# PM1440TL VS PM1440GT



## Batmanacw (Oct 15, 2021)

I have a limited budget but I need a bigger lathe than the PM1030V I'm running now. I don't have money sitting around. I'll have to finance it. I'm okay with that. I'm passing on projects because of my wimpy lathe. 

I see in the specs that the PM1440TL weighs a hell of a lot more than the PM1440GT, and the TL has a gear box that can run all the different threads without change gears. The GT has change gears for 13 tpi and Metric. 

I know more weigh is always supposed to be better, but I am trying to figure out what all I'm giving up other than a bit if time on threading metric and a lot of machine weight i may never even notice. 

The spindle bore of the TL is 2.55" vs the GT at 2"

I have no issue working within the limits of my machines. I could do a hell of a lot with a geared head lathe with a little more hp than my 1030v. 

What am I missing?


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## woodchucker (Oct 15, 2021)

First, I don't have a PM, I am a SB 9 owner to put this into context.

I could not imagine *not *having a gearbox. I use my gear box to change feed, or threading so often. Sitting there changing gears would make me enjoy things a lot less.

The larger spindle bore is something I crave. You can never have enough spindle bore.

I think the TL being heavier is not only the gearbox. I think you are getting a superior machine. Having change gears is a hobbyist thing, having a gear box puts you in a serious user category, hence a better built machine.  Hence the bigger bore, the gear box etc.


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## Batmanacw (Oct 15, 2021)

woodchucker said:


> First, I don't have a PM, I am a SB 9 owner to put this into context.
> 
> I could not imagine *not *having a gearbox. I use my gear box to change feed, or threading so often. Sitting there changing gears would make me enjoy things a lot less.
> 
> ...



The change gears are for metric and 13tpi. The rest is in the gearbox. The feed rates are in the gear box. 

You aren't selling me on the extra $5k with extra weight. I'm trying to get a real feel for the difference running day to day. I don't thread metric often but I do occasionally.


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## rabler (Oct 15, 2021)

Looks like the GT is made in Taiwan, other models made in China.  Also looks like the GT is spec'd to better precision, tighter fits, better bearings, etc, as well as a removable gap.


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## woodchucker (Oct 15, 2021)

rabler said:


> Looks like the GT is made in Taiwan, other models made in China.  Also looks like the GT is spec'd to better precision, tighter fits, better bearings, etc, as well as a removable gap.


the tl  is made in Taiwan also according to the PM site


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## woodchucker (Oct 15, 2021)

I didn't see where it mentions a gearbox on the GT for threading or feeds?


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## rabler (Oct 15, 2021)

woodchucker said:


> the tl  is made in Taiwan also according to the PM site


Didn't see that.  I was comparing the GT to others in the 12-14" category, a little confusing to put another 14" in a different category.


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## woodchucker (Oct 15, 2021)

rabler said:


> Didn't see that.  I was comparing the GT to others in the 12-14" category, a little confusing to put another 14" in a different category.


I agree, I don't like the website layout, or how the specs are laid out.


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## Batmanacw (Oct 15, 2021)

woodchucker said:


> I agree, I don't like the website layout, or how the specs are laid out.



The TL is a different lathe in the same size class. Definitely nicer. I am going to have a hell of a time financing the $13k for the GT and accessories. The TL is like taking on a car payment.


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## Batmanacw (Oct 15, 2021)

woodchucker said:


> I didn't see where it mentions a gearbox on the GT for threading or feeds?


Scroll down to description.


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## woodchucker (Oct 15, 2021)

Batmanacw said:


> Scroll down to description.


I did..  I didn't see it mention a gearbox.

it's not clear from this:

Inch AND Metric thread cutting ability is a standard feature
True INCH PITCH main lead screw, cross feed, and
compound lead screws make it easy to use for the INCH
measurement System, yet still has the Metric readings on
dials for the ultimate in versatility for any job that may come
about


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## Batmanacw (Oct 15, 2021)

woodchucker said:


> I did..  I didn't see it mention a gearbox.
> 
> it's not clear from this:
> 
> ...


Turns out I read it in the instructions. Much easier than my current lathe.


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## mksj (Oct 15, 2021)

Question would be what do you need. A 1340GT is a lot of lathe and well made, lighter but accurate. If you  need a larger bore, then 1440GT or TL. There is also the Acra 1440C which is similar to the 1440TL but 2600 lbs and D1-4 chuck mount. Cost is similar to 1440GT, same universal gearbox as TL. There is a recent thread on the 1440C. Cost of machine is one part, chucks and tooling is quite expensive and goes up with bigger lathes.


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## Batmanacw (Oct 15, 2021)

mksj said:


> Question would be what do you need. A 1340GT is a lot of lathe and well made, lighter but accurate. If you  need a larger bore, then 1440GT or TL. There is also the Acra 1440C which is similar to the 1440TL but 2600 lbs and D1-4 chuck mount. Cost is similar to 1440GT, same universal gearbox as TL. There is a recent thread on the 1440C. Cost of machine is one part, chucks and tooling is quite expensive and goes up with bigger lathes.


I really want a minimum of a 2" bore. Other than that and the 6" 3 jaw instead of the 8" 3 jaw on the GT, the Acra looks really excellent.


I can get the GT with all the accessories I want and delivered for $13k.


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## Dhal22 (Oct 16, 2021)

Can I buy your 1030?


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## B2 (Oct 16, 2021)

I have have the PM1440GT, but have not been using it long enough to form a strong opinion. It seems like a very nice lathe.  I did not even consider the larger TL lathe as it too big to get into/ fit into basement room and was considerably more $.   I am pretty sure that both of them are made in Taiwan so should be high quality.  It is not mentioned on the front page of the web side, but I think it is in the description. 

Most importantly, if you have any questions about the two machines just contact Matt, the owner, of PM.  (or I will try to provide info about the GT but I am only a hobby machinist so..... ) He is very helpful and always responds.  However, he does travel at times and so a response may take a day or longer.  Also, he has "support" folks who are pretty knowledgeable.   Just give them a call.  Also, if I read your location correctly, you are not that far away. probably less than a two hour drive from PM.  PM is located out by the Pgh airport so you do not have to come all the way to the city.  If they have them in stock you could just visit them and see the machines.  I live in Pittsburgh so they are close for me and I have been to the PM site a few times.  They are well set up, a nice facility, and have lots of inventory of parts and machines and Matt has been in this business for several years, ~15-20, so clearly is an ongoing concern.  I am pretty sure that he was a machinist before starting this business.  There have been folks on this site who drive there from farther distances than you have to pick up their machines. 

