Thread: Impero II: the cousin of parting tool

Originally Posted by cba_melbourne

With a fine flat file of course. Do a google search for "lathe file". Some folks use emery cloth backed by a flat file.

Doesn't ISO thread form fit just fine?......... no filing required.

Originally Posted by cba_melbourne

BSW is not used for much anymore nowdays, except for water pipes, Meccano toy screws, and brass light fittings. Not applications that traditionally require much accuracy in threading.

I didnt say it was used much. I said it was a better thread form in regards to fatigue. Just like metric MJ

Originally Posted by cba_melbourne

Why that? There is nothing wrong with cut threads if done right. Its a matter of what the application demands.

Because roll formed threads are better.

Originally Posted by cba_melbourne

The tip radius for metric threads is certainly well defined in the standards.

Yes well defined over a large range,,,,,,, yet they will still go together just fine.

Originally Posted by cba_melbourne

If it was not so, why would the makers of threading tools offer "full form" tools at all?

Because they can, but that doesnt mean there is only one radius that can be used.

Originally Posted by cba_melbourne

Its all about what the thread is being used for in the end. Up to you if you choose to follow the standard,

Nothing to do with following standards or not.
My point was there is a larger range of radius that can be used on ISO M thread and still be in spec, so a range of pitches can be cut with the same root radius. Where as BSW root and crest are r=0.137P end of story.

At least.... as I understand it

Stuart

Originally Posted by Steamwhisperer

Actually you might find all these tolerances came about because of the steam engine due to the massive forces involved during their operation.

Agreed Phil - one of the places I would want to see a full form thread.

In the meantime -
I started this thread some time ago because I'd found an interesting threading tool and wanted to share it. I revived it recently because I'd found another one that I thought others may find interesting. Can I ask if people want to start tit-for-tat exchanges on technicalities they start another thread? It has been established that W/W is a full form thread. It has been established that you can take short cuts. I think most would agree that no one in their right mind should use a thread with a built in stress raiser for a critical application. That is all that needs to be said.

I would much prefer to see threads where people talk about what they are doing, interesting tools they have/ have seen or comment/ question constructively on other's work. Someone commented to me the other day that there only seem to be a few people doing that these days, and it makes the forum a far less interesting place to be. I'd prefer it to be a place that encourages people to preserve skills and learn new ones rather than a place where the armchair experts come to argue.

Michael

Here is some of those form threading tools I have...

I have often wondered if you could make proper form threading tools out of dies, cut up...

20150410_191935.jpg

Not sure that dies would do it RC - they have a curvature to them.
You might be better off working out a way to make thread chasers.
I must admit that the pictures in post 21 have me intrigued
(https://www.woodworkforums.com/showth...30#post1856830 )
How would you put fine parallel grooves on the back of a tool steel insert. Now if you could work that one out, you could also make your own thread chasers. Probably one of those Wickman optical grinders with a shaped wheel would do it if we knew someone who had one of them.
Perhaps a lapping process - embed diamonds in a shaped copper or Al lap and cut the grooves individually? They don't look all that deep or wide. A milling cutter might do it but it becomes tricky at that size.

Michael

[QUOTE=Michael G;1857183]
How would you put fine parallel grooves on the back of a tool steel insert. Now if you could work that one out, you could also make your own thread chasers.

Wouldn't a shaper do that for you? I imagine it would be quite easy.

Peter Heuts

This thread got me thinking.....
I dug through one of my drawers and found these:

Peter Heuts

Originally Posted by WoodBee2

Wouldn't a shaper do that for you? I imagine it would be quite easy.

A shaper could, but if the thread insert is made of say M2 tool steel and the shaper tool is made of M2 tool steel...
(That's why I was thinking grinding)

Well done on your fossicking - looks like you have the same style of tool holder. Makes me wonder whether there was a standard insert if that style is as common as it seems to be.

Michael

Originally Posted by Michael G

A shaper could, but if the thread insert is made of say M2 tool steel and the shaper tool is made of M2 tool steel...
(That's why I was thinking grinding)


Michael

It might be possible to rough it out if the HSS in the workpiece was in the annealed state, but it will still have to be touched up after hardening one way or another, I would imagine.

[QUOTE=Michael G;1857198]A shaper could, but if the thread insert is made of say M2 tool steel and the shaper tool is made of M2 tool steel...
(That's why I was thinking grinding)

I haven't tried it personally, but in the shaper group on yahoo some people say they use carbide tooling on shapers with succes.

Well done on your fossicking - looks like you have the same style of tool holder. Makes me wonder whether there was a standard insert if that style is as common as it seems to be.

I don't know if there was a standard, but I do know my two holders don't use the same insert. I tried swapping and it didn't work. I will search some catalogs of dutch tool suppliers to see if those inserts are still available. I have seen some more of these tools at various people, so who knows......

Peter Heuts

Hi Guys,
There seem to be bucket loads of Coventry dies kicking about and Tracey Tools sell them complete with a holder, would it be feasible to make a holder for these that can be fitted in a lathe tool post to cut and finish external threads in a similar manner.

Originally Posted by BaronJ

Hi Guys,
There seem to be bucket loads of Coventry dies kicking about and Tracey Tools sell them complete with a holder, would it be feasible to make a holder for these that can be fitted in a lathe tool post to cut and finish external threads in a similar manner.

Hi BaronJ,
I gave it a crack here.
https://www.woodworkforums.com/f65/multi-screwcutting-166136

Phil

Originally Posted by WoodBee2

I haven't tried it personally, but in the shaper group on yahoo some people say they use carbide tooling on shapers with success.

I think it would be a matter of experimenting with it. Probably need to be a brazed tip. I'd be concerned about the impacts the tool would get every time it stroked. For a 55 or 60 groove tip support would need to be considered too. Hmm.

Michael

Originally Posted by BaronJ

Hi Guys,
There seem to be bucket loads of Coventry dies kicking about and Tracey Tools sell them complete with a holder, would it be feasible to make a holder for these that can be fitted in a lathe tool post to cut and finish external threads in a similar manner.

BaronJ,

Several years ago I picked up a number of old Coventry and similar dies from the junk heap of a factory which had recently closed to use for tool steel stock. They were mostly Whitworth and BSP. I used one of these to cut a 10TPI x 1 5/16 Whitworth form thread on an adapter which allowed me to use the threaded chucks from the small lathe on the larger D1-4 lathe by holding the adapter in the 4 jaw chuck. The thread turned out well. I had to use the die upside down though, because I was cutting to a shoulder and the relief for starting the thread in the die holder was too long to allow this.

The die in the photo was not the one used for the thread - this has been hidden by the shop gremlin some time in the last 5 years, but is similar for illustration purposes to the one used.

I realise that the thread profile will be slightly off because of the difference in helix angle between 3/4 10 TPI Whitworth and the
1 5/16 spindle nose, but it is probably still a better thread and finish than I would have got with a home-ground single point tool. It should cut the exactly correct profile on the 3/4" workpiece which it was designed for, so it is probably worth hanging onto any common sized dies you come across.

Frank

Hi Guys,

Thank you for your replies and the pointers.
I have a box of these type of inserts all marked with the thread size that they were designed to cut. Actually I found a Coventry die head in there too. Unfortunately it won't fit anything that I've got. It has a large round spigot with a through bore. Maybe suitable for a Ward 3 or 5 multi tool tail stock. I'm surprised that it hasn't gone rusty, since it must have sat for around 30 years in that cardboard box. I was going to take a photo, but for some reason the camera batteries are flat. So later.