JSR's workshop chronicles

A place for general potato gun questions and discussions.
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 25919
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 258 times
Been thanked: 159 times

Donating Members

Tue Dec 15, 2020 7:32 pm

Looking into thread cutting and I think Steve Jordan has the right idea:



To that end I made a not-pretty-but-it-works spindle handle with an acetal collet to lock it in place by friction:

Image
hectmarr wrote:You have to make many weapons, because this field is long and short life
User avatar
mrfoo
Specialist 2
Specialist 2
Afghanistan
Posts: 215
Joined: Wed Apr 29, 2015 11:05 am
Has thanked: 45 times
Been thanked: 36 times

Wed Dec 16, 2020 6:42 am

Neat. Yeah, hand-cranking is the safest way to go, but it's properly slow. The next one is to thread away from the chuck, for normal threads that means mounting the tool upside down and running the spindle backwards.
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 25919
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 258 times
Been thanked: 159 times

Donating Members

Thu Dec 17, 2020 6:02 pm

mrfoo wrote:
Wed Dec 16, 2020 6:42 am
The next one is to thread away from the chuck, for normal threads that means mounting the tool upside down and running the spindle backwards.
Good tip, hadn't thought of that! You can still crash into the tailstock but there's definitely more margin for error.
hectmarr wrote:You have to make many weapons, because this field is long and short life
User avatar
mrfoo
Specialist 2
Specialist 2
Afghanistan
Posts: 215
Joined: Wed Apr 29, 2015 11:05 am
Has thanked: 45 times
Been thanked: 36 times

Fri Dec 18, 2020 7:34 am

Do you have a threading dial on your carriage? They save an awful lot of pissing about - without one, you need to stop the machine, reverse back to your starting position, feed in a bit, rerun your thread, lather rinse repeat until done, all without disengaging the carriage feed. This puts extra strain and wear on your half-nuts, and the leadscrew.

With a threading dial (for most thread pitches, at least), you can disengage the nuts, feed back manually without even stopping the lathe, wait for the relevant point on the dial to come round, and re-engage. It's approximately a trillion times faster and largely idiot proof, especially if combined with threading away from the headstock.

Making a finish pass away from the headstock when doing "normal" turning can help with surface finish issues as well, you're changing the way the headstock bearings are loaded up, which can help if your bearings are getting a bit tired (like mine, but I can't afford the 800€ to buy new ones) or just not terribly good from the factory (as can be the case with chinese lathes)

When turning away from the headstock, mind, it's a very good idea to have a center in place, as you're pulling the workpiece away from the chuck...
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 25919
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 258 times
Been thanked: 159 times

Donating Members

Sat Dec 19, 2020 8:00 am

mrfoo wrote:
Fri Dec 18, 2020 7:34 am
Do you have a threading dial on your carriage? They save an awful lot of pissing about - without one, you need to stop the machine, reverse back to your starting position, feed in a bit, rerun your thread, lather rinse repeat until done, all without disengaging the carriage feed. This puts extra strain and wear on your half-nuts, and the leadscrew.

With a threading dial (for most thread pitches, at least), you can disengage the nuts, feed back manually without even stopping the lathe, wait for the relevant point on the dial to come round, and re-engage. It's approximately a trillion times faster and largely idiot proof, especially if combined with threading away from the headstock.
I guess I do!

Image
hectmarr wrote:You have to make many weapons, because this field is long and short life
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 25919
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 258 times
Been thanked: 159 times

Donating Members

Tue Dec 22, 2020 5:37 pm

Actually gave it a go and pretty happy with the result.

Image
hectmarr wrote:You have to make many weapons, because this field is long and short life
User avatar
mrfoo
Specialist 2
Specialist 2
Afghanistan
Posts: 215
Joined: Wed Apr 29, 2015 11:05 am
Has thanked: 45 times
Been thanked: 36 times

Wed Dec 23, 2020 2:43 am

Yay! Nice results. Threading is hard to get right.

Is the threaded piece in the foreground 2 pieces stacked on one another, or is it camera distortion that makes it look - ummm - "bent"?

