Draw bar too long?

M

monkeyb0y

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Ok stupid question. I just wired up my Bridgeport 2hp Varispeed and when I put an R8 collet in it to tram the head the collet wouldn't draw up tight. It stuck out from the quill about 1/4 inch. The draw bar came with the mill but did they give me the wrong one or am I doing something stupid. The draw bar measures 22.5 in overall with a 4 in nut then a 0.25 in "washer"/spacer and a 18.25 in shaft the last inch being threaded. I'm new to all this and have been reading all I can but have little practical experience so I could easily be overlooking something so basic no one mentions it.

Thanks
Kevin


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Your probably right that its too long but you would think that things would be pretty standard on an r8 setup. You could just shorten the drawbar you have.

I made a new drawbar for my mill and did intentionally make it longer than the orig so I would have something to play with if/when I stripped threads. I made mine out of solid stock but usually there is a head and bar connected with a roll pin, you could make a shorter bar, keep the head and orig bar in case you find some r8 holders that need your longer bar.

A vid of the making of my drawbar if your interested.

[video=youtube_share;mmaqK4VtulY]http://youtu.be/mmaqK4VtulY[/video]
 
I ended up adding spacers under the head of the nut until I was satisfied it was correct. I don't understand how the prior owner used it the way I got it. wobble like crazy. . .
 
Hi, it sounds more like you are missing a stepped washer and not a wrong draw bar (DB). There should be a stepped washer right below the DB hex. This washer locates in the top end hole of the quill and centers the DB at its 3/8" shaft and the hole. If you turned the head 180° for any reason with the DB out, this washer we are talking about probably feel out and got lost. And about shorting a DB. If you have a well made one the threads should be rolled instead of just cut. The rolled threads are the best thing to have and I would not go and modify the threads in any way. I would shorten elsewhere…Good Luck.
 
Thanks for all the input. I will probably try turning a spacer to put on the shaft. If that doesn't work I'll just get a new drawbar. At least the cause of the problem wasn't me!


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Hey guys, I always use a double nut mechanism on my drawbars... This can save your bacon if you ever get a situation whereby the DB gets hopelessly tight against the top of the spindle. Using this method, you always have a way to loosen it. You'll also notice I have a small spacer. It helps keep the DB from wobbling (even though that doesn't seem to impact anything) but also limits the amount of engagement into the R8 device to a sane level. I screw it in about 1" which is about 2.5 times the diameter of the bar -plenty of engagement...

Ray

DoubleNutDrawbar.JPG

DoubleNutDrawbar.JPG
 
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