I've just gotten a BP 1J head to replace my M head, and I'm looking
for an adapter to mount it on a round ram BP. My machine is one of
the later round rams: 5-inch diameter ram with a clevis on both ends.
The head mounting knuckle does not have a pitch pivot, it only pivots
in the yaw axis.

I get the impression from reading posts here and elsewhere that BP
manufactured such an adapter, but I haven't come across one yet.
Maybe I just don't know the proper name. If anyone here can point me
in the right direction I'd appreciate it.

It doesn't look like it would be all that hard to make one if it can't
be bought. Can someone tell me the specs on the gear that engages the
worm on the 1J mounting flange?

Any help much appreciated. TIA.

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dka wrote:
I've just gotten a BP 1J head to replace my M head, and I'm looking
for an adapter to mount it on a round ram BP. My machine is one of
the later round rams: 5-inch diameter ram with a clevis on both ends.

No, I think that's the EARLIER round-ram, designed for the M head.
The 1955 or so round ram only had a swivel (roll left-right) and not the
knuckle (pitch up/down) like the original round ram.

Anyway, my 1938 round ram M-head machine (Serial # 1388) has the clevis
on each end as you describe.

The head mounting knuckle does not have a pitch pivot, it only pivots
in the yaw axis.

I get the impression from reading posts here and elsewhere that BP
manufactured such an adapter, but I haven't come across one yet.
Maybe I just don't know the proper name. If anyone here can point me
in the right direction I'd appreciate it.

I don't think so. And, having done it, I KNOW why! The J head is SO much
heavier than the M head, that the knuckle will barely hold, and you have to
wail away at the single bolt or the whole head will pitch down at the first
shock.

It doesn't look like it would be all that hard to make one if it can't
be bought. Can someone tell me the specs on the gear that engages the
worm on the 1J mounting flange?

Is this for the roll (you call it yaw) pivot, or the pitch pivot?
The problem is the RAM doesn't have the worm teeth cut into it.

Anyway, Bridgeport makes a flat plate adaptor that is used to mount
the J head onto T-ram machines for multi-spindle duplicators, etc.
The back of it is a big rectangular plate with bolt holes at the corners.
What I did was mill a circular area on the back of the plate large enough
that the small knuckle piece that mounts the M head will fit securely
against the back of the adaptor casting. Then I drilled 4 holes in
the adaptor to bolt it to the knuckle. I had to make my own T-nuts
as the original bolts from the M head were too long. I then counterbored
the front of the adaptor to recess socket head cap screws, so they wouldn't
bind up on the J head mounting flange.

So, the old clevis goes back on the ram. Then, the adaptor plate is
mounted on the clevis. Then, the J head has any fixture removed from
it, so the round swivel is available. This is then mounted to the adaptor
plate with the standard J head T-bolts.

This ends up making the J head stick out an inch or two farther than
it really needs to, but that usually is not a problem. You have the
ability to move the head in all axes as before with the M head.
But, you have to clamp it down TIGHT, or things can slip under cutting
loads. I had to tear my whole setup down and carefully clean each part
of oil and grit, and haven't had any slipping since I did that.

I searched my pictures, and I can't find a single one that shows the
adaptor plate at all! I'll have to take some new ones!

Jon