# Keep PM-1236T or get back in line for PM-1340GT?



## skcncx (Nov 10, 2022)

*If your PM-1236T is ready in a few weeks for pickup... or you can wait until March/April 2023 for the bigger brother PM-1340GT... would you make the switch?*

According to PM, my PM-1236T should be ready for pick up in a few weeks. While I've been waiting the past couple months I've wondered if I should upgrade to the PM-1340GT.  PM will allow me to do that... but I have get get back in line. The PM-1340GT is not due in until March/April next year... A little fear of the "better option" is kicking in, though... in reality, for hobby use I can't make a strong logical case.

Other than the obvious 1" larger swing, heavier, 4" extra length and hardened gears... they are supposedly similar overall build quality.  Both appear to be great lathes given their size.

*What am I missing?*

My intermittent hobby use likely won't see the absolute need for hardened gears and the extra 1" swing doesn't sway me, the extra 4" length may come in handy.... seems like keeping the PM-1236T is the logical choice... just a nagging feeling I should consider getting back in line for the PM-1340 GT.

I'll post pics soon, but I've done a custom stand using David P Best design with a frame built around a harbor freight top tool chest.... it can handle either lathe.


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## Cadillac STS (Nov 10, 2022)

Is the spindle bore the same?

Is the larger lathe a new model upgraded from last years?  What is new?


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## skcncx (Nov 10, 2022)

Cadillac STS said:


> Is the spindle bore the same?
> 
> Is the larger lathe a new model upgraded from last years?  What is new?


I don't believe anything is new on the 1340GT... the comparison between the 1236T and 1340GT is the same as it has been for awhile.

Bores are both 1 9/16.  Gear boxes the same... they are VERY similar.

*PM-1340 GT*... "All shafts in headstock hardened and ground along with gears which are precision ground, set in with a close tolerance fit, which leads to longer life and quiet running when compared with other geared head lathes*"

Is this upgrade on the 1340GT a game changer?

PM-1236T*... Meant for hobby-type or light industrial users who are not using the machine for heavy production, but still want the benefits of a high quality machine at a lower price point (Typical examples where the PM-1236T is suitable: high end hobby users, R&D shops, or industrial users who may use it a few days per week. If it will be used daily, please select PM-1340GT, gears and shafts in the 1340GT are different, they are a hardened alloy steel, meant for daily use, pro gunsmiths, industrial shops, production, etc.)

This is my use case for sure... but I've never (almost never) wished I didn't get the "better" option after purchase.


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## davidpbest (Nov 10, 2022)

Based on conversations with a PM-1236T user, the CH (that's the distance between the top of the compound and the center-line of the spindle) is approximately 1.2" on the 1236T.  The same CH dimension on a 1340GT is closer to 1.7".   That suggests to me that the 1236T would be best equipped with an AXA-sized QCTP rather than the BXA-sized unit that is appropriate for the 1340GT.  I'm not saying you can't use a BXA on the 1236T, but you will have more tool height restrictions and challenges than you would with an AXA-sized QCTP.   Therefore, if you plan to use an Aloris-style QCTP, and you want the larger tooling sizes that the BXA-sized units allow, you'd be better off with the 1340GT.

If you want more specifics on this, DM me.


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## skcncx (Nov 10, 2022)

davidpbest said:


> Based on conversations with a PM-1236T user, the CH (that's the distance between the top of the compound and the center-line of the spindle) is approximately 1.2" on the 1236T.  The same CH dimension on a 1340GT is closer to 1.7".   That suggests to me that the 1236T would be best equipped with an AXA-sized QCTP rather than the BXA-sized unit that is appropriate for the 1340GT.  I'm not saying you can't use a BXA on the 1236T, but you will have more tool height restrictions and challenges than you would with an AXA-sized QCTP.   Therefore, if you plan to use an Aloris-style QCTP, and you want the larger tooling sizes that the BXA-sized units allow, you'd be better off with the 1340GT.
> 
> If you want more specifics on this, DM me.


Thanks! Yes, we've had a few DM conversations on this aspect, mainly related to the Aloris #71 and #77 parting tool.  The 1.7" certainly gives you more room... as the BXA on the 1236T with only 1.2" CH can be limiting, essentially requiring the need to bottom out many tools to get cutter on center line.  

Cart before the horse, I've already sourced my Aloris branded BXA tool post, so either lathe, BXA is what I have .  In my head, I've resolved to the 1.2" CH... but my thoughts can change on that for sure.

I'm sure BOTH the 1236T and 1340GT will be great for me... and while I don't care to wait another 4-6 months... this is the last lathe I'll buy... unless I made money and had a "real", non hobby reason to buy another.

*Anything else that would make it worth waiting for?*


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## TorontoBuilder (Nov 10, 2022)

We just finished a variable speed conversion on a 12x37 that I love... but happily are in the midst of selling it on the hopes of getting a 13x40, neither is a PM but I'd do this route with any brand of lathe because those extra inches are sometimes vital to a project.


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## Ischgl99 (Nov 10, 2022)

I had a similar dilemma when I bought my 1236T two years ago, it was in stock and the 1340GT was a few months out.  I decided to get the in stock machine and not wait any longer, I would not have the patience to wait another 4+ months after all the time you have already waited.  
I didn’t think the hardened gears was a major issue, maybe it will have an impact at some point, but if I need to replace gears, I can probably replace them with hardened gears.  The 12” swing or 36” length hasn’t been a limiting factor, but having it and not using it is always nicer than not having it and needing it, so point in favor of the 1340GT.
David’s point about the AXA toolpost being ideal on the 1236T is valid.  I already had an AXA toolpost, so started with that and planned on a BXA, but decided against that since it would be close to bottoming out with 5/8” toolholders.  Since you already have the BXA, you might run into some clearance problems with the 1236T, but it doesn’t seem like it would be something you couldn’t modify around, so I wouldn’t use that as a deciding factor.  One plus for the 1340, you might be able to use larger parting blades on that one then you would be able to on a 1236.  I haven’t checked that, but having the extra half inch to center height could give you more options in a BXA size post.

