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Member postings for jacques maurel

Here is a list of all the postings jacques maurel has made in our forums. Click on a thread name to jump to the thread.

Thread: screw cutting made easy
16/06/2013 22:14:23

Thank you to Bazyle for the links.

I'll give more informations on the snap tap attachment. in the following days. The principle of function is very simple but confusing. I've made my own attachment and discovered that there are many hidden traps in the conception. It's almost impossible for an amateur to make a copy of the genuine as no adjustement is possible. Here is a first photo:

snap tap first.jpg

Thread: A variable Lead threading attachment. Author Ted McDuffie
16/06/2013 21:37:15

The anwer to the 2 questions of Ady 1 is yes.

Answer to Michael Williams: the drawing 1 is just here to explain the principle.

J Maurel

15/06/2013 23:59:18

The purpose of this attachment is not to correct the lead but to use the standard gear boc leads for machining any odd lead, so no change gear is needed (only the standard gear box is used).

Of course there is some geometric error as the linkage goes away, but for about 50mm long (short thread) this is negligeable (less than the lead screw error).

Thread: screw cutting made easy
15/06/2013 23:52:31

Some answers:

Big pain 1: 2mm lead is standard from the gear box.

Big pain 2: I use the thread dial indicator after each infeed so the delay for starting the cutting pass. From the infeed increasing you can see that there are not 6 videos sellotaped, only the 2 last (slow speed) are such.

Big pain 3: The tool is stopped and withdrawn (this is the purpose of this attachment) on a standard lathe. The result is like CNC.

This attachment was (is?) commercially available, called "Snap Tap" from a Swedish company (now Seco tool I think).

Thread: A variable Lead threading attachment. Author Ted McDuffie
15/06/2013 16:40:26

This link will work :**LINK**

Thread: screw cutting made easy
15/06/2013 16:35:32

Sorry I've made a mistake for the video link (while this attachment is of some interest)

Here is the good link: **LINK**

15/06/2013 16:26:05

Do you know this threading attachment ? The tool is stopped and withdrawn just before the shoulder. This attachment is almost completely contained on a toolholder set in the toolpost. It’s not as efficient as the “single tooth dog clutch” but far easier to make and few costumization is necessary, whichever lathe you use. The result is like the one obtained on a CNC lathe, the tool is withdrawn always at the same place, no circular groove is made!


Thread: A variable Lead threading attachment. Author Ted McDuffie
15/06/2013 16:19:56

With the universal threading attachment (and the others variable lead attachments) it’s possible to use the “Thread dial indicator”, so it’s possible to open and close the “Half nuts”,(as you are using a standard thread from the gear box). This makes thread machining far easier!
It’s possible to work against a shoulder from left to right as described in this video:


12/06/2013 15:10:46

The calculation is BC = 30/(p'/p-1) mm, p' being the lead to obtain and p the standard one.
Ex for p' = 20 TPI (1.27mm) and p = 1mm, BC = 111 mm (position 2).
The charts and graduations are here to help when setting the lathe for standard leads (imperial and module for a metric lead screw, metric and diametral pitch of an imperial one).
Almost any lead can be obtained within the range of the lathe gear box.

My attachment is quickly set up (contained on a toolhoder). Because for me the time for removing and resetting the top slide, is the same as the time for setting and resetting the banjo arm.

Ex : chart for machining module leads from a metric lead screw:

threading chart sample.jpg

10/06/2013 22:52:25

There are numbers stamped on the lever and charts are given so it's easy to cut any lead. On the photo (metric lead screw) one side of the groove is graduated for imperial leads, the other for module leads (for cutting single start worms). No change gear is needed, all cutting is from the standard gear box but the thread must be short (50 mm) read the article for details.
positions for b.jpg

06/06/2013 21:06:18

This was in ME issue 4270 (march april 2006) general view:

universal threading attachment.jpg

06/06/2013 21:04:04

I've published a "universal threading attachment" almost completely contained on a toolholder, based on Thales theorema, point E being fixed and BC being adjustable:


Thread: Carbide tips for the new year
07/01/2013 18:01:32

bonne année 2013 usinage.jpg

Thread: Bonne Annee
02/01/2012 23:03:30
Yes I'm the paradoxical gear maker.
Look for:
J Maurel
Thread: mastering chips
01/01/2012 08:41:47
Thread: weird gears
03/11/2011 22:39:35
my last gears videos:
2 teeth gears:
3 teeth gears:
Thread: screwcutting from a shoulder
01/11/2011 18:31:20
Some answers:
To Mr withnell: you can make a thread right upto a shoulder with this method like with a single tooth dog clutch, but the tool is starting from the shoulder.
To Mr Gilhespie: This attachment is for a standard lathe but yes the result is the same as with a CNC , the tool being retracted always at the same place!
To Mr Humphrey: the top slide is not moved but the tool is special with 15° rake angle and set at the helix angle (3° for a standard coarse iso thread). So it was possible to have a good result on FCMS with no lubricant (the video is clearer with no lubricant).
01/11/2011 08:11:23

This method is I think the simplest one for screwcutting near a shoulder with a standard lathe, you need only a thread dial indicator, a carriage stop and a left hand tool. This method is described in the book: “screwcutting in the lathe” (by Martin Cleeve) p 80 (special application of the leadscrew indicator) of my 2003 reprint.

By far the best method for screwcutting near a shoulder is to use the « single tooth dog clutch » as described in the thread : « screwcutting simplified ». But making this attachment is a complex job and it must be customized for each lathe.

Other method: the “high speed screw cutting attachment” described in MEW N°168 uses an automatic quick opening of the half nuts, of course this is valuable only when the half nuts can be opened without losing the pitch. This attachment must also be customized for each lathe.

An universal attachment (requiring no customization) being able to stop the tool near the shoulder and even to retract it would be a good thing, does it exist?.....

29/10/2011 10:10:01
watch the video:
J Maurel
Thread: Rotary broaching - the easy way
20/09/2011 16:03:49
read my article about "polygonal punching tool" in ME N°4310 oct 2007 it gives informations about the hole to drill before punching.
J Maurel
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