Bridgeport drawbar explodes

Anyone ever have this happen?
Scard the sh|t outta me when it did. I was tightening a collet up, and when I applied pressure, it turned a
little (tightening) and then POW~!, with pieces of it flying around and bouncing off other machines. One hit me in the cheek, making me happy to be wearing my safety glasses.
Turns out that the top piece (the hex drive) was fine, and so was the pin that joins it to the long hardened diameter. It was the hardened diameter that exploded.
Now I gotta get it out of there... <sigh>
Will probably try welding something to what's left of it.
Best,
Weyland
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If the *hex* broke off like you stated, you should be able to put a pile of rags on the table under the tooling, then punch the rod so the tooling falls down onto the rags. Then simply unscrew the rod off the tooling. Ken.
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Ken Sterling wrote:

Hey Ken,
No, the hex part is what *supposed* to be the sacrificial part on this drawbar.
The actual drawbar has the long small diameter with the thread on it and then it steps up to a large dameter that sits on the top of the quill.
That large diameter is drilled for about 1.500", and the hex is turned down to that drilled size to fit inside it. Then, there's a cross pin that holds the two together.
Best,
Weyland
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Sorry..... I was thinking the hex was the thrust bearing part. If there is a "hole" left in the end of the large diameter, you may try a large "easy out"...?? Ken.
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Ken Sterling wrote:

Hey, don't be sorry. You were trying to help~! No, there's no good hole left, as it only left about 1/3 of the diameter in tact, with the rest broken down to the bottom of where it was drilled.
I'm only seeing two solutions here - Weld sonething to the end of the remains and hope I can unscrew the drawbar, or try like heck to get a drill in the remains of the bore and drill it straight and deep enough to seperate the large and small diameters.
And since the thing is hardened, I really don't wanna hafta try that one.
Best,
Weyland
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Weyland, I looked at my drawbar this afternoon in the shop, and on *mine*, the hex *is* the bearing part.... straight rod right up and into the bottom of the hex, with a roll pin thru the hex and rod at the bottom of the hex. Regardless, as a wild assed experiment.... since you were in the process of tightening up the collet when it broke, there is a chance that it is not completely tight yet. I think I would try a block of wood UNDER the collet, and then try cranking up the knee against it, pressing the collet up into the spindle. It may *give* a little bit to take pressure off the rod and let you unscrew it with a pair of needle-nosed pliers or such. Possibly worth a try anyway. Ken.
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Ken Sterling wrote:

Nah. On this one the bearing part is round, and the hex part is pinned to the top of it. Probably a cheap aftermarket, but I've been running it for 3 years, since I bought the machine.

I *WISH*. I was on the ass end of the tightening procedure. (most likely with *me* being the ass on the end of the wrench)
It's a welcome thought, though, and I'll certainly wish for such luck when I go to fix it, Monday morning.
Best,
Weyland
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wrote:

Hey Weyland,
Glad you were not hurt too bad. Sounds scary! I don't quite follow what happened, and it doesn't matter to my point, which is that rather than trying to weld up something that already exploded once, "alternate source" draw-bars are pretty cheap, probably under $20 US, and readily available.
Good luck on getting the bits and pieces out. Maybe you were only going to weld to get it out?
Take care.
Brian Lawson, Bothwell, Ontario.
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Brian Lawson wrote:

Yep~! Right now, there's nothging to grab in order to loosen it up and get teh collet out.
Best,
Weyland
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Weyland wrote:

You should be able to pull the entire belt drive housing off the top of the main head casting. If step pulley (1J) then take the motor off first, then remove three nuts on vertical bolts and the whole belt housing should just go straight up.
If vari-speed (2J) then the motor/belt housing is a bit trickier to get apart, and I don't know it well enough to describe it. But the entire assembly can still be lifted straight up off the head if you have a hoist or engine crane to lift it with.
Once you have the belt housing off, the remains of the drawbar should be exposed, as the top of the spindle will be sticking inches above the main casting.
To put the belt housing back on, you jsut have to re-align the spindle splines with the ones in the pulley, and slide it straight down. You need to do this carefully, it is possible to bend the spindle.
Jon
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Jon Elson wrote:

Hey Jon,
Yeah... I was really trying to avoid all that...
And I did.
Placed a bolt in the remains of the hole and Mig welded around it. Got enough of a purchase on it to loosen the drawbar and unthread it. LUCKILY.
Ordered a new drawbar Saturday, should be here tomorrow or Wednesday to get me back in business.
Some pics here -
http://solutionsmachining.com/images/drawbar/resized-dscf1567.jpg
http://solutionsmachining.com/images/drawbar/resized-dscf1568.jpg
http://solutionsmachining.com/images/drawbar/resized-dscf1569.jpg
http://solutionsmachining.com/images/drawbar/resized-dscf1570.jpg
Best,
Weyland
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