Help turning/threading can

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DS6
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Help turning/threading can

Post by DS6 » Sat Apr 06, 2013 7:47 am

ok, so I'm fairly new to machining. picked up a hobby lathe for my for 1 22 build and have been playing with it for a bit to get use to things.

my problem is, working with a 6+ inch aluminum tubing for the can. what is the best way to go about turing it and threading it as it comes out faar from the chuck and gets a little un stable towards the end. i'm not sure if i'm just not centering it right or what. I canput the live center in the tailstock and push it all the way into the end of the tube to keep it sturdy but then i wont be able to turn in down all the way to the end. I haven't even tried to start threading it yet so now sure how that will work.

rqlasl
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Re: Help turning/threading can

Post by rqlasl » Sat Apr 06, 2013 9:02 am

You will have to use a steady rest or a plug with a center in it for your live center.

Make the plug almost size for size with your id, dril a center in it.

Then as you machine it will stay put and hold everything in place.

Ive had to do this and it works great. Good luck

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Bendersquint
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Re: Help turning/threading can

Post by Bendersquint » Sat Apr 06, 2013 9:10 am

DS6 wrote:ok, so I'm fairly new to machining. picked up a hobby lathe for my for 1 22 build and have been playing with it for a bit to get use to things.

my problem is, working with a 6+ inch aluminum tubing for the can. what is the best way to go about turing it and threading it as it comes out faar from the chuck and gets a little un stable towards the end. i'm not sure if i'm just not centering it right or what. I canput the live center in the tailstock and push it all the way into the end of the tube to keep it sturdy but then i wont be able to turn in down all the way to the end. I haven't even tried to start threading it yet so now sure how that will work.
Are you not using a steady rest or any exterior support?

Have you considered having a shop do the threading since you are new to it? One shot deal, better to have someone do that that does it all the time.

DS6
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Re: Help turning/threading can

Post by DS6 » Sat Apr 06, 2013 11:33 am

boy do i feel like an idiot! :roll: no, i didn't even know what a steady rest was, but now that i do, i think that will solve my dilema. thanks!

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twodollarbill
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Re: Help turning/threading can

Post by twodollarbill » Sat Apr 06, 2013 7:31 pm

If your hobby lathe is a mini-lathe, the steady rest will handle up to 1" diameter.
With some slight modifications to it, it can handle 1 1/4" diameter stock.
Like Bender said, I would let your local machine shop thread your tube to specs
and I would let your lathe do the work on the internals.
With the small lathes, you get the best results the closer your
work is to the chuck.
Say if you are making a 1" long K baffle, best to cut your bar stock
in pieces 1 3/4" long.
So 1/2" mounts in the chuck and your work stays 1/4" away for the chuck.
The steady rest should only be used if there is no other choice.

DS6
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Re: Help turning/threading can

Post by DS6 » Sun Apr 07, 2013 7:51 am

twodollarbill wrote:If your hobby lathe is a mini-lathe, the steady rest will handle up to 1" diameter.
With some slight modifications to it, it can handle 1 1/4" diameter stock.
Like Bender said, I would let your local machine shop thread your tube to specs
and I would let your lathe do the work on the internals.
With the small lathes, you get the best results the closer your
work is to the chuck.
Say if you are making a 1" long K baffle, best to cut your bar stock
in pieces 1 3/4" long.
So 1/2" mounts in the chuck and your work stays 1/4" away for the chuck.
The steady rest should only be used if there is no other choice.
that is what i'mm working with, 1.25 material. i looked at a few steady rests thatcan handle up tp 2inches though that are compatable with my lathe so that is definatly the right direction.

ranb
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Re: Help turning/threading can

Post by ranb » Mon Apr 08, 2013 11:00 pm

I learned how to cut threads on my lathe just by experimenting on scrap aluminum tubing. All it takes is the steady rest and a thread tool bit. It is worth it to learn.

Ranb
SilencerTalk was a place I could disccuss making registered silencers without being told I was a criminal. That is no longer true. http://www.silencertalk.com/forum/viewtopic.php?f=132&t=99273

DS6
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Re: Help turning/threading can

Post by DS6 » Mon Apr 08, 2013 11:19 pm

ranb wrote:I learned how to cut threads on my lathe just by experimenting on scrap aluminum tubing. All it takes is the steady rest and a thread tool bit. It is worth it to learn.

Ranb
thats exactly what i'm doing. :D

cncjerry
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Re: Help turning/threading can

Post by cncjerry » Tue Apr 09, 2013 1:44 am

I make my own one-off threading tools by starting with a brazed carbide external tool, like the cheap ones you find everywhere in sets, as they are sharp. You heat the brazed tool to remove the carbide chip and braze that back onto a shaft of your choosing. You will need to grind away, or by using a diamond sharpening tool, make more relief on the area below the sharp point to clear the internal radius of the tube to be threaded. The trick is to not remove too much material as the tip will become fragile. If you are cutting fine threads, you can pivot the tool and use negative rake if you braze it to a round rod.

The reason I use the brazed tools like this is that they start very sharp, sharper than the typical internal indexed carbide threading tools. You can make a tool like this in about 10 minutes, a lot faster than grinding an HSS tool by hand. With a sharp tool like this you can make very fine threads which I like to use on threaded tube with endcaps. I've been using .5mm for endcaps.

Also, anther use for a steady rest is to reduce the runout of a chuck when drilling precisely centered holes in a shaft. If you have for instance .001 TIR at the chuck, by extending the shaft out thru a steady rest 10", you cut the runout by a factor of 10. We use this technique when making clock gears and pinions.

Jerry

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