# ERL-1340 Lathe VFD Control System and Additions



## mksj (Mar 24, 2019)

Ordered an ERL-1340 last year to replace my PM-1340GT that I had for 6 years. I was moving and I felt it was "easier" to sell the 1340GT and order an ERL-1340 through QMT to be delivered to my new address. It took about 4 months to get the lathe in and then setup delivery. Due to the weight of the lathe and where I live, I needed to order in a forklift and have the lathe locally brought to my house after being dropped off by the trucking company.  The weight of the lathe changes shipping requirements, delivery requires a forklift and it is more difficult to arrange transportation.

Getting it into the garage and getting it cleaned up. I cut out the pallet underneath it and lowered it with a jack and wood blocks until I could attach the mounting feet. Unlike the large RML, there is no provision for using a forklift to lift it under the base.










I opted to go with the 3 Hp single motor speed version since I planned to add a VFD/control system, and I haven't had good success matching VFDs to with dual speed motors that are not constant Hp at both speeds. Kent sells the same lathe named the TRL-1340 which has 16 speeds, 8 mechanical like the single speed and a 2 speed motor, but at 1750 RPM it is only 2.5Hp, 3500 RPM it is 5 Hp. The gearing and speeds are different between the single speed and dual speed motor versions, but a VFD is more optimal with the 3 Hp single speed in my opinion. I also have a 3Hp vector motor that I might install at a later date, but so far the stock motor does very well. The stock motor plate indicates limited to a maximum of 72 Hz, probably this is to limit the maximum spindle speed which is 2500 RPM. I have it programmed to 80 Hz for a bit more range at lower speeds.

The first item on the agenda was replacement of the control system and all the wiring to accommodate a VFD and  a new control systems designed around a Yaskawa V1000. I went with the CIMR-VU2A0020FAA, 5HP (19.6A) model which is a 3 phase input, but derated it for single phase use. The build out is setup so the it can accept either single phase input or 3 phase input, I added a DC choke on the VFD buss to minimize the increased harmonic distortion encountered with single phase input. I also went with this particular VFD/model because its depth is about 1" shorter than the single phase unit and about 1.5" shorter than the Hitachi WJ200. This allowed me to use the stock control system box on the lathe as opposed to adding a separate VFD cabinet.  It is a very tight fit, and fitting all the components the the cabinet was a challenge.

The control system incorporates a proximity stop system, multiple braking rates, joystick jog, various coolant system option (24VDC, 120 and 240VAC), freewheel command for the manual foot brake and various interlocks. The only component that was not replaced was the spindle switch and its cable. I also added 120/240VAC sockets to power other machinery.  I went with separate 12 and 24 VDC power supplies as the splash shield and main overhead LED light draw over 50 watts.

The front panel switches were replaced with higher quality switch gear, this was more difficult than I expected because the limited space provided behind the panel. It required light grinding the edge of the transmission case so it would not short one of the switches. All new cables were fabricated, and all the cables are shielded.

I stripped all the components from the control box panels, and remounted the new components.

Stock electrical cabinet. Out with the old and laying out the component locations.








On the bench wiring everything up,  unfortunately I only have a small table to do this.  The VFD braking resistor is mounted behind the back plate and the wires come through a black rubber grommet.





System installed, note that the VFD just clears the control cabinet door. Everything just fits. The cabinet size and material is sufficient that no external cooling holes/fans are needed. The VFD internal fan comes on only when in the run mode.





The Yaskawa programming is also quite different than the Hitach WJ200 so required a different approach to the system build/design.  Programming the V1000 is pretty easy with the Yaskawa software, much more user friendly then the Hitachi software I use, but it required a custom cable and USB to serial adapter to connect the computer to the VFD. I worked through a number of the program variables until I was satisfied with the operation/function. Luckily I had several months to review the 500+ page technical manual.