Meanwhile, and polluting your thread a bit (sorry) but it's a workshop thing, my surface plate is getting there. 2 corners are still a bit low, putting me at class 1* overall, but the central par (800x200) is at class 0*. I'm pretty happy with that, it's more than I need.

A not very interesting video I made is https://www.youtube.com/watch?v=mpwiL3BgiIY

* For this size of plate, that means, compared to the theoretical best plane, the total deviation of highest and lowest points must be less than 11.2µ (4.4/10000") for class 1, and 5.6µ (2.2/10000") for class 0.
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 25919
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 258 times
Been thanked: 159 times

Donating Members

Fri Jan 01, 2021 6:25 am

mrfoo wrote:
Wed Dec 23, 2020 2:43 am
A not very interesting video I made is https://www.youtube.com/watch?v=mpwiL3BgiIY
That was actually an amusing and informative watch, I can see why you thought my workshop was more organized... obviously you've just been at it longer

J'ai aussi apprécié le contraste avec le bloke anglais pottering about dans son atelier avec la radio francophone :lol:
Is the threaded piece in the foreground 2 pieces stacked on one another, or is it camera distortion that makes it look - ummm - "bent"?
It's one piece, the reflection makes it look weird.

Here's some more efforts in steel this time, I have to say that after being the bane of my machining existence for many years cutting threads is a real pleasure now!

Image
hectmarr wrote:You have to make many weapons, because this field is long and short life
User avatar
hectmarr
Corporal 5
Corporal 5
Argentina
Posts: 918
Joined: Sat May 07, 2016 3:49 pm
Location: Argentina
Has thanked: 137 times
Been thanked: 136 times
Contact:

Fri Jan 01, 2021 9:00 am

jackssmirkingrevenge wrote:
Fri Jan 01, 2021 6:25 am
mrfoo wrote:
Wed Dec 23, 2020 2:43 am
A not very interesting video I made is https://www.youtube.com/watch?v=mpwiL3BgiIY
That was actually an amusing and informative watch, I can see why you thought my workshop was more organized... obviously you've just been at it longer

J'ai aussi apprécié le contraste avec le bloke anglais pottering about dans son atelier avec la radio francophone :lol:
Is the threaded piece in the foreground 2 pieces stacked on one another, or is it camera distortion that makes it look - ummm - "bent"?
It's one piece, the reflection makes it look weird.

Here's some more efforts in steel this time, I have to say that after being the bane of my machining existence for many years cutting threads is a real pleasure now!

Image
Beautiful machined parts, as we would say around here "the child's perfect dream" !!
I don't understand anything about machining but what I see is great. May this new year 2021 be very good for you, and for all the colleagues on this site. CONGRATULATIONS!!! :) :) :) :) :)
I am the author of the first semi-automatic hybrid, check this out :shock: ...viewtopic.php?f=28&t=26676
And of the hybrid that can shoot in the shortest time: :shock: viewtopic.php?f=28&t=27190
User avatar
mrfoo
Specialist 2
Specialist 2
Afghanistan
Posts: 215
Joined: Wed Apr 29, 2015 11:05 am
Has thanked: 45 times
Been thanked: 36 times

Fri Jan 01, 2021 9:24 am

jackssmirkingrevenge wrote:
Fri Jan 01, 2021 6:25 am
I have to say that after being the bane of my machining existence for many years cutting threads is a real pleasure now!
Nice result!
User avatar
Gippeto
First Sergeant 3
First Sergeant 3
Posts: 2497
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Has thanked: 2 times
Been thanked: 10 times

Donating Members

Fri Jan 01, 2021 12:49 pm

Nice work Jack. :)

As far as useful skills go, threading is right up there with grinding tools...opens options and doors to all kinds of new projects!

Al
"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Moonbogg
Staff Sergeant 2
Staff Sergeant 2
United States of America
Posts: 1666
Joined: Mon Oct 13, 2008 10:20 pm
Location: SoCal
Has thanked: 89 times
Been thanked: 55 times

Fri Jan 01, 2021 9:00 pm

Those parts look super clean. Nicely done! Smooth as a baby's arse.
Post Reply