Bridgeport 2j speed adjustment

[ronan walshParticipant @ronanwalsh98054]

I fitted a Bridgeport 2j vari-speed head to my Tom Senior mill during the summer. The head is a heavy old lump, about 180lbs so no way i could lift it by myself and my shed to too low to use a hoist or lifting gear.

So i split it into two separate pieces, the upper and lower. Having now got the whole thing back together, aligned, trammed etc, and i am starting to run the machine, there is an issue with the speed selection of the spindle.

It is controlled by a handwheel which you wind in either direction to raise or lower the speed. I do not know how to adjust this particular feature, there is no mention in the manual.

Would anyone happen to know how to do this correctly ?

[ronan walshParticipant @ronanwalsh98054]

[KWILParticipant @kwil]

This is a Vari-Drive head, winding the handle adjusts the relative diameters of the 2 belt pulleys giving a continously variable speed. The lever on the side of the head selects the back gear for the lower range, in low you have to reverse the motor direction of course. Spindle speed is indicated on the front of the head.

[JezParticipant @jez]

Only turn the handwheel when the spindle is running though…

[ronan walshParticipant @ronanwalsh98054]

Thanks fellas, yes i know that much. What i need to know is how do you adjust the screw in the centre of the head, on the top that controls how much the front sheve opens and closes ? I have a situation where when i wind the handle the spindle speeds up, and then slows down again even though i continue turning the handle in the same direction.

There must be a method or procedure on how to adjust this system.

[ronan walshParticipant @ronanwalsh98054]

i think i found the trouble, there are two clamping bolts that go into the movable sheave on the motor shaft to take the tension off the spring. I thought they were supposed to be there, so i have removed them and things have improved. But it turns out the speed indicator plate on the front of the head is the incorrect one for my head. So i will have to find and buy one.

[Clive FosterParticipant @clivefoster55965]

Ronan

A copy of the Bridgeport manual would be great help to you. Only basic servicing details but great parts book section showing where everything lives making it fairly easy to figure out what all the bits do. If you haven't there are several sources on the internet or PM me and I'll transfer a PDF copy.

The speed dial reading is adjusted by shifting the pivot point on the pressure pad that moves up and down to alter the front varidisk spacing when you turn the speed adjustment handle. Adjuster is a long threaded rod with a screwdriver slot on top sticking out vertically pretty much in the middle of the top casting. Loosen the lock nut and twiddle to shift the pivot point up and down. You need to get the operating chain set about right before you start. All seems a bit hit and miss to me as there appears to be no hard start or stop points on the machine. No setting guides around that I know of.

I printed out a couple of the 50 hz strobe disks from an article somewhere, maybe by Tony Jeffree, to get calibration roughly right. Seems to have worked near enough for the last decade or so.

Clive

Edited By Clive Foster on 25/08/2018 20:10:27

Edited By Clive Foster on 25/08/2018 20:11:55

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