Other small mills

The other vertical mills we might see in a home/hobby or engineering prototype shop present the same problem - which way to jump, 2M, 7B&S, or R8 collets? In some particularly grim cases, there are even more choices than that.

The little Clausing vertical mill (made by Atlas Press, naturally) took 2M or 7B&S collets, but somebody had the good sense to give different model numbers to machines taking either collet size - the 8520 used 2M taper collets, the 8525 used 7B&S. However when they replaced these with the slightly heavier 8530, they seem to have dropped that distinction (that is, I don't think there was a model 8535). All of these Clausing mills that I've been able to date have been from the 1960s.
The original Johansson incarnation of the Clausing mill, made by Johansson Machine Tools. Johansson was later bought by Atlas Press. The Johansson spindle took 7B&S collets standard, with 2M available as an option.
The Rockwell 21-100 vertical mill and its 21-122 combination horizontal/vertical variant - also children of the 1960s - used R8 collets right from the start.

Many many moons ago, I made some pretty fancy R&D-type parts on one of these mills. Good machine.
The dimunitive Bench-Master, dating from the 1940s-'50s, is an honest-to-gawd benchtop knee mill - the Johansson/Clausing line and the Rockwells are too tall to be used on a standard-height bench. The Bench-Master can be converted to a horizontal mill, too, by swapping spindle assemblies. The thing is bigger than it looks - that's a 6x18" table. The spindle takes 2M collets.
With the full-sized floor-standing Millrite, the collet situation is really dire - practically anything could be in that spindle bore. To be fair, the majority I've seen take R8 collets.
Hardinge made a small vertical mill, weighing just under 500 pounds on its stand. This was the BB, although Hardinge also made a small horizontal called the BB. Why Hardinge had so much more trouble than everyone else with sensible names for their products has always been a mystery to me. Here is one of the vertical BBs, the BB2V, which took 2VB collets. They look like small 5C collets, with a maximum capacity of 1/2". The overall length of a 2VB is 2.438", vs. the 5C's 3.281". Hardinge probably made other BB vertical mills taking other collets, but I haven't seen any yet.
The more common Hardinge mill, available in a TM ("toolroom mill") and a UM ("universal mill") variant, is often seen with a Bridgeport M head tacked on. However, what looks like a Bridgeport head may not be, really, as Bridgeport seems to have made a variant M head for Hardinge, sold by Hardinge as the H head. Some Hardinge fans claim it's a variant of the Bridgeport C head, but I doubt it. The one in the photo at right is an M. In any case, there's no reason to assume that the Hardinge versions use the same collets as the Bridgeport ones. I would expect the H heads to take 2VB collets but need confirmation on that.
Just to complicate things further .... there was a Hardinge attachment to convert the TM and UM mills to vertical mills. Although a neat package, the attachment looks like an overcomplicated and fussy arrangement, as it uses the mill's horizontal spindle as a drive. There may have been 4C and 5C collet versions - the situation remains obscure.
The Vernon is sort of a vertical mill - jig borer cross. The Art Deco detailing gives a hint as to its dates of manufacture. It seems to have been available with either a 7B&S or LB spindle. (LB is yet another collet with a 1/2" maximum capacity.)
Just about all the small (meaning smaller than Bridgeport size) modern mills are Chinese. Most common are these 6"x26" mills, apparently copies (more or less) of the Johansson/Clausing/Atlas mill. But unlike the original, these take R8 collets. They are imported or sold by -  
Harbor Freight
Central Machinery 40939-1VGA

I like that red color, myself, although I imagine it might make it hard to buy insurance.
Penn Tool Company
Top Tech DM-150
Yangzhou Euro Brother Machine & Tools Co., Ltd.
Top-Tech DM15

This version is available with either an R8 or #3 Morse taper spindle.
Shaoxing Yuejian Machinery Manufacture Co. Ltd.

Also available with either an R8 or #3 Morse taper spindle.
Wholesale Tool
In Canada, Busy Bee
Also in Canada, Machen Manufacturing
In England, we find this snappy dual-tone version sold by Chester
626 Turret Mill

Chester sells this mill with either an R8 or #3 Morse spindle.
Also in England, from Warco
VMC Turret Mill

Also available with an R8 or #3 Morse spindle.
A slightly larger variant - 8"x30" - is sold by
Wholesale Tool
Busy Bee
Craftex B048
Grizzly sold a version, but it has been discontinued. The Grizzly operator's manual is still available.
The 1008 has power feed on the X axis.
G1004 & G1008
I know of no knee mill currently in production which uses 2M or 7B&S collets. Fortunately, even though the machines aren't being made, the collets are.

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  Updated: January 2, 2005