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10th April 2015, 04:15 PM #31SENIOR MEMBER
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10th April 2015 04:15 PM # ADSGoogle Adsense Advertisement
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10th April 2015, 04:40 PM #32GOLD MEMBER
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Doesn't ISO thread form fit just fine?......... no filing required.
I didnt say it was used much. I said it was a better thread form in regards to fatigue. Just like metric MJ
Because roll formed threads are better.
Yes well defined over a large range,,,,,,, yet they will still go together just fine.Because they can, but that doesnt mean there is only one radius that can be used.
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
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10th April 2015, 07:25 PM #33Philomath in training
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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
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10th April 2015, 08:35 PM #34Pink 10EE owner
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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.jpgLight red, the colour of choice for the discerning man.
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10th April 2015, 09:11 PM #35Philomath in training
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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
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10th April 2015, 09:50 PM #36Member
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[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
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10th April 2015, 09:53 PM #37Member
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This thread got me thinking.....
I dug through one of my drawers and found these:
Peter Heuts
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10th April 2015, 10:11 PM #38Philomath in training
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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
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10th April 2015, 11:42 PM #39SENIOR MEMBER
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11th April 2015, 02:24 AM #40Member
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[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
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11th April 2015, 05:26 AM #41Golden Member
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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.
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11th April 2015, 07:04 AM #42SENIOR MEMBER
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Hi BaronJ,
I gave it a crack here.
https://www.woodworkforums.com/f65/multi-screwcutting-166136
Phil
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11th April 2015, 08:05 AM #43Philomath in training
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11th April 2015, 01:03 PM #44Senior Member
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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
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11th April 2015, 08:36 PM #45Golden Member
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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.
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