Simple task, but ask first.

Thought I would ask the group before I barge in the workshop and just do it!
Making two steering rack extensions for my kitcar. Length of en3 bar, mild
steel 25 mm dia. Have turned one end down to 14 mm and drilled the other end 12 mm. to the required depth.
Bought some taps and dies off ebXy and I am considering just fitting to the lathe slow speed and going for it single pass with the split die. and a few passes to allow me to clear the chips with the tap, taper then plug.
I have done the die bit before on both 12mm and 16 mm, in both instances I used good quality HSS cutters. because I only need two off I got carbon steel.
Does the group think this would be too brittle for the job and I should used hand power to turn the headstock rather then electric?
Cheers
Adrian
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Personally, I use hand power when tapping in the lathe and I sometimes only use it to just start the thread, finishing to depth by hand in a vice.
Hth,
--
Boo

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Boo wrote:

Me too, though not the vice bit. Hand power gives a better feel.
Small carbon steel taps are bad for breaking, but larger ones are less liable to break.
I have broken a couple of carbon steel dies, but it's not as common or easy as breaking taps (and the fault then lay mostly with the cheapo too-large diestock allowing the split dies to open too much, and I was threading stainless at the time).
-- Peter Fairbrother
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On Tue, 02 Sep 2008 15:41:58 -0500, Adrian

When we made the axles for the Caterpillar trolley, we had 40mm square bar turned down to 1.25" for the roller bearings, then we had M16 tapped into the outer ends to take a cap head screw.
We did it all on the Littlejohn lathe, but the tapping was done by hand, using the tailstock to support the tap, and the tap holder handle was supported on the toolpost/saddle, moving across the top as the thread went in. The axle was set up in the 4-jaw chuck with the fixed steady on the round outer end of the axle.
I'd always be a little cautious about power tapping in the lathe, it's so easy to break the tap, especially with standard 3-flute taps.
There are some pictures of the trolley manufacture here:
http://www.stationary-engine.co.uk/Caterpillar/CaterpillarMenu4.htm
or on the US server here:
http://www.oldengine.org..members/diesel/Caterpillar/CaterpillarMenu4.htm
Peter -- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk http://www.oldengine.org/members/diesel http://www.stationary-engine.co.uk http://www.oldengine.co.uk
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There's a typo in that second address:
http://www.oldengine.org/members/diesel/Caterpillar/CaterpillarMenu4.htm
Peter -- Peter A Forbes Prepair Ltd, Rushden, UK snipped-for-privacy@prepair.co.uk http://www.prepair.co.uk http://www.prepair.eu
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Cheers All that have answered.
Looks as though use the lathe for rigidity and straightness. But hand power to turn the work, or cutter..
Cheers
Adrian
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On Wed, 03 Sep 2008 11:49:25 -0500, Adrian

I tend to single point the thread until nearly done and only then use the die to clean the thread form up. Using a die straight off without a tailstock die stock. often produces a drunken thread.
Mark Rand RTFM
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During my apprenticeship, I was taught to start a die off with the tailstock with a normal die stock. Just put the die up against the end of the bar, make the tailstock meet the die stock, the stock handle rotated against the saddle, and as turning the chuck by hand, just keep pressure on the die stock by slipping your hand over the tailstock wheel.
This has worked fine for me. Never had a drunken thread this way. I only ever had drunken threads when I tried using a die stock in a vice.
--
Best regards,
Dave Colliver.
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