Coburn Precision 500 Horizontal Mill

[mjonkman]

I was browsing around a local used machine dealer and bumped into a Coburn Precision 500 horizontal milling machine. I've never heard of the company or the mill before but its a nice hobby sized horizontal mill and it comes with a vertical head attachment. The dealer mentioned it may be missing a few parts so I need to go back and really look it over. I searched the web high and low and I could not find any reference to the machine *except* that a used machine dealer in Florida also appears to be selling the same mill. It appears that the manufacturer Coburn or Coburn Rocket primarily manufactured(s) optical equipment so I'm not sure if this was a short lived venture into machine tooling or what. The serial number on the machine I was looking at was only 2098 so assuming it started at 1 that still isn't a huge number of machines. The one I'm looking at was originally a high school machine. Does anyone have any information on this machine or have one and could share any insight into the machine I'd appreciate it.

The Florida dealer's listing including pictures can be found at:

http://inv.ammetalmaq.com/q/webinv/000502=p,4652,0M1974,,list,,,20241324

SPECIFICATIONS:
SPINDLE:
Motor 3 HP
Electrics 220/440/3/60
Speeds--number 16
Speeds--range (rpm) 50 to 1500
Spindle taper #30

TABLE:
Size 8-1/2" x 34"
Longitudinal travel--power 22"
Cross travel--manual 7"
Vertical knee travel--manual 8"
Longitudinal feeds--number 8
--range 0.002 to 0.024 ipr

GENERAL:
Dimensions (L x W x H) 52" x 52" x 66"
Weight 1,500 lb

Sincerely
Mark R. Jonkman

 

[RWL]

I'm not sure if it's the same company, but I have tooling from a Coborn grinder. They were made in England. I got mine from someone who specialized in diamond grinding.

 

[Bishop]

Looks like a pretty stout machine for its size. I would love to find something like that, keep us posted please.

Shawn

 

[mjonkman]

It definitely seems to be a fairly stout machine. As near as I can track down this particular Coburn manufacturing is based out of Muskogee, Oklahoma. The primary business of the company was creating lens grinders and related tooling for the eye glass industry. Apparently the head of the company would drive around in an Olds 88 Rocket hence the Rocket on the logo - don't know whether that statement was true but some gentleman on an optical board was recalling seeing the guy in Dallas at a Bausch and Lomb lab or something like that. I've found only references to the two machines in existence. There is one reference somewhere to a Coburn Rocket Shaper with the same logo but it was a very specialized shaper and might have been related to the eye glass industry as well. I need to figure out what is missing before I purchase the machine. Without the benefit of a manual, exploded drawings or access to someone else with the same machine it makes it difficult to make any missing parts (if there are any). The arbor was missing all the bushings/collars and the nut but if I understand correctly it is a reasonably standard #30 taper arbor and thus could be replaced with a new one or just make all the collars and nut - we are either machinists or pretending to be one (in my case). But if say there is something more complex missing say with the vertical head or the x-axis feed system that becomes a much bigger deal. I'm going back to look at it tomorrow morning and will spend some time going over it in depth. I have to sell my Atlas 6" lathe before I can buy it - mostly to free up the area in the shop to put it and recover the cost of the machine.

Sincerely
Mark R. Jonkman