Bridgeport head question

Hi All,
I'm a long term lurker but first time poster and I have a question about
Bridgeport heads that I'm hoping someone might be able to help with.
In my home shop I have a Korean stepped pulley Bridgeport clone that was
made in the mid 80's and looks identical to an original Series I
Bridgeport. It's a great machine that was reconditioned a couple of
years ago, and so close in appearance to an original Bridgeport does it
appear to be that original Bridgeport parts were used to refurbish the
head without any problems.
A couple of months ago a friend gave me a variable speed Series II head
that came out of a large production factory where he works. It was
apparently an accessory for a large Bridgeport horizontal mill that was
being scrapped, and as far as I'm aware this variable speed head has
done very little over the years other than sitting around getting
incredibly dirty.
I'd like to replace the old stepped pulley head on my machine with the
Series II head, but the problem for me is the spindles. The Series II
head has a standard R8 taper while my clone has an ISO 30 taper and
changing to the Series II head will obviously mean none of my current
tooling will be suitable.
Of course, I could just bolt the Series II head on and buy some new
tooling, but I've collected quite a bit of ISO 30 stuff over the years
and replacing it all would be costly. I also wish to avoid adapters as
they can make life complicated.
What I was wondering is how interchangeable are the top and bottom
halves of Series I & II Bridgeport heads?
What I was thinking is that if I could transplant the variable speed top
half of the Series II head onto the bottom half of the old stepped
pulley head I'd kill a couple of birds with one stone in that I'd retain
the use of all my tooling and benefit from the new bearings that were
fitted to the old head not long ago and that have not done much since.
I appreciate that the old machine isn't a genuine Bridgeport and there
may be problems associated with that, but what I was hoping to find out
was that assuming for a moment that the old head was identical to a
Bridgeport stepped pulley head would such a swap be possible?
Any help would be greatly appreciated,
Reply to
Noddy
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You can sell your ISO 30 tooling and buy R8 tooling, you should come about even without messing around ravaging those heads.
i
Reply to
Ignoramus19246
Hi,
I did think of that, but down here in Australia R8 tooling is not all that common and it's a 4-6 week wait with horrendous postage charges from the US. We fare better buying from Asia, but it's still not very handy.
Reply to
Noddy
As I recall the spindles are interchangeable. Maybe not always the quill though. The quills, I have been told, were individually fit into the heads. I don't know how true this is. But if your machine is an exact copy of a Bridgeport then measure the O.D. of the quill and see if it's the same as the Bridgeport quill. If they are the same then using this link:
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should be able to swap quills pretty easily. If the quills do differ substantially then swapping spindles will probably work. Eric
Reply to
etpm
Have you considered swapping the entire head? If the bolt hole pattern is the same you're part way there. You'd need to pull your head to verify the mating dimensions. Likely the biggest issue would be the worm wheel for side to side adjustment assuming the series II has one.
Personally I'd suggest selling the head if that won't offend your friend, and buy an inverter. Right now you mostly have to worry about wearing out belts and bearings. If you think R8 tooling is scarce and expensive, wait until you need parts for that head...
Jon
Reply to
Jon Anderson
Nope, won't work. The spindles are different. Due to the height of the varispeed drive, the 2J spindle is longer, the splined part sticks up higher to where the driving spline is. Then, the rest of the spindle is a lot longer, so the longer drawbar is at the top of the head. I'm not sure how many other critical differences there are, but this is the big one.
Oh, this is not a series-I vs. series-II difference, this is 1J vs 2J. Most series-II machines have 3 or 4 Hp motors and are completely scaled up from the 1J and 2J heads. Series-II heads (3J and 4J) typically have NMTB 40 taper, never R-8.
Jon
Reply to
Jon Elson
The spindles are the same -- the difference is made up by a longer hex on the drawbar. The length below the hex is the same for both the 1J and 2J.
Reply to
Ned Simmons
Listen to Gunner and Jon. get a VFD for your mill and have your variable speed and taper 30. You won't like R8 after having Taper 30. You're just asking for trouble trying to make one out of two.