If both were coming in at the same time, I would say go for the 1340, I most likely would have if both were in stock.  But, I put more emphasis on getting a machine and getting to work, so didn’t wait, and don’t regret the decision at all.


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## 7milesup (Nov 10, 2022)

skcncx said:


> fear of the "better option" is kicking in


To alleviate that fear you should get a 1440GT.  It is a great fear reducer.


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## RandallsRaceShop (Nov 10, 2022)

Don’t make a decision you’re going to regret. 
If you think you want the 1340GT, get it! 
It’s the one I want & so a couple of months ago I placed the order & made the down payment! 
I’m following the guys’ advice around here, “buy once, cry once”...,...,...I’m buying once & I’m most definitely going to cry once!


This is just my .02


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## skcncx (Nov 10, 2022)

Ischgl99 said:


> . Since you already have the BXA, you might run into some clearance problems with the 1236T, but it doesn’t seem like it would be something you couldn’t modify around,


I figured, or it seems... just about ANY machine, there's always some working around "something".... I have always found it odd PM doesn't pair it with an AXA setup... I've already sourced various 5/8 shanked tool holders and already thinking I'll be getting the XL tool holders that do lower it another small it.

I think even David had to right something up on his PM-1340GT for one tool because he couldn't get it high enough. So I guess, high or low could be issues.



Ischgl99 said:


> But, I put more emphasis on getting a machine and getting to work, so didn’t wait, and don’t regret the decision at all.


Yep, that's what I'm waffling on.  Placed my order end of July.. what's 5 more months in the long run.  I'm planning to augment with a mill as well, likely their 833TV bench top mill and that might be available mid December so that could wet my appetited for a bit.  I have not real plans/project for either.... just setting up shop... all this tooling while I dig into metal working/machining.

Either way, if I decide to defer or just pick up on my current order... I'll have a great lathe.


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## skcncx (Nov 10, 2022)

RandallsRaceShop said:


> Don’t make a decision you’re going to regret.
> If you think you want the 1340GT, get it!
> It’s the one I want & so a couple of months ago I placed the order & made the down payment!
> I’m following the guys’ advice around here, “buy once, cry once”...,...,...I’m buying once & I’m most definitely going to cry once!
> ...


I'm not sure what I want  or will wish which I should have gotten.   Both of these are the right size/class of lathe for me.  Since they are so similar, I'd prefer they only offered one... decision made then and I don't have to slice/parse the slight similarities and differences.

If I do switch my order, I'll only regret the wait while I'm waiting, not after it's here.  Cost between the two is about $1,200, since it's about $500 more for just the lathe and you must get your own chuck, figured $700 for that.  Not much in the end.


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## skcncx (Nov 10, 2022)

7milesup said:


> To alleviate that fear you should get a 1440GT.  It is a great fear reducer.


ha, funny how all this started.  Atas 618, great to test my desire for this stuff... then considered the PM-1228 as a big upgrade... but thought, I really want more quality... landed on PM-1236T Taiwanese built... and now thinking... just a little more wait & cost for 1340GT.  1440GT... I guess I just need a few days.... though, the extra $4K, that get's me pretty far into a purchase of a benchtop mill.


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## mksj (Nov 10, 2022)

I owned the 1340GT previously, started out wanting something smaller, then 1236 but ended up with the 1340GT. Although I was space limited (1 car garage for my shop at the time), the 1340GT gives one a bit more dimensional space. So you also need to think of the size chuck and also the jaws hanging out. Going with a Taiwanese (or similar) machine was important because of previous QC issues I had with a  Chinese mill. The 1236T and the 1340GT  are basically the same lathe other than the slightly taller headstock. Going to the 1440GT is a big jump up in cost, and at that price range there are a number of other lathes to consider, including some good used machines. As they get bigger, they more stable, but are harder to move. 

So a few things about the 1236T vs. the 1340GT. The 1236T comes with an economy chuck, which you will probably replace in short order for a better chuck. So yes it comes with a chuck, but I would recommend their 6" Adjustable Ultra Precision 3 Jaw Chuck, D1-4 Mount in either case. Probably add the 8″ High Precision 4 Jaw Independent Lathe Chuck, D1-4 Mount and their 5C (or ER40) Adjustable Collet Chuck, D1-4 Mount. At the end of the day you will want/need all three, they all serve a different use, and they are reasonably priced. This makes the price difference between the lathes around $700. I would also recommend going 3 phase, the motors will last a lot longer and you will not be limited as to stop/starts, and you will get better surface finish. How you power it is your choice, there is some posted information on the basic VFD install available through QMT and also posted in this site. Yep, adds a bit more cost but gives way more control over the lathe. In my case with the 1340GT the quick electronic braking was a must. My reflexes just were getting a bit slower as I got older. 

Unfortunately tooling up for the lathe is an expensive proposition, and easy to spend a substantial amount doing so. The one thing I found out the hard way, was buying cheap, I almost always ended up replacing it and buying  better quality  that I have used ever since. In particular with chucks and tooling, I must have gone through a 1/2 dozen chucks that were crap, and finally bought some decent ones that I have been using for many years.


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## Aukai (Nov 11, 2022)

Free shipping to California.


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## skcncx (Nov 11, 2022)

mksj said:


> I would recommend their 6" Adjustable Ultra Precision 3 Jaw Chuck,


I was eye balling that one as well.  Also considering a Toolmex set tru chuck, but similar size, it's about $1200 vs the $700 QMT one.

Not sure what size, it seems 6", any reason not to get an 8" 3 jaw?  Seem the 1236 and 1340 are usually paired with 6" 3 jaw and 8" 4 jaw... not sure if there's a primary reason.



mksj said:


> I would also recommend going 3 phase, the motors will last a lot longer and you will not be limited as to stop/starts,


I eventually plan on 3 phase, VFD convert but went single so it would be easier to get started.

*Can you explain the "not be limited as to starts/stops?"*  Is that because without electric braking it takes a while to spin down to a full stop?  I much prefer electric, fast braking as well.  Maybe if I switch my order and wait longer, just go 3 phase from the get go.



mksj said:


> there is some posted information on the basic VFD install available through QMT and also posted in this site.