The micrometer stop on the ERL-1340 is quite massive and the stop rod does not rotate, so the proximity stop bracket design did not require a separate guide rod used in the 1340GT and 1440GT lathes. I opted for a newly available proximity sensor which offers a 12 mm sense range vs. 8 mm. So far it works well, but the repeat accuracy is more like 0.004" vs. 0.0004" for the 8 mm version I previously used. The longer sense range is useful in heavier lathes with longer stopping times and also allow for higher threading speeds probably up to 600 RPM.





Once the control system was finished, the next project fabricating a new post for my Dorian QCTP, the foot they provided was way too small for the lathe. The lathe came with a lantern stile tool post and the foot was threaded with a M16-2.0.  I milled the  Dorian foot for temporary use, and then cut a new 5/8" O1 post which I threaded M16-2.0 thread on the bottom and a 5/8"-18 UNF on top to hold down the QCTP. The metric thread was cut in about 6 passes at 450 RPM using the cross slide only, the ERL-1340 is remarkable rigid and quiet, the threads came out very clean, see below. The pitch is close to a 13 TPI so each passes is very short. I use lay down threading inserts.





stock Dorian foot milled for a temporary fit. Ideally a CXA tool post may be a better size as the cross slide is wider than the QCTP.








I installed a Tachulator tach with SFM since the MachTach is no longer available. The Tachulator only comes with a optical sensor which I do not like to use, I was able to adapt a magnetic hall sensor to the unit with minimal modifications. An aluminum ring with 4 magnets was turned to fit over the spindle shaft and a mount for the hall sensor fabricated. The Tachulator along with a 3 turn precision speed pot is mounted in a Hammond 1590SBK enclosure which was a tight fit. it attached under the DRO with a machined L bracket.








Turning the magnet spindle ring.





I then installed the DRO, I went with an Easson 12B head with Glass scales on the X and Z0, the tailstock Z1 uses a SRA magnetic scale which is compatible with the Easson. The SRA magnetic scales are very small, so there is no problem fitting it to the backside of the tailstock.

















Next on the build list was the spider, I started out with 3" 4140 HR round, the initial finish was not great until I advanced the feed rate to 0.007-0.008 IPR and was able to brake the chips a bit better. DOC was around 0.080" at 400-500 RPM. The outer diameter was sized and then held with the steady rest. The steady rest is quite massive and has roller bearings on the fingers. I then center bored 40mm to a depth of 6" using a 1" carbide boring bar, and a step for it to slide over the spindle. The tolerance of the internal diameter at 6" was quite respectable, within 0.001". One of the more noticeable features of the ERL is the absence of any flex or chatter that I previously experienced with the 1340GT. No substitution for weight and size. Once the 4140 was sized and fit on the end of the spindle shaft, I then put it in the rotary table and drilled/tapped threads for both internal and external to the cover spider bolts. I had previously made different  brass tipped spider bolts with knurled lock rings. It all came together quite well, but the swarf from the 4140 can be quite nasty.

Notice the surface finish difference midway by increasing the feed rate.





Center boring to 6" depth with a 1" carbide boring bar. No vibration or uneven finish.





Tapping with the rotary table.





Internal and external spider bolt positions,  Tachometer magnet ring and sindle factory balance ring in black. Everything is indexed for position.









I then installed a 48" high output LED light bar under the back of the splash shield, angled forward about 40 degrees. This prevents shadows, but does not shine in your eyes. I adapted a Flexbar splash shield that mounts with T-Nuts to the back of the cross slide which is adjustable for front to back and also side to side.  This is a great addition given the additional space to the splash shield. I finished yesterday installing a rack on the back splash for the most common holders and chuck keys I use.





With Flexbar splash shield and back splash rack.





I added Gates Tri-Power belts, they have worked well in the bast and the motor pulley is quite small, so a tight wrap for the belt. The stock belt is a pair of BX76, but I ended up using a pair of BX74 Tri-Power belts that had the same diameter as the stock belts.

