Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.
Luc, I changed the three phase motor(s) on my Tree mill.
I only had a 1hp in inventory at the time so that's what it is. I haven't found the need for the 3 hp it had.
Of course I had to fab an adapter plate which involved machining the end "bell" of the 1 hp motor to accept an aluminum adapter plate.
I also had to machine a shaft extension to fit the variable pulley for the "vari-speed" drive.
In my case I also had to adapt 2 other 1 PH motors to the knee lift and x, y, feed but such is the price to pay for "Class" (oops, pride in my Tree showing ).
You didn't say what Chinese mill you had? There are Chinese mills and then there are "real" Chinese mills. If you try to take a big cut out of steel on any mill not designed for it the head is going to flex and you are going to have chatter. Just saying.
I would say build your own RPC and use a buck/boost transformer to get to correct voltage. Then you can concentrate on finding a good deal on a good mill (with tooling if lucky) rather than cutting your potential playing field by over 90%. With a surplus 3ph motor of ~3-5hp, often found free (or nearly), you should be able to build a RPC using one of several plans on the internet (there is a dedicated forum on the topic at the PM site) for less than $100. Way less if you don't go for the relay start (pony motor or pull are other options). I've built 2 since I caught this bug. The first was a simple 3 hp with start relay (free motor, maybe $50 in parts), the second a more complicated staged 5/10/15 hp unit I developed myself with the help of folks in the PM forum.
I went with the 220v RPC to the 3phase transformer as I need the 220 3 phase for my lathe. The 3 phase transformer and 6x12 surface grinder came out to $350 total, so it was certainly cheap enough. If you expect to run other 550V equipment, and no 220v 3phase equipment, then it might be cheaper to build the RPC with a single phase transformer to a 550V idler - but you will not be able to run 220 3phase.
You really need to find sources for surplus motors and controls to make the RPC the best way to go. Buying the components new would cost way more than it would be worth. For my setup, the 5hp motor, contactor, box, caps and switch probably cost less than $100. And it takes some time - I like to look at this stuff though, and I collect it before I need it. I have about 10 contactors of various sizes from various sources. I've used at least 6 in the last 10yrs, so I buy them when I find them cheap. Pays to shop at the local scrapyard if they will let you! If you can't find surplus parts, you may as well pay for the VFD. Or probably better yet to re-motor.
For my latest more complicated 5/10/15 RPC, I got the main NEMA steel enclosure at scrap for about $0.15/lb (as I recall). It came with some goodies now on the shelf for other projects, but was mostly virgin and undrilled. The motors were also from scrap. Both Baldors, with both looking near new (other than scratches from rough handling) were very cheap and in great shape at something like $0.35/lb. My contactors (3) were 15hp rated and came from 3 ph industrial AC controls as did the A/B industrial 30 mm momentary buttons (2 x single start stop, 2 x double push/pull mushrooms) and the fuse block. The frame was welded from random stuff in the scrap pile, the casters from HF at about $4 each x2. The only thing I had to go out and buy was the selection of caps used for both start (of the 5hp, it then starts the 10) and run balancing.
Luc,
I didn't make a drawing but even if I did it would be specific to the single phase motor I used and the mounting flange of the original 3 ph motor from the Tree mill.
If, however, you should be lucky enough to score a Tree 2UVR like mine I would be delighted to help you through the conversions.
mrlucmorin wrote:Now, I'm looking into buying a Bridgeport (or a clone of), but most machines that I find for sale are 600VAC 3 phase machines (I'm in Canada).
Some manufacturers do offer those machines with 220VAC single phase motors, so I'm thinking it should be possible to replace the motor and control transformer on a 3 phase model to turn it into a single phase one.
Looking for new or used? The manufacturer may well offer different motors as an option if you are ordering a new machine -- I ordered mine with optional motors.
It seems that my best option is to go with a 575VAC 3PH mill, as this is what's available on the used market in Canada. This way, I don't limit the scope of search too much.
This means I'll have to use a rotophase, and I've started looking into building one, and it doesn't seem all that complicated actually.
61-63 wrote:You didn't say what Chinese mill you had? There are Chinese mills and then there are "real" Chinese mills. If you try to take a big cut out of steel on any mill not designed for it the head is going to flex and you are going to have chatter. Just saying.
I second that question. What Chinese mill did you tire of?
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