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Bridgeport model j knee mill with 2 heads
Bridgeport Manual Vertical Mill J Model
* Infinitely Variable Speed Range - 80-2720 RPM
* Quill Feeds - 0.0015", 0.003", 0.006"
* Electrics - 220/440/60/3
* Machine Weight - 3,000 lbs. (approximately)
* Bridgeport Model J Milling Head
* Bridgeport Model M Milling Head
The M head, unlike its successor, the J head, doesn't have back gears or power spindle downfeed. The M head is certainly much easier to move around and get into odd positions than the far bigger and heavier J head. Based on the samples I've myself encountered, perhaps 75% of all M head spindles take collets with a Morse #2 taper (hereinafter 2M). Most of the rest take collets with a Brown & Sharpe #7 taper (or 7B&S). A very few take B-3 collets. All three collets are small (1/2" diameter max), much smaller than the R8's capacity. And to answer the obvious question - no, the M head spindle can't be reground with an R8 taper. It's just too small. They are still available from Hardinge.
* Location: Paramount, CA 90723, United States
