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phase conversion, keep my lathe?

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Forum topic by restored posted 02-01-2015 03:24 AM 2434 views 0 times favorited 31 replies Add to Favorites Watch
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restored

33 posts in 1552 days


02-01-2015 03:24 AM

I wish I new how to change the text so this would be easier to read. Why, because I need some much needed advice, opinions, and sharing of others knowledge. I hope I can condense also so I don’t go on for ever.
Currently I own a Powermatic #90 Lathe that I rebuilt a few years ago. I changed the 1 HP 3 phase motor to a 1.5 HP Dayton. Probably my first mistake. But not having 3 phase in my shop it seemed like my only choice.
I started turning about 5 years ago on a 12” Jet and was hooked. I wanted some larger a real machine. My back ground is a design build remodeling contractor, and a let’s say unpolished cabinet maker. My basic understanding of electricity is basic. My understanding of motors is less than basic.

I have decided that I want to be able to turn at least a 20” bowl. Here are my issues. I believe my PM was built in the 70’s. P M built this model with a # of varying speeds. Not knowing but the basic things to look for in a nice hunk of iron, I wasn’t educated about the speeds. The lathe has a Reeves drive that runs smooth. The only issue is that at times if I have the speed at 1000rpms, the drive will walk faster and pick up RPM’s. It is something I have lived with, as the thought of pulling the motor and dealing with the spring and belt system again, and the fact that it doesn’t do it all the time, like I said I live with it. This machine weighs close to 800 lbs. When I put a close to 12” piece of green wood already rounded on the band saw, which isn’t balance perfect, the first 5 to 10 minutes of truing up is a real adventure. It will walk the whole lathe a foot and a half until I’m true. The 800 rpms x the centrifugal force due to the weight, increases the the actual energy immensely Of course I have the tail stock right up tight, and I typically do use a face place with screws. After hitting true, I keep the speed on 800. I have never experienced any type of bogging down.

I have a couple choices as to accomplish my dream of settling for a minimum swing of 16” on the inboard side. I have spent the last 4 to 5 months searching every day for a larger lathe, with the low speed and the increase swing. This hunk of iron is 50 years old and strong as an ox. I wonder how well a 16” Nova with the DVR speed control I desire will be a machine I will be passing on to my grandson.

My budget is around 2000.00 plus the proceeds from the powermatic, of which I’m asking 1200.00. Do i keep what I have, change the motor back to a 3 phase 220 motor, and purchase a VFD converter (I realize there is also rotary and static, of which I would love your opinions and knowledge) Will I be able to slow the speed to 200 rpms, with the reeves drive set at a low speed of 800, Will the converter override the Reeves drive, if I run something like a foot speed pedal. If I can do this I would then look at purchasing a heavy duty P M outboard turning rig and attach it to the 90 with welding, brackets or connectors of some type, so it can be removed. This part from P M is in the 500.00 range. Can I do this. Issues reeves drive , belt system, the clutch system on the reeves. I have thought about mounting the motor inside the cabinet. Can I find a belt the right width, and increased length. Am I dreaming and the engineering to do this is a crap shoot.

Do I wait continue to save my pennies until I can afford my dream lathe. A One Way 2436. I also love the Powermatic 2035. With the prize tag of 4000. 00 it is still out of my price range. I’m not whining, but my days of working for myself are done, as I’m had both my back and neck restored with rods and a total of 10 screws with fusions. I had a wonderful surgeon in Boston. I can stand up, and turn for 3hours at a time twice a day. I’m hooked. It’s great mental therapy and I’m grateful I have found it. I have a 1450 SF shop with nice machines. It was my retirement plans. Walking by the lathe without putting on it is difficult. I am allowed to make about 1000.00 a month beyond my disability. Which I need to do, and do it this my is my first choice.

Rework my 90, keep looking and buy used. Keep saving and buy a jet 16” OR similar. Does anyone have any input on grissly’s, Baliegh’s, Luguana, etc. Then any input on converters. If I do this should I increase the size of to accommodate other machines that i might purchase. This has been a way of survival. Jointers are the machine I can find at reasonable prices, clean up, adjust the beds if necessary, sharpen and reset the knives and resell. I have 3 6” ,, in my shop know. I need the help of electrician’s machinist, turners. Rotary vs. VFD, Do I need an additional motor to send the 3 phase power to a new 3 phase motor. Or does the drive or converter take the existing power and convert it to 3 phase. So far I’m sold on the VFD. It seems like it draws the power on a more consistent basis. Able to hold 60HZ. better than the rotary. I’m out of my league when I say this, but I have interpreted the 60 HZ to be the power the motor is putting out, and there can be a number of reasons that the motor is not able to maintain that, and bogs down. Please correct me and clarify. A voltage drop can cause this. I have seen a Makita skill saw turn at about 100 Rpm’s being on the end of 200 ft. of extension cords which were plugged into the last outlet on a circuit about 100 ft from the panel, and who knows how many interruptions in the line. I knew it would be long, may not even be accepted. But I do need as much help and experience opinions to help me decide what direction I should commit to and follow through. Thanks to all of you for reading.