The GT has a gear box for threading English treads.  You can read the threads that can be cut with the standard gears on the front tables of the lathe.  However, there are a lot of other thread ratios that can be gotten at with the gear box.  I just have not had time to fully explore this.    It requires gear changes to go to metric and 13 tpi as you mentioned and comes with a number of metric conversion gears.   Changing the gearing is pretty much standard process.  I also have an old South Bend 10 heavy which I have used for a few years.  That old machine has a wonderful gear box that only requires two levers!   The SB10 also requires gear changes to get to metric but I never got around to finding a set.   But you should call and find out about delivery time as the supply chain problems may have depleted his inventory of either model. 

You did not post a picture of the front of the 1440GT.  I do not think there is a good picture on the site or in the manual of the front of the head stock so that you can see the tables and the levers.  However I have posted on where I describe my recent 3ph VFD conversion posting.


			https://www.hobby-machinist.com/thr...tronic-components-pm1440gt-vfd-3-phase.95058/
		


In this posting there are two descriptive documents, Part 1 and Part 2, attachments. Part 1 is  about the PM1440GT and its electronics as it arrives (Almost, I put it on casters on it at PM before it left PM to come to my location).   Anyway, inside the attachment "PM 1440GT Part 1 FacOriglElecDescript DNL L910_1440.pdf" you will find Photo 3 which show the cover listing of threading and feed rate tables as well as the two gear shift levers P, Q, R, ... and  W, X, Y, .. and knobs A-B and C-D.  I think the two knobs are just factors of 2x each, i.e.  1x, 2x, 4, and 8x.  These two knobs, as well as the upper left-right knob can be rotated to the vertical (up or down) position, but I think this disengages the drive.  The two levers set the basic threads.  The photo was posted as a high resolution image so you should be able to expand it to see the print very clearly.  (If HM lowers the resolution just let me know and I will post an original or send you one such).  (In the photo I had not removed the plastic protective cover yet and it is a bit wavy.) You will note on the TPI table printed at the top of the gear and belt cover that only a few possible combinations are actually listed. The table at the bottom is for metric.   There are to many combination to fit in the small space and the table includeds the 2x, 4x, 8x, lines so most are not even listed.  The combinations not listed do seem to work, but I have not tried them all.   I have not tried to do it yet, but I think one can figure out the gear ratios and then make a complete table of possible TPI without actually doing any measurements. (We will see.)   The two feed rate tables for the cross slide are redundant between the English and metric. 

Part 2 of my posting, "PM 1440GT Part 2 VFDDescript links wTable1 DNL LA10_1830.pdf", contains my design for the VFD conversion.  Somewhat different from what others have done as I got rid of the big relays and transformers that come with the machine, used a few transistors instead and then I could fit everything in the original lathe stand.... no external boxes.  The loose photos on the posting go with Part 2.  You have to look in Part 1 to see the original machine photos as there are only 3 of these.

I assume you will being using 3phase power as you are considering the TL (only 3 phase motor available), but if not you can get the GT in single phase as well.   I purchased the 3phase version knowing I was going to convert it.  This has several advantages, especially the drive frequency variation.  I sometimes wind electrical coils and it is nice to be able to set the frequency to a very low value and then gear the spindle down so that the spindle is turning very slowly.  I also put a 10 pulse per revolution Hall sensor so I can get nice RPM readings, but more importantly I am now installing an electronic counter so that I can determine not only rotations, but fractions of a rotation in my windings.  If you have not used a proximity stop for threading it is pretty handy.    Others have posted about this, but it comes easily, and is accurate, with the VFD conversion. 

Also, if you have not heard about it, there is a set up one can built called an "Electronic Lead Screw" that can generate any tpi you want with no gears or gear box.  It uses a encoder at the spindle to determine the rotation and phase and then uses a stepper motor at the lead screw to determine the rotations of the lead screw via electronics.  It appears to be a considerable built, but do able.  Others on HM have repeated this work.  See Clough42 on Youtube.   There are several videos of his efforts.   He even sells some of the parts needed.  



   But if you are making your living machining you may not have time for this effort!  Maybe I will do it someday!

Hopes this helps.  These are not easy decisions!

Dave


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## B2 (Oct 16, 2021)

Sorry, meant to mention that the lever positions on the PM1440GTgear box are upper: P,Q,I,R,T (5) and lower: W,X,Y,X (4).  So there are a combination of 4*5 gear ratios=20.  Then this is multiplied by the 4 possible factors of 2x.  1x,2x,4x,8x so that makes 80.  I have not figured out yet if they are very useful!  TBD.  Plus there are the change gears that are supplied.  I did not see a photo nor a list of the change gears that come with the GT, but I have attached a photo: stamped = 69, 65, 49, 42, 36, 25, 24T

Dave


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## Batmanacw (Oct 16, 2021)

B2 said:


> Sorry, meant to mention that the lever positions on the PM1440GTgear box are upper: P,Q,I,R,T (5) and lower: W,X,Y,X (4).  So there are a combination of 4*5 gear ratios=20.  Then this is multiplied by the 4 possible factors of 2x.  1x,2x,4x,8x so that makes 80.  I have not figured out yet if they are very useful!  TBD.  Plus there are the change gears that are supplied.  I did not see a photo nor a list of the change gears that come with the GT, but I have attached a photo: stamped = 69, 65, 49, 42, 36, 25, 24T
> 
> Dave



How wide is the bed on the GT? I'm having trouble finding that info.


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## B2 (Oct 16, 2021)

Here is a photo with a rule of the lathe bed.  By the way, my old SB has 10 threads by 7 multiples of 2.  Total is 700 different threads!


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## BladesIIB (Oct 16, 2021)

I can’t speak to the GT but I have the 1440TL and love it. It is a Taiwanese lathe and the accuracy has been great for me so far. I have been running it for a year now and you can see several of my projects and posts on this forum. Not having change gears does make the headstock longer if that is a factor. That is why the TL is longer overall than the GT. The TL also has a quick change gear box on the carriage to change feed direction even under power. I don’t believe the GT has that?  The quick change is a huge time saver because typically the direction you feed for facing is opposite the direction you feed for turning. Much faster than changing the direction at the headstock every time. I think they are both very nice lathes just depends what you need. Good luck.


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## B2 (Oct 16, 2021)

I agree the large tpi gear box selection and changing feed directions on the fly would be very nice to have.   I certainly like all of the possible tpi on my old SB.  The TL would not fit through the hall and the hall way turn going in to the shop area.  I even laid out the lathe foot print in cardboard and did trial runs  with the cardboard of the installing transport steps ... all before I purchased machine!  Also, I was pretty sure I would not be able to fit a lift in the area with the machine so I put it on casters.  Maybe I should have just knocked out the wall!   However, the bigger the lathe the more it, and accessories, cost.   

