For example, can I swap a step pulleyed head, for a variable speed head? Are the mounting arrangements the same?
Are bridgeport heads interchangeable?
Sep 19, 2008
3 Replies
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:
An "M" head will need an adapter.
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
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