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[Newbie] 3/4" Weldon to Cat 40

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lis2323

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#1
Hello everyone.

I'm new to the site and a retired farmer with (really) basic machine shop training from high school over 50 years ago. I don't pretend to know anything.....

Anyhow. I recently acquired a "First" ( Bridgeport clone) with a Cat 40 spindle. What's my best route for adapting a Weldon shank for using annular cutters? I seem to be able to find only MT and R8.



Thanks in advance for any help.

Terry
 
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Tony Wells

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#2
You simply use a 3/4" end mill holder that is CAT 40 taper. No more complicated than that. That's if I understand correctly. I am reading that you have an annular cutter shank of 3/4" diameter. Weldon is first just a brand name, but it's come to mean any tool shank with a flat or sometimes 2 on it. Normally you will see these driven by holders with set screws, but unless you need the torque transfer, there is no reason you can't use them in a collet. For that matter, if you have a CAT 40 collet set that will hold it, go right ahead.
 

Superburban

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#4
There is a tool holder made for Weldon shank tools. The Weldon shank refers to the flats on the tool, and they did (possibly still do) make a special tool holder that was designed just for the tooling. It has two set screws, one to tighten on the flat spot, and the other tightens on the body of the tool. weldon.jpg
Thats why some tool holders are marked to tighten one set screw first, it is the one that was designed to tighten on the flat spot.



Tapers_Weldon_1.jpg

http://www.tools-n-gizmos.com/specs/Tapers.html

I have seen some tooling marked as Weldon shank, that has four flat spots (A square section on the shank).I believe they are designed to transmit even more force to the tooling, but have not seen any reference stating such.

I don't see why either could not be held in a same diameter tool holder. Just be sure to tighten on the flat spot first.
 

lis2323

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#5
Thank you for all the replies. New question regarding the same machine. This First machine has what I can ASSUME is a NMTB 40 spindle.


The ONLY tooling that came with the machine was a Cat 40 TG100 collet holder. I am using a 3/4" collet presently to hold annular cutters.

This is the part that has me confused. The drawbar fitted (and used ) has 7/16 20 threads (as opposed to 5/8 11 ) which thread into the Cat 40 tool holder.



With this info what would be the easiest way to fit a drill chuck to this spindle. I have NO other tooling at this point except for R8 for a smaller mill drill.

Thanks in advance.




Sent from my iPad using Tapatalk
 

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Alittlerusty

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#6
Getting a chuck or an arbor to fit one you have with a 3/4" shank comes to mind . A 3/4" straight shank to jt33 or any other common taper could be bought quite cheap . I think you will need to make a different draw bar to use when switching to cat 40
 

lis2323

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#8
Just reread my post. I suppose I should clarify.

The Cat 40 tool holder that came installed in the spindle accepts a 7/16 -20 threaded drawbar similar to an R8.


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4gsr

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#9
Just reread my post. I suppose I should clarify.

The Cat 40 tool holder that came installed in the spindle accepts a 7/16 -20 threaded drawbar similar to an R8.


Sent from my iPad using Tapatalk
That just doesn't sound correct! The standard draw bar thread for National 40 taper is 5/8-11 UNC right hand thread. Can you post us some pictures of what you have there?

Edit: I fixed your red "X" in the posting and reposted your picture.

I now see what you have there. Someone made a threaded adapter to fit in the back of your CAT 40 holder that has a 7/16-20 thread in it. Which with any CAT 40 or 50 holder has to have an adapter or extension to get it to mate up with an existing draw bar.
 

lis2323

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#10
That just doesn't sound correct! The standard draw bar thread for National 40 taper is 5/8-11 UNC right hand thread. Can you post us some pictures of what you have there?

Edit: I fixed your red "X" in the posting and reposted your picture.

I now see what you have there. Someone made a threaded adapter to fit in the back of your CAT 40 holder that has a 7/16-20 thread in it. Which with any CAT 40 or 50 holder has to have an adapter or extension to get it to mate up with an existing draw bar.
Thanks. I kind of assumed that was an adapter, but never having seen a Cat 40 holder before I wasn't sure. The top of the spindle has a short length of 5/8" OD tune which I suppose helps align the smaller 7/16" drawbar.

Edit. I will have to remember about how to post pics on this forum.


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