Thanks, I have those documents!  QMT actually referred me to this site.. they don't support the conversion.



mksj said:


> Unfortunately tooling up for the lathe is an expensive proposition, and easy to spend a substantial amount doing so


Yea, I'm feeling that.  I've sourced a good starter amount of tooling so far.. 5-6 tool holders (screw type for carbide inserts), Aikron DRO, Aloris BXA post, tail stock chuck, precision level, a few BXA tool holders... I'm easily over $1k in just "getting started" set.


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## skcncx (Nov 11, 2022)

Aukai said:


> Free shipping to California.
> View attachment 426298


Got me thinking!  It'd be a no brainer if it was a days drive.  I have hesitancy on being responsible for shipping such a large item... picking up from PM there's less worry... maybe all irrational.


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## Ischgl99 (Nov 11, 2022)

skcncx said:


> Either way, if I decide to defer or just pick up on my current order... I'll have a great lathe.


That is it in a nut shell, both are great lathes that will give you many years of enjoyment.  

Mark mentioned the economy chuck that comes with the 1236T, it is average at best, but it does work.  It doesn’t have any manufacturers markings on it, so I assume it is Chinese.  Mine came with about 0.007” runout, I disassembled it and cleaned it and it wasn’t any better, but after some use it is now about 0.002”.  I suspect there was a burr in there somewhere I didn’t find when cleaning it and eventually wore off.  The included chuck did have an influence on my decision to get the 1236T, but I wrongly assumed since I was buying a Taiwanese lathe that a Taiwanese chuck was included.  I don’t use it all that often, I prefer to use collet chucks or my 4 jaw chuck.  If you buy a 3 jaw chuck, I would get one with replaceable top jaws so that you can make custom top jaws.  I have a 5” Bison 3 jaw from my old lathe that I was considering using on my lathe because of the top jaws, but it fits perfectly on my dividing head, so that is it’s new home.


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## skcncx (Nov 11, 2022)

Ischgl99 said:


> That is it in a nut shell, both are great lathes that will give you many years of enjoyment.
> 
> Mark mentioned the economy chuck that comes with the 1236T, it is average at best, but it does work.  It doesn’t have any manufacturers markings on it, so I assume it is Chinese.  Mine came with about 0.007” runout, I disassembled it and cleaned it and it wasn’t any better, but after some use it is now about 0.002”.  I suspect there was a burr in there somewhere I didn’t find when cleaning it and eventually wore off.  The included chuck did have an influence on my decision to get the 1236T, but I wrongly assumed since I was buying a Taiwanese lathe that a Taiwanese chuck was included.  I don’t use it all that often, I prefer to use collet chucks or my 4 jaw chuck.  If you buy a 3 jaw chuck, I would get one with replaceable top jaws so that you can make custom top jaws.  I have a 5” Bison 3 jaw from my old lathe that I was considering using on my lathe because of the top jaws, but it fits perfectly on my dividing head, so that is it’s new home.


Yea, hear you on the chuck... I was planning to source another, figured that was in the mix soon.  Though, like you did, the economy chuck, if I keep my 1236T order, could be used in some way for mill work.  At the same time, it will be good enough with my beginner skill level.

Although, I think I'm talking myself into switching. I'll also switch to 3phase and at least start with a basic VDF setup.... The 3 phase is even farther out, May/June 2023.... oh well, I can and have plenty other projects so the wait is not preferred but I have that luxury as it's all hobby related.


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## mksj (Nov 11, 2022)

The optional 6" set true style scroll and 8" independent QMT/PM chucks are made in Taiwan and they both offer very good quality/vale, and I see no reason to pay more at this point. The value of a good chuck is not only the runout (TIR) but also the grind of the jaws and the skew when clamping stock. I have also had issues with balance problems of cheaper chucks due to irregular castings, this can be a significant issue with the 1236T/1340GT because they are light weight lathes. The TIR of a chuck is primarily an issue if you chuck up your stock multiple times and each time the chuck will hold the stock slightly different. A 8" scroll chuck is pretty darn big, in particular for this lathe. Most people prefer a 6.3" (160 mm), and for bigger stock use a 4J 8" independent.  That being said, if you just wanted one chuck to do it all, you might look at the Bison 4 jaw 8" combination chuck, this is a scroll plus independent in the same chuck. It is easy to get the stock in/out and dial down the TIR, the scroll repeats to around 0.001", but it is a heavy chuck around 65 lbs. I use to use the combination chuck and the 5C for almost all of my turning, but these days I am back to using my 6" PBA setrite (set-Tru) 3J because it is less cumbersome switching chucks.

A single phase motor usually used an electrolytic start capacitor which is energized for a very short period when starting the motor,  the capacitor can heat up very quickly with repeated on/off cycles and will fail. The other concern with single phase motors, is that if the motor does not wind down before you reverse it, it can continue in the same direction say if you through the spindle switch from forward immediately into reverse.

A single phase motor also delivers power in pulses, which can show up in the surface finish of the piece you are turning, a 3 phase motor the power delivery is smoother because each wave is staggered by 120 degrees. The issue with buying a single phase lathe and then converting it to 3 phase at a later point is that both of these lathes have very small space for the motor. You are very limited to the type of motor that will fit and a replacement motor new can be $600+ unless you get lucky and find one on eBay. There are numerous threads on replacement motors for these lathes. The 1236T the motor space is even smaller, so a very tight fit. The stock 3 phase motor for these lathes works well enough and I have not heard of any issues with it.

You can get very deep in the hole when tooling up, I did it over years as I learned more, and got rid of some of my initial purchasing mistakes. If you plan on keeping your machines for a long time (and using them), then you are left with only buying consumables down the line.

If I recall, Mike's (Aukai) is 3 phase with a VFD, would be a good deal if shipping could be worked out.

Bison 8 Inch Combination Chuck, note the clearance to ways can be an issue when holding stock. Also be mindful that the jaws have a maximum extension to keep enough teeth in the scroll portion of the chuck.