Karl
Reply to
Karl Townsend
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you should be able to swap quills pretty easily. If the quills do
Excellent. Many Thanks Eric, I'll give that a try.
Reply to
Noddy
Bugger.
Thanks Jon. In my original ramblings I had my terminologies mixed up. The vary speed head is in fact a 2J head, and my original is a J head (or, at least, a very close copy of a J head).
Reply to
Noddy
HI Jon. I'm going to try a straight swap today, as the lower halves of the two heads look identical.
That's also something to consider, thanks.
I've been more than happy with the machine's original J head, and the only reason I'm playing around with this now is because it's (so far at least) a zero cost option. Ideally, if I could somehow get the machine swapped from a stepped pulley to variable speed drive without spending a lot of money I'd be happy.
Reply to
Noddy
Thanks Karl, I'm exploring that avenue as we speak.
It may be a smarter option for me to sell off the 2J head and use the proceeds from that to fund a VFD fitout on the original head.
Reply to
Noddy
Is there some simple way to mount the second head on the back end of the ram?
jsw
Reply to
Jim Wilkins
I suppose I could, but I don't imagine it would be simple. I already have a slotting head on the back anyway, and as I have no R8 tooling mounting the head as it is wouldn't benefit me much.
Reply to
Noddy
My apologies, but my Bridgeport terminology wasn't correct in my original post. I've since discovered that the vary speed head is in fact a series I 2J, and my original is a copy of the J head.
Oh boy, what a small world :)
Jon, I am indeed that Noddy, and I'm sorry for losing contact with you. We did a "tree change" about 18 months ago and moved from suburbia to a couple of acres in a semi rural area about 50km West of Melbourne, and in doing so I had to change internet service providers. Somehow in the move I also managed to loose a lot of my contacts, and I'm still trying to get them all back.
I'll send you my current email address if you're interested, as I'd be delighted to continue where we left off.
Reply to
Noddy
Well... my shop CNC for some years was an older Millport converted. It's a step pulley head, and I ran it with a VFD. I'm converting it back to manual. Moving down under soon, and pondered which to keep, my J2 BP or the Millport. I've put enough miles on the BP to replace the VS sheave bushings twice. The Millport with VFD gives me a wider range of speeds, and is quieter. All it needs is belts and bearings to freshen the head, which I can source fairly readily. J2 VS parts, I'd probably have to have shipped from the States.
You should be able to just do a straight up swap on the two heads. I thought you had a Series II head, which is something of a monster by comparison. But given you have a lot of QC tooling, sell the VS head, buy a VFD, and you'll probably still have some money left over.
BTW, are you down under? I was corresponding with a Noddy in AU some time back, but emails started bouncing and I lost contact.
Jon
Reply to
Jon Anderson
Please do! Since my last email, I've scaled back my plans. Not going to try and open a commercial shop there. It's just going to be for my hobby, and maybe a little side work for the vintage car/machinery crowd. Still hoping to make it there by the end of this year, but looking like it's going to be early next year.
Jon
Reply to
Jon Anderson
Wow, sorry to give out bad info, I think Ned is right!
Jon
Reply to
Jon Elson
One thing to check before you do this is the condition of the parts of the variable speed pulleys to make sure that they don't need replacement and thus will quickly lead to problems. The things to check are:
1) The Delrin sleeve inside the sliding pulley half, so it will slide properly on the motor spindle (and on the quill spindle as well).
2) The key which slides in a slot in the motor's spindle, and a similar one in the quill's spindle. This is steel with a skin of Delrin so it slides smoothly in the keyways. it bolts into the moving half of the pulley, IIRC.
If the latter is worn out (worn to the steel) it will start wearing the keyway so it will not allow things to slide smoothly while varying the speed. And this one will require replacing the spindle of the motor -- or the rotor with the spindle. (I've had to do this with an old machine.)
Good Luck, DoN.
Reply to
DoN. Nichols
Another reason for keeping the step pulley and using a VFD is that your power bill will go down significantly. When Bridgeport went from the manual to the variable speed in the J series heads, they had to increase the horsepower to make up for that lost to friction in the belts of the vari-speed pulley.
Good Luck, DoN.
Reply to
DoN. Nichols

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