Nothing is impossible to the man who doesn’t have to do it himself. rf

-- KRT


31 replies so far

View Mike82352's profile

Mike82352

17 posts in 710 days


#1 posted 02-01-2015 06:35 AM

I would go with a VFD. If you still have your 3ph motor, and it’s a 230/480 volt, even better. The VFD will allow you to go from 0 – 60hz or 0 – 1750rpm’s or whatever your motor rpm is. Most motors can be ran to 90hz. without any trouble. You can get VFD’s that take a 110 volt input and get 230 volt 3ph out. Most 110 volt Vfd’s go up to 1.5-2hp. For larger motors, you may need a 220 volt input? I installed a VFD on my lathe and I have one on my mill machine.

-- Want....... what you already have......

View bonesbr549's profile

bonesbr549

1176 posts in 2527 days


#2 posted 02-01-2015 01:21 PM

Ok, as someone who loves old tools and had to get 3 phase, I went through an education to say the least.

I would say if you only plan on ever having one single 3 phase tool, then go with a VFD.

I went with a RPC, because of two reasons. First, I have multiple motors that will use 3-phase, and second, wanting as close to balanced true three phase as possible, due to the equipment I am running, I went with a 10hp RPC. If you decide you want a RPC, remember the idler motor (generates 3rd leg), hp rating is more than it can provide. A 10hp model, will give you 7.5hp at 3-phase.

I can Highly reccomend American Rotary Phase converters. Great guys to deal with and they don’t look down on newbies.

Good luck.

-- Sooner or later Liberals run out of other people's money.

View Fred Hargis's profile

Fred Hargis

3926 posts in 1953 days


#3 posted 02-01-2015 01:50 PM

I think I would convert your existing lathe to 3 phase (with a VFD, skip the other stuff in your instance) and wait for the time to get your dream lathe, whatever it turns out to be. Besides, by waiting you just may fall upon a used dream lathe that can save you some money. the 2436 doesn’t show up very often, but you never know. I’ve seen maybe 2 or 3 in the last few years come up for sale.

-- Our village hasn't lost it's idiot, he was elected to congress.

View REO's profile

REO

889 posts in 1534 days


#4 posted 02-01-2015 02:12 PM

the vfd will get you speed control for a reasonable cost and the least investment of time. Not really 0-xxxx because the motor looses torque as the rpm decreases and there is a danger of ineffective cooling at slow speeds. less than 30 Hz for continuous load is questionable. Not the power rating of the motor but the frequency of change in the AC current. most AC motors are of the synchronous variety which means they will run unloaded at a given rpm depending on the poles 1800 or 3600. the nameplate rating tells you what the speed will be at rated hp 1750 OR 3450. Hp is a consideration of speed and torque. As speed is decreased so is available torque. what the VFD does is vary the Hz to vary the speed of the motor because the motor wants to run synchronously with the Hz of the electricity being delivered to it. the RPC it will not give you speed control. DC is a viable choice if you want performance from 0- max without pulley changes, torque is still lost at slower speeds but not as noticeable as ac variable speed. In all cases the best option is to use the pulley changes with some sort of VS technology for wide speed variation and high torque transmission. your machine is a nice piece of equipment it can be modified to take a group of pulleys and even a jack-shaft for deeper lows and higher highs if you wish. The dancing lathe can be dampened with additional weight etc.

View Bill7255's profile

Bill7255

352 posts in 1744 days


#5 posted 02-01-2015 02:41 PM

I have a PM 90. I know that they made these lathes with two different speeds, one 1000-4000 and 500-2000. Mine is the 500-2000 speed version. There were also two different motor mountings. I have the one with a jack screw (I think that is what it is called). I changed my motor to a 1ph 220V 1 hp Dayton. This was easy as both motors had the same frame. The motor I bought off eBay, but looked it up on Grangiers and it listed for over $400. Should be a good motor. I have had 0 problems. I am not exactly sure the benefit you think you will gain going back to 3ph, unless you think it will solve the speed problem. I have never had my lathe walk like you have, however these lathes are top heavy. You could try putting weight in the bottom of the cabine such as sand bags. Agree with other posters on waiting to get the lathe you really want.

-- Bill R

View baldric's profile

baldric

10 posts in 720 days


#6 posted 02-01-2015 05:41 PM

I think the only problem slowing a motor down, is the cooling of the motor,
its working quite hard but the fan is going slow!