There are always compromises.   So, having a big budget is not the whole story.  You have to factor in what you will be using it for.   Big machines for big work parts!  Small machines for small features!  Most of my work parts are not large.  Mills:  CNC for repetition of parts or complex 3D parts.  Manual machine for one off quicker results.  My mill is CNC, but there are lots of small cut times I wish I could just turn the crank... not the insentive knob on the pendant.   It is not set up well for manual operation.  Also if you are doing a hand cut you can both feel the pressure on the crank as well as see the chips etc.  Hence, you just slow down or speed up.  None of this "intuitive feel" with CNC.  

One can never really know what one is getting just from the web sites, manual etc.  Even going there to look at the lathe is not complete.  I am still learning .... one has to use the machine for a while ....  

Dave


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## Tipton1965 (Oct 16, 2021)

Another thing to consider if you go for a heavier lathe like the TL is how to get it moved into it's final resting spot.  The GT can be lowered with a lift gate according to the PM website.  The heavier TL will be shipped on a flatbed and you will be required to provide the means to unload it and move it to wherever you need it moved to.  Unless you own a capable forklift or front end loader you will have to either rent one or hire a company to move your new machine.  This can be a substantial additional cost depending on who you hire.  And if the company can only get your machine moved close to where you want it, you are still tasked with the final placement duties.


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## Batmanacw (Oct 16, 2021)

Tipton1965 said:


> Another thing to consider if you go for a heavier lathe like the TL is how to get it moved into it's final resting spot.  The GT can be lowered with a lift gate according to the PM website.  The heavier TL will be shipped on a flatbed and you will be required to provide the means to unload it and move it to wherever you need it moved to.  Unless you own a capable forklift or front end loader you will have to either rent one or hire a company to move your new machine.  This can be a substantial additional cost depending on who you hire.  And if the company can only get your machine moved close to where you want it, you are still tasked with the final placement duties.



The other major consideration for me is the available space. The smaller GT can easily fit in my 12 x 20 shop in the space I have picked out.

The GT is a smaller and lighter lathe with several features I really want.

That being said, looking back over years the GT would easily handle ever project I've done. My latest project was a 11.5" sprocket but I was boring it out to 3". Then making sleeves 3" od and 50.1mm id.
I can run plenty of decent size projects on the GT. It's not like it's a mini lathe.


B2 said:


> I agree the large tpi gear box selection and changing feed directions on the fly would be very nice to have.   I certainly like all of the possible tpi on my old SB.  The TL would not fit through the hall and the hall way turn going in to the shop area.  I even laid out the lathe foot print in cardboard and did trial runs  with the cardboard of the installing transport steps ... all before I purchased machine!  Also, I was pretty sure I would not be able to fit a lift in the area with the machine so I put it on casters.  Maybe I should have just knocked out the wall!   However, the bigger the lathe the more it, and accessories, cost.
> 
> There are always compromises.   So, having a big budget is not the whole story.  You have to factor in what you will be using it for.   Big machines for big work parts!  Small machines for small features!  Most of my work parts are not large.  Mills:  CNC for repetition of parts or complex 3D parts.  Manual machine for one off quicker results.  My mill is CNC, but there are lots of small cut times I wish I could just turn the crank... not the insentive knob on the pendant.   It is not set up well for manual operation.  Also if you are doing a hand cut you can both feel the pressure on the crank as well as see the chips etc.  Hence, you just slow down or speed up.  None of this "intuitive feel" with CNC.
> 
> ...



How often have you found rigidity to be an issue?


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## ddickey (Oct 16, 2021)

Batmanacw said:


> How wide is the bed on the GT? I'm having trouble finding that info.


Definitely not 10.25".


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## Batmanacw (Oct 16, 2021)

ddickey said:


> Definitely not 10.25".


7.5"
I emailed PM.


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## B2 (Oct 17, 2021)

Sorry Folks. I did not mean to create confusion.  

Because it was not clear to me how you wanted to define the bedwidth spec, I simply posted a photo looking down at the bed ways of the GT.   I never use the end of a tape measure, but simply start at some location and then measure from there.  In this case I placed the 10" mark about at the top of the front way, outside edge of where the V is truncated at the peak.  Then you look to the other side and you will see that the back way.  So roughly you will see that the distance between the ways is about 5 to 5.25" depending upon "exactly" how you want to measure the ways.  If they were true V shape and you could measured from peak of the V to peak of the V you would get about 5".  However, I doubt that any salesman would give you that number when he could give you a larger one.  With the photo you can define bed width how ever you wish and still have the photo to determine the value.  Note this photo is high def so just enlarge it you want to see an area better.  If you want to defined it as the width of the maximum machined area that the saddle rests upon then you would get more like 7.5", but there is other parts that are not machined which add strength.   So take your pick.   

If you want a different photo just let me know.   

Trying...

Dave


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## Downunder Bob (Oct 17, 2021)

I would go for the TL every time regardless of size. Just a better machine.


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## ddickey (Oct 17, 2021)

@B2 No confusion here. I said not 10.25" because the TL is.


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## Batmanacw (Oct 17, 2021)

Downunder Bob said:


> I would go for the TL every time regardless of size. Just a better machine.



For me the TL is too big to fit in the area I have available, it cost $5000 more, and the GT is big enough for what I do. I have not ruled out the TL but I have to decide if I will ever see $5000 more value in my hobby shop fixing stuff for farmers occasionally. I can do a ton on my whimpy PM1030v, but it takes a lot longer than a bigger lathe. 

The TL should be significantly faster than the GT just because the rigidity will allow bigger cuts. If I was cutting large pieces of tough steel into small pieces of tough steel I'd see the benefit of the TL. I'm not hogging all day long. 

The GT can take 0.1" a side on low carbon steel on a 2" to 3" diameter. For my purposes that is plenty. Sure I'd like to take bigger cuts. Is that worth $5k in my shop?

I recently had a small job where I had to bore out about 10mm out of a cast iron sprocket bore. I had to do it on my mill because my little lathe couldn't swing it. 

On the GT it would have taken 15-20 minutes due to the interrupted cut. That is dramatically faster than my boring head. The TL would be able to be pushed harder but is it worth the money for me?


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## Downunder Bob (Oct 18, 2021)

Fair enough, only you can make that call. All the best with whatever you decide

Have you looked at the PM12xxT or 13xxT lathes as comparison They are great machines and somewhat cheaper


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## 7milesup (Oct 18, 2021)

All I can add to this conversation is do not buy a Chinese lathe. Taiwanese or old American iron.  If you know what to look for some old iron can be had, but it takes time to find them.
I had a PM1022, sold that, and bought an Eisen 1440E. The difference between the two is shocking regarding quality and capabilities. 
Good luck in your decision.


