I had to do larger quantity and had more time then i would go to using a coventry die holder and the dies, but that can get costly.
It can be very gratifying cutting threads on the lathe using point cutters and doing multiple cuts. So it can be worth doing, but I used to find it took to long and many times needed finishing off with a hand chaser to look better.
On or around Tue, 31 Oct 2006 12:10:23 -0000, "Andrew Mawson" enlightened us thusly:
not sure how old it is TBH. it's been around a bit, judging from various repairs... possibly 1.75 wasn't standard, but it is a standard metric pitch for various sizes.
BTW, any of you lot know of a likely source of the parts to rebuild the brake? The internal parts are missing...
I was disappointed with the limited metric range of my imperial/metric student (MkII). I've swapped (for other reasons) from having one imperial/ metric & one metric/imperial (which had a very good range of both) lathe to two Imperial only. Luckily I don't do a lot of metric threading, though. Anyone got spare metric changewheels for a 17" DSG? Thought not, I expect I'll have to make them.
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
On or around Wed, 01 Nov 2006 08:49:53 +0000, Tim Leech enlightened us thusly:
Mind, on the Mk1, notwithstanding the missing 1.75 on the chart, you can get
1.75 by using one of the other positions, but the metric gearset. In principle, I reckon, using the metric output gear you can get almost any pitch; although it's not in the chart; just needs a bit of work to translate the numbers. For example, to get 1.75 I was using DA18 I think, which is not labelled as a metric pitch but works nonetheless.
I didn't have any extra gears for mine, but it wasn't really a problem as I could do metric threads easily on the TOS, even if it was a bit big for some jobs. Bit of a bugger though when you forget, & are halfway through the job & realise that thread isn't in the box....
Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
On or around Wed, 01 Nov 2006 16:26:26 +0000, Tim Leech enlightened us thusly:
Mine has the typical norton type box with about 9 or so positions along it,
2 levers on the left with ABCD, and on the top a lever which engages the leadscrew (as distinct from the power shaft) which is labelled imperial-neutral-metric.
I assume the leadscrew is imperial, and the "metric" position applies suitable gearing to make it behave like a metric one. For every position of the ABCD levers and the gearbox you can have either "metric" or "imperial" - but I assume that some of the "metric" answers wouldn't make sense.
I'll have to have a think about it and try and translate the TPI figures on the chart to make sense when in metric mode.
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