Thread cutting on the lathe ??

[morrisman]

My crummy drawing shows the side rake ..its a terrible drawing but you get the idea

[Steamwhisperer]

there is enough side clearance and yes the top is flat.

Hi Andre,
you have remembered to increase the clearance to allow for the lead angle of the thread...haven't you??

Phil

[welder]

thanks guys I wish I was near the lathe to try these tips out but I'm not for two weeks

[4-6-4]

Greetings chaps. All this palava about thread cutting. My first thread was in the first year of my apprenticeship. The leading hand got me a piece of black 1 1/2 Dia bar. Showed me how to use a thread gauge and grind up a HSS tool bit. He then showed me how to cut a thread on it to suit a nut which was supplied. Then I had to cut a thread on the other end of the bar. It looked as though a mouse had chewed it. On showing my effort the response was to cut that thread off and do it again. Which I did until the whole bar was in the scrap bin But it had the desired result.
I was taught the method where you take side cuts using the top slide. The trick is that you do not cut on both sides of the thread at the same time. Almost from the start move the top slide a few thou forward each cut. Do not be impatient and take more than 5 thou cuts. Every now and again reverse the direction of the top slide to take a few cuts on the trailing edge. Its bloody hard to describe the method, If you can come to Melbourne I will give you a crash course. Yours 4-6-4

[Ueee]

Every now and again reverse the direction of the top slide to take a few cuts on the trailing edge.

Hi 4-6-4,
I take it you mean to flip the angle of the cross slide round to 30deg (or whatever angle) the other way, so you have the handwheel on the left? I have never tried to clean up the trailing edge before, but is there any reason you could not just feed the cross slide in by a thou to clean the trailing edge up? You would have to back the compound out a bit so you would not be cutting on both sides, and it would also mess up your feed measurement, but if you could get around these problems surely it would be easier than swinging the compound round and resetting the toolpost.
On the subject of tool shape, i forgot to mention i grind my tool just less than the desired angle-so my 60deg tool is more like 59.9 deg. This way when i set the leading edge to the correct angle the trailing edge cannot drag and has the tiniest of clearances.

Hi Andre,
I thought you had a 260? You had better post some pics of the lantaine in the show us your lathe thread! I nearly bought a Lam a few years back, was in immaculate condition, being owned by 2 retired F and T's and hardly used. It went for a bomb though so i missed out. Felt beautiful to play with the wheels. (Although not as nice as Blondie did when she was together)

[pipeclay]

What 464 was describing was the plunge method with the cross slide,not the offset method with the compound.

What he does is advance the compound everytime he takes a cut with the cross slide,then probably near close to full depth he will return the compound to his zero and then take an advance towards the tailstock with his compound when he advances his cross slide.

If you attempted to do it the way you think you would need to track the thread every time.

Andre has posted photos of hios lathe in that other thread,you may need to search.

[Log]

Hi welder, I personally think you would be better off learning to thread without setting the top slide around. It is very easy to come to grips with, is simple and doesn't require mucking around with swinging the top slide setting so it's quicker.

Same as 4-6-4 is how I was taught and I've only ever used and seen this method used in industry. You don't lose your guide readings on the crossslide dial or DRO for other tools on the toolpost or other tools for quick change toolpost.

As per 4-6-4 for each cut just advance the top slide 2 to 3 thou during the initial cuts(can be more if doing bigger threads and deeper initial cuts); when getting close to size and for the last couple or so light cuts you can stop advancing the topslide so both sides of the tool are taking light skims. Various minor changes to methodology can be effected to make sure you are getting nice finish on both flanks of thread etc.

Use of a good extreme pressure cutting oil or compound helps to get a good finish too. Rocol RTD (is available in squirt bottle size) is one of the ones that I like. When using RTD or other, you don't need much on the thread, a small trail along thread occasionally will suffice.

Cheers.

PS. For toolsteel I like to dress the top and sides of the tool with a fine oilstone so the chip can slide easily and also this helps reduce "welding" of material on top of tool, caution though not to accidentally round the cutting edges.

[Ueee]

What 464 was describing was the plunge method with the cross slide,not the offset method with the compound.

What he does is advance the compound everytime he takes a cut with the cross slide,then probably near close to full depth he will return the compound to his zero and then take an advance towards the tailstock with his compound when he advances his cross slide.