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## mksj (Oct 18, 2021)

With a budget of around 13K, the 1440GT is the only lathe with a 2" spindle bore. The Sunmaster lathes (ERL, RML, TL) are a step up in overall build quality and mass, so a bit less chatter and smoother in operation, but you can hit similar accuracy with all these lathes. Availability and also price increases may be a factor in what you finally decide to get. I ended up with an ERL-1340 mostly because I had a large investment in BXA sized tooling/chucks and also the delivery issues of the 1440TL due to wt./size was more difficult. The 1440GT can be delivered via lift gate, which is around the typical weight maximum for many shipping companies. Over 2000 lbs you need a forklift to offload the lathe and often need a rigger for local residential delivery. So if you were to go with a heavier machine, something to checkout before you purchase. Examples below.








						New ACRA 1440C lathe with Mark Jacobs VFD
					

Earlier this summer I received my new ACRA 1440C lathe. At 2700 pounds there was no way I was wanting to deal with the unloading duties.  I ended up having it delivered to a local crane service company.  When it arrived they unloaded the machine from the delivery semi and loaded it on their flat...




					www.hobby-machinist.com
				











						ERL-1340 Lathe VFD Control System and Additions
					

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...




					www.hobby-machinist.com


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## B2 (Oct 22, 2021)

@Batmanacw​
I have been looking at the threading gears built into my PM1440GT.   Not talking about manually changing the gears under the cover.   There are more than are listed on the cover, 6 times the 4 sets of factors of 2x=24.   In concept there are 4x4 possibilities, 16:  P,Q,R,T by W,X,Y,Z.   The position labeled "I" does nothing for threads only for feeds.   It is only used for the feed.    The question is how many and are they of any real value. My first measurement of this indicates there will be 16, but at least two are the same or nearly the same.  Also some of them are useless as far as standard threads are concerned

In doing so I have installed a counter to measure the spindle turns.  It seems to work well and I will have results for you soon.  However, in the mean time, if you have not pulled the trigger yet on the order you may want to look again at the PM1340GT.  It is cheaper and appears to be a very nice lathe.... It is a smaller with a smaller bore, but it appears to have more TPI settings with easier access.  More importantly, the way the TPI is selected is far better than the way it is done on the 1440GT.  Look in the manual at the front picture.  I find it very hard to get the 1440 levers to go to the selected letter position, but on the 1340 is is like my old Southbend .... much better.

If I can read the front of the 1340 it has 8 fundamental gear settings by 5 2x levels to yield 40 real TPI settings.  My SB has 10 fundamental by 7 factors of 2x to yield 70 TPI settings.  The 1440 has shown only 6 by 4 (2x) to yield 24.  The extra possible ones are TBD if of any value.  .

I have never tried to thread using the feed rates.  In concept, if they could be used then there might be even more TPI values, but useful???

Dave

Sorry for this Edit.  I originally had " My SB has 10 fundamental by 7 factors of 2x " backward.  So I just fixed it.


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## Cletus (Oct 23, 2021)

May be interesting to implement an Electronic Leadscrew on one of those larger lathes.  I am now doing such on my 16-year old Grizzly G4000 9x20


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## B2 (Oct 23, 2021)

I agree, but some work.  I am not fond of trying to position the levers and getting the gears to mesh on my PM1440GT.   Where to put the electronics?   Also, I have spent a lot of time doing my unconventional VFD conversion with extra features,  https://www.hobby-machinist.com/thr...tronic-components-pm1440gt-vfd-3-phase.95058/  and so it would be nice to just make things for a while.  With this VFD conversion and my RPM Hall sensor I was able to add a spindle rotation counter pretty easily.


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## B2 (Oct 23, 2021)

Ok. Here is what I measured, so far, for the TPI and then the mm/turn for my PM1440GT. This also displays the lever positions not listed on the PM manual or front of the lathe for available TPI. Note I use my Hall effect spindle counter, which makes 10 counts per revolution (10 magnets), to count the number of turns over a 10 inch travel distance. So the numbers should be pretty good....assuming I did not make any mistakes in distance which might have changed the number a little bit (distance change of a few 0.001". So I did the measurement at 10 inches and 10x the revolutions so I essentially divided my final count result by 100. I am only giving this for the 8x gear position. If you want the 1x, 2x, or 4x then just divide by 8, 4, 2 to get the smaller TPI values. The RED numbers are the ones that are on the front panel of the lathe, but I did measure them again also. So, while the numbers are not really standard threads some maybe useful. For example T-X at 26.2TPI /2 =13.1 TPI. Maybe this of value and is a close approximation to the thread that the PM manual says requires an external gear change. The metric numbers were gotten from the inch table. I may go back and do the same for the feeds. Note that for threading the "I" lever position is not connected (NC), but works for the feeds. Some of the other lever positions also seem to work for feed rates. (not listed in the manual).  

I will also attach the tables where the 2x factors have been computed.  What would be interesting is to see if any of these odd ball numbers get cleaned up better by using a different set of external gears.  The set used for these measurements are the same as the table on the front of the lathe.

Dave


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## Scott-ak (Oct 23, 2021)

I read the whole thread, I have the GT and run it almost every day (it's not my first or only machine). You lost me when you said you aren't fond of trying to position the levers. They are about as simple as it gets. Maybe a cnc would suit you better than a manual machine


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## B2 (Oct 24, 2021)

Hi @Scott-ak

Wow! Read the whole thread! Thanks for your comment, I am looking to learn more as I am still pretty much a newbie at machining.   I am glad you are happy and satisfied with your 1440GT.   Am I to assume that it is the PM version?   I have a CNC mill.  Don't think I want a CNC lathe yet.  CNC commonly gets in the way of getting the job done.... However, I can see that an electronic lead screw would make my 1440GT much easier to use.

Yes they are simple, in concept, but on my machine... not easy to move nor easy to move to the correct position.  Maybe after I have broken the machine in for a few years the edges of the gears will be worn off so that they slide together more easily. Maybe the edges of the gear teeth are still to sharp/precisely cut.   Also, sometimes just getting either thread gear handle to move is difficult.  Seems I spend a lot of time turning the spindle (by hand or via jog) to get the gears to align so that the levers will move.  Then there are the couple of positions where the P-Q-R-I-Twill not drop in.  I.e. nothing is engaged even though the lever is aligned with the letter.  I have even started threading only to have the lever slip a bit and the gear drop out.  The saddle just stops moving.   Likewise for the A-D knob.  Sometimes it just does not want to engage.  Getting it to disengage does not seem to be as much of an issue.  Yes, I am familiar with getting the gears to align, just difficult so far.    As far as dropping out once engaged I think this is just a poor design.  I suspect that there are small detent stops and springs with ball bearings that are suppose to fit into the detent (small depressions) to ensure that the lever is properly located.  I found these in the speed levers, H-M-L, when I had the knobs off while making a new front panel. I posted a picture of these detent stops in my VFD conversion posting.  If you want to see a picture of them then:  See photo 14a at post #4 of  https://www.hobby-machinist.com/thr...tronic-components-pm1440gt-vfd-3-phase.95058/ .  Anyway this detent method is just not a good way to lock the lever positions.  They should be spring loaded pins that drop in to place like what is done in the PM1340 threading levers or in my old SouthBend 10.

The middle position, M, is poor at best and sometime the gear does not engage, but more importantly, once running I find it sometimes jumps out of position and the spindle stops turning or grinds the gears.  Once, again changing these positions is still difficult. Maybe with gear edge wear (break in) it will be easier.   I am not the only one who has observed this jumping out of gear and it maybe partly due to the motor not running smoothly at a constant RPM.  In all fairness to the lathe and motor, the motor is not designed to run at non-60Hz frequencies.  But doing so is a good portion of why I went to all of the trouble to do a VFD conversion... to be able run at lower frequencies.  I also purchased 3 phase because the motors are suppose to run more smoothly than single phase.  (I may run some tests where I try to measure the motor frequency stability at both 60 Hz and at lower frequencies like 20 or 25.  The motor does work at even lower frequencies as I use the 6Hz for jogging the spindle.)  However, a 3HP motor designed for variable speed is not cheap.  Some folks have changed this motor, but not to a true variable speed design.  The worst example I have seen of this unstable motor running at variable speeds in in a you tube video.  Here it is shown that the speed lever will jump out, and back into, the M position while accelerating up to speed.  It is awful.  



.  I did not have nearly this much of a problem and thought I had it fixed by changing the VFD acceleration profile.  So I posted that result on YouTube:  



.  The fellow replaced his motor with a Marathon E470 motor.  But I do not think that this is a true variable speed motor.  Still expensive.

So, my reference to changing gears is largely due to my having a Southbend Heavy 10 for the last 20 years. I purchased it use from a machine shop. I think it was built in the 1970s.    This machine has the drop in pin style of gear box and works very well.  Only a minimum amount of hand spindle turning is all that is ever needed to get engagement.  These gears never drop out as the pins are secure.  Wonderful old machine.  The threading gear box has 10 main gear settings for each of the 7 factors of 2x gear settings to yield 70 possible TPI values. I suspect that you have seen it,  I will post an attachment photo of the SB TPI pin levers gear box. Anyway one only has to move ONE lever to achieve 10 thread changes.   (It was a disappointment that my modern machine offers so few, 6 an only if you move two levers.... see the red entries of the table I posted above, post #37)

Anyway, I thin the PM1440GT is over all a very nice machine and I am looking forward to using it for a long time.  One thing I may do at some point is to rebuild the SouthBend cross slide parts so that I can make decent threads......and parts of the tail stock. But there are a lot of other projects in the que first.   Most of the rest of it seems to be pretty good.

Dave.


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## mksj (Oct 24, 2021)

I think you should get some time on your 1440GT and become a bit more familiar with it, I do not agree that the motors cannot be used at other speeds other than their base speed/60Hz. The issue/limitation with a TEFC is they loose cooling efficiency below 15Hz, otherwise they run fine and typically  will run to 2X their base speed with no issues. Newer motor will have constant Hp above their base speed until around 100 Hz at which point the Hp may start to decrease. Inverter vector motors (4P) will run to 5400-6000 RPM in constant Hp all day long.  Standard motors have a 4:1 constant torque (15Hz), inverter motors are typically 10-20:1 (6 Hz) and vector motors 1000-2000:1 (0 Hz or 0 speed). Since the Hp drops in a linear fashion below the base speed, for all practical purposes you would not be running the motor on a lathe below 15-20 Hz unless jogging. In your case because you are doing slow speed (less than say 10 Hz) counting for winding, etc. the stock motor is not designed for that. But for its intended purpose and given the number of headstock speeds, the VFD just allows speed change on the fly and maybe to tune the speed to the work. Your motor will have tighter speed regulation then say a single phase motor, but absolute speed regulation is not needed in a manual lathe.

I installed the VFD control system on the first video 1440GT lathe, and I indicated that there were other issues that caused the motor to cog. In the vast number of cases, the motor cogging can be eliminated by shortening the acceleration to 2-3 seconds and going to linear acceleration.  This is based on about a dozen 1440GT system installs that I have worked on and also reflective of the programming I provide to the system owners. I am doing more VFD installs with other VFD models so stock 1440GT might behave differently with other types of VFD's.

The Marathon E470 replacement on the 1440GT is usually used for individuals who had a single phase machine and wanted to convert to 3 phase/VFD. Only with one individual (in the video posted) did he switch to the E470 (CT 20:1), and I found him a new one at 1/2 list price. It is a better motor, but the stock motor does just fine down to ~20 Hz. I am currently doing another 1440GT control system and sourced a new Marathon Y541 (CT 1000:1) inverter/vector motor in a shorter than normal configuration. Should be a good fit for the 1440GT and was 1/3rd list price. The major issue with replacement motors for lathes with motor's in the back is space, on the 1440GT the overall motor body length in limited to around 10" and requires a new motor mounting system because of the motor electrical box. Either of these motors will run at a crawl all day long. I have also done quite a few inverter/vector motors replacements on many other lathes, it is all about the install and the tuning. In every case the motors could not be stalled, did not have a speed regulation issue, or even got warm with continuous use.

The gearboxes on the lathes mentioned in this thread, I have either owned or worked/run all of these lathes and for the most part have not had the issues you are noting with yours. When the lathes are new, the engagement can be a bit stiff, and require and understanding of when the gear is engaged. One key is to have the drive engaged and manually turn/rock the spindle and feel the gear engage and the lever detent. The same goes for the half-nut, on a new machine if it pops out then it was not fully engaged. With a proximity stop system I have always recommended to manually engage the half nut statically by slightly moving the carriage until you feel it completely engage and then leaving it engaged through the whole threading cycle. There is no issues with thread registration, and when turning at 500-600 RPM, hitting the threading dial mark can be very difficult. All of these lathes will cut most of the common thread pitches one needs, the 1340GT has additional gears for odd metric pitches and cannot do a 11.5 pitch, other than that they are all very capable. If you need have a lathe with a stack of change gears or need oddball pitches, then go with an ELS system like this one: https://www.rocketronics.de/en/els/

With regard to the original discussion of this thread, all of the lathes mention will do very accurate work, if the requirement is a 2" or larger spindle bore than it boils down the 1440GT, 1440/1640TL, RML-1440/1640.  The latter two are made by SunMaster, they are a step up in weight/quality and have a universal gearbox (no change gears). If you are on a tight budget then go with the 1440GT if you can get one, if you have a bit more financial reserve and able to deal (delivery and moving) with a lathe that will be over twice the weight of the 1440GT then consider the SunMaster series.  If you do a lot of metric threading then the universal gearboxes on the SunMaster's is a real plus. If you are going to be doing larger diameter or heavy turning then maybe consider the 1640. Cost wise the prices just keep climbing and availability may be the determining factor as to what you finally decide. I have worked with 100's of VFD installs on these different lathes, most everybody has been very happy with their lathes, you can't go wrong with any of them.


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## Janderso (Oct 24, 2021)

7milesup said:


> All I can add to this conversation is do not buy a Chinese lathe. Taiwanese or old American iron.  If you know what to look for some old iron can be had, but it takes time to find them.
> I had a PM1022, sold that, and bought an Eisen 1440E. The difference between the two is shocking regarding quality and capabilities.
> Good luck in your decision.


I agree with the older iron Or Taiwan made machines. My mill is a Taiwan Sharp brand.
I was fortunate to find a Clausing Colchester 15x50 in very good condition. It was purchased from a machine dealer.
I paid less than $5,000 which left lots of money for tooling.
Quality machines are out there. This lathe is 2,700#= lots of rigidity and 7.5 hp with a spindle bore of over 2”.
New machines are tight and should be very accurate.
There are always so many choices.
The darn PM lathes are on forever backorder.


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## B2 (Oct 24, 2021)

Hi Mark,

Thanks.  Yes, I agree I need, and would love to have, more time on my lathe 1440GT.  For those of us who are really hobby types or use the shop to make things for other projects... and so do not make a living in their machine shop this lack of experience is all ways an issue.   The real reason I have a decent shop is that I ran into projects that needed parts that I could not easily get.  I have done a fair amount of precision optics and was building a very specialized microscope and needed to be able to do very fine threading at high TPI for some of my optical mounts and slides.  My old SB just could not do everything I needed any more.

I have had my solid state VFD installation running in one form or another for over a year now, and in the current version for most of the year, and have not observed any problems or failures.  It works a lot better than the operator!  I am still using the original motor as it seems to work fine.  At least... good enough for me.   I typically run it at 20-25Hz and certainly has no problem going faster, but when I want, it seems to run fine right down to 1Hz and I have not noticed any overheating or other issues.  Maybe I need to run it much much longer?  It even starts from a dead stop at 1Hz.   I jog at 6 Hz.     I doubt that it has much horse power at these low speeds, but it at least starts.  As the U-tube video showed, the fellow had problems during acceleration and I think he even mentioned interacting with you.  Yes, he said on his post that he switched to the Marathon E470 motor to fix his problems, but I don't think he mentioned you're getting it for him at 1/2 price!  If you find another at that price let me know.  I only see the ~$600+ adds.

Due to our previous discussion, regarding the proximity sense distance that one really needs for different cutting conditions,  I went ahead and added a counter to my VFD design.  I was going to do this anyway for my winding projects.    Using this feature was how I obtained the TPI values for the non-factory gear positions. (see the table above).  However, in this counter install, at the flip of a switch, it is also set up to start counting only after the proximity sensor trips.  This way I get an accurate measurement of the fractional (1/10 turn resolution) turns of the spindle during the electronic braking process to stop.  Also, who is to say that the Hitachi really breaks the spindle in the spec time?  As I noted I have a 10 magnet Hall sensor set up so can resolve 1/10 spindle turn.   I will get around to these measurements one of these days.   Anyway, when running at ~25 Hz I noted a small amount of RPM fluctuations in the spindle RPM and so it occurred to me that I could probably measure spindle speed stability for various settings, loads, gears, frequencies, etc.  I also have a spectrum analyzer in my shop that I could connect to the Hall sensor signal and do a  bit more detailed analysis.   It is also possible that this fluctuation is either due to my 10 magnets not all being perfectly space or that the counter is just not that stable.  However, I did test one like it with a decent function generator before and did not see this behavior. 

Stability perspective:  At 60Hz the measured RPM fluctuations appear to be a few parts in 1000, say 1000 +-5.  At 25Hz it is more like 1000+-10.  At less than 5 Hz it appears to be more like 1000 +-50.  Around 2-3 Hz I can hear the spindle speed gears clicking slightly which will stop if you put a drag load on the part.  At 1Hz there is no clicking from the speed gears.   Overall, for my work I consider all of these to be suitable.

At this point I cannot see any reason to change from my original stock motor as things seem to work fine.  No acceleration problems and I have never really observed any issues once the machine is up to speed.    However, all of this is TBD with more time and experience.

Dave L.


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## Beckerkumm (Oct 24, 2021)

This is all interesting as I like the vfd conversion Mark did for my lathe.  The Smart Brown has a 4-1 reduction using a Matrix clutch and an 8-1 backgear which is seldom used.  With just the clutch I seldom need to run less than 30 hz but routinely run 90-100 hz .  I like vector duty motors enough that if I find a Black Max, AB CM202, or Baldor IDNM NOS for less than $400 delivered I buy it for future machines.

There is a short write up over at Ruemema.de about the various spindle power choices by the guy who does maybe the most precise lathe restorations on the planet.  He has hesitations on vfd conversions but I think mainly on lathes with no clutch or speed range choices.  He talks about the torque at the tool moving when the hz gets too low but it is all above my pay grade to understand.  Dave


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## B2 (Oct 24, 2021)

From my readings on HM it appears that a lot of folks are happy with Mark's VFD conversions.  I think it is great that he provides this help to folks.   I did my own because that is what I do... and because I wanted to get everything in the original PM1440GT stand cabinet with a minimum of wire runs to other boxes.   It was shortly after I started looking into what was required that I realize that one really does not need the large transformer nor relays that are in the original machine at all.   That is also why I made my own braking resistor so that it would fit in the same volume with the VFD etc.   No big wires to run any where outside of the original electronics hole/cabinet in the lathe stand.

Dave L.


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## mksj (Oct 24, 2021)

The 1440Gt builds I do for others, either are all self contained within the lathe or the VFD is mounted in a separate cabinet. It depends on the space one has, each build is tailored to the individuals specs. The VFD is mounted vertically in the headstock cabinet for proper cooling, they are not designed for horizontal orientation. The braking resistor is a aluminum cast unit, typically 50 Ohms/500W mounted to the interior bulkhead, there is no exposed connections to  possibly come in contact with. Everyone does it differently, it is whatever works for each person. The control circuit topology is specific to the VFD used. The design and integration is dependent on a number of factors. I also integrated the complete control system into my lathe.

PM 1440GT complete VFD control system built into the headstock cabinet. MachTach tachometer and speed pot are in a separate enclosure mounted below the DRO.






Marathon E470 Motor installation, requires a new motor mount and modification to the belt cover.









ERL control system fully integrated into the stock cabinet, system is setup to accept single or 3 phase power.


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## B2 (Oct 25, 2021)

Hi Mark @mksj ,

Just to be clear, I am not trying to compete with you.  I think the service and assistance you are providing to folks is great and I am glad YOU are doing it!   It is clearly needed and I thank you for your contributions and comments.  I used them in selecting the VFD and setting up my VFD parameters.  While I am very happy to, and like helping folks, I have no interest in providing this sort of service other than maybe just to learn from the process, or especially to help others learn.  I certainly have no interest in trying to make a living or earn extra money doing so. Time is far more important.   Learning, teaching, and helping are my guiding objectives and I have lots of other topics I want to pursue before my time runs out!

Yes, "Everyone does it differently, it is whatever works for each person."  This diversity is good as much can be learned from the process.  I suppose the approach chosen depends a lot on one's design philosophies.   I had objectives in doing my own VFD design.  I wanted everything to be in the back of the lathe stand and I wanted a minimum of long or complicated wiring runs. Anyway as you stated:  "what ever works for each person."  It seems that my system works very well and there are no heating problems at all.  Most importantly I got to learn a lot in doing my own conversion.   You might want to try a solid state design sometime even if you want to mount the VFD vertically and put everything in an external enclosure.   I would even be willing to help you do so if needed.   I think you would find it takes less space, less time to build, and would cost less for the components.  This would be especially true if the control electronics circuit board(s) were a pcb.  You could even get it externally populated to avoid the point to point soldering that I did.  Of course I was learning about VFDs etc. during the process, but I did spend considerable time designing, building, and figuring out how to mechanically interface the transistor circuit board to the cables.  I posted my design in great detail so that others would not have to spend so much time at it.  https://www.hobby-machinist.com/thr...tronic-components-pm1440gt-vfd-3-phase.95058/

I did not want to put the VFD and/or braking resistor under the non-enclosed head stock.  I noted your design and thought it was clever, but difficult to get at physically.  Just as importantly, I did not want either a big "Sea Slug" shaped braking resistor but, especially, the vented case VFD to be exposed to the dirt, belt debris, cutting debris, and especially the dripping oil from the over head gears and belts as well as the dirt and dust from the floor below.    Yes, I know one could, and should build another shield/cover, for them when put in this location, but.....but why put them there if you do not have to do so.     Also, I hated the thought of running power and, especially, control wires back and forth between the circuits etc. in the rear stand enclosure and the VFD in the non-enclosed stand under the head stock .... as well as to the front control panel.  I learned long ago in electronics the fewer connections and the shorter the wires the better.  Exposed wires which are subject to wear, especially control wires to the front panel are an additional potential problem.  So, I did not want to hang an external enclosure on the wall.  

WRT to the VFD mounting I suspect that Hitachi suggests vertical mounting for two reasons.  1) Visibility and access to the VFD keypad in a standard front facing cabinet.  2) Airflow cooling ... as "warm air rises."  However, if one blocks the air flow from either below or above the VFD by mounting other things, i.e. cabinet walls or especially by heat generating devices such as relays, transformers, etc., this "warm air rises" conduction advantage of the VFD vertial mounting is eliminated ... or can make things worse.  Air flow around any heat generators or heat sinks is important for their own life time... so non-crowding of these devices is important.  Meanwhile, the built in VFD head sink fan provides greater air flow than, any "rising warm air" could possibly provide. One might worry about the fan failure, but these are rare and I suspect that Hitachi chose a decent small fan.   So I mounted/oriented my VFD so that one can glance down behind the lathe, look through the Plexiglass cover plate to quickly see the display, which I find to be very handy.   If one is willing to make seeing the VFD display a bit harder then it could be mounted vertially.  Space is not the issue in the rear enclosure.  Then I provided additional air flow, via the opening at the bottom of the cover plate (to be screen filtered for floor dust), via the fan opening in the enclosure opening.  I also reversed the fan in the VFD heat sink to agree with this air flow pattern design.  This air flow pattern also provides air flow over and through my open e-brake resistor assembly.  So the air flow layout is consistent.  I.e. air flows from the bottom left entry across the VFD heat sink,  over the e-brake resistor bank and then to the cover plate exit.  However, the best I can tell only having a vent would be more than sufficient.  The fan I mounted in my cover plate does not seem to be needed, but is a VFD longer life safety factor.  Furthermore I have checked things regularly and nothing ever seems to be more than barely warm.  In addition, the VFD heat sink is mounted to a smallist Al plate at the VFD back which helps to trap the VFD fan generated air flow inside the VFD heat sink......... so  heat from from the VDF heat sink flows into to the VFD back/bottom plate.  If I had found heat to be an issue at all I would have had to do is also mounted this plate to the large enclosure backing plate via bar bracket (like I did to support the ebrake resistor bank) that would then be mounted to the large plate that is used for all of the electronic components in the enclosure.   Then a thermal contact based conduction path would have been VFD heat sink to Al backing plate to large enclosure plate.   But it has not been an issue at all so just did not bother with this last connection.

While I have not wasted time to cut open a "Sea Slug" shaped resistor, I suspect that they are constructed in the same manner as the power resistors that I used in my e-brake assembly.... a high resistance wire coil surrounded/potted in a somewhat thermally conductive ceramic material to insulate it from the Al cover.  This resistance wire, when bare, can run at glowing hot without burning out, but hopefully it does not have to. The resistors are rated at a continuous usage wattage, but by the very design can dissipate far higher values for short periods of time.  It is the time average power that is important.  So when power is initially applied to one of these, it is cold and starts to warm up, but the heat diffusion to the Al surface is pretty slow even on lathe usage time scales.  (If you have an electric stove top think how long it takes for one of the burners to get hot. These are also made with a resistance wire buried in a ceramic.)  The lathe e-braking time, at least for non-monster sized lathes, is short compared to these thermal diffusion times.  Likewise, for lathes the time between e-braking events is long compared to the e-braking time (but is user dependent).   So there is a long averaging time for the heat dissipation.  That is, this duty cycle is very low.  So while I built an 8 resistor, 400 Watt e-brake resistor assembly, I doubt that one needs any where near this dissipation capacity for the lathe application. It seems to be way over kill.  Since most folks have never worked in this field they have little appreciation for heat and power dissipation so it is almost always over specified.  At one point in my life I designed power supplies so I did worry about, and studied and modeled, this quite a bit.   (An application where this sort of e-brake power dissipation might be needed is one where a continuous control system was being used and so the duty cycle on the e-braking could much higher.  An example of such might be in in the newspaper web handling process where very large heavy rolls of paper are constantly being accelerated and decelerate to maintain flow and to prevent delicate web (paper) breakage.   As I mentioned, I started and stopped (e-braked) my lathe a bunch of times as quickly as I could and then touched one of my resistors to find it had only slightly warmed.   It certainly was not hot to the touch.  (This could be much different if I was trying to over come the inertia a 4' diameter x 3' wide paper roll!) This was without the enclosure cover fan in place.  Even if they were to get hot they are mounted on a highly thermal conducting Al plate which in turn is mounted on the large Al plate that holds all of the other components.  So heat in the resistors, if not air cooled, would travel to the resistor mount plate and then from this plate to the large Al plate.  But it does not appear that this heat diffusion path is even needed.

Sorry for the Sea Slug (sea cucumber) analogy, but I sometimes scuba dive at Grand Cayman Island and every time I see one of these big e-brake resistors this is what I am reminded of...not very pretty and very slow moving.... https://en.wikipedia.org/wiki/Sea_slug#/media/File:Fish3923_-_Flickr_-_NOAA_Photo_Library.jpg .  PS.  There are some very pretty and smaller Sea Slug species, but they are less common around Grand Cayman.

Regards,
Dave


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## B2 (Oct 25, 2021)

Batmanacw said:


> How often have you found rigidity to be an issue?


I just saw this at the bottom of your earlier post.  Sorry I did not respond.  I am probably not the best person to answer this question as I have not done any big jobs yet.  I seldom do.  Most of my work pieces are small.  

However, I will say the following.  While leveling the lathe I found that when I adjusted 3 corners for the bed the 4th was commonly hanging in the air even though I was near level. Then when I would lower the hanging corner any more than just making contact the floor one of the other corners would lift.   That is the bed was so stiff that it did not seem to twist enough for me to observe it even with the weight being only on 3 feet or almost all on three feet rather than four.   During this I had the tail stock and tail stock stand etc weight hanging on that end of the lathe.  The saddle was in the middle of the ways.  When leveling the lathe I first tried to level the head stock, but there is no clear surface to use for measurement.   There are 4 leveling screws/feet under this end and 2 under the tail stock end.  There maybe a better way to do the head stock level, but my approach was simply to put a long bar ~1.25" dia. steel bar in the chuck and put a level on it and then to start adjusting the screws.  To get the front to back level I then put the level on the bed ways at the spindle.  My 90 year old concrete floor was intentionally poured to differ by almost an inch in height over the length of the lathe for draining with a little front to back slope as well.  The lower floor height is at the tail stock. In the z-axis I tried to match the level readings I had gotten on the spindle chuck bar etc.  So the leveling bolts at the tail stock are extended out ~ an inch longer than the head stock feet bolts.  

I also wanted to mention,  I find the big scale on the handle for the z-axis to be confusing at best.  It starts at 0 and goes up to 0.58" for one turn.  So once over that it starts at 0.0 again.  This means that if you want to go more than 0.58" then you have to add the next rotational readings to the 0.58."  This must be repeated for each turn.  This is confusing, but not impossible.  However, when you are going the other way you have to count down from 0.58 and then add that amount to the amount you have already traveled.  While math comes easy to me, I do not practice or naturally do counting down from 0.580" on a hard to read scale and then add this to 0.580.    So the solution to this is to get a DRO and never look at that wheel scale!  Besides, mine is off by 0.004" per turn anyway and this would have to be compensated for!  The z-axis the lead screw is 4TPI.  The cross slide is fine, 10TPI and 0.1" per turn as mentioned in the literature.  

Dave L.


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## Scott-ak (Nov 1, 2021)

I have not experienced the jumping out of gear. I have had plenty of times where I did not have it properly engaged. That occurs very seldom now after some time with the machine. As for changing the threading/feed gear box the only time I've had any real trouble is the C-D when changing for large pitches, 6 tpi etc. Even then it only takes bumping the jog and it goes in/out fine. I use the VFD for phase conversion. I simply don't see the need for all that other stuff. The gear train provides all the flexibility needed. The only time I've thot finer control of rpm might help is when picking up a thread for a repair and 50 rpm feels fast. I get it, some folks like to tinker w/tech and all the bells and whistles are cool but I don't see them as helping turn out a better part. I don't think PM machines are gods gift to machinists. They certainly have their shortcomings. Use'm for what they were designed for and it should serve you well. Trying to make it something it isn't just leads to frustration. Einstein said something like 'everything should be made as simple as possible and not one bit more'.


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## B2 (Nov 1, 2021)

Thanks Scott-ak, 

 I appreciate your comments, observations and perspective.  I will figure out the gear jumping some time, but I do find it hard to get the speed gear into the M position and keep it there.  I just do not feel the detent.  A little to one side or the other of the M position and the spindle just free wheels (does not engage at all). This would probably be ok, but is also dependent upon whether one is shifting from H to M or from L to M.  I suspect I will eventually get use to this and it may start to come naturally.  Or, I may I just need to tighten the detent ball spring more!

Yes, phrases like "keep it simple stupid" and "measure twice and cut once" do not go wasted on me. And yes, I agree, bells and whistles do not make better parts or necessarily enble making them faster.   However, I have no real regrets in adding the extra features to my VFD conversion. They sort of come with the VFD and I had to do all the work anyway.   So far I have found all of them, except the coolant add-ons, to be of value.  (The coolant pump system is just messy and I seldom need much coolant/lubricant for my jobs.) For those of us, who don't do enough machining to develop proficiency can probably appreciate the proximity sensor approach to threading, or approaching a desired shoulder, more than those who cut threads regularly.  

I am not really a machinist and make no pretense to be! You sound like you have the skills of a lot of practice.  By trade I am a research scientist and teacher and sometimes a technical consultant. (Electronics, optics, magnetics, materials...)  As such implementing the VFD conversion and exploiting the extra features of the Hitachi VFD is just sort of what I enjoy doing .... solving another puzzle, but certainly not a necessity!  As mentioned earlier, I have an old South Bend Heavy 10 (love the extended threading gear box) and I have messed up more than one re-thread due to my lack of skill or the wear on that old machine. Nevertheless, I have found the SB to be very helpful at making my small parts.   Nevertheless, I appreciate the simplicity of just turning on the old SB and its running the same way it did last week or month.  I seldom even move the belt over to another of the three fixed spindle speeds.  

I do a lot of what some folks would call strange, or unusual, experiments and so commonly need to build parts.  Hence, the machine shop ....  I very seldom make a second copy of any one thing, but do sometimes do the work over to achieve an improvement.  Some of these experiments require unconventional parts and I use my lathe and mill to make some of these.  I like having the RPM meter as I do run the motor at lower than conventional speed and it is nice just to see what the speed is.  I have recently, and am in the process of, added an electronic counter so that I can quickly determine the number of spindle turns (actually number of tenth spindle turns).  I have wound more than one magnetic core and being able to run the lathe at very low RPM, or to be able to jog it at very low rpm is nice.   Neatly wound tight cores, even on rectangular shaped mandrills, for magnetic devices, is a necessity.  On the SB I always had to turn the spindle by hand, which takes a long time and is hard work, when making 500 turns.  Also, I commonly would lose count and knowing the winding's number of turns is important.  When you lose count there is no easy solution... take it a part, discard the wire, and start over.  Now, I will have an automatic count!

Dave L.


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