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Diamond B12 Realistic Expectations?

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Chainsaw Driver

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#1
Good evening gentlemen,
It's been a few years since I wrote about my little Diamond B12 mill, and I've been so busy selling one place and buying another I haven't had time to work on it. I've managed to get it running, including the vertical head attachment, unfortunately the motor is shot and I have to start it by rolling the pulleys by hand. It has very little power this way and won't engage and run in higher speeds, only the medium or slowest speeds. The motor rebuild is $350 plus I need an additional $600 in tooling to really get it going. Assuming I expend the dollars what would be your thoughts on it's long term usefulness and will the motor rebuild provide sufficient power to really do some work? I checked the runout on the table and most of the trip is within .0005" until you get to the end then it runs out .004". Seems pretty tight for a 1945 model. I really liked how the horizontal cutters work and seems like an efficient way to make slots, grooves and rabbits.

It's been very difficult to find parts for it, I think I've figured out how to get a drill chuck into the vertical head, by using a collet and straight shank chuck. I cannot find any Brown and Sharpe tooling for the vertical head except a few collets and the occasional end mill holder. The horizontal portion uses a Brown and Sharpe #9 which seems a little more versatile although I only have a 7/8" drawbar which limits me to the 2-1/2" cutters.

In conclusion, I would appreciate any experiences or insight you could provide on this little mill. I've always dreamed of having a Bridgeport and am trying to decide if I should spend the money to truly get her into production or move on to a larger machine.
 

den-den

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#2
Good evening gentlemen,
It's been a few years since I wrote about my little Diamond B12 mill, and I've been so busy selling one place and buying another I haven't had time to work on it. I've managed to get it running, including the vertical head attachment, unfortunately the motor is shot and I have to start it by rolling the pulleys by hand. It has very little power this way and won't engage and run in higher speeds, only the medium or slowest speeds. The motor rebuild is $350 plus I need an additional $600 in tooling to really get it going. Assuming I expend the dollars what would be your thoughts on it's long term usefulness and will the motor rebuild provide sufficient power to really do some work? I checked the runout on the table and most of the trip is within .0005" until you get to the end then it runs out .004". Seems pretty tight for a 1945 model. I really liked how the horizontal cutters work and seems like an efficient way to make slots, grooves and rabbits.

It's been very difficult to find parts for it, I think I've figured out how to get a drill chuck into the vertical head, by using a collet and straight shank chuck. I cannot find any Brown and Sharpe tooling for the vertical head except a few collets and the occasional end mill holder. The horizontal portion uses a Brown and Sharpe #9 which seems a little more versatile although I only have a 7/8" drawbar which limits me to the 2-1/2" cutters.

In conclusion, I would appreciate any experiences or insight you could provide on this little mill. I've always dreamed of having a Bridgeport and am trying to decide if I should spend the money to truly get her into production or move on to a larger machine.
Before you spend $350 on a new motor, try replacing the capacitor and cleaning the contacts of the centrifugal starting switch (I am assuming this is a single phase motor).
 

Chainsaw Driver

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#3
Good advice unfortunately, when I tried to wire it for 240 the motor smoked and quit working, I was able to rewire it for 120 and got it to turn over. Thank you for the reply.
 

markba633csi

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#4
I have a Diamond (B12 or M20 not sure which) and I use it all the time.
You probably smoked the capacitor which could be replaced and rewire for 230v (mine is)
I bought a few BS9 collets for the spindle and I put end mills and flycutters in there sideways (a mirror is helpful)
Mark S. 1012161001-00.jpg
 

markba633csi

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#5
Give a shout if you need some help with the motor
We are kind of an exclusive club, us Diamond owners, not too many around
Mark
ps what tooling does your vertical head take? Can u post a pic?
 
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cjtoombs

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#6
While a desire to keep the mill as original as possible is understandable, you might check on just replacing the motor. Motors are cheap on eBay, usually the shipping is more than the motor. As for tooling, you will have to buy a bunch of tooling for any mill you want to use. I'd try the capacitor replacement suggested above first, if that doesn't work I'd probably look for another motor, unless the originality is that important to you.
 

Chainsaw Driver

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#7
Thank you for your replies, I went ahead and bought a new motor. The mill is running well but was ticking at high speed. I pulled out the shaft and bearings and found the spindle end thrust bearing broken. I wasn’t able to find a replacement part so I cleaned it up and refit the halves and reassembled. It’s running very well now, no clicking. I haven’t milled anything yet but the run out is <.001 on the horizontal spindle and about the same on the vertical head. I’ve put quite a bit into her and can tell she won’t be as useful as a Bridgeport but I think having it will be handy. Now I have to figure out how to repair damaged t slots. Previous owners demolished the slots and t nuts no longer fit. I’m thinking about running a t slot mill through them, anyone done that?
 

cjtoombs

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#8
You might try just filing the inside of the T slots if that's all thats the problem. If they have been crushed downwards, then the t slot mill might be the choice, but you will need to do it on another mill, there won't be enough travel on that one to do it's own table.
 

Chainsaw Driver

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#9
Good call on the travel, I haven't gotten far enough to learn that yet. Thank you. the slots are crushed and indented both on the edge and underside. I filed the the edges but now the issue is the underside. Since I don't have another mill and likely can't afford one anytime soon, I may try to mill the center on this one and see if I can get it work well enough for now.
 

hanermo2

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#10
I cannot possibly see any harm in running a T-slot cutter in them.

The location on setups is on the topside, so whatever is underside should not matter. Imo. Imho.
Any kind of scraping/sanding hand/jigs would work fine - imho.

But milled-flat slots on the undersides will give better more consistent setups, and be easier setups to make, and more resistant to vibration.

But how will you run a vertical t-slot cutter on a horizontal mill ??
 

markba633csi

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#11
I had to do some filing on my slots too, not a lot, mostly the sides towards the ends of the table.
Glad you got it working, one limitation of these machines is the small amount of Z travel, only about 8 inches. A low profile vise is essential.
Mark S.
 

Chainsaw Driver

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#12
Hanermo, I have the original vertical head attachment. I'm able to run the mill either way. Thank you for your replies, I appreciate the help. I don't have a low profile vise but have absolutely noticed the limited Z movement. I bought a chuck and arbor to use for drilling and quickly realized there will be limited use for drilling. Milling shouldn't be a problem... I will run some milling tests this weekend to see how it runs.
 

markba633csi

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#13
It may seem like a disadvantage having to swap handles on the Y and Z axes, but there's been many times not having a handle
on one of them saved me from doing something stupid and wrecking a part I was making. Maybe the Diamond folks in their wisdom
engineered it that way on purpose intending the machine be used by beginners/trainees to do repetitive jobs, I don't know. It is a very sturdy mill
and able to remove a fair amount of metal. I'm pretty happy with mine.
Mark S.
 

cjtoombs

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#14
Palmgren made a low profile 4" vise that is a nice match for a Diamond B12
 

Chainsaw Driver

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#15
I managed to make a few chips this morning. I ran a 1/2" end mill in my vertical attachment on some brass and was very pleased. I milled three sides and they were square to each other or at least as good as my square. I have a question on the milling attachment, mine appears to be original and there doesn't appear to be any grease fittings or oiler holes in it except at the very top there appears to be a vent. Does anyone know how or where to lubricate these little vertical heads? I can tear it down but that seems counter productive. As always, I appreciate the help.

Thank you
 
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