# What is a drawbar used for on a jacobs chuck??



## refueler1 (Aug 3, 2008)

How does a drawbar work??


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## d1carter (Aug 3, 2008)

refeuler:
Most homemade draw bars are made of threaded rod that goes through your headstock and screws into the back of your morse taper. It should have a washer and nut on the outside of your headstock to hold your Jacobs chuck in the MT. You must have a Jacobs chuck that is drilled and tapped to accept a draw bar. Hope this helps...


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## low_48 (Aug 3, 2008)

The drawbar is used when you expect vibration with working with the chuck and you are not using the tail stock. The vibration can break the hold of the taper and the chuck will fall out. No vibration and tail stock up, you won't need the drawbar. I once tried holding a tenon cutter in a jacobs chuck , and feeding the chair rung up to the headstock in a v block. The chuck would not stay in the headstock. It constantly came loose. I had to set up in a drill press.


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## ldb2000 (Aug 4, 2008)

Jack the drawbar is a must anytime you are turning with a jacobs chuck without the tailstock up against the workpiece , it keeps the chuck from working loose and becoming a dangerous flying object .
You can make a drawbar from a bolt (sized to fit your chuck) that is long enough to pass through the headstock and thread into the chuck (the PSI chuck says it is threaded for a drawbar) and you will need a washer big enough to cover the hole in your spindle (handwheel) a delrin or similar spacer with washers on the handwheel end will make it easier to tighten the drawbar in place .


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## Randy_ (Aug 4, 2008)

d1carter said:


> .....You must have a Jacobs chuck that is drilled and tapped to accept a draw bar.....


 
This is an important point as many drill chucks will not be drilled for a draw bar as they are not needed on a drill press.


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## refueler1 (Aug 8, 2008)

ldb2000 said:


> Jack the drawbar is a must anytime you are turning with a jacobs chuck without the tailstock up against the workpiece , it keeps the chuck from working loose and becoming a dangerous flying object .
> You can make a drawbar from a bolt (sized to fit your chuck) that is long enough to pass through the headstock and thread into the chuck (the PSI chuck says it is threaded for a drawbar) and you will need a washer big enough to cover the hole in your spindle (handwheel) a delrin or similar spacer with washers on the handwheel end will make it easier to tighten the drawbar in place .



I kinda thought that was what it was used for but not having ever used a jacobs chuck, I had to ask, thanks.


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## Daniel (Aug 8, 2008)

Don't feel bad, i owned a lathe for over 20 years before I knew how to use one. And I found out just the way you did asking the folks around here. Better safe than injured


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## randyrls (Aug 8, 2008)

Randy_ said:


> This is an important point as many drill chucks will not be drilled for a draw bar as they are not needed on a drill press.



To join the thread;   If you want the drawbar, look for a jacobs chuck intended for metal machining.  Jacobs chucks for machining tend to be heavier and of better quality than drill press chucks and commonly have the drawbar hole.  The chuck does not have a thru hole.  The drawbar threaded end is only in the headstock end of the chuck, but doesn't go all the way thru.

Randy;  You may be interested in this video of a production machine shop:
http://www.pcntv.com/pcn_online.html 
under "PCN Tours" play "Plouse Machine Shop".  You will need quicktime to play the video, but it is  interesting.


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