View restored's profile

restored

33 posts in 1552 days


#7 posted 02-01-2015 06:29 PM

I believe what I’m hearing is just about the same from everyone. Bill, I’m not sure If you understand some of my concerns. Actually I have seen P M 90’s since with low speeds down to 300. I could very well be wrong but P M produced more than just 2 speed ranges when making this model. The centrifugal force difference at 300 RPM’s is huge. Yes I can add weight, attach to the floor, I realize this will hide some of the vibration. However the 40 lb. chunck of wood is still spinning at 800 RPM’s. If added weight was the answer to the problem, then why are all the top top lathe manufacturers been making great efforts to reduce the speed, some as low as 0, while maintaining the the power and torque ratio’s to be correct. With that said I believe we are all agreeing on the same course of action. The cost of a new or used 3 phase motor to fit this machine can be had for reasonable money. Lets not forget I will still have a basically new 1.5 single phase Dayton The members who have dealt with the conversion of, I know have a better grasp of the electricity than I do. REO, you are way over my head but I am hearing bits and pieces. My questions moving forward. I’m pretty much convinced going back to 3phase is the only safe and practical way to continue to use this nice hunk of metal as it was intended and more. I don’t believe it was made to turn 12” bowls especially in a high school. Spindle turning upward to 6 and 8 ” diameters yes. This is the main reason why I haven’t put any real time or money into the outboard side yet. What I am having trouble understanding. First , I buy the 3 phase motor, I don’t believe I should go below 1.5 hp, and it wouldn’t hurt to increase to 2 hp if I’m set up to turn 20 + inches. I purchase a VFD converter. I do have a business contact that this is all they do. They did supply the first motor and even installed it in the machine for me for only their cost of the motor which was around 220.00. So between here and there I will need the help to purchase the proper size diverder. Am I wrong in assuming to oversize on both motor and VFD. Easy to have and not need then need and not have. Cost does play a part in this, but I have bought older planers up to 30” and jointers, and a large band saw at auction that were all 3 phase. I resold. A couple pieces if I had 3 phase I would have kept and sold my single phase machines. With a rotary phase converter I also need a motor with this, Y or N. How in which the lathe operates with it’s need to draw different amounts of power in second intervals, can a VFD be used on the out feed side of a rotary phase to produce a cleaner current for the lathe? Or would this be an absolute foolish waste of money, or if it is the cleanest power to the lathe hook it up separately. Second set of questions is concerning the reeves drive, and how it’s current low of 800 and high of 4000, does the VFD over ride or ignore the rpm numbers on the faceplate. It was 3 phase when I got it. What do I need to do to the lathe itself to with it’s current setup to achieve what I want. I have given this much thought and what I do know, is I know what I want. I would like to bbe smart and logical about the whole process, but in the end if I have spent 3 to 4 hundred more and have got what I want, That’s fine. If I pick up the phone in the morning and call nova, and order their top of the line 2024 with an outrigger for outboard turning. am I going to have a better lathe, besides the fact that I can;t turn a baseball bat or the legs are so ugly I cringe looking at it. But I know form follows function. Reo the one place I am realy lost is your explanation of the HZ. used and lost. I was under the impression the VFD was the convertor that best dealt with this. Increasing HP help with torque. Cleaner poer to the motor help with torque. Not having a great understanding I have come across many different opinions about what is in the new machines, converting single to 3 phase. So even inside the dozens of models they all have different set ups themselves. This is more complicated than talking to 3 different mechanical engineers and designers on the best hot air system is and how to install it. That is like going to the doctor to get a second opinion. it will be different. Thanks to all so far, please don’t stop. Has anyone have a buddy who turns on a vega or stubby bowl lathe? A lathe very similar just came up this morning claiming to turn up to 2 and 3” bowls, ( speeds 2 HP. thats all I know. The worst salesmen in the world are those selling their lathe. What more do you need to know it’s 40” long. Go Patriots, lets, take the air out from the Sea Hawks.

-- KRT

View crank49's profile

crank49

3980 posts in 2431 days


#8 posted 02-01-2015 07:05 PM

I have not done this myself yet, but have read and studied and seen YouTube videos of using a VFD designed for running a 3 phase motor actually running a single phase motor.
You apparently just use two legs of the drive.
You still have all the features of the VFD like speed control, soft start, electronic braking, RPM display, etc.
The voltage in and out is programable.

