Are bridgeport heads interchangeable?

For example, can I swap a step pulleyed head, for a variable speed head? Are the mounting arrangements the same?

Reply to
Ignoramus18195
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In general, yes. There's a company near me (western Wisconsin) that rebuilds and sells Bridgeports all the time. They never ship a J-head out, they always update it to a variable speed drive.

I don't think this applies to the M-head though.

FWIW, the last time I was there in person (a couple of years ago) they had a whole pallet full of those J-heads. Maybe they part 'em out when they repair machines for others.

Pete Stanaitis

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Ignoramus18195 wrote:

Reply to
spaco

An "M" head will need an adapter.

Reply to
Tom Gardner

1J (step pulley) and 2J (varispeed) are interchangeable, in fact the main casting is identical. The ancient M head is NOT the same, however, a much smaller bolt circle. As long as it is a V-ram or rigid ram machine, it would be unlikely to have an M head. The 1J has 4 belt speeds and a geared low range, with a toothed reduction belt below the vee belt. It also has power down-feed with a 3-speed selector. The M head has 6 speeds, no back gear and no power quill feed.

One other thing, various J heads have different spindle tapers, mostly your choice of R-8, NMTB 30 or a couple quick-switch systems.

There are the 3J and 4J heads on Series-II machines, definitely NOT interchangeable with 1- and 2J. (Note, Series-II tracers and multi-spindle machines often had several 2J heads on them.)

There are also BOSS heads which have a coaxial ballscrew machined into the quill. These are CNC-only, no provision for normal manual quill feed.

Jon

Reply to
Jon Elson

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