The New South Bend 10K

Now I just need to figure out where to mount the magnetic pickup. Question: I can glue the magnet to my spindle pulley but I have a concern. Over time could the small magnet magnetize the pulley or the spindle and cause it to attract chips? That would be bad. Should I make an aluminum ring and mount it on that so the magnet is not in contact with the pulley?

Robert

Unless the magnet you are using is some super high-intensity magnet I doubt that one little magnet can magnetize your spindle. But I have no factual data to back up my opinion, so your mileage may vary.

I would not worry about the tach magnetic magnetizing your pulley, it is very small. I have much stronger magnets on mine and do not have any issues, and have done multiple systems with these tachs and have not seen a problem. It may be the start up and stopping motor noise is the current injection into the motor wingdings from the KB controller. Often a loud hum when starting motors with a load, and stopping with braking. Since it is smooth when running, it should not affect the cutting performance.

This magnet:



Thanks guys. I agree probably wont cause an issue.
R

I used the lathe all day today and I must say I am very impressed with this controller! The automatic braking is very nice. Stops the lathe in a few seconds. If I lift a cover or hit Estop it stops in less than 1 sec. It maintains speed well under typical load. Yes it is noisy but I can live with that. The finish seems fine so far.
I have one nagging concern. I typically don't kill the main power when unchucking or rechucking a part or changing tools. I just turn the controller to the "off" position. The controller is therefore still powered up. My concern is about the unlikely event of a controller malfunction starting the motor when I am not expecting it. I think the controller is more likely to malfunction "in flight." Although I think a malfunction at rest highly unlikely I would feel better with an absolute lockout. So I had a small brainstorm...
I am going to add some type of chuck key lockout switch. It will physically break the connection to the motor when the key is out of the ____. I have seen several examples of this but I am not sure which is best. I have considered: a cup or socket that receives the key, a hinged hanger for the key, and a spring loaded platform on which the key is set. I must contemplate these! Comments or examples welcome. I think this will make a very nice addition to this system.
Robert

I do not see the need to make it overly complicated regarding chucking and disconnecting power. The spindle direction rotary switch carries minimal current and I can not see it spontaneously closing in the stop position. Still, when I build my control systems, I do build in a minimum double redundancy for all my controls to operate. I am not sure how you wired your E-Stop, but it could be fitted with a dual block NC switches. When depressed, it disconnects the COM signal going to the spindle direction switch, and the other contact block disconnects the connection between EN and COM (which kills the drive controls). By pressing the E-Stop, it would be impossible for the motor to start, even if there was a short or faulty switch. You have three separate switch that are serially connected. Some VFD used a similar arrangement and use a latching relay for the activation of the EN-COM type of connection, it also prevents it from restarting if the power goes out. If changing the drive belt or any work on the lathe, I would turn off the power.

I would be more concerned about killing the power to the lathe and forgetting the spindle direction switch in in the forward or reverse position and the machine restarting. I prefer to use a power relay that will only latch with the spindle switch in the stop position, and this relay would then connect the EN-COM and and the COM to the direction switch going to the +/-15V control terminals. The E-Stop kills power to the power relay, which then disconnects all the signal pathways. It is possible to use a contactor or a switch to disconnect the motor, but I do not think it is necessary. These drives have power supply capacitors, it is probably not a good idea to turn on/off the controller frequently because of the current inrush.

mksj- Perhaps other SCR constollers work differently but my KB controller is still active when the Enable and COM connection is broken. My EStop breaks this connection. Keep in mind, that this causes the controller to actively power to a stop (not coasting.) In fact with the direction switch at off and EStop depressed, if you try to rotate the spindle by hand the control will send power to the motor to try to prevent it from moving. So a malfunction spinning the chuck does not seem to be out of the question.
Robert

Thank you, Robert, for posting this thread & the detailed steps to convert to a variable speed drive.

Your thread & another on a different site, convinced me to purchase a 10K last Friday. I am now anxiously awaiting it.

I an a hobby machinist & welder, former owner of a Smithy CB 1220 for 22+ years & a recent owner of a Grizzly G0705 milling machine.

I am looking to go to the next level. My experience no way matches yours or most of the others on this site. I am eager to learn. Hopefully, I can tap some expertise from members...& eventually give back to the community.

Just saw this thread. I have to say this is very cool.

What is your maximum speed now? Is it 1500 RPM? Do you anticipate any problems running the lathe at say 2500 RPM? I am considering purchasing this lathe now that it is being discontinued and is on close out. But 1200 RPM is just too slow for some of my smaller parts. Do you think the bearings can handle this higher speed?

Cheers!

I can now get over 2500 RPM if I wanted to but I have no way of knowing if the bearings would tolerate it. Others may have better advice on this. Also the chuck is rated at 2500.
How in the world did this thread get triplicates of attached files??? I did not do that and it has changed since my post?
R