PBA 6.3 Inch 3J Scroll Setrite




PM/QMT 8 4 Jaw Independent (jaws were offset to bore/thread a hole off center)




5C chuck at speed, much safer for the hands when working close to the chuck.


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## skcncx (Nov 11, 2022)

mksj said:


> The TIR of a chuck is primarily an issue if you chuck up your stock multiple times and each time the chuck will hold the stock slightly different. A 8" scroll chuck is pretty darn big, in particular for this lathe. Most people prefer a 6.3" (160 mm), and for bigger stock use a 4J 8" independent. That being said, if you just wanted one chuck to do it all, you might look at the Bison 4 jaw 8" combination chuck, this is a scroll plus independent in the same chuck.


I don't see myself changing chucks at lot and when using my Atlas 618, I did find myself re-chucking parts about half the time... so TIR is somewhat important to me.  So far, all I've used is a 3 jaw scroll chuck.

*I was not aware of a combination chuck.... I'll have to check that out.*

I did notice the PM set tru 3 jaw was balanced and that seems like a great aspect to their chuck since these lathes can't overcome an imbalanced chuck with just their mass.



mksj said:


> A single phase motor also delivers power in pulses, which can show up in the surface finish of the piece you are turning, a 3 phase motor the power delivery is smoother because each wave is staggered by 120 degrees. The issue with buying a single phase lathe and then converting it to 3 phase at a later point is that both of these lathes have very small space for the motor. You are very limited to the type of motor that will fit and a replacement motor new can be $600+ unless you get lucky and find one on eBay. There are numerous threads on replacement motors for these lathes. The 1236T the motor space is even smaller, so a very tight fit. The stock 3 phase motor for these lathes works well enough and I have not heard of any issues with it.


I was antsy to get my PM-1236T order in a few months ago and settled on single phase (quicker shipping and less hassle to get started) but I know in the end a 3 phase is better... the braking feature will become a big deal for me.  Already aware of the limited options and tight fit... so now... seems like going 3 phase really is the better option from the get go... and certainly will need to rely on all the VFD/wire schematics already posted on this site... I can do the physical wiring up but must rely on some documentation.

Thanks for all your input!


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## davidpbest (Nov 11, 2022)

skcncx said:


> I don't see myself changing chucks at lot and when using my Atlas 618, I did find myself re-chucking parts about half the time... so TIR is somewhat important to me.  So far, all I've used is a 3 jaw scroll chuck.
> 
> *I was not aware of a combination chuck.... I'll have to check that out.*


I'll underscore what others have said - ultimately you will want a 3-Jaw scroll, a 4-Jaw independent, and some kind of collet chuck (ER40 or 5C).   I have a 6" 3-jaw made in Taiwan with Set-true adjustability provided by PM - it's in the same general quality category as my Bison chucks.  I also have their 8" 4-jaw which is fine, but nothing special.  To me, one often overlooked aspect in selecting a chuck is to pick versions with 2-piece jaws.  That gives you the flexibility to put on sacrificial jaws and makes it a lot easier to rotate them 180°.


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## skcncx (Nov 11, 2022)

Well..... I made the switch... back in line for another 6-7 months.  That's the only downside, well cost too but those are non issues once you get past them.

*Came down to these primary reasons... *(no single one, all combined aspects of the change)

Single phase to 3 phase
I'll get the HITACHI-WJ200-015SF VFD as long as it supports the braking resistor option.  That seems to be the "go to" for this lathe.  May try out the auto stop feature when threading toward chuck (one day, some day kind of thing).



Taller compound to center line height for greater range for tooling
Already have the BXA Aloris tool post.
1.2" on 1236T vs 1.7" on 1340GT.



Planned on getting a better chuck anyway... now I have to.  The 1340GT doesn't come with one.
I'll heed the advice from others... start out with quality set-true 3 jaw and add on from there.



Extra 4" length may come in handy one day


Focus on getting benchtop mill for this winter and the myriad of other projects I have in the queue... while I wait.


I won't continue to second guess my order on the 1236T

If I hadn't already started with so much tooling that overlaps with Aukai's PM-1340GT package, I'd go that route... still food for thought.


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## skcncx (Nov 11, 2022)

davidpbest said:


> I have a 6" 3-jaw made in Taiwan with Set-true adjustability provided by PM - it's in the same general quality category as my Bison chucks.


I'll likely land on PM's option.  There's a supplier near me that has the TMX Set Tru 3 jaw for $800... but no backing plate and that's nearly a $400 extra charge.  So $500+ compared to PM's option.



davidpbest said:


> To me, one often overlooked aspect in selecting a chuck is to pick versions with 2-piece jaws. That gives you the flexibility to put on sacrificial jaws and makes it a lot easier to rotate them 180°.


Out of my ignorance are these equivalent?... "2-piece jaws" and "Removeable bolt on jaws can be reversed".    PM's adjustable 3 jaw has removeable and soft jaws available... I assume that's the same as saying "2-piece jaws".


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## davidpbest (Nov 11, 2022)

skcncx said:


> Out of my ignorance are these equivalent?... "2-piece jaws" and "Removeable bolt on jaws can be reversed".    PM's adjustable 3 jaw has removeable and soft jaws available... I assume that's the same as saying "2-piece jaws".


Yes, but you might ask if they are American or Metric tongue and groove compatible.  Here is where I get my jaws:






						MonsterJaws Mfg - High Quality Chuck and Vise Jaws (Machinable Soft Jaws)
					

MonsterJaws Mfg Chuck Lathe Mill Vise Machinable Carvable Soft Jaws Aluminum Steel




					monsterjaws.com


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## Beckerkumm (Nov 11, 2022)

I'll second ( or third ) the recommendation for a quality combo or set tru 6" chuck.  I'm primarily a used guy but don't think used is a good option for a chuck unless NOS or very lightly used.  There is one exception to my rule.  I have watched for a decent looking used 8" with outside jaws for the larger diameter stuff.  It doesn't need to be set tru and can even be direct mount which are fairly unloved and often priced to reflect that.  Putting a turned slug into the smallest part of the jaws allows you to bore out the second notch and then putting a turned piece into the second notch allows you to bore out the third and give very good concentricity for the two positions.  The scroll needs to be decent to be repeatable but not a horrible risk if you are careful when buying.  Dave


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## davidpbest (Nov 11, 2022)

skcncx said:


> Out of my ignorance are these equivalent?... "2-piece jaws" and "Removeable bolt on jaws can be reversed".    PM's adjustable 3 jaw has removeable and soft jaws available... I assume that's the same as saying "2-piece jaws".


