What are factors for what "class" of lathe to buy?

skcncx said:
It does look very clean, reached out on it and the seller's focus is more woodworking so this just sits... so a good deal to be had... I'm out of town for a bit... so, hopefully it's still available when I'm back... being so close is really nice. Otherwise, I keep coming back to the PM-1228 if nothing else pops up.
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Sorta what happened when I was looking, when I showed up to look at them, hard pressure sale and not as shown. I had a tool maker/machinist friend with me to help with grading them. Of course this might be a diamond in the rough.;)
 
The Smithy looks to be the same as the Bolton 1440, you couldn't pay me enough to get one of those. Bolton's have a very poor reputation and even worse is customer support/parts. Run, don't walk away.

 
I had a Bolton 1340 and after much frustration, mainly fixing issues from it having been dropped but also some things related to the maker, I ended up selling for $500.

Yes, the Jet probably has a threaded spindle like my machine. I don't really have plans to run it backwards, people have been threading towards the chuck for more than 100 years so I don't think it's that big of a deal.

I'd rather have a well appointed Taiwan machine than China built since many of the issues you can face are hard to resolve, but that's just my preference.

I did learn a lot from working on the Bolton but ultimately a belt drive machine with VFD serves my needs better than the gear head.

John
 
Ischgl99 said:
For me, the biggest issue was I did not want a DC motor. I have a lot of industry experience with VFDs and controls, so for me to add that to the 1236T was a no brainer. Saving a few grand helps pay for a lot of tooling too. As I mentioned earlier, I love my 1236T, but not sure I would have bought it at these prices.
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Just for my understanding... I buy the 1236T with a 3phase motor and put a VFD on it instead of just getting a single phase motor... am I correct in the following?
  • A VFD will convert my shop's single phase 220v outlet to 3 phase the motor needs

  • I primarily use the VFD to change RPM of the spindle
    • Essentially rendering the 1236T RPM gears lever useless... just park it in one position.

  • Depending on features of VFD I could
    • Configure ramp up time (slow start)
    • Configure braking time/power
    • Add a proximity sensor stop to stop the carriage and spindle

  • Anything other benefit?
Any recommended VFD? I'll see of PM has any recommendations as well.

Pretty soon, I might be at the 1340GT... per every ones advice and part of my gut... I may lean toward the go all out approach... and even the 1340GT stays under my hard limit of 72" long. That's only $500 more though less included accessories. I just have to settle on the fact that moves of this in my shop won't be as easy and a far more substantial stand that can be raised up on casters in the event It needs moved for a period of time.
 
I would not say the gears are useless. The beauty of combining a vfd with a gearhead machine is you have the benefits of any rpm but by choosing the correct gear, you can get a wide range within a motor speed for 40-80 hz or so. That allows you to keep the motor rpms in the sweet spot for maximizing torque and HP and eliminates the need to upsize the motor to compensate. A vfd conversion for a Monarch 10ee with no backgear retained requires a 7.5-10 hp motor and still doesn't quite match the low end torque of the original 3 hp DC motor it came with originally.

Gear changes are less frequent but the combination with a vfd doesn't eliminate them. Dave
 
Beckerkumm said:
I would not say the gears are useless. The beauty of combining a vfd with a gearhead machine is you have the benefits of any rpm but by choosing the correct gear, you can get a wide range within a motor speed for 40-80 hz or so. That allows you to keep the motor rpms in the sweet spot for maximizing torque and HP and eliminates the need to upsize the motor to compensate. A vfd conversion for a Monarch 10ee with no backgear retained requires a 7.5-10 hp motor and still doesn't quite match the low end torque of the original 3 hp DC motor it came with originally.

Gear changes are less frequent but the combination with a vfd doesn't eliminate them. Dave
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Another benefit of a VFD is being able to ramp up speeds during a cut like parting, to keep a more consistent finish.

I have a VFD on my 1340, and I still use the gears often, like Beckerkumm suggests.
 
Yes, an appropriate VFD will convert single phase to three phase power.

I have an old Monarch 12"CK with a VFD to power the 3 phase 3 HP motor. I use the headstock gears to change RPM extensively. VFDs effectively lose some power under 60Hz. Easy to get 3:1 or 4:1 RPM change out of VFD, but 100 rpm to 2000 rpm of a typical lathe spindle is 20:1. Think of gears as getting in the right ballpark, and the VFD as tweaking RPM without stopping the lathe.
 
I'm checking out American RPC's and they are up there . :grin: I guess $1500 doesn't get you what it used to .
 
I believe the last iteration on the 1340GT/1236T Basic VFD install is in the post below. It is designed to be used with the Hitachi WJ200-015SF that can be purchased through QMT/PM or Drives Warehouse depending on if they are in stock. It is not a plug and play power source like an RPC, so requires some simple rewiring as outlined in the basic install document. There is also a document as to recommended components for the VFD cabinet, the links are old but one can search for current listings. It does not work with the proximity stop system, which requires a completely different type of system.
www.hobby-machinist.com

Pm1340gt Lathe Basic Vfd Control Conversion Using The Stock Control Board And Switches

Not really and issue since the resistor's I recommend are completely sealed and the wiring is embedded. You could also mount it on the inside of the VFD cabinet which I have seen done. It does not get warm so heat is not an issue. My original 1340GT VFD with the WJ200 had it in the headstock...
www.hobby-machinist.com www.hobby-machinist.com

The usable speed range for a VFD using the standard motor is probably 20-100Hz, but you loose power below the motor's base speed of 60Hz. So ar 30 Hz you would have 0.75 Hp instead of 1.5Hp. In addition you loose the mechanical multiplication of torque, so the applied torque at the spindle would also be 1/2 at 30 Hz. This is OK for threading and smaller diameter work, but not for heavy cutting.
 
rabler said:
Yes, an appropriate VFD will convert single phase to three phase power.

I have an old Monarch 12"CK with a VFD to power the 3 phase 3 HP motor. I use the headstock gears to change RPM extensively. VFDs effectively lose some power under 60Hz. Easy to get 3:1 or 4:1 RPM change out of VFD, but 100 rpm to 2000 rpm of a typical lathe spindle is 20:1. Think of gears as getting in the right ballpark, and the VFD as tweaking RPM without stopping the lathe.
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That makes sense.. I'd get some range out of the VFD but gears still used to go into a different ranges as well as using the gears in your favor for torque, etc.

For braking and ramp up, seems like a good thing to set... my 550 watt consew sewing machine motor on my Atlas 618 has pretty good braking, I have appreciated that when you turn it off, everything comes to a stop pretty quickly.
 
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