Lathe Shopping. Help!

Suedepflow

You have been given some good advise!
Getting another 7x12 to get you by and keep your orders up will free up your mind and give you some time to make a sound decision!
Go with either PM or grizzly! They have a positive track record and a parts dept to deal with. Remember the others are sold by independent resellers that don't care about after sale service!
The PMV 10x30 or the G 9972z will be a winner.

Tomh
 
SuedePflow said:
What do you mean by "get on the list"? Backordered and not currently available?

I can't help but to notice the PM1022 is strikingly similar to the Baileigh PL-1022VS. Same machine? The Baileigh is available to ship today for $1800...

http://www.baileigh.com/bench-lathe-pl-1022vs


Is my understanding of power transfer with variable speed correct or no? Do you get full motor torque at any speed or is it directly proportional to the speed? I just don't want to run into the same stalling issues like I did with my 7x10.
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There all basically the same machine, but may have different specs or options. One big difference between the various vendors is the level of support your going to get after you buy the machine. I just bought a PM-1127VF-LB from Quality Machine Tools and have been really impressed with the customer service.
 
mksj said:
Power delivery differs depending on whether it is a DC or AC motor (and type) and the type of drive (I believe the 1022 model is a BLDC). DC motors having high starting torque, AC motor with a VFD usually have flat torque from low speed (15-20Hz) up to its base speed at 60Hz. Three phase AC motors typically will give a better finish (more even power delivery) then single phase AC motors The variable speed lathes have 2 or 3 speed ranges. Very unlikely you will stall one of these lathes. The information/specifications on the 1022 model is pretty lacking, but this (and other) review is worth reading and similar to other reviews independent of the brand YMMV. http://www.hobby-machinist.com/threads/new-precision-matthews-1022v-lathe.22615/ .
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So you think a 3ph 1-HP AC motor would be better than a 1HP DC motor?
Just reading about VFD's, it seems that a DC motor supplies 100% torque no matter the spindle speed. Whereas an AC VFD motor (non-vector controlled) supplies 100% torque from ~10-100% speeds only.

Grizzly's 1022 lathe has a 3ph 1-HP AC motor. Drive unknown.
Precision Matthew's 1022 lathe has a 1HP DC motor.
Baileigh's 1022 lathe also has a 1HP DC motor.

mksj said:
If your facing material, a power cross feed is really nice. It is a real quandary of getting a lathe of decent quality at this price point. Buying from Baileigh would be pretty low on my choice of vendors reading other reviewers experience with their machines. Machines may look similar, but how they are speced, what they come with and post purchase support are major factors. Saving a few dollars upfront may not be worth it in the long run. There models that are not listed on the Precision Mathews/QMT site, so may be worth giving them a call, alternatively something like the Grizzly G0752. Something in the 11x27, 12x28 or 11x30 gives you a wider work scope and a step up in performance/features.
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That surprises me. The buzz about Baileigh has always been positive in the circles I used to run with. Very nice notchers and benders. And I have one of their horizontal bandsaws and I love it.
 
Does a gearbox lathe such as the G9972z offer any advantages over a variable speed lathe other than price?

Regarding the G9972z, Grizzly lists "Range of speeds: 150, 300, 560, 720, 1200, 2400 RPM". If I'm not mistaken, that means this machine can only run at these 6 set speeds, right?
 
SuedePflow said:
So you think a 3ph 1-HP AC motor would be better than a 1HP DC motor?
Just reading about VFD's, it seems that a DC motor supplies 100% torque no matter the spindle speed. Whereas an AC VFD motor (non-vector controlled) supplies 100% torque from ~10-100% speeds only.
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Well, I think I got this backwards. Reading further about it, it seems the DC motors are voltage controlled, so torque output is greatly reduced at lower speeds. This sounds like exactly what I experienced with my 7x10 lathe. Same thing with an AC motor and a v/hz controller.

It seems to me that AC with a vector controller is the way to go for variable speed and DC might be better for a gearbox lathe.
 
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It sounds like the Grizzly G0752 is the hot ticket. Same base lathe as the G0602, but with a 3ph AC motor and vector VFD. I can't find a reason to wait for the G9972z instead of ordering the G0752 today. Anybody else want to chime in on this?
 
SuedePflow said:
What do you mean by "get on the list"? Backordered and not currently available?