I just checked the PM web site.  This is similar to the 6" 3J I bought from them - different manufacturer, but very similar in all regards:






						6″ Adjustable Ultra Precision 3 Jaw Chuck, D1-4 Mount – Precision Matthews Machinery Co.
					






					www.precisionmatthews.com
				




This is the chuck they supplied for me (with depth-stop blocks I added): made by Chandox in Taiwan:


__
		https://flic.kr/p/XU9P1r

I also own this chuck, which would be the functional equivalent to the one PM sells, although this Bison does not come with a D1-4 backplate:





__





						6" BISON  3 Jaw  SET-TRU Chuck Forged Steel  7-866-0600
					





					www.ajaxtoolsupply.com


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## skcncx (Nov 11, 2022)

davidpbest said:


> I just checked the PM web site.  This is similar to the 6" 3J I bought from them - different manufacturer, but very similar in all regards:
> 
> 
> 
> ...


PM's 3 jaw adjustable is most cost effective option.... I was looking at the TMX version from ajaxtool supply https://www.ajaxtoolsupply.com/tmx6settrufo.html and their D1-4 backing plate https://www.ajaxtoolsupply.com/tobaforse6in.html.  Bison is just about $100 more for backing plate and lathe on each time.

Both TMX and Bison are forged... not sure really the differnt between forged, steel and the semi-steel the make them from.  PM's "balanced" seems great... maybe that's standard for forged chucks.

PM's on back order until April next year... though, no big deal, since I switched to 3 phase 1340GT.... that's not due until May/June 2023.


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## mksj (Nov 11, 2022)

Semi-steel is a lower grade cast steel, as such the chuck is rated to a lower top speed, forged is a higher grade steel which has a higher maximum speed. This becomes more important if your lathe can achieve those maximum speeds, and you are spinning a large chuck. Example is an 8" semi-steel will usually be rated to 2,000 RPM, where a forged would be 2,500 RPM. Otherwise they are the same, other than semi steel is much less expensive. On a smaller chuck, say 6" you are looking at maximum speeds in the 5K range, so pretty much a non-issue. Do recall recently another HM member that bought an Bison 8" combo in semi-steel, the company (Small Tools) found they were on back order and offered him a forged for the same price.

*Act Fast, this is probably one of those deals that one rarely sees. This is the Bison 8" combination chuck at 47% off ($794) from Grizzly. *You can buy a Gator D1-4 back plate (about 1/2 the cost of the Bison), that is what I installed on mine.








						8" 4-Jaw Plain Back Independent Chuck at Grizzly.com
					

The jaws on this chuck move independently, so you can use them for holding odd shaped pieces or where zero tolerance is required. Forged steel body with a large thru-hole, this chuck has heavy-duty reversible jaws, (hard top jaws and hard master jaws), and a set of mounting bolts and eye bolt...




					www.grizzly.com
				




Link to chuck at Bison America




__





						Bison
					






					www.bison-america.com


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## skcncx (Nov 11, 2022)

mksj said:


> Semi-steel is a lower grade cast steel, as such the chuck is rated to a lower top speed, forged is a higher grade steel which has a higher maximum speed. This becomes more important if your lathe can achieve those maximum speeds, and you are spinning a large chuck. Example is an 8" semi-steel will usually be rated to 2,000 RPM, where a forged would be 2,500 RPM. Otherwise they are the same, other than semi steel is much less expensive. On a smaller chuck, say 6" you are looking at maximum speeds in the 5K range, so pretty much a non-issue. Do recall recently another HM member that bought an Bison 8" combo in semi-steel, the company (Small Tools) found they were on back order and offered him a forged for the same price.
> 
> *Act Fast, this is probably one of those deals that one rarely sees. This is the Bison 8" combination chuck at 47% off ($794) from Grizzly. *You can buy a Gator D1-4 back plate (about 1/2 the cost of the Bison), that is what I installed on mine.
> 
> ...


That is a good deal. So , still figuring out the “combination”… independent and scroll type? Or is it scroll but you can fine adjust them independently… I must be dense on this.


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## mksj (Nov 11, 2022)

Think off a scroll chuck and then add a screw type adjustment on top of that that acts the same as an independent chuck.  Look at the previous picture and you will see the carrier that is operated by the scroll and then the jaw position with a scroll adjuster between them,

You use the scroll to get the work in/out of the chuck and for repeat work that you do not need sub 0.001" accuracy on the repeat. You can tweak opposing jaws to null out any TIR if needed. As there are slight difference in jaw torquing, this accounts for a slight variation with repeat use of the scroll. The other plus of this chuck is three-fold, first it can hold work down to 0.2" because the jaws are narrow at the tips, second is it can hold work more securely because of the opposing jaws, and third you can compensate for holding power if the work is not perfectly cylindrical.


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## skcncx (Nov 11, 2022)

mksj said:


> Think off a scroll chuck and then add a screw type adjustment on top of that that acts the same as an independent chuck.  Look at the previous picture and you will see the carrier that is operated by the scroll and then the jaw position with a scroll adjuster between them,
> 
> You use the scroll to get the work in/out of the chuck and for repeat work that you do not need sub 0.001" accuracy on the repeat. You can tweak opposing jaws to null out any TIR if needed. As there are slight difference in jaw torquing, this accounts for a slight variation with repeat use of the scroll. The other plus of this chuck is three-fold, first it can hold work down to 0.2" because the jaws are narrow at the tips, second is it can hold work more securely because of the opposing jaws, and third you can compensate for holding power if the work is not perfectly cylindrical.


Thanks for the explanation! So I get all the benefits of a 4 jaw independent and the speed of a scroll chuck.

