Thanks Walt, yes I am pretty sure I can manage to cut threads at a very slow speed.
I heavily modded my mini lathe during the restoration.
I added a treadmill 2.9 hp motor with a treadmill controller and by passed the internal gearing that drives the lathe.
I can bring the lathe to a literal crawl and still make cuts to do threads.
I do not know if we are allowed to post links for videos on the mods.
Here is a link showing what kind of depth of cuts I can take.
I added angular contact bearings as well lapped my cross slides to get nice smooth tight action.
I can even part with very low rpms and have a great deal of torque and as well consistent speed while under load.
I do not show a video demonstrating this and will do one showing the low end rpm capability.
Thanks for all the help everyone.
Much appreciated being such a brand new novice to all this.
From: "Walt Hutchens waltah@earthlink.net [7x12minilathe]" <7x12minilathe@yahoogroups.com>
To: "ckinzer@att.net [7x12minilathe]" <7x12minilathe@yahoogroups.com>
Sent: Wednesday, February 17, 2016 10:33 AM
Subject: Re: [7x12minilathe] Threading
ckinzer@att.net said:
> On a mini-lathe it would be way better to do it using a hand crank
> in the spindle (there are plans for these around). The mini-lathe
> isn't really good for doing slow speeds.
> Your typical 12 x 36 lathe such as from Grizzly will go down to 70 rpm.
All true but just for another perspective: I'm pretty new at this and
I've cut a metric thread with a lead (advance per revolution) of 2.8
mm which isn't far from 8 TPI under power. It required care but wasn't
really 'exciting.' Like so much else with machine tools it requires
thinking ahead and preparation, that's all.
TRY a feed of 8 TPI (gears as suggested earlier on this thread) with
the carriage well away from everything and the RPM as low as it will
go and be stable on your machine. Could you control that for the job
you're planning? For 8 TPI a mini-lathe may require a dozen or more
passes; can you stop the cut so many times with the accuracy needed
for the part you're making?
Cutting up to a shoulder with a minimal run out groove is a lot more
challenging than if you have an inch of clearance in which to get
stopped!
There are mods to the mini-lathe that will reduce the RPM by up to
1/2: something to keep in mind if much threading is to be done.
Walt Hutchens
7x14 MicroLux 2-7x10 HF/CM
> On a mini-lathe it would be way better to do it using a hand crank
> in the spindle (there are plans for these around). The mini-lathe
> isn't really good for doing slow speeds.
> Your typical 12 x 36 lathe such as from Grizzly will go down to 70 rpm.
All true but just for another perspective: I'm pretty new at this and
I've cut a metric thread with a lead (advance per revolution) of 2.8
mm which isn't far from 8 TPI under power. It required care but wasn't
really 'exciting.' Like so much else with machine tools it requires
thinking ahead and preparation, that's all.
TRY a feed of 8 TPI (gears as suggested earlier on this thread) with
the carriage well away from everything and the RPM as low as it will
go and be stable on your machine. Could you control that for the job
you're planning? For 8 TPI a mini-lathe may require a dozen or more
passes; can you stop the cut so many times with the accuracy needed
for the part you're making?
Cutting up to a shoulder with a minimal run out groove is a lot more
challenging than if you have an inch of clearance in which to get
stopped!
There are mods to the mini-lathe that will reduce the RPM by up to
1/2: something to keep in mind if much threading is to be done.
Walt Hutchens
7x14 MicroLux 2-7x10 HF/CM
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