# PM1340 lathe - motor swap to Marathon E-467, what pully to use?



## Rich V (Jun 1, 2017)

I'm swapping out the 1phase stock motor for a Marathon E-467. For those who did this what did you use for the motor pulley?
The E-467 has a 7/8 in shaft with a 3/16 key. I need a pulley that approximates the one on the stock motor, preferably the two slot V ways.
This will be used with a VFD so I guess I could run a single slot pulley.


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## DAT510 (Jun 1, 2017)

For my VFD upgrade, I'm considering one of these Variable Pitch Pulleys.  That way I could adjust ratios,  if I don't care for my initial setting.

https://www.mcmaster.com/#v-belt-pulleys/=17vwe66


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## mksj (Jun 2, 2017)

I would use a fixed ratio, I see no reason to use a variable pitch pulley in particular with a VFD. You can calculate the speed ratios off the stock pulleys and motor speed, then adjust the VFD setting to the desired top speed.  I use a 2.5" OD pulley (MB25x7/8" has a pitch diameter of 2.2) on my inverter motor going to the low speed headstock pulley groove, the motor pulley is very close to the stock one (2.3/3.4" OD). Using the stock 3 phase motor on the low speed pulley setting, the maximum spindle speed will be around 1200 RPM at 90Hz on a VFD.

I run my Baldor inverter motor to 125Hz so it works out to a slightly higher maximum spindle speed  compared to using the high speed pulley ratio running the stock  motor at 1750 RPM. The inverter motor at 60 Hz works out to the same spindle RPM as the low speed pulley ratio. So anything from 2.5-2.8 OD +/- is fine for an inverter motor which can spin higher. The E467 should be able to hit 100Hz on the top end, and be usable to 20Hz on the low end, so I would look at a motor pulley a bit bigger, something in the 3.4" OD +/- range 0r a pitch diameter of around 3.2". This should give you a single pulley speed range close to the stock lathe and no belt changes. You can dial up the overload to 140-150% on the E467, and on an inverter motor I have mine set to 180% which the VFD can deliver for short periods up to 1 minute.
https://www.mrosupply.com/motors/ac-motors/severe-duty-motors/2270020_e467_marathon-electric/
https://www.mrosupply.com/sheaves/light-duty-sheaves/finished-bore/706879_mb34x78_maska/
https://www.mrosupply.com/sheaves/light-duty-sheaves/finished-bore/706891_mb38x78_maska/

https://www.mrosupply.com/motors/ac-motors/inverter-vector-motors/2270267_y551_marathon-electric/
https://www.mrosupply.com/sheaves/light-duty-sheaves/finished-bore/706849_mb26x78_maska/
https://www.mrosupply.com/sheaves/light-duty-sheaves/finished-bore/706855_mb28x78_maska/

Blue = non-inverter motor    Red = inverter motor







One recommendation for individuals using the stock 3 phase motor motor running off of a VFD and wanting to not have belt changes, is to flip the stock pulley on the motor so you are using the high speed 3.4" pulley on the motor going to the low speed pulley on the headstock. You give up a little Hp/Torque at the lowest speed, but running the VFD in sensorless vector mode helps control the motor speed better under varying loads. The belt length will change based on the pulleys used, I have been using the Gates Tri-Power BX belts for 3 years, the original Gates belt showing almost no wear. The stock motor using both speeds required a BX24 and BX25 belt. With the inverter motor and the MB25 motor pulley, I use a the BX25 belt.


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## davidpbest (Jun 2, 2017)

For what it's worth, on my VFD conversion, I used a TB Woods BK2878 pulley - 7/8-inch shaft 2.95-inch OD to match the new VFD-rated Baldor motor.   I got it from Amazon for under $12 (*http://tinyurl.com/yap56e3w).   *The belt I ended using is a Gates BX27 Tri-Power, 21/32-inch width, 13/32-inch height, 30-inch outside circumference.  Fits perfectly for this pulley and motor configuration.    My effective RPM range is 30-2100 with this setup.   https://www.flickr.com/photos/davidpbest/30222923404/in/album-72157672547607804/


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## Rich V (Jun 2, 2017)

I decided to get a 3in OD (2.6in pitch) pulley from McMaster. https://www.mcmaster.com/#6204K159
This looks like the one David used and gave a very nice speed range.

Thanks for your help gentlemen, you are a true asset to anyone owning these PM machines.


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## diamond (May 11, 2019)

I realize I'm resurrecting an older thread but I'm looking at some options discussed here.

