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Looking to purchase PM3520b

E

Eric Lofstrom

Joined
Mar 30, 2006
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Location
Washington State
I am looking to purchase a Powermatic 3520b and want to know if it actually has enough power to turn pieces over 20" diameter (outboard, of course). I want to know if the low speed setting 0-1200rpm provides enough torque at low rpms (0-500) to turn large pieces.

I currently have a Nova 3000 with 1hp (variable speed) and really like being able to set the belts to the lowest rpm (around 300 rpm), but I want more power, stability, and torque for those large pieces.

Thanks in advance for any input,
Eric 🙄
 
You will have plenty of power in the low speed. I've turned up to 19" inboard and have never changed my belt from the high setting.
I'm planning on doing some turning bigger this year but haven't had the time to build my outboard tool rest.
 
Yes, it will have plenty of torque. It is possible to stall out just about any motor including the 3520's motor. But it should be fine up to 30 or 35 inches. Beyond that you might be overstressing the bearings.
 
Eric,

The maximum torque output of the 3520 at low speeds is the same as the torque at the motor's "base" speed (the speed of the motor when operated on 60 Hz power, the normal power line frequency in the US). The reason for this is that motor torque output is approximately a linear function of motor current and, therefore, the controller must limit the maximum current to the motor's rated FLA (full load amps) to avoid overheating. This would be true for any lathe with electronic variable frequency drive (VFD). So much for the good news . . . . .

Now, the bad news . . . . If you compare the low speed torque of two lathes that have the same size AC induction motor, where one has a conventional stepped sheave design for speed control and the other has a modern high-tech electronic variable speed drive, the stepped sheave design will win the torque war. Why? In a mechanical drive system where the motor is always running at the same speed, the mechanical horsepower that it is capable of producing is constant so if the output spindle speed is less than the motor shaft speed, then the spindle torque capability is greater than the torque at the motor shaft. On the other hand, the variable speed motor is limited to producing less horsepower as the speed is decreased because horsepower is defined as the product of speed and torque.

It is for the reason that I briefly described above that you generally find larger motors on modern lathes with variable frequency drive. Manufacturers generally have two recourses to have decent low speed torque capability with VFD systems. The first is larger motors and the second is to have two or more speed ranges by using stepped sheaves. Hmmmm....it almost seems as if we have come full circle...we are back to stepped sheaves except that now we have a way to make incremental speed adjustments between the large steps.

Bill
 
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Thanks for the helpful input.

I haven't actually seen a PM 3520 in action, so any other input or comments are greatly appreciated.

I have breifly looked at the PM 3520 forum...although I'm just beginning to scratch the surface of the wealth of information.

Thanks again!
 
Turnin' Against the Wind

Eric,

I have both seen and used the PM3520 and all that I can say is that it will probably be all that you will ever need or want unless you become a world famous turner, in which case getting a more expensive lathe will be "no problemo". After using the 3520, it even inspired me to verse . . . . . .

Was it just yesterday
Or was it long ago
Powermatic was lovely it was the lathe of my dreams
There in the wood shop with the stebcenter running slow
And the gouges that I used
The piles of wood that I turned
Caught like a wild man out of control
'Til there was nothing left to turn and no room more for bowls
And I remember what I said to myself
How I swore that it never would end
I remember how I held the gouge so tight
Wish I had known more of what I didn't know then

Against the wind
I was turnin' against the wind
Sucked into the vortex, I was turnin'
Against the wind . . . . . . .

. . . . well, you get the idea. It goes on, but I should stop.

Bill🙂
 
Yeah, I listen to Bob Seger songs on the rock classics station too!

And I'll add that a lot of the pro turners use pretty standard lathes. Nick Cook uses a 3520 for his work. I'm sure the other pros use similar lathes and you don't always have to go to the high end lathes to be able to produce volumes of product.
 
purchasing pm3520b

The 3520b has a 2 horse motor and you use the 1 to 1200 speed to get max. torque.It has the most torque of any in its class. Cant go wrong, unless, of course if you have unlimited financial resources. Thanky, Maxundefinedundefined
 
Songs of the 3520

boehme said:
Eric,

I have both seen and used the PM3520 and all that I can say is that it will probably be all that you will ever need or want unless you become a world famous turner, in which case getting a more expensive lathe will be "no problemo". After using the 3520, it even inspired me to verse . . . . . .

Was it just yesterday
Or was it long ago
Powermatic was lovely it was the lathe of my dreams
There in the wood shop with the stebcenter running slow
And the gouges that I used
The piles of wood that I turned
Caught like a wild man out of control
'Til there was nothing left to turn and no room more for bowls
And I remember what I said to myself
How I swore that it never would end
I remember how I held the gouge so tight
Wish I had known more of what I didn't know then

Against the wind
I was turnin' against the wind
Sucked into the vortex, I was turnin'
Against the wind . . . . . . .

. . . . well, you get the idea. It goes on, but I should stop.

Bill🙂
Click to expand...

I can't afford a 3520 can you write me a song about the Jet 1642?
 
Saw the PM 3520b this morning...WOW!

I took a look at one (in person) this morning and I am impressed. I like the heft and smaller footprint combined with the sliding headstock feature...and for the money- very nice!! I think I am sold...now I just have to prepare for the purchase.

Any suggestions regarding accessories I should buy with it?


PS- Nice song lyrics Bill! 😀
 
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