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Van Norman #26, mounting Bridgeport J-head

leeko

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Joined
Jun 30, 2012
Location
Chicago, USA
Hi all

I'd like to mount my Comet (Bridgeport clone) J-head to my van Norman #26, to give me a quill. I'm working through some possible mount options, and I came across the van Norman subheads which mount directly to the casting around the spindle nose. If I can use that same scheme, it would be the simplest option.

The main question I have is whether the weight of the J-head and motor will be an issue. It should be around 200lb, compared to the ~60-80lb on the van Norman subhead. See attached picture from the manual, which shows it attached via another angle bracket, which I'd guess is probably at least another 30-40lb.

If that's not a reasonable option, the other possibility would be a C-shaped plate bracket on the front of the ram, that attaches to both the overarm T-slot, and the dovetail on the underside of the ram.

Has anyone done similar? All the Bridgeport conversions I've seen so far are for round overarm machines. Mine has the other style of overarm, which runs in something like a T-slot.

Thanks in advance,

Lee
 

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I think that the weight might not seem as an issue right away if you choose the simplest way, it could last in the beggining but overtime it could cause you more trouble than good, so I recommend playing it safe and going by the books with this one.
Better safe than sorry
 
FYI, in your 2nd photo showing the Van Norman Sub Head, you'll see that the right angle adapter has a center in it. That's for additional support by using a center in the overarm support, similar to what you'd have when supporting a horizontal milling arbor. I had a Milwaukee Midget Mill head that was on a V/N 22L. It was mounted to the round overarm, not the spindle. I put it on a Hardinge TM mill, again using the overarm for support. I actually made the bushing eccentric to gain as much daylight under the spindle as I could.
 
Oh that's interesting! I definitely hadn't noticed the center in the subhead, thanks for pointing it out.

I'll need to play around with a mockup of the bport head and figure out where it will fit best. It's a 3hp head from a Comet mill, and seems like it might be a bit heavier/beefier than a bport head.

Thanks again,

Lee
 
Is this just the head off of a Comet milling machine, or did Comet sell a J-head clone? What type of mounting setup does the head have? Photos please.
 
Is this just the head off of a Comet milling machine, or did Comet sell a J-head clone? What type of mounting setup does the head have? Photos please.

I'm not sure - it says Comet on the front. I assumed it's a J-head clone, but maybe that assumption was incorrect. Don't have any firsthand experience with Bridgeports.

The mounting arrangement for the head I have, is a flat disk with a recessed worm pinion. The bolt pattern is approximately 4-1/2" x 3-3/4".

The only pictures I have atm are showing the bolt holes - it's tucked away in my storage spot for the moment

Lee
 

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I did some searches for Comet J-heads and all I came up with were Comet knee mills, which appear to be a Bridgeport clones. It sounds like you may have the head from one of those machines. There are several sellers on eBay that have Comet manual copies. This item (link), the manual for a Comet 1-1/2 turret mill, has an image of a nice diagram of the head (page 16 of the manual). You might see if that looks like what you have.

My suggestion is to fabricate an L-shaped plate with with a dovetail in the upper surface of the bottom leg, either milled into the bottom leg or formed by bolt-on bars on either side. The bottom leg of the L plugs into the dovetail on the bottom of the ram. The top edge of the vertical plate could be set up to engage the dovetail in the overarm. Now you have a sturdy vertical plate on the end of the ram that can be used to mount a J-head or anything else. (I've considered doing something similar to that for my No. 16.) I don't know if that puts the head too far forward to reach the entire table, but it's something to consider.
 
Hi Cal,
Thanks for the link. It looks similar, though mine is a 3hp model rather than 2hp.

What you describe with the L shaped plate is what I meant as my second option in my original post (rather poorly described :). ) it sounds like that will be the way to go.

Do you think a 1-1/2" thick plate would be sturdy enough for the vertical part, or should I be looking at something thicker?

Thanks again!

Lee
 
1-1/2" seems like overkill for the vertical plate, but if you have some on hand, why not? However, any thickness you add to the front of the ram will move the J-head's spindle farther from the column. You'll want to make sure that there's enough Y-axis on the table to have some useful work envelope.
 








 
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