The ERL-1340 at first seemed to be a bit large,  but once I started using it the working height is no different than my 1340GT, although it is much deeper. It is amazingly solid even with some off center boring with the jaws far offset, nothing seems to ruffle its feathers.  The engagement of the carriage feed are very light to the touch/accurate and so far I have seen no positional change in the DRO when turning without locking any of the gibs. So will probably hold off on a cross slide lock for now. The mechanical foot brake is a nice addition for holding stock when stationary for tapping, but the VFD electrical braking is very fast. The universal gearbox is a pleasure to use, just need to get use to all the gear selections. Overall, very pleased with the lathe.


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## bitpool (Mar 24, 2019)

Thank you for the play by play. Looks like a great machine.

Sent from my Pixel 3 using Tapatalk


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## dpb (Mar 24, 2019)

Being half-assed retired, and wanting to learn, I was fortunate enough to find a community college machinist certification program that gave a full semester of manual only lathe and mill instruction.  The lathes were Kent 1340TRLs.
While in school, I bought a PM 1440GT.  I do some barrel work, and I appreciate the short headstock on the 1440, but if that was not an issue, I would trade it for the school lathe, with no regrets.
Excellent write up.


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## 7milesup (Mar 24, 2019)

Totally awesome.  Great work!


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## tweinke (Mar 24, 2019)

Beautiful work! And congrats on the new lathe.


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## jbolt (Mar 24, 2019)

Shiny! Gotta love that universal gearbox.


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## Bamban (Mar 25, 2019)

Very nice machine, Mark. Thank you for the thorough write up.

The smith who recently trained me how to true up 700 action has the TRL1340V version of yours. I was impressed how solid and precise the lathe was. 

nez


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## [X]Outlaw (Mar 25, 2019)

Sweet machine and amazing work on the control system as usual!


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## wrmiller (Mar 25, 2019)

Very nice Mark! And I'm very jealous. 

If I ever win the lottery there's a RML 1440VT in my future. Until then I'll muddle along with my little 1340.


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## Boxster9 (Mar 25, 2019)

Nice work Mark, as always.  I need to remember the take away - If you want a new Lathe, sell the house with the old lathe and buy a new home and a new lathe.  Does this work with Mills too?  Seriously, Mark, it is a real beauty and what you have done in adding several great additions only enhances what you can accomplish with it.  I would love to see more of what you did in adding the Tailstock DRO.


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## mksj (Mar 25, 2019)

Appreciate the comments, agree that the lathe headstock id a bit long for barrel work, although you can use a shorter spider with the bolts under the cover.

Some additional information on the DRO install I posted here: https://www.hobby-machinist.com/thr...th-glass-and-sra-m-dro-magnetic-scales.77261/

The tailstock magnetic scale install is fairly straight forward but you need to mock up everything first so you have enough travel, nothing interferes with the levers and also the back dial ring when the scale is fully retracted. I had room on the back of the tailstock to mount it, but it could also be mounted on the top or front if you do not have the space. I went this route because I had an extra axis on the DRO, otherwise I would have just used a battery operated DRO scale.

The reader mount has a cutout for the rail to pass through (clearance was 0.001"), this sits on top of a 1/8" plate so the scale is not flat against the tailstock. The reader head slides from the back into a U cutout and retained by two small metric allen cap screws, there is a small adjustment for the reader height, but the reader did not seen to be effected by height, even when it was close to 1/4" away from the scale. It is adjusted for about a 0.1" gap. You can also use different height back plates (behind the scale) if you are off a bit, and the reader mount has small adjustments  (mounting holes slightly oversized) for vertical movement and rotation.  Basically clamped everything up and made sure nothing was binding (and the scale worked),  marked the location of the bracket with tape and then drilled the mounting holes. The front of the magnetic scale is retained with two allen screws.


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## INTJ (Mar 26, 2019)

As always, nice job Mark!  I’ll het it feels good to have a lathe up and running again.  You went for a while without one.

Blaine


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## BrentParker (Mar 27, 2019)

Mark, 
   Congrats on the move and the new lathe. Your typical excellent work and mods, Sir. Enjoy.


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## MarkM (Apr 1, 2019)

Congrats Mark!  A lifer!  As always very informative and nice work!


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