Round, square , odd shaped stuff it works for… then the only thing I’d likely need a 3 jaw for is if I plan to turn hex stock… i think that profile needs a 3 or 6 jaw.

I assume plain back means it’s flat and then any 6” d1-4 it’ll adapt to for mounting to lathe. I assume there’s a standard for mating plain back chucks to d1-4 backing plates.  Thanks for the tip on saving $ with the more cost effective backing plate, that doesn’t have to be a bison brand.

So I assume for most work on the 1340gt an 8” chuck is a good size though jaws could get close to interfering with ways.. but I’ll turn most diameters 2” and less.  Can reverse the jaws as well.


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## Beckerkumm (Nov 11, 2022)

I think a d1-4 direct mount 8" independent is listed on Ajax for $885.  I don't know if the steel is the same but I've found that if I call and ask for a best price, they will quote a little less than the listing.

A combo 8" is pretty heavy and sticks out a long way from the spindle bearings so you want a stout spindle to handle it.  Dave


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## davidpbest (Nov 11, 2022)

That is a good deal on that Bison combination chuck. Mark, do you know the adjustment range limit at each jaw?


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## skcncx (Nov 11, 2022)

davidpbest said:


> That is a good deal on that Bison combination chuck. Mark, do you know the adjustment range limit at each jaw?


This is from the spec sheet... they don't seem to list the range of travel for each jaw, I assume you mean the independent travel portion.

Looks like they just give you the min to max clamping range.

The grizzly site indicates it's a forged steel body, but according to bison, the 7-848-0800 is cast iron/semi steel.  The 4805-8"  7-849-0800  is the forged steel version.  Cast iron is rated at 2000 RPM, forged steel at 2,500... PM's adjustable 3 jaw is rated for 4,000 RPM and listed as Tempered Steel body.... just noticing all the spec differences.

I'm wondering if 8" for turning aluminum at high speeds on the 1340GT... I'd be better using a 6" chuck with less mass.  But this combo chuck and sale will be hard to pass up.


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## skcncx (Nov 11, 2022)

Beckerkumm said:


> A combo 8" is pretty heavy and sticks out a long way from the spindle bearings so you want a stout spindle to handle it. Dave


That's a concern I have and don't have a good sense if I do a lot of aluminum turning in the higher speeds... 1-2" diameter stock mostly, a 6" maybe  better fit.  There's a lot of dynamics and different aspect to ordering and sizing all these accessories to the late and type of work.  I have no sense of how stout the PM-1340GT to handle a heavier 8" chuck for daily use and turning in the 1000 to 2000 rpm range.


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## davidpbest (Nov 11, 2022)

skcncx said:


> This is from the spec sheet... they don't seem to list the range of travel for each jaw, I assume you mean the independent travel portion.


Yes, that’s why I asked Mark.  I passed on a Bison combination sweet deal a few years ago because I couldn’t get to the bottom of this spec.  I often chuck up very oddd sized parts, including flat plate ~5” x 1” and couldn’t get comfortable that a combination is a full functional substitute for a conventional 4-Jaw.  Neither is it a replacement for a Set-true 3-Jaw if you do a lot of work with hex bar stock (which I do).


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## Beckerkumm (Nov 11, 2022)

I'm not sure the Grizzly link is really a combo chuck.  The picture is but the description is just of an independent chuck.  Dave


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## skcncx (Nov 11, 2022)

Beckerkumm said:


> I'm not sure the Grizzly link is really a combo chuck.  The picture is but the description is just of an independent chuck.  Dave



They also say it's forged, but it's cast-iron/semi steel.  Makes you wonder what they'll send you.  Drives me nuts when pictures, descriptions and part numbers don't line up.

Based on the model number shown, it does map to Bison's combination chuck on their site.

 Model# 7-848-0800


GrizzlyBison-america.com


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## Aukai (Nov 12, 2022)

I only ran steel 8" to 700-900 RPM with zero issues, I did not switch the pullies around, and change the belt, so all you did for RPM was twist the dial. That would need a tachometer, so I kept the low range, and upped the RPM in low range


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## Beckerkumm (Nov 12, 2022)

Probably worth the chance on the Grizzly sale for those who can handle that chuck.  Worst case is Grizzly would give you your money back.  Bast case is really good.  Dave


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## mksj (Nov 12, 2022)

The model number listed and list price is that of the Bison combo, my old links go to that chuck. David, the travel of the independent is around 2.5", the scroll portion is a bit over 2". So by moving the jaw back plus the scroll you have close to 4.5" , but the jaw may hit the ways at that point. . I have spun the chuck up to around 2000 RPM, but usually I prefer my 5C or 6" 3J scroll for high speed work. The chuck is not any longer then a standard scroll 8" with back plate (4.5"),  I do not see that as an issue vs, the pressure exerted when cutting which is further out. Below is the chuck on my 1340GT. The Gator back plate is an 8", use to be called the FLD-200D4,  you would need to check with one of the chuck suppliers like Ajax Industries or Small Tools. You would need a back plate for most of these chucks except if you get a direct mount. Depending on the manufacturer, you may have to turn down the registration step slightly for the chuck to mount, but you do not need to do a face skim cut.









						8" Bison 4 Jaw Combination Chuck
					

Nice reports guys. Mine is still in the box. I am still stuck on using the 6J set thru for barrel work when not using the front spider.




					www.hobby-machinist.com


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## davidpbest (Nov 12, 2022)

mksj said:


> David, the travel of the independent is around 2.5", the scroll portion is a bit over 2".


Thanks Mark, that's about what I figured.  Glad I didn't buy it.


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## skcncx (Nov 12, 2022)

davidpbest said:


> Thanks Mark, that's about what I figured.  Glad I didn't buy it.



Regarding the combination chuck travel " travel of the independent is around 2.5", the scroll portion is a bit over 2"."

*Is that a lot less than a standard 4 jaw independent? * Seems like the total range of .16 - 7.87' is pretty big... though, that does assume you've reversed the jaw to get to the max.

I'm still thinking a 6" 3 jaw, as I do plan to do hex stock.... but I know a 4 jaw is likely needed at some point... and the concept of the combination chuck is pretty attractive, plus to sale.


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## mksj (Nov 12, 2022)

Actually quite the opposite, the range is greater than a standard 4J, so your overall range is 4.5" for each jaw. You are limited by any type of chuck to maintain at least 4-5 teeth in the scroll/screw so they do not break. The jaw range on my PM/QMT 8" 4J independent is maybe 2.5" per jaw. Chucks have reversible jaws to fit large diameter work, but I have much more range on the combination chuck then any of my other chucks. As I mentioned, a number of other forum members have bought the combo and have been very happy with it. I use it less these days more because I am constantly swapping back and forth to my 5C, and for smaller work my PBA 6" is about 1/2 the weight.


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## skcncx (Nov 13, 2022)

mksj said:


> Actually quite the opposite, the range is greater than a standard 4J, so your overall range is 4.5" for each jaw. You are limited by any type of chuck to maintain at least 4-5 teeth in the scroll/screw so they do not break. The jaw range on my PM/QMT 8" 4J independent is maybe 2.5" per jaw. Chucks have reversible jaws to fit large diameter work, but I have much more range on the combination chuck then any of my other chucks. As I mentioned, a number of other forum members have bought the combo and have been very happy with it. I use it less these days more because I am constantly swapping back and forth to my 5C, and for smaller work my PBA 6" is about 1/2 the weight.



I think *my only hesitation on the 8" combo chuck was it's size when turning at 1500-1800 RPM*. That is where I've been when mostly when turning aluminum.  Maybe that's not even needed for 1-2" round stock.  The fact it is a primary chuck on a 1340 GT for some relieves some of those fears.

Aside from size, if you swap it frequently, the only downside I see is it's not good for hex stock.  Though it appears you can turn hex stock with a 4 jaw.

Realistically, *I don't see myself switching my chucks that often so I'm trying to land on the best style and quality chuck to start.*  If I can take advantage of this current sale on the bison combo chuck, I may not have a real need for a 6" 3 jaw set tru for a long time.

Turning hex stock and how much I do is speculation on my part... I have no specific projects in mind.

The scroll and independent feature makes it seem like a no brainer, why aren't they more common (or commonly talked about), etc at at least brought up when the topic of "if you only had one chuck question."

An ER40 or 5C for my line up will need to be out of a specific need.  Though I start with common bar stock most of the time from .5" to 1.5" so I may end up finding I would use one more than I think.  Pros and cons to both ER40 vs 5C.


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## Ischgl99 (Nov 13, 2022)

The downside to the combo chuck is expense, I can get a 4 jaw chuck for significantly less than that and do just about everything I need.  After using it for a short period of time, dialing in stock is quick enough that I won’t switch to the three jaw chuck unless I have multiple parts that need to be done.


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## davidpbest (Nov 13, 2022)

mksj said:


> Actually quite the opposite, the range is greater than a standard 4J, so your overall range is 4.5" for each jaw. You are limited by any type of chuck to maintain at least 4-5 teeth in the scroll/screw so they do not break. The jaw range on my PM/QMT 8" 4J independent is maybe 2.5" per jaw. Chucks have reversible jaws to fit large diameter work, but I have much more range on the combination chuck then any of my other chucks. As I mentioned, a number of other forum members have bought the combo and have been very happy with it. I use it less these days more because I am constantly swapping back and forth to my 5C, and for smaller work my PBA 6" is about 1/2 the weight.


Mark I'm still not clear on the clamping range.  If the part is (for example) 1" across in one direction, and 8" in the other (flat plate for instance), what are the limitations between minimum on one axis and maximum on the other?  Sounds to me like it's a total of 5" maximum difference, right?


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## mksj (Nov 13, 2022)

Best to show some pictures, as there is both a scroll and movable jaws, each which has a movement range. The scroll can only move to the center open section of the chuck otherwise the scroll plates will hit each other, the jaws are then advanced and can hold down to 0.2". I did some checking of repeatability of the scroll on clamping the same diameter rod and it stayed within +/-0.0003" TIR and then clamping a rod twice as large and it was +/-0.0005" TIR. I made dual chuck keys with magnets, so I can quickly center the stock, otherwise the standard chuck key has a smaller square on one of the arms for the independent adjustments.

The main downside is the weight and cost, and it all depends on the type of work one does. Most shops just use a 4J independent for larger stock because it often needs to be centered and they are not doing repeat work, or they just redial in the TIR. Smaller work, they may use a 3J or collet. I like that I can quickly get stock in/out of the chuck and do not need to waste my time redialing it in with my 4J independent, and I find that it holds work more securely then my 3J scroll in some circumstances. High RPM wise, it is less intimidating then my 3J which has two piece jaws that stick out much further from the chuck face.

Bison Combo Closed





Bison Combo Scroll Carriers Stop, and Must Advance the Jaws





Bison Combo Distance of Movable Jaw Travel





Bison Combo Maximum Internal Jaws Clamping, But Pushing the Limit.





Bison Combo TIR Zero 1





Bison Combo TIR Zero 2


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## Janderso (Nov 13, 2022)

7milesup said:


> To alleviate that fear you should get a 1440GT.  It is a great fear reducer.


Or a 15x50 
Bigger is better imho


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## Janderso (Nov 13, 2022)

Beckerkumm said:


> I think a d1-4 direct mount 8" independent is listed on Ajax for $885.  I don't know if the steel is the same but I've found that if I call and ask for a best price, they will quote a little less than the listing.
> 
> A combo 8" is pretty heavy and sticks out a long way from the spindle bearings so you want a stout spindle to handle it.  Dave


I had the same experience with my Bison Four jaw. I called Ajax to verify I was buying the correct D1-6 adapter fir the 10” chuck.
They gave me a very good price for the pair.


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## davidpbest (Nov 13, 2022)

mksj said:


> Best to show some pictures, as there is both a scroll and movable jaws, each which has a movement range.
> 
> Bison Combo Maximum Internal Jaws Clamping, But Pushing the Limit.
> View attachment 426647


So my suspicion is correct - 5" is the max difference possible between one pair versus the other.  Hence you could chuck up a 1x6" plate, but not a 1x7".  

