# Bridgeport Draw Bar Question



## Rick_B (Dec 25, 2012)

So the Bridgeport series 1 J head I bought came with a draw bar that had two spacers at the top. With both spacers installed standard R8 collets are capable of engaging the draw bar but my Jacobs super chuck which came with an R8 type collet will ot reach the draw bar. the collet on the chuck is a bit different in shape than the other collets (fatter at the bottom). if i use just one spacer then the chuck collet and standard collets work.

I'm wondering if the typical set up is to use one, two or no spacers at the top of the draw bar. Also is it usual that the collet for the chuck would be different than the standard R8 collet?

Thanks
Rick​


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## Charley Davidson (Dec 25, 2012)

I don't think I have any spacers in mine at all


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## Kennyd (Dec 25, 2012)

I have no spacers on my BP either.

There is supposed to be a washer however:

*http://www.masconews.com/parts/bptseries1-j-head-top-housing-p1.html*


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## Rick_B (Dec 25, 2012)

What I'm calling a spacer is a 1/4" thick circular piece that fits over a raised diameter on the daw bar jut under the hex portion of the bar.  It also fits down into the upper section of the quill/spindle and sits on a "ledge" of sorts.  I'm wondering if it issimply a shock absorber when you need to rap the draw bar to  release the collet?

my draw bar is 18-1/4" in length from under the hex portion.  I'm begining to wonder if one, two or no spacers makes a difference as the ax change in bar length woud be 1/2".  it seems the only advantage would be less treading to release the collet with the possible disadvatage of less treaded engagementwith the collet?

Rick


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## xalky (Dec 25, 2012)

There are no spacers on mine either. Just a washer. I'd remove the spacer(s) for use with the chuck. You want to make sure that there are enough threads engaging the collet. Heck the spacers may not be necessary for the collets either.


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## Rick_B (Dec 26, 2012)

I agree that adequate thread engagement is necessary - is there a number that can be wrapped around that - say 1/2" of engagement?  can you have too much engagement - say an inch or so?  I'm asking because I think here is a good compromise with sing one of the spacers - i need to check that out vbetter today though.

Rick


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## OldMachinist (Dec 26, 2012)

Use what ever number of spacers work.
New draw bars normally come with a selection of spacers to allow them to be used on bridgeports and clones. Also the threads are extra long so if you strip part of the trheads you can cut them off, remove a spacer and still have a working draw bar.


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## Richard King (Dec 26, 2012)

I have rebuild I would guess over a 100 heads over the years and the heads have 1 washer.  It harder then the hex and top of the spindle spline.  It has the same principle you use a flat washer under any other bolt.  2 soft metals that are tightened together will gall up. Many time I see the Hex is longer as short folks can reach it easier.  Plus the more threads in the collet the better.  Take a look at your collets and see how long the threads are.  Spray the draw bar threads with Dykem bluing and screw it in and remove it and check how far it goes in.  The more the better I always say. 

One more issue is the setscrew key that fits in the the keyway in the collet.  Many times they are squished, burred or broken off.  They are easy to repair.  Crank your knee down  so you can feed your quill down a few inches.  On the back of the quill you will find a 1/4 20 set screw, some have 2 screws, others are lock-tighted, dig out any chips in the hex hole and remove it.  they should be snug and not tight. Then use a pin spanner if you have one or insert a hard dowell pin in one of the 2 holes on the bottom of the holes drilled in the bottom of the bottom spindle bearing retainer ring and hit it with a punch counter clockwise and remove it.  Never use a punch directly in the holes as they are soft and will get damaged!  Then with a flashlight look around the spindle for another set screw as this is the key. 

These usually have 2 screws too, a thin one behind the key screw to lock it in so it doesn't turn.  Some of the imports loc-tite them in.  You can buy  new one from High Quality Parts, Bridgeport or there a couple of others who sell Bridgeport parts.  Or if you are careful you can make one, but I would buy one, less hassles.  The whole time being careful to keep every thing clean.  When it is out look at the threads on the cap and you will see a hole drilled into the threads, this is where the set screw goes in.   

Check it for burrs and then screw the cap back in.  and tighten it until you can see the hole and insert the set screw and only tighten it snug and put the lock screw in behind it and tighten it a little harder or loc-tite it with the blue easy to remove type.  Many times you can tighten the retaining ring tighter when the bearings are worn.  Be sure not to over tighten it with the spanner or dowel pin, but make it snug to tight, not biggest hammer you have tight. 

If the set screw hole goes past the set screw more then a 1/4" then you cn use a # 8 drill to drill a new set screw hole, just deep enough for the set screw to go in past the threads. be careful not to drill to deep and drill it straight in, not angled.  Also be careful not to tighten that set screw as it will warp the quill and make it egg shaped and the quill will get stuck about 1" from the top.    Good luck  and if you need more advice on Bridgeport or other brands of repair or rebuilding come over the the Machinery Rebuilding forum and ask me or PM me.  I am a moderator on that forum as  I am a Journeyman Machine Tool Rebuilder, by trade.


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## xalky (Dec 26, 2012)

Rick_B said:


> I agree that adequate thread engagement is necessary - is there a number that can be wrapped around that - say 1/2" of engagement?  can you have too much engagement - say an inch or so?  I'm asking because I think here is a good compromise with sing one of the spacers - i need to check that out vbetter today though.
> 
> Rick


 Common sense rules here. I would say that bare minimum thread engagement would be 1/2" ... 3/8" if your not tightening it too much. There really is no max, providing that the rod doesn't bottom out.


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## Charley Davidson (Dec 26, 2012)

After looking at mine it does have a spacer of sorts. It looks like a bearing and is about a half inch thick.


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## smallfly (Dec 26, 2012)

when i rebuilt my bridgeport mill i noted that the drawbar was all rounded and ''egg shaped'' and just plain worn  out  where the washers or spacers everyone is referring to --come in contact with the bar at the lower end of the ''hex''. i placed drawbar in  lathe and ''squared up'' lower portion of hex. then i ordered ''hardened steel washers '' from a bearing supply house and also a couple of thrust washers -which have inserted roller bearings .  i stacked one hardened washer on either side of each thrust washer.  i tilted power head  to horizontal  and carefully reinserted  bearings and washers and drawbar. there is suppose to be a rubber ''o'' ring to hold all these parts on the drawbar --but that stuff and groove for ''o'' ring were long since worn away.  well it works very smooth now -nothing seizes . if you have a lathe you can make the drawbar whatever length you desire.  just my $.02 . re  steve  in  mt.


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