Author Topic: Stop for Coventry Die head  (Read 7111 times)

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15293
  • Hampshire, england.
Stop for Coventry Die head
« on: March 01, 2013, 06:16:50 PM »
I have picked up a 1/4" coventry die head to help me speed up my stud making and an looking for details of a suitable stop to use for it.

I assume that the stop fits in the space behind the chasers and somehow extends between the chasers to provide the stop. Photo's would be appreciated ;D

Jo
Enjoyment is more important than achievement.

Online Jasonb

  • Full Member
  • *****
  • Posts: 9463
  • Surrey, UK
Re: Stop for Coventry Die head
« Reply #1 on: March 01, 2013, 06:36:16 PM »
Just e-mailed you while you were typing this, all is explained. Basically just hold the tailstock lever or stop turning the handwheel and the thread already formed will draw the front forwards until it opens.

So long as you keep the feed pressure on it will carry on cutting. A stop could be set to limit the tailstock travel.

J

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15293
  • Hampshire, england.
Re: Stop for Coventry Die head
« Reply #2 on: March 01, 2013, 06:44:21 PM »
Yes I like  :ThumbsUp: that set the lever feed tailstock stop on the Prazimat/capstan head to the appropriate length and hey presto it would stop pushing. Now to think about the Cowells, which has a standard screw feed.

Jo
Enjoyment is more important than achievement.

Online Jasonb

  • Full Member
  • *****
  • Posts: 9463
  • Surrey, UK
Re: Stop for Coventry Die head
« Reply #3 on: March 01, 2013, 06:46:45 PM »
Just remember to stop a bit before the bolt head or chuck as the head will move a couple of mm before it opens, don't know how this will work out a ssome of those small studs only need a short thread.

J

Offline pgp001

  • Full Member
  • ****
  • Posts: 812
  • West Yorkshire - UK
Re: Stop for Coventry Die head
« Reply #4 on: March 01, 2013, 09:59:42 PM »
This is one of my solutions, very quick to set up and remove.



And another.



Yet more.



Phil

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: Stop for Coventry Die head
« Reply #5 on: March 02, 2013, 03:14:42 AM »
Jo

I want video of your solution....my turret tailstock is getting close to being attended too....and a die head is on the wish list....provided I survive "sequestration"....

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline ths

  • Full Member
  • ****
  • Posts: 1801
  • Kangaroo Valley, NSW, Australia
Stop for Coventry Die head
« Reply #6 on: March 02, 2013, 06:14:52 AM »
'Sequestration'?

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: Stop for Coventry Die head
« Reply #7 on: March 02, 2013, 06:46:59 AM »
'Sequestration'?

 :lolb:......It's what happens when the collective government officials can't get their heads out of their Q)(*SKLJ and get a budget passed...resulting in loss of government contracts...potentially putting many millions out of hard working tax payers out of work.....


Nice name huh?

Regardles of which side of the isle your on....it's pathetic....( NO DON"T GO THERE!)

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15293
  • Hampshire, england.
Re: Stop for Coventry Die head
« Reply #8 on: March 04, 2013, 03:46:32 PM »
 :thinking: Whilst I can see that a stop on the feed would work to open the head I am still wondering why/if a set of internal stops would not work. I can imagine the classic way of using one of these heads would need a few attempts to set it up. Now if you could make up a set of defined stops and just pop one in the back of the head would that not be better?  :noidea:

I also wonder if the motion of the head is causing a minimum possible thread length for a stud. Does anyone know what this minimum length is. I often have threaded lengths on my smaller studs of 2.4 mm. On the 12 BA they can be even shorter. :shrug:

Jo
Enjoyment is more important than achievement.

Offline ths

  • Full Member
  • ****
  • Posts: 1801
  • Kangaroo Valley, NSW, Australia
Stop for Coventry Die head
« Reply #9 on: March 04, 2013, 10:28:01 PM »
Thanks Dave, I have since found out about it, and will not go into political tail chasing!

Jo, I assume that when you say that the head is a 1/4" version, that this is the largest diameter it will accommodate? What sort of cutters came with it?

Cheers, Hugh.

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15293
  • Hampshire, england.
Re: Stop for Coventry Die head
« Reply #10 on: March 05, 2013, 07:54:33 AM »
Yes 1/4" or 0BA is the largest it will cut which for my current size of model making is ideal.  In fact I reckon I could use it on the Cowells it is so cute. ;D

It came with a bunch of metric cutters but I seem to have acquired most of the standard BA ones in the mean time.  ;D

Jo
Enjoyment is more important than achievement.

Offline metalmad

  • Full Member
  • ****
  • Posts: 687
  • Australia Skype - metalmad11
Re: Stop for Coventry Die head
« Reply #11 on: March 05, 2013, 11:27:08 AM »
Tool envy
A little bit every day, sometimes the same little bit

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15293
  • Hampshire, england.
Re: Stop for Coventry Die head
« Reply #12 on: March 05, 2013, 11:39:01 AM »
 :lolb: 

And I have casting envy  :naughty:

Jo
Enjoyment is more important than achievement.

Offline pgp001

  • Full Member
  • ****
  • Posts: 812
  • West Yorkshire - UK
Re: Stop for Coventry Die head
« Reply #13 on: March 05, 2013, 01:13:13 PM »
:thinking: Whilst I can see that a stop on the feed would work to open the head I am still wondering why/if a set of internal stops would not work. I can imagine the classic way of using one of these heads would need a few attempts to set it up. Now if you could make up a set of defined stops and just pop one in the back of the head would that not be better?  :noidea:

I also wonder if the motion of the head is causing a minimum possible thread length for a stud. Does anyone know what this minimum length is. I often have threaded lengths on my smaller studs of 2.4 mm. On the 12 BA they can be even shorter. :shrug:

Jo

Jo

The photo's I posted of different holding methods are different for a reason.
The set-up with the capstan feed tailstock is used when making batches of studs with a reasonable thread length and they are cut under power with the lathe chuck turning, the stop collar on the back end of the tailstock spindle is set to produce the correct thread length, I measure how much is sticking out of the chuck jaws or collet for each stud.

The set-up with a block mounted on the cross slide was my dads invention prior to me inheriting the lathe when he died, the other set-up with a post clamped directly to the lathe bed is my improved version of it that is a lot faster to set up and take down.
With that method the lathe spindle is locked and the thread is cut by hand using the spare leadscrew hand wheel, doing it this way you can produce very short threads without having to worry about any stops at all, you just count the turns from when it starts cutting, then when you get where you need to be, simply pull the hand wheel away from the job and this trips the die head open and lets you retract it out of the way.

Hope this helps
Phil

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15293
  • Hampshire, england.
Re: Stop for Coventry Die head
« Reply #14 on: March 05, 2013, 01:14:46 PM »
 :ThumbsUp: Yes thanks Phil.

Jo
Enjoyment is more important than achievement.

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal