Author Topic: 10 TPI LEAD SCREW  (Read 9305 times)

Offline doubleboost

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10 TPI LEAD SCREW
« on: August 08, 2010, 12:08:19 PM »
A friend of mine has bought a Ralgan lathe
He is in the process of rebuilding it
The cross slide screw and nut are very badly worn  :( :( replacements are a fortune :( :(
My colchester bantam will cut 10 tpi no problem :D :D but internal left hand  :doh: :doh:
The shaft is 1/2 inch diamiter 13 inches long i have some imperial silver steel  :) :) :)

A tool was ground and the thread slowly took shape :D :D

the thread was nice and sharp
:( :( :(
Now for the nut  :doh: :doh:lathe running in reverse tool in from the back upside down :) :)
A pice of bronze bar was used

The old and new


 :D :D :D :D :D :D

Offline Stilldrillin

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Re: 10 TPI LEAD SCREW
« Reply #1 on: August 08, 2010, 12:15:24 PM »
Super job!  :clap:

I bet your friend's pleased....  :thumbup:

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline cidrontmg

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Re: 10 TPI LEAD SCREW
« Reply #2 on: August 08, 2010, 02:50:21 PM »
Excellent. A cross slide screw + nut for another 50 years.
Are there still available these parts for Raglans +/- off the shelf? From Myford? I guess the factory closed some 40 years ago.
Olli
Penafiel
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Offline kvom

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Re: 10 TPI LEAD SCREW
« Reply #3 on: August 08, 2010, 05:37:52 PM »
a 1/2-10LH tap only costs $100 or so at McMaster-Carr.  Looks like you saved some bucks doing the internal threading on the lathe.  :beer:

Offline Bernd

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Re: 10 TPI LEAD SCREW
« Reply #4 on: August 08, 2010, 06:08:56 PM »
Fine job there doubleboost. Looks better than the orginal. Probably works better too.  :thumbup:

Benrd
You can't fix "STUPID".

Offline andyf

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Re: 10 TPI LEAD SCREW
« Reply #5 on: August 08, 2010, 06:19:17 PM »
Great job  :thumbup:

I may need to make a similar Acme nut, in the not too distant future. May I ask how you went about the internal threading? A fully-profiled form tool which left you with a flat at the bottom of the valley when you got to full depth, or a tool with a 29o point which, once at full depth, you shuffled along with the topslide on successive passes to widen the valley?

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline Brass_Machine

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Re: 10 TPI LEAD SCREW
« Reply #6 on: August 08, 2010, 09:48:49 PM »
Nice job. That's some sharp (lol) looking threads. Very very nice.

Eric
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Offline sbwhart

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Re: 10 TPI LEAD SCREW
« Reply #7 on: August 09, 2010, 02:29:54 AM »
Great bit of work  :clap: :clap: :clap:

Stew
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Offline Davo J

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Re: 10 TPI LEAD SCREW
« Reply #8 on: August 09, 2010, 03:20:08 AM »
Hi,
Rdg Tools have them for 8.51, I just gave another bloke from in the US the link the other day, he ordered 2 and cost him $55 US dollars delivered.
http://www.rdgtools.co.uk/acatalog/ACME_TAPS__LEFT_HAND_.html

Dave

a 1/2-10LH tap only costs $100 or so at McMaster-Carr.  Looks like you saved some bucks doing the internal threading on the lathe.  :beer:

Offline doubleboost

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Re: 10 TPI LEAD SCREW
« Reply #9 on: August 09, 2010, 04:35:20 PM »
Hi
Andy
The thread is actually a square profile the tool was slightly narower than the finished thread once it was cut to depth i slowly widend it untill a good fit was achived.
I was talking to rob wilson he sugested making a silver steel tap at the same settings as the screw this would be used to finish the internal thread  :bow: :bow: :bow: :bow:
John

