Bridgeport 3ph to 1ph motor bracket interest?

Last month I picked up a 1977 Bridgeport knee mill for the shop. The price was right - only problem was that the OEM motor was a 5hp 3 phase unit, and nearest 3 phase is a mile away unless I want to tap into the 480,000 volt lines a couple hundred yards away (no thanks).

I did some research into options to fix this and did not like the penalties for using a phase converter. So after a few hours doping out electric motors I figured out a way to use 5hp single 220v motor (Dayton 6K633) from your local Grainger (around $500) This should also work with their 3hp motor too. Both of these motors will mount the OEM spindle pulley in it's correct location without shims.

As you see it mount up nice, even welded in a nut the same size as the drawbar so tensioning the belt is a snap. Would like to know if there is any interest in us making more of theses, would run about $60 to HAMB Alliance guys...

 

penalties???? What penalties? Who ever told you this hit them with a large stick. A rotary Phase converter works very well. I used one on a Van Norman 562 Surface grinder for over 10 years. The guy who bought all my shop equipment still uses it. yes yes I know not totally efficient. Wont get all the benifits of 3 phase etc etc. I heard all the "experts " Of course none had ever actually seen one or used one. Listen, you bought the machine right because it was 3 phase. A rotary converter used will run $350 to $500. The $50 bucks in inefficiency of hydro you will loose per year by running the 3 phase converter compared to single is irrelevant. What you have saved on buyng the machine will more than cover that.
Buy it, plug it in, enjoy. I have helped buddies hook up 3 phase static converters too although the rotary are desired. Roto-Faze being my favourite. I had to step up my voltage too from 220 3 ph to 550 3 ph. Never, not once, ever, even for a millisecond, did I regret using a 3 phase converter. One of the problems here is electricians although well trained are not often familiar with phase conversion and tend to be gun shy about it. Understandable because it isnt in their normal scope of duties. The place that sells you the converter will often help with all you need to know. I did mine myself. I plugged the Roto-Faze converter into my welder plug. It is then an appliance and outside the scope of rules.
Don

 

I'm going to run my 3 ph. motors on a VFD (variable frequency drive)... I have four machines to run and each VFD is less than $150.00. The neat thing with a VFD is having a variable speed option...

I guess I'm surprised that mill has a 5HP motor... my old Fray has a 1 HP. Is that a 56C-frame motor?

 

no, 184T frame.

My father did talk to a local outfit that sells converters; they were the ones against it and suggested replacing the motor. 1/3 power loss is not insignificant in my book, nor is
the roughness mentioned by various sources researched by him.

 

I run a 3hp rotary phase converter on my lathe ( 240 $ delivered ) without any problems at all. I purchased the converter in August and probably have 20 + hours on it.
A VFD is really the way to go. It doesnt use any power unless your machine is on unlike the rotary. And it is infintly adjustable for RPM .. start up / stop speeds etc.

Only down side I have heard is that at slower speeds the motor is spinning slower so its not cooling as it should.

edit: Roughness ??? might be worth it to find somebody with one and check it out.

 

Go here for rotery phase converters http://www.andersonconverters.com/index.html

You won't have the 1/3 loss of power and you have the option to make a 3 phase circut for other 3 phase machines you pick up cheap 'cause most home shops can't use them.

 

Also check out practicalachinist.com, the HAMB of machining.

 

Just remember when sizing a VFD for 3PH conversion to buy a drive way oversized, like a 5HP drive to run a 2HP motor...

 

Best deal is to buy a single phase VFD with a 3 phase output but they are only available for max 3 HP.

If you have more than 1 three phase motor you don't need a rotary converter. Save $$$ and get a static converter, size it properly, and you can use one of the machines as an idler motor to help start the other machines and add efficiency. Thats what a rotary converter is - a static converter mounted to a 3 phase free running motor.

check out http://www.phase-a-matic.com/StaticInstallation.htm

 

well, that wasn't the course I took, but judging from the responses there is little market for this bracket.

 

Scarebird came up with something innovative and useful. Obviously not something everyone needs or wants. But for the right person, a solution to a problem. Thanks for posting Scarebird.

 

I think it's a marketable bracket, I just don't think that the market is necessarily on the Hamb...but I do sincerely believe there is a market!

 

perhaps. I will make notes from the prototype and file it.

