# 'precision Universal Tool' Boring Head Problem



## oldplanecollector (Aug 10, 2016)

I acquired a Precision Universal Tool Company boring head and had to disassemble since someone broke the adjustment pinion gear.  I found an old posting on another forum warning about disassembly because of all the tiny internal ball bearings but I had no choice but to disassemble so I could clean it out. 

It's not really that bad if you take it apart in a plastic tub to contain all the parts and had tweezers to reassemble all the ball bearings. Problem is, after I reassembled I noticed the tool block (that holds the boring bars) doesn't retract to center line of the head itself.
In picture of the bottom the black line is center of head, red line is center line of tool block. 
Does anyone else have one of these and can confirm if their head is the same or if yours retracts where center lines line up.
I've disassembled and numerous times trying different things to see if I could get it to line up and everything ends up with same result.


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## 4GSR (Aug 13, 2016)

These are not popular as many of the others are.  I've tried to bid on them over the years on eBay and kept getting out bid.  Wish you could post more pictures of the other parts to give us an idea of how all of this works.  If the tool block is supposed to retract back to center, sounds to me a spring has been over stressed and taken a new set.  This would prevent the slide from returning to zero.   Just an WAG.  But more pictures would help, especially of any springs, if any.  Ken


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## oldplanecollector (Aug 13, 2016)

I figured it out.
NO springs to retract anything (only springs are to hold tension on a bearing cap.
I was looking at pictures on ebay and noticed I installed the tool block backwards, disassembles flipped and its all good now.
The tool block is not dovetailed like some others, its really just a square block with a gear rack cut into the back. It has a rack on the back of the block that is driven by two gears in main body that then engage into another rack.  These units have 4 separate ball bearing assemblies, 4 gears, and 2 gear racks. The set-up allows the head to rotate while the center section remains stationary using a stop bar. you can then turn the adjusting knob to advance boring head while under power.  It's not what I'd call an automatic like an ENCO head I have that the whole head rotates and you grab a collar while spinning to advance the feed.

I got this unit with a MT5 shank which is part of the main body. I have nothing that big to hold it so needed to turn down to 3/4 dia. I tested hardness over 70 rockwell, but its only case hardened. Ground off roughly 0.030 and it was soft enough to turn the rest on the lathe.

I took a couple pics when I disassembled last time. Assembling these tweezers and grease are your best friends.  I would never have gotten the bearings back together without holding them in place with grease.

pic is the main body



pic below is the botton view of  adjusting body



pic of top view of adjusting body. notice I still have wires hanging off that I used to pull up on 3 tension springs so the retention clips can be installed using tweezers.  The springs are holding that top cap on. Under there is a whole set of tiny balls (pic shown in my original posting)  Another set of larger ball rides on top of the cap.


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## 4GSR (Aug 13, 2016)

Thanks for posting.  Now I know what is inside one of them.
I'll stick to my Chandler boring heads I have.  Much easier to take apart and work on than this one.
Ken


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