I’ve had some motor issues (vibration) with the stock 1340GT motor.   Considering between the Marathon Y551 and the E467 in the links Mark shared above.   They are $653 and $322 respectively on mrosupply.com.

Debating if the 2x more expensive Y551 is worth it.   My takeaway is it all comes down to if I want to be able to run the motor at wider frequency ranges with a single pulley setup.   Are there other advantages I should consider?   

Rich V are you happy with your setup with the 467 installed?

I probably will go ahead and "buy once cry once” and go for the Y551 if I’m going to do this.   I'm one of those types that will wonder what if I'd gone with the better option?  David I see you are getting a 30-2100rpm usable range with a VFD rated motor.   If I’m going to do this I’d like to shoot for a similar speed range.     

With the stock motor single belt setup and pulley flipped, VFD freq range 30hz min to 90hz max, I’m getting about 70-1800 rpm.   That isn’t bad and if it wasn’t for the vibration that is in the motor I’d live with it.

A second question is if I go this route I’m guessing the programming in the Hitachi VFD I used from your guide Mark when I installed your modded control panel would be significantly different for such a motor as the 551 to optimize for it’s capability.   If I put this motor in, would the programming be significantly different?   I’ve gotten familiar with some of the more basic areas of the VFD programming but there is a lot in there that I don’t know.   Or would the motor parameter auto tuning take care of all that?

As always, appreciate any advice.   This site is amazing due to the helpful input from everyone.


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## zjtr10 (May 11, 2019)

Diamond is your machine out of warranty?
The motor on my 1440GT died and PM sent me a new one. No problems


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## mksj (May 12, 2019)

I would suggest you go with the E467 unless you can find the Y551 or Baldor IDNM or similar for the same price. They come up on eBay occasionally. You can run a single speed with either, only difference is the pulley size. E467 to 100Hz and probably around 3.0" motor pulley, Y551 125Hz and around 2.4-2.5" pulley. You will need a new motor pulley because the shaft size is different. MRO supply carries the single pulley's and they are inexpensive. Minimum speed is 15-20 Hz for low load work.

Only need to change the max speed VFD settings and do an aut-tune to load the motor tuning parameters. Either motor will be a significant upgrade over stock, and the stock motor is quite good. Question would be is the vibration a bad motor or a tension/belt issue.


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## diamond (May 12, 2019)

I should have mentioned the vibration is present in the motor with the pulley/belt off.  Just running the motor up to speed like that I can feel it with my hand on the tool post.  It's slightly worse with the pulley on (again no belt) so I think the pulley is also not balanced well and adding to the situation.

With belt on it's still there, no matter what tension (and even tried a link belt, which I took back off.  Didn't like the noise it made).

The E467 is looking like a good option for me.  Given it can handle a 20-100hz range that would fit my needs well.  I'll probably go this route.   Thanks for confirming the tuning Mark.

Zjtr:  Didn't contact Matt because this is one of those things that is probably in the gray area.  If it was a dead motor, I would be calling him up in a heart beat and you're right I know he would take care of me.  This is me being picky however and I don't feel good about making him go over board. The motor (again belt off) just kind of starts resonating at higher speeds, it's quiet up to 50hz then progressively gets worse as I speed it up.   At 75hz and above it is noticeable enough I think it could affect surface finish.   However since >60hz is technically out of spec for the machine as I bought it, I would not expect PM to have to address it.   Just how I see it.

Oh and I did try putting a washer on the cap screw holding the motor adjustment bar to lock it down.   That made the motor more solid for sure but didn't change the vibration.


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## Rich V (May 13, 2019)

diamond said:


> Rich V are you happy with your setup with the 467 installed?



Yes very satisfied with how the 467 + VFD performs. Clean unfaltering power at all speeds.
The speed rang is so great I find I use only one high and one low gear setting, just adjust the VFD to cover most everything I need.
It's nice to take a 0.05" cut on a 1.5 inch bar of 17-4 SS at high speed and get no motor bog down.
Watching the chips pour like rain is very satisfying.


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## rafprecision (Apr 18, 2020)

Hey Guys,
Been ~1.5 yrs now, since receiving my PM1340-GT and PM30-MV. Upon receiving, worked on getting the lathe outfitted with VFD, and other "retrofits" as found on this forum. mksj helped a lot! Thanks Mark! Also, PM30-MV has been "cnc'd" since, using Centroid Acorn, DMM AC servos and drivers, and CNC kit from ProCutCNC.