I had the opportunity to buy that 8" Bison combination several years ago.  I ordered it when it was on sale for a smoking hot deal, then they emailed me an said they oversold their inventory position and offered me the "Semi-Steel" version at the same price as the forged steel version that was on sale.  I wasn't comfortable running an 8" Semi-Steel on the 1340GT at speeds above 1200 RPM so I turned down that offer.  Glad I did not since I routinely need wider than 5" difference between the two axis of the jaw pairs.

In addition, I wouldn't want my principal chuck to have single piece jaws either - too many times I've needed to make my own jaws for clamping thin-walled tubing material and have needed jaws with a profile that matched the ID or OD of the part being turned.


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## mksj (Nov 14, 2022)

The jaws are reversible on the combo and could hold a 1x9, possibly a 1x10. In comparison to the PM/QMT direct mount which I have, it holds a smaller diameter and it also has one piece reversible jaws. When you get into a Bison direct mount 8" independent 4J chuck with one piece jaws they run close to 1K in semi-steel and the two piece jaws are over 1.4K in forged steel, and neither of those can hold small stock. At that price you could get the combo and a 6" 3J scroll.

The combo is more versatile, for a 4J, and if I need soft jaws, they would go on my 3J 6" scroll chuck. So it comes down to preference and cost. I find the combo much more functional as a 4J chuck and getting it at a lower price makes it attractive. But a good 3J scroll with two piece jaws adds to the versatility if you need soft jaws. So far I have not used soft jaws, and if I need a soft interface I make caps out of aluminum.

Each person develops their own preference based on their experiences and what they do, there is no right answer for everybody.


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## skcncx (Nov 14, 2022)

For what it's worth, I have found that the 8" combo chuck listed in this thread has 2 variants, at least 2 common variants, there appear to be 2 more as well.  The one that has been linked to, and that's on sale for a big discount at grizzly is the semi-steel one, rated at 2,000 RPM.

8" Bison 4 jaw combo chuck

Semi Steel : 4605-8" /  Part # 7-848-0800 / 2,000 RPM
Forged Steel : 4805-8" / Part # 7-849-0800 / 2,500 RPM
Not sure when, but many pictures of the semi steel one, grizzly and photos from @mksj shows it rating at 2,500 RPM marked on the chuck itself... though that is not the case anymore and pictures are just outdated.  Supposedly the same semi-steel chuck as always, they've just changed the rating.  That's essentially straight from bison-america's response via email.

The forged one goes for about $500 more than the semi steel.  Typically, $1500 for semi steel and $2,000 for forged.

I've had a little extra free time at work today .

Apples to oranges... but PM's 3 jaw, adjustable (set tru style), balanced and rated at 4,000 RPM is one great deal!


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## mksj (Nov 14, 2022)

Mine is forged steel, but all moot since the maximum speed of the lathe is in the 1800-2000 RPM range. You will find that for a given diameter chuck, that they will have similar maximum speeds for semi-steel vs. forged steel which has to do with the centrifugal force applied and the structural strength of the material. The maximum speed on my 6.3" PBA 3J scroll is 4900 RPM. Below is the Bison specs for their combos. If I had to pay the full list price of the chuck in today's market, I would think twice about buying the chuck, different story if you can snag it for close to 1/2 price.


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## skcncx (Nov 14, 2022)

mksj said:


> Mine is forged steel, but all moot since the maximum speed of the lathe is in the 1800-2000 RPM range.


Yea, I shouldn't get hung up on semi-steel vs forged.

Out of curiosity, can you visibly (or easily) tell the difference between cast iron and forged steel if you are seeing it in person?

Sounds like they did change the one you have then. That model number is labeled as cast iron in their docs.  It looks like the 4 digit specifies the material 4605 - semi steel / cast iron, 4805 - forged steel, etcs...  Not sure what 4505 or 4705 would be.


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## mksj (Nov 14, 2022)

I purchased mine probably 14 years ago, so do not recall the part numbers from back then. Since I have not had a forged and semi-steel side by side I would not know the visual difference. Although my forged chucks usually appear a bit cleaner in the castings and finish. Usually forged is around 30% more expensive, but only necessary if you need the additional speed rating. 





						Lathe Chucks Technical Information | MSC Industrial Supply Co.
					

To determine which type of spindle nose mounting your lathe requires, consult the diagrams below, then read the chart beneath the appropriate diagram.




					www.mscdirect.com


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## maticulus (Dec 1, 2022)

In case someone here currently on the backorder waiting list, or is looking for a deal is interested and is in driving distance of PM, they have these up for bid;









						(2) Damaged PM-1440E-LB METAL LATHES SOLD AS IS FOR PARTS TO MAKE 1 MACHINE  | eBay
					

Find many great new & used options and get the best deals for (2) Damaged PM-1440E-LB METAL LATHES SOLD AS IS FOR PARTS TO MAKE 1 MACHINE at the best online prices at eBay! Free shipping for many products!



					www.ebay.com


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## Wvlarry (Dec 4, 2022)

maticulus said:


> In case someone here currently on the backorder waiting list, or is looking for a deal is interested and is in driving distance of PM, they have these up for bid;
> 
> 
> 
> ...


They also have 2 PM-1440BV, same deal, damaged in shipping. Not sure how to post link for them.


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## maticulus (Dec 4, 2022)

Wvlarry said:


> They also have 2 PM-1440BV, same deal, damaged in shipping. Not sure how to post link for them.



Just copy the browser address and paste. Pretty concerning coincidence of "injuries" for this many of the same lathe in transit. Hope I don't run into any problems when my order arrives.









						(2) Damaged PM-1440BV METAL LATHES SOLD AS IS FOR PARTS TO MAKE 1 MACHINE  | eBay
					

Machines are being sold as is, for parts. Machine 2 is to be used for parts ONLY, it is not being sold with the ability to turn it in to a working machine. (The casting on the carriage is broken so its not salvageable).



					www.ebay.com


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