if you have a big lathe, can you tell me the diameter of the rod in your banjo please

[Dale Winburn]

The total length of my banjo is 12", I get very little deflection even when the eye bolt is in the center. The banjo works well for my use. I maybe would go 1 1/4" with a 15" banjo.

[dustin wassner]

thats what I was thinking, especially after seeing what the american beauty and powermatic is. what are your thoughts on cold rolled normal steel ($20) vs cold drawn 4140 (37$)? For what its worth, I am already over budget with the project...

By the way Dale, the homemade lathe on your website was the first I ever saw like this and was the initial inspiration to decide to make my own. So, thank you.

[Dale Winburn]

My bar is cold roll steel, don't know much about types of steel so can't help you there. Thanks for your comments about my homemade lathe, it still gets a lot of use. I have recently upgraded my bed to an 18 inch bed and variable speed three phase motor with VFD.

[dustin wassner]

thats great Dale. I did this exact approach with mine. What frequency are you able to drop to? I have read about overheating the motor if running at a low frequency for extended periods of time, but I have never heard anyone who says this define what an extended period of time is.

[Olaf Vogel]

thats great Dale. I did this exact approach with mine. What frequency are you able to drop to? I have read about overheating the motor if running at a low frequency for extended periods of time, but I have never heard anyone who says this define what an extended period of time is.

Hard to define. If the motor is working against a lot of resistance at low speed (hence pulling a lot of amps), then you risk overheating.
I use very precisely calibrated solution:

1 - put my hand on the motor - during normal operations - feel the temps
2 - when running slow, retest and compare.


Or you could hook up thermo couples with digital meters.
If you are concerned, get a strong fan and blow it over the motor to reduce temps.

BTW - a good way to cool down most motors, is to take off the load and run them at full speed.
That gets the air flowing and resumes normal cooling.
(not sure if the works for fully enclosed motors)

Stopping and waiting is not good - the heat just builds up.

[dustin wassner]

that is precise...

a thought: when I look at the american beauty/powermatic/etc motor and rpm ranges stated in their manual, they are all using vfd with ac motors, and on their low gear setting, the low rpm divided by the high rpm for that gear setting is pretty consistently 4%. I am not sure if this means that they are turning the frequency down to 4%, assuming running at 100% frequency equates to the highest rpm in the given range for that gear setting. I also did not ready in any of their manuals that running the motor for long periods of time with the frequency turned all the way down would do damage. If they are in fact going to 4% frequency, I am unnecessarily worried, as I was concerned that dropping to 15% frequency would cause overheating.

[Dale Winburn]

My motor will go to zero rpm, never had a problem, but when I'm running for long periods at low speed I do as Olaf suggest and feel the motor. My motor is an inverter duty motor (made for use with a VFD).

[Michael Schneider]

Dustin,

Hard to give number. The insulation grade of the motor will determine slow/torque of motor. Insulation grade of "F" is the best grade available at a reasonable price. Insulation grade of "F" are usually tagged inverter grade. It is not exactly what you are looking for but if you have not bought your motor yet, buy one with an insulation grade of "F" for high grade insulation that can handle the heat of low speed and high torque.

Note: Insulation class of "H" is the best, but it is very high $$$$, and likely not necessary.

Have fun.

Michael

[Leo Van Der Loo]

What you guys are talking about is NOT a banjo camlock, but just an excenter shaft that will deflect if not thick enough, actually most all of them will if clamping the banjo tight.

A banjo like Oneway uses has the camlock in it, and the banjo itself is where the forces are applied to, it will not bend or sag, patented as well, I don’t think any of the other lathes have it.

Oneway Banjo.jpg Oneway banjo Camlock.jpg

[dustin wassner]

thanks, Leo. I did see a video that describes how the OneWay design is different than the others. But I think with my limited tools it is not an option unless I can buy the cam and shaft separately. I have the part #'s 3811 for the cam assembly and 2702/2409 for the shaft, but am unable to find anywhere that sells them. Any idea where I would find them?

[Leo Van Der Loo]

thanks, Leo. I did see a video that describes how the OneWay design is different than the others. But I think with my limited tools it is not an option unless I can buy the cam and shaft separately. I have the part #'s 3811 for the cam assembly and 2702/2409 for the shaft, but am unable to find anywhere that sells them. Any idea where I would find them?

As usual you order parts at the manufacturer, Oneway, they have a 1-800 number.

Are you able to machine the ledge in your banjo housing, the camlock needs that to work.

[Brice Rogers]

I am finding all of this information interesting. I own a Griz G0766 and this is the first time I've had a cam lock banjo. I didn't realize that there are several different approaches.

On the Griz 0766 they use a sliding cam lock. The locking rod has a longitudinal slot in it for the eccentric cam mechanism to slide on. If I were making a duplicate, I think that I would find the machining of the slotted cam a challenge.

I like the idea of square shaft that Leo posted (One way). Seems like it would be easier to fabricate.

I also like the approach posted earlier for the PM where the shaft is round, uses an eyebolt and the ends are off-axis. Seems like it would be easy machine with a lathe and a 4 jaw chuck.

[dustin wassner]

Brice, can you post a pic of your banjo design?

How would you go about fabricating the oneway design? I am trying to wrap my head around it but think it would be easier to just use the solid round rod the entire length.

[Dennis Ford]

The Powermatic at full speed is 120 hz (which is double normal 60hz power)

that is precise...

a thought: when I look at the american beauty/powermatic/etc motor and rpm ranges stated in their manual, they are all using vfd with ac motors, and on their low gear setting, the low rpm divided by the high rpm for that gear setting is pretty consistently 4%. I am not sure if this means that they are turning the frequency down to 4%, assuming running at 100% frequency equates to the highest rpm in the given range for that gear setting. I also did not ready in any of their manuals that running the motor for long periods of time with the frequency turned all the way down would do damage. If they are in fact going to 4% frequency, I am unnecessarily worried, as I was concerned that dropping to 15% frequency would cause overheating.

[Don Bunce]

The Oneway design looks interesting, but wouldn't lend itself to DIY easily, and I don't see where it would have that much advantage over a traditional round bar as long as you use an adequate size bar to start with. I wouldn't use anything less than 1 1/4".