Cutting metric threads on non metric lead screw

This doesn't quite answer your question but, if you just need 1 bolt, why not save some time and trouble by using a die?

Lewis.

Yep, but, the threaded bolt is on the dial end of a threaded lead screw that moves the cross feed and wanted to try and figure out how to make the metric thread. But, in the name of progress, your right I could figure that out in the calm of another day. That begs the question, can I cut a thread through tool steel (pre hardened of course) with a simple tap and die set? I have never threaded a raw stock without a lathe, I occasionally use the tap and die set to clean- up threads. I also wonder how I would hold the non-business end of the part while putting the large amount of force needed to cut the thread.

thanks Lewis

Or buy a bolt. Try Fastenal.

Pete Stanaitis

snipped-for-privacy@gmail.com wrote:

I can't just do that, the bolt threads are part of a one piece lead screw that moves the cross feed. The bolt threads into the handle.

Click this link to clear the brain cramp It is exactly on topic. It even talks about your 1.5 mm thread.

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JCam wrote:

I don't know if this will work for you

Karl

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Unka' George ================ When we are planning for posterity, we ought to remember that virtue is not hereditary. Thomas Paine (1737-1809), Anglo-American political theorist, writer. Common Sense, ch. 4 (1776).

Make the part with an "English" thread and then re-thread the handle to that size.

Bob

The Home Machinist issue May/June 2007 has a great article on how to cut threads without the correct gearing. "Expanding Thread Cutting Options on Lathes with Quick-change Gears" by Kim Steiner Try your news stand.

Roger

Why are you making a screw from pre-hardened tool steel?

Seems to me you could make the screw from leaded brass and it would do the trick.

If you want go ahead and use a drill blank to make your screw. and that you can thread with a die just fine. If you really need it hard, you can harden it after you cut the threads.

Cutting threads on hardened steel is best done by a thread grinder.

I have never threaded a raw

There are several ways to do it. First of all you could stick it in a vice and use the die in the die stock. Not much different than the force needed to tap.

Another way to thread is to make your screw a little long and give the end a lead (taper). Start the die square by removing the chuck or center from the tail stock and butting up the end of the tail stock shaft to the die.

Grab the three jaw chuck and turn it slowly to you while holding the die stock. Advance the tail stock to keep it square until you get a few threads cut. now you can use the lathe to do the pushing if you want (Slow speed, lots of cutting oil.) or just continue turning the chuck by hand. You can also set the cross slide to grab the end of the die stock.

If you have a small lathe chuck you can cheat a bit and use the chuck wrench for additional leverage.

You will get the best thread quality if you use sufficient oil and back off the die to break the chips.

Unfortunately its not that simple. Firstly, in order to precisely convert between metric and Imperial threads you need a 127 toothed gear somewhere in the train - your 37 and 47 toothed gears will only give you approximations. Secondly, the thread pitches cut on an Imperial gearbox equipped lathe are in fixed ratio groups. On my lathe, for example, I have 8 starting ratios (4, 4.5, 4.75, 5, 5.5, 6, 6.5, and 7 TPI) and for each of those the gearbox can multiply them by the 5 fixed ratios of 1, 2, 4, 8 and

1. This gives 40 different TPIs in 8 groups of 5, giving TPIs from 4 to

Some time ago I bought a 127 tooth gear and decided to investigate what other gears would be needed to cut all the common metric threads from

I hope this helps.

...

I can only speak for my Monarch 10EE and my Leblond. Both these machines have levers to move for different thread pitches. And both machines have a gear train at the left end of the tail stock for ranges of thread pitches and feeds. This is where you swap out for the 47 and 37 tooth gears.

Scott Logan goes into considerable detail on his web site to explain how to accomplish metric threading on machines with loose change gears.

karl

Thanks all, great amount of feedback on this, you're the best.....I love this group !!

John