I can't help but to notice the PM1022 is strikingly similar to the Baileigh PL-1022VS. Same machine? The Baileigh is available to ship today for $1800...

http://www.baileigh.com/bench-lathe-pl-1022vs


Is my understanding of power transfer with variable speed correct or no? Do you get full motor torque at any speed or is it directly proportional to the speed? I just don't want to run into the same stalling issues like I did with my 7x10.
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You will not have the same stalling issues for the simple reason that the lathe is much more powerful and well geared for torque at low speed. Yes, there is reduced torque at low speed, but you have to be pushing the limit of the machine to feel it. The only time I stalled the lathe was when I tried to make 0.480" depth of cut in 6061, I normally rough 6061 with a 0.200" DoC and accidentally dialed it in twice. It is not a big commercial lathe, but it will get right in and do the job with no issue. If you are worried about power, you need to look for a floor model with a 3ph motor, and not even bother with a lathe in this class.

The Baileigh lathe is not the same machine, though they probably come from the same factory. QMC does carry baileigh lathes, it is probably his version of the lathe you linked. The main differences are that Matt has them custom tweaked for his market, so you get a lathe made by a machinist rather than a sales department. The other big difference is price, the Bailiegh is much more expensive when you consider it comes with basically no accessories. I called and asked Matt if they where the same machine, he detailed some of the major design differences, not the least of which is a much lower min RPM (50 vs 125) and longer cross slide travel (5" vs 2.75") - the bailiegh is really a 6" lathe pretending to be a 10" lathe (it is a POS). If you make a spreadsheet like I suggested, you will quickly cross all the Bailiegh lathes off your list - they seem to be designed by the sales department and marketed to purchasing agents (I assume the bigger models are better designed).

So, yes the PM is always on backorder. The factories place a limit on how many machines can be ordered at a time. According to Matt, only the big houses like Grizzly can demand bigger quotas, and Grizzly tends to throw its weight around a lot in china. Matt has pretty much all the lathes sold before they leave China, though sometimes you can buy one while it is in transit. His machines are popular for a reason.

As for the Grizzly, it certainly looks like a good machine and was high on my list for a while. I probably would have purchased one if they cam with a longer bed - 22" is just too short for me.
My own opinion though is that power x-feed >> VFD.
 
Not wanting to cut in line here guys so I hope an additional question is ok. I've been sort of shopping for another lathe as well. I currently have a Taig. I love it but she is pretty small. I looked at the specs on the G9972z and noticed the 8TPI on the lead screw. Is that exact or a close approximation? I was under the impression all of those had metric screws. That is one reason I have shied away from Asian lathes. Not that I'm being snobbish but I have a hard enough time getting it right as it is. I currently use lathe dials for the most part although sometimes I use a dial indicator.

Thanks in advance for your input


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Chip Hacket said:
Not wanting to cut in line here guys so I hope an additional question is ok. I've been sort of shopping for another lathe as well. I currently have a Taig. I love it but she is pretty small. I looked at the specs on the G9972z and noticed the 8TPI on the lead screw. Is that exact or a close approximation? I was under the impression all of those had metric screws. That is one reason I have shied away from Asian lathes. Not that I'm being snobbish but I have a hard enough time getting it right as it is. I currently use lathe dials for the most part although sometimes I use a dial indicator.

Thanks in advance for your input


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You will hear vicious rumors like this on some of the "pro" forums, it is simply not true. Sometimes machinery salesmen will feed you this as a lie to sell you a machine, sometimes they actually believe it. You should be able to download the manual of any machine you are considering, the manual will tell you the truth.
If it says 8TPI it is 8TPI.
TBK, there is no machine with an "approximated" lead screw. Seriously, why would any factory tool up to make an approximate thread when they can just make a real thread. Chinese factories may be have all sorts of issues, but there is nothing wrong the Chinese engineer who designs the equipment.
The approximation part comes in when an imperial thread is cut from a metric lead screw. This entire approximation is handled by the change gears. When you buy a lathe with an imperial lead screw, it can be made to cut "approximate" metric threads the same way the metric machine cuts approximate imperial threads.

Pretty much all of these machines do have metric screws in the cross and compound, with an imperial dial added. You can spot these machines easily - the dial will register 0.040" per turn. The type of lead screw can be spotted by the number of teeth on the change gears, this is a separate topic. You should be able to find what gears go in an imperial or metric machine for cutting imperial threads and go from there. The gear ratios are pretty standard across all machines.

You can blame the French for this by the way. When the meter was arbitrarily set to 1/0,000,000 of the distance from the north pole to the equator measured through Paris, they lost any chance for convergence with the imperial system. The meter has basically gone down hill since then and is now some distance of how far light travels in some bizarre tiny fraction of a second and is still almost as arbitrary as before since the actual conditions for measurement only exist in a lab. Wouldn't it have been nice if the meter was 2 or 4 feet long and converting from metric to imperial was a simple matter of dividing by 2 or 10 depending on the direction of conversion?
 
TBK.......


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