If you attempted to do it the way you think you would need to track the thread every time.

Andre has posted photos of hios lathe in that other thread,you may need to search.

The way both you and 4-6-4 described the procedure is a bit hard to understand, but logs description cleared that up. It was clear in my last post that I did not understand what 4-6-4 meant hence I asked. I am just a book machinist so what would I know, right? Can someone show a pic of the tool used for this method, I imagine one like Mike drew at the top of the page would not cut on the trailing edge.

Andre has no posts in the show us your lathe thread, I will have to look in the shed thread when I have more time

[Log]

The way both you and 4-6-4 described the procedure is a bit hard to understand, but logs description cleared that up. It was clear in my last post that I did not understand wha .4-6-4 meant hence I asked. I am just a book machinest so what would I know, right? Can someone show a pic of the tool used for this meathod, I imagine one like Mike drew at the top of the page would not cut on the trailing edge.

Andre has no posts in the show us your lathe thread, I will have to look in the shed thread when I have more time

Yo Ueee, The pic of the Ifanger threading tool on this link may help. http://www.ifanger.com/fileadmin/Web...ng%20tools.pdf

I really like these tools but don't(unfortunately) own one, have only used em in industry. They are good because one can rotate the tool around to clear the leading flank and when they need sharpening only the top has to be ground down with a little top rake backwards(toward front of lathe).

I sharpen toolsteel tools like welder's pic but with a little back rake and sometimes a tiny side top rake. Too much rake will cause loss of correct thread angle on finished thread.

Hope this helps.

Cheers.

[welder]

I asked my Tafe teacher and he said I had my compound wrong which I did I had it set to 29 on the scale he said I had to set it from 90 so it reads 61 on the scale. he also said we can grind my tools on the cutter grinder.

[Ueee]

Yo Ueee, The pic of the Ifanger threading tool on this link may help. http://www.ifanger.com/fileadmin/Web...ng%20tools.pdf

I really like these tools but don't(unfortunately) own one, have only used em in industry. They are good because one can rotate the tool around to clear the leading flank and when they need sharpening only the top has to be ground down with a little top rake backwards(toward front of lathe).

I sharpen toolsteel tools like welder's pic but with a little back rake and sometimes a tiny side top rake. Too much rake will cause loss of correct thread angle on finished thread.

Hope this helps.

Cheers.

They look real nice Log, I'm trying not to drool on my paperwork....
I wonder if you could use a Diamond tool holder to the same effect? The problem would be clearance on the leading flank. I will try the compound set at 90deg method next time i need to thread something.

Andre,
For some reason i thought you had a hercus, i can see your lantaine in your shed pics now.

[Log]

They look real nice Log, I'm trying not to drool on my paperwork....
I wonder if you could use a Diamond tool holder to the same effect? The problem would be clearance on the leading flank. I will try the compound set at 90deg method next time i need to thread something.

The Eccentric Engineering one can,
Diamond Tool Holder

It doesn't have the round shank in the main body like the Ifanger one so it must be made with a leading edge clearance to suit most helix of normal encountered threads.

Cheers.

[Log]

They look real nice Log, I'm trying not to drool on my paperwork....
I wonder if you could use a Diamond tool holder to the same effect? The problem would be clearance on the leading flank. I will try the compound set at 90deg method next time i need to thread something.

Andre,
For some reason i thought you had a hercus, i can see your lantaine in your shed pics now.

Ueee, compound to be set at 0 degrees, ie slideways parallel to lathe bed. I think you understood that anyway.

Cheers.

[Ueee]

Ueee, compound to be set at 0 degrees, ie slideways parallel to lathe bed. I think you understood that anyway.

Cheers.

Yeah, i got that...my brain is still in drool mode...... i wonder if you could turn the shank on a diamond holder to use in a boring bar holder......You would want to be doing a lot of threading to make it worthwhile.

[Ueee]

PS. For toolsteel I like to dress the top and sides of the tool with a fine oilstone so the chip can slide easily and also this helps reduce "welding" of material on top of tool, caution though not to accidentally round the cutting edges.

The thread Mike started here https://www.woodworkforums.com/f65/la...pening-155954/ Is a geed read about edge build up and the finish on the toolbit.