Been looking at "upgrading" lathe, even more, with an "inverter grade" motor. Having "searched" this forum, time and time, reviewing everyone's questions and comments, I "pulled the plug" today and ordered a new Marathon Y551 motor, 2.5 and 3.0 pulleys from McMaster-Carr, and a GATES-BX27 belt. Let you know how this "upgrade" goes, once complete. Looking forward to it!! 

Thanks everyone, for your Q/A's! This forum is GREAT!

Here's a "snap-shot" of my setup...


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## davidpbest (Apr 18, 2020)

I upgraded the motor on my 1340 to a Baldor IDNM3587T which is almost exactly the same size as the Marathon. *This link shows *what I did for belt and pulley. The pulley is a TB Woods BK2878 - 7/8-inch shaft to match the Baldor motor, 2.95-inch OD. The belt is a Gates BX27 Tri-Power, 21/32-inch width, 13/32-inch height, 30-inch outside circumference. Fits perfectly for this pulley setup. Good luck with the upgrade.


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## ptrotter (Apr 19, 2020)

David, what was your reasoning behind for going with the Baldor motor rather than the Marathon E467 or Y551 motors?


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## mksj (Apr 19, 2020)

Paul,

They are all excellent motors, it is more a function of what you can get and the price. Both David and I purchased Baldor IDNM 2 Hp motors, their price was dirt cheap and they were NOS. I would equate IDNM as equivalent performance wise to the Marathon Y551, both are good for about 3X their base speed and have a constant torque on the order of 1000:1. On the lathe I recommend a ~2.3-2.5" pulley and setting the maximum Hz to around 125, or around 3600 RPM. Both of these motors have a small encoder jack shaft that needs to be sawed off in order to fit on the 1340GT. If you had the room you could fit an encoder to the jack shaft and do a closed loop feedback which would be more appropriate for a mill/CNC type of operation. Using open loop sensorless vector control my speed control was usually +/- 1 RPM regardless of load. Since these motors have constant torque down to almost 0 RPM, they have a lot of low end grunt.

The Marathon E467 (145TTTN16628) is a severe duty all cast iron TENV inverter rated motor, with a maximum speed of around 100-120Hz and a constant torque on the order of 10:1. It is a great replacement for the stock PM-1340GT motor at about 1/3rd the list price of the IDNM/Y551, the street price is around $400. On the lathe using the E467 I recommend a ~3" pulley and setting the maximum Hz to around 100, or around 3000 RPM.

FYI, the motor space on many of these lathes are very tight, so standard TEFC motors will just not fit in most cases. The TENV motors are much more compact because they have no fan/shroud, so often 2-3" shorter in overall length. They are usually heavily finned and either cast iron or have aluminum finned case with cast iron end caps, they are quite heavy. You do not have the speed cooling issues seen with TEFC motors, and even under load they rarely get warm.


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## davidpbest (Apr 19, 2020)

ptrotter said:


> David, what was your reasoning behind for going with the Baldor motor rather than the Marathon E467 or Y551 motors?


Mark is certainly the expert here, not me, but as I understood the choices at the time, the Baldor IDNM 2HP units as well as the Marathon Y551 and Y526 are rated at full HP up to 2X base speed, the E467 is rated to full Hp 1.5X base speed.   Plus I was able to buy the Baldor as NOS on eBay for less than I could find a new Marathon at the time.   Nothing is a drop in replacement and some modification is required.   In my case, the motor mount needed new holes.   Be careful with the new pulley placement that it doesn't rub the removable side cover of the machine - something you may not realize until everything is buttoned up and you try to install the cover.


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## rafprecision (Apr 23, 2020)

Hey Folks! The Y551 motor arrived today! Got it hooked up to VFD and "auto-tuned" ...






While here... slow speed (in reverse), a little oil, and a hack saw...






Mounting will be a "bear", however!!! 

Looks like I will have to drill holes (x4). 

More later.

Mitch


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## rafprecision (Apr 23, 2020)

And it will definitely fit! ...


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## rafprecision (Apr 25, 2020)

Got her mounted, "purring like a kitten"! Still need to button up the wire box, however. Top speed, ~2060rpm @ 120Hz ...











Not much room to spare, against that "belt adjustment" bracket. Have the BK4828 fully "pushed out" flush to end of motor shaft...


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## rafprecision (May 3, 2020)

Hi All,

Now that I have completed this "upgrade" ...






... I have the "stock" 3-phase motor available to anyone wanting to "upgrade" their single-phase 1340GT, to three-phase w/VFD.
Willing to send to "buyer" for just the shipping costs, maybe $100.00 or so. Don't have exact shipping costs at this time, however.

LMK, if you are interested.

- Mitch


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