I'm kind of curious if anyone else has seen or used one of these high speed heads? It's flat belt driven with six speeds. They are,950rpm,1350,2200,3250,6500,and 12000rpm. I haven't seen any info about them and have never seen one for sale, even on Ebay. Is anyone else familiar with them?
The M head was the original offering when the BP round-ram knee mill was introduced in 1938. It had six speeds from 275 to 4250 rpm. Speeds up to 12,750 rpm were available on request.
It's a basic head, smaller than the J, with no power downfeed. I've never used one.
Some comparisons with the J head:
Motor power: (M) 0.5 hp (J) 1 hp
Quill travel: (M) 3.5" (J) 5.0"
Spindle dia: (M) 1.437" (J) 1.875"
Spindle taper: (M) #2MT, #7B&S, & others (J) R-8
Max tool shank: (M) 0.50" (J) 0.875"
Drilling cap: (M) 0.50" (J) 0.75" (in mild steel)
Boring cap: (M) 1.5" (J) 6.0"
Milling cap: (M) 1.0 in^3/min (J) 1.5 in^3/min
At one time, Dave Sobel had a couple of those
high speed, flat belt M heads. I think
the model designation is more complicated
than just "M" but I'm not sure on that.
Thanks Leigh and Jim! I have one of these and am thinking strongly of selling it. It's an interesting piece but surplus to my needs. I've been a machinist for 30+ years and I don't remember seeing another one. I'll probably put it on Ebay along with it's knuckle and collets, hopefully someone will want it.
Picking up on this rather old thread - Just bought a circa 1971 BP with high-speed M head. Apparently it has sealed bearings as the nameplate says "SPINDLE BEARINGS GREASED FOR LIFE". Has a 1hp motor & flat belt / pulleys for 6 speeds, ranging 950 - 12000rpm. My guess is that maybe it was geared toward precision woodworking / pattern making. My question is, what are the pros / cons of the high-speed vs "standard" M head? (I realize there are big differences between any M head vs J / 2J heads etc.). My plan is to use this mill for gunsmithing, mostly pistols. I do plan to install a VFD for better speed control. BTW does anybody know, how rare are these high-speed M heads? Also wondering what the value might be, as I saw somebody's asking $1495 (head only) for one like mine on eBay - that's $295 more than I paid for entire mill w / AcuRite DRO & Kurt vise - anyway thanks in advance for any feedback to this post!
I wish I had some help for you. I have been looking at these with interest lately. I have a small Johansson mill all apart and waiting to get scraped with some minor head issues and have been thinking about mounting the hi speed m head instead and using it in my guitar shop. I can think of a ton of stuff I could use it for, mostly in wood and bone/ivory.
I would love to hear how you like yours when you get it running, there are a few heads I know of available and I am on the fence over the money. FWIW I usually see them for definitely less than that one that has been on ebay for a while.