# Mill drawbar repair



## kvom (Mar 26, 2012)

My Bridgeport came with a clone of the Kurt pneumatic drawbar closer, and I've find it very useful over the past 3-4 years since I've owned it. Last week I noticed that the collets were not being secured properly, so I unbolted the closer and pulled out the drawbar:







A glance at the end of the bar showed that the threads had been stripped:






I mounted it in the lathe and turned down the stripped part to 1/4" and then tried to line up some threaded pieces I turned with the good threads, using a 7/16-20 nut to "synchronize the threads. First I tried Loctite 620, and then JB Weld, but in both cases it was not strong enough to stand the necessary torque. So today I mounted a SHCS in the lathe using the rubberflex collets to spare the threads, and parted off the head.






Then I drilled and reamed the remaining bolt 1/4" (bolt was quite hard, so I needed to use a carbide endmill as a drill).






Then I turned off the good threads from the bar and replaced them with the hollow bold body:






Then I had a friend of mine weld the upper end of the bolt to the bar, and thereafter cleaned up the welds using the lathe.

Good as new it appears. Now I can get back to the loco buld.


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## lazylathe (Mar 26, 2012)

Nice repair job!!!
Keeping it simple, i like it a lot!!!

Andrew


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## rmw (Mar 26, 2012)

I had to do that the other day. I didn't think to use a nut to sync up the threads.. Good idea!
Greg


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## Swifty (Mar 27, 2012)

When I had my own tool room I had 4 bridgeports in daily use, the threads were stripping every so often. We cut the thread off the drawbar and drilled a hole in the end, then grabbed a 7/16 unf cap screw and cut the head off then turned a spigot to fit in the drawbar. They were then silver soldered in place. Far cheaper than buying or making new drawbars, they worked very well. When these stripped, just grabbed a new screw and replaced the old one.

Paul.


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## kvom (Mar 27, 2012)

That would have worked just as well (or faster). However, I couldn't find a long screw at the local hardware store, so did it this way.


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## platypus20 (Apr 5, 2012)

I did mine last week, used a piece of 7/16"-20, B-7 hardened all-thread and pinned and then plugwelded a coupling nut to. Works perfectly, short one is for mill/drill and longer one is for the Jet mill.


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## MachineTom (Apr 5, 2012)

What they are designed for is to cut off the worn threads, then drive out the pin at the top of the drawbar, stretch out the drawbar, then drill and install the pin.


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