Caution, the above comments about cooling are important.
I would still keep the multi speed mechanical drive and use it to get to the really low speeds in combination with the VFD output. that would give you the best of both worlds.
Higher torque at low speed and electronic speed adjustment and feedback control.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View REO's profile

REO

889 posts in 1534 days


#9 posted 02-01-2015 08:25 PM

There is no reason to use a RPC or phase converter AND a VFD. The VFD takes in the power you supply, turns it into DC current internally for the electronics and then outputs AC to the motor. AC power is Alternating power its voltage swings from positive to negative and back to positive so many times a second. Here in the US it does this sixty times a second…60 Hz. In Canada they use 50 Hz. If you take a motor that runs 1725 (1800 synchronous) and plug it in in Canada you will get about 1440 rpm (1500 synchronous). this is what the VFD does it changes the Hz of the output to the motor to change the speed. This is in a nutshell description. There are settings in some VFD’s that will try to maintain constant torque through the speed range but they too become iffy below about 30 Hz (speeds below half the rated speed) and require a better insulation class on the windings. you can also increase the speed over rated RPM by feeding a higher HZ into the motor IE: 120 hz from the VFD will make the motor run 2x the rated speed at 3450 when you are using an1800 rpm rated synchronous motor.

View Nubsnstubs's profile

Nubsnstubs

826 posts in 1190 days


#10 posted 02-01-2015 08:39 PM

The VFD controls the rpm of the motor. It has nothing to do with the reeves drive. When you start up, your motor might turn at 200 rpm, but if your Reeves drive is set at 800, your actual RPM is going to be much lower at the spindle. When PM made the lathes, whether the motor is 1725 or 3450 rpm, it was an instant start to designated rpm, but spindle rpm is reduced because of the difference in pulley size from motor to spindle. If you keep your Reeves drive, then you get a whole lot more reduction with the VFD. You wont gain any rpm, but you can reduce it. Confused yet? I know I am… Jerry (in Tucson)

-- Jerry (in Tucson)

View crank49's profile

crank49

3980 posts in 2431 days


#11 posted 02-01-2015 09:51 PM

Just to be clear.
I was NOT suggesting using the phase converter and the VFD.
I WAS suggesting keeping the Reeves variable speed drive and using it with the VFD in combination.

But, the main point I was trying to make was that a three phase VFD will run a single phase motor, so the OP would not have to find and install his old motor or buy a new three phase motor.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View Mike82352's profile

Mike82352

17 posts in 710 days


#12 posted 02-02-2015 03:58 PM

I installed a VFD on my lathe, I found a 1 1/2hp 3ph motor on ebay for $50 shipped. I already had the VFD. I kept the Reeves drive, this allows me to run a higher hz at slower speeds and not heat up the motor. I have used a VFD on my Mill machine for several years with no issues.

-- Want....... what you already have......

View REO's profile

REO

889 posts in 1534 days


#13 posted 02-02-2015 10:05 PM

Crank49 I understood your post. Restored asked about using both. Keeping the reevs drive is good too I was suggesting that if he wanted to really get down to the basement he could add a jack shaft with MORE pulley ratios.

View JamesVavra's profile

JamesVavra

298 posts in 2776 days


#14 posted 02-09-2015 03:09 AM

I actually bought a VFD and a 1.5HP 3-Phase motor to modify my old Jet 1442VS. It had a reeves drive to do variable speed, and I planned to setup the VFD to run at a few different speeds – basically the opposite of how most of the bigger lathes are setup.

I also wanted to change the way the motor was mounted, since it was in the way most of the time.I got the VFD programmed, but never fabricated a new motor mount.

In the end, I wound up buying a bigger lathe (the Rikon 70-450). I still have the VFD and motor and would be willing to sell them if you’re interested.

I know you’re looking at the Oneway eventually, but have you seen the new lathe that Grizzly just announced? It not shipping yet, but they’ve got crazy good introductory pricing. It’s a 22” swing lathe with a 3HP motor and it’s currently priced at $1700, including shipping. It is not a Oneway by any means, but it seems like a heckuva deal.

http://www.grizzly.com/products/22-x-42-Variable-Speed-Wood-Lathe/G0766

James

View JamesVavra's profile

JamesVavra

298 posts in 2776 days


#15 posted 02-09-2015 12:52 PM

For anyone that’s interested, I found links on eBay to exactly the motor/VFD combo I have. These aren’t my listings. If anyone wants them, I’d do $325 for the pair + shipping (UPS from 37206). I’ll also throw in the cabling I bought for it – I think it’s around 12 feet of the super-flexible, rubber coated 10/4.

This is the VFD: http://www.ebay.com/itm/NEW-220V-1-5KW-VARIABLE-FREQUENCY-DRIVE-INVERTER/151250904435

I just checked the motor: It’s a 2 HP Baldor. Brand new – was custom built for some specific job and has a 10” shaft. http://www.ebay.com/itm/231475424824

James

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