 

I think that's gonna be a HARD SELL. I say this because a couple reasons. First you are still having to spend ~500 bucks for the motor PLUS the cost of the adapter and still have to rewire the forward/reverse switch. A fella could build a sweet rotary for a fraction of that amount. Also once you go 3 phase rotary converter you get the benefit of being "3 phase" ready for your NEXT purchase - and there USUALLY are more purchases once you get a mill. YMMV

 

Single phase will be a tough sell.I was sorta lucky on the mill i picked up for my home shop it already had a single phase motor on it from the factory.It works ok.Runs out of power on some things and you need to stop the motor to switch direction.If i have heavier work to do i have other machines at our shop to use.Nice bracket anyways.

 

If the Bridgeport has a 5hp motor it must be larger than the common Series 1 which usually has a 1.5-2hp motor.

I found a cast aluminum plate in a local motor shop that adapts a 2hp C-face motor to the Bridgeport Series 1 8-speed head.

 

Very nice bracket Scarebird, unfortunately $500 is STEEP for a motor, thats the only downfall to it really. I got a great deal on my 1975 Bridgeport as well and built my own rotary phase converter for $75. If you could find a cheaper alternative for the motor, I think your bracket would sell like hotcakes.

my Bridgeport just before I wired it up,

 

I had a Bridgeport set up that exact way with a single phase motor atop. It worked great but my shop did not have the headroom. So I ended up with a regular Bridgeport with the low profile 3 phase motor. I have not yet decided what to do about it in terms of converting.

 

That's not a bad price for the bracket given your development and construction and margin. I would consider it but two potential issues: (1) I do not have the head room to install a motor any taller than the stock Bridgeport little pancake motor and (2) I would not buy a $500 motor in any case.

I have been wondering if there is a way to mount a single phase motor off to the side, upside down. Would solve my headroom issue.

Or, maybe I need a converter. I would love a single phase to three phase motor generator combo.

 

I'm using a VFD now on my bridgeport, I will be doing a DC motor swap with it soon and your motor mount will help me out a whole bunch. If they are up for sale I'll take one. Let me know where to send the funds to. Here is a link to the DC motor info with the:
http://www.truetex.com/dcdrv.htm

 

Sounds like this thread took a left turn. That bracket can be used on any 1ph electric motor with that frame, 184T. I don't think the new Grainger 5hp is the only application. Looks like a sound conversion and being resourceful could save hundreds.

 

No offense intended, but that's kinda b*** ackwards... VFD technology is leaps and bounds ahead of DC drive technology, plus there's the maintenance of the DC motor to consider. Personally I hope I never have to deal with another DC motor or drive as long as I live!

If you have the VFD, why swap to the DC motor?

 

No offense taken.Just want to try something different.

 

I've heard 2Hp for a 1Hp motor but my motor shop and two suppliers that sell VFD's tell me I can use a 1.5 HP as long as I'm not starting a motor under load like an air compressor, water pump, etc.

 

You can get away with it, your drive just won't last as long.

As with all drives, you can set the accel/decel speeds so that you ramp up to full load speed, that also takes the load shock off the motor.

 

BTW here is no noticible roughness to power from a rotophaze converter. other than switching it on you would never know it is there. I used my rotofaze on my surface grinder long enough to go through three 17 inch stones. Used to to between 5 and 7 heads per day 5 days a week. Figured a stone was good for 600 average head planings. Something wrong with the story. "The company that sells them tried to talk my dad out of them?" Must be a company that can sell them. Cant be a company that is actually in the business. They are used all the time. I know right now were there are 5 with in 15 minutes or so of my place. One runing a 3 ph hoist. One running a flywheel grinder, two running a surface grinders, One in a farm situation My surface grinder was a 7 hp main motor and a 1hp reversing feed motor. Regardless of what these guys said to your dad they work well. You will NOT notice anything wierd. It will operate normal. Obviously those guys have never used one and are scared of the unknown. i bet if we started a thread how many guys have a phase converter in their shop or have used them it would shock us how common it is to use them.
Don
Don

 

Just a heads up , these guy's have offered a single
phase conversion for some time.

http://www.machinerypartsdepot.com/site/1478157/product/SP2SP

 

sure wish i had paid closer attention at a buddies place as he has a series of capacitors for running the 3ph. electric pressure washers he works on and said it was really inexpensive. found the info on the internet some years back.

 

I agree, Iv'e been running static converters on two bridgeports, and a grob bandsaw for 10 years with zero problems, and I run the **** outta them, I am running a rotary on my lathe. Static converters are cheap, a hell of a lot cheaper than a 1 or 2 h.p. single phase motor.

 

That's pretty much what a static phase converter is, just a bunch of capacitance that takes one of the legs of 220V and puts it out of phase with itself and the other leg, thereby creating a "ghost" of 3PH power.

All of these 3PH conversion devices are working on the low voltage too (240V 3PH) not 480V...just a little more info.