Offline andyf

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Re: 10 TPI LEAD SCREW
« Reply #10 on: August 09, 2010, 05:11:02 PM »
Hi
Andy
The thread is actually a square profile the tool was slightly narower than the finished thread once it was cut to depth i slowly widend it untill a good fit was achived.
I was talking to rob wilson he sugested making a silver steel tap at the same settings as the screw this would be used to finish the internal thread  :bow: :bow: :bow: :bow:
John

Thanks, John.
It did occur to me that, if making a silver steel screw and bronze nut to match, maybe one could get the nut nearly there on the lathe, and gash flutes into the first turn or two of the finished screw to use it as a tap to finish off. But hardening/tempering  might distort the screw, and I don't know how well silver steel would cut bronze if left in the raw.

Andy
Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline Tinkering_Guy

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Re: 10 TPI LEAD SCREW
« Reply #11 on: August 11, 2010, 12:49:47 PM »
Really?  I'd be quite surprised if heat-treating silver steel/drill rod would deform it.  (If done properly, that is.)  It's basically designed to be heat-treated, n'est-ce pas?

Didn't you say you were making the leadscrew out of SS?  If you made it a bit longer, you could part off the end and make it into a tap exactly matching the leadscrew's threading.  :D

Or am I all wet?
Tinkering_Guy
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Offline Bernd

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Re: 10 TPI LEAD SCREW
« Reply #12 on: August 11, 2010, 02:56:35 PM »
If you made it a bit longer, you could part off the end and make it into a tap exactly matching the leadscrew's threading.  :D

Or am I all wet?

Nope, your quite dry on that one. Tap would be made the same way. Nice short cut you thought of Tinkering_Guy.

Bernd
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Offline doubleboost

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Re: 10 TPI LEAD SCREW
« Reply #13 on: August 12, 2010, 04:39:58 PM »
Finished job  :D :D :D :D




It took some time but was well worth it

Offline andyf

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Re: 10 TPI LEAD SCREW
« Reply #14 on: August 12, 2010, 06:58:24 PM »
Looks really good  :thumbup:

It was for a friend, wasn't it? I hope you get much :beer: :beer: :beer: at his expense this coming weekend  :D

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline RichardShute

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Re: 10 TPI LEAD SCREW
« Reply #15 on: August 16, 2010, 06:52:52 PM »
Hi,
Rdg Tools have them for 8.51, I just gave another bloke from in the US the link the other day, he ordered 2 and cost him $55 US dollars delivered.
http://www.rdgtools.co.uk/acatalog/ACME_TAPS__LEFT_HAND_.html

Dave

I used one of those RDG taps to make a feedscrew nut for my little S&B Sabel. Beware that oversize is normal for an Acme tap, I can't recall, but it's in Machinery's, a 1/2" tap is to be expected to be about 1/32nd big ie 17/32 OD. Note that the RDG one I got was a chunk bigger still, played havoc with trying to work out why the damned thing wouldn't go up the hole.
Unlike 'normal' tapping, you will not be able to use an Acme tap to 'tap' the hole, you will need to rough most of the material out with a lathe tool and use the tap just to finish it off. In my case I was using some gunmetal which is a brilliant bearing material, but sticky as hell on the tap and it was a buttock clenching job. I wouldn't be near the front of the queue to volunteer to repeat the exercise. While I was at it, I modified the design to incorporate backlash adjustment by making the nut in two halves so I can take up wear in the future.

The tradtionally quoted material for a feedscrew would have been En19 (now known as 709M40 in BS970), but I don't doubt silver steel will be very servicable, especially as you got a decent surface finish on it. Nice job.

Richard
« Last Edit: August 17, 2010, 06:18:21 PM by RichardShute »
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Offline Chazz

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Re: 10 TPI LEAD SCREW
« Reply #16 on: August 17, 2010, 02:39:55 PM »
A Meteroligst (sp) told me once that when hardening a shaft or any item with a large length to diameter ratio to consider nitriding to minimize distortion and promote lubrisity (sp).

Cheers,
Chazz
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