spindle lock on powermatic 3520c

[Ron Stadler]

OMG, I feel im going to burn up my motor, twice now i have turned on the lathe with the spindle lock engaged. I hate the fact that you can do this and must rely on yourself not to forget you engaged it . Does anyone else have this problem, and does anyone have any ideas on how not to forget or solutions to this. thanks

[Robert Cherry]

You could do like pilots and hang the equivalent of a ‘remove before flight’ flag on it. That’s what I do with my bandsaw to remember to tension and de-tension the blade.

[John K Jordan]

OMG, I feel im going to burn up my motor, twice now i have turned on the lathe with the spindle lock engaged. I hate the fact that you can do this and must rely on yourself not to forget you engaged it . Does anyone else have this problem, and does anyone have any ideas on how not to forget or solutions to this. thanks

I put a persistent spindle lock on my 3520b and while I have not yet forgotten to release it I've thought about how to prevent it. My idea was to mount a microswitch inside the headstock housing, triggered somehow by the lock shaft, perhaps by drilling a hole for a pin or a screw.. I haven't looked at the details yet but I think I can simply wire it in with the the low voltage stop switch on the VFD so turning on the lathe would do nothing until the spindle lock was released.

I think an interlock like this should be built into every lathe, just like a car that prevents you starting the engine if not in park or from putting it in gear without depressing the brake peddle.

(For those who have left a chuck key in a drill press an interlock could also be enabled when the key was removed from some docking position. Perhaps some drill presses already have this feature.)

I don't know how the spindle lock is configured on the 3520c but perhaps a mechanical solution or reminder is also possible. I remember seeing some mechanism (on what, I can't remember, maybe it was on a bandsaw) that swung a flag into view. Maybe a simple spindle lock microswitch could turn on a blinking light as a reminder. An optical or magnetic sensor could also work.

BTW, I recently wired up a logic circuit to prevent someone from driving my little Kubota diesel utility truck with the parking brake engaged. (Someone once burned up the brake on my older Cub Cadet) I tied into the brake pedal position indicator switch and the neutral indicator switch on the hydrostatic transmission so my module will scream a ear-splitting warning if the transmission is taken out of gear with the brake engaged. I've breadboarded and tested but have not yet installed. It took a power transistor and some resistors. I think the PM lathe would be easier.

JKJ

[JohnC Lucas]

If the C is anything electronically like my A it won't hurt a thing. There is circuitry in my A series that automatically senses if something is binding up the spindle and simply shuts off. This can happen on a big catch also. I have turned the lathe on with the wood hitting the tool rest on occasion and nothing happens. It just shuts off. Same thing with my homemade index wheels. I have occasioanally hit the on button by accident with the index engaged. Nothing happens. Of course on the A and B series the spindle lock does not stay engaged. A lot of people complained about that which is why they added the new twist lock system to the C. I guess it's just a matter of getting into the habit of lock the spindle, do what ever you want and then unlock it before doing anything else. Another complaint that is hard t answer for the designers. My 3520A has a switch and speed dial. If you use the switch to shut the lathe off the lathe comes back on at that same speed. That is a feature I love because I can stop the lathe, do an inspection of the piece and then turn it back on to the same speed I was using. Very convenient for my style of turning. Of course if your turning pens and finish the project and forget to turn the speed dial down before turning that 16" bowl you can get in trouble. I have several friends who never use the on/off switch. They simply turn the speed dial down, partly for that safety reason. so how would a designer please us both. So in short. It won't hurt your lathe to turn it on with the spindle locked, but it would be better to get in the habit of simply unlocking it as soon as your done using it.

[John K Jordan]

If the C is anything electronically like my A it won't hurt a thing.

That's good to know! I put the sliding spindle lock stop on my B but it's right on the front where I can see it. I mostly just use it when loosening chucks with the wrench and when tightening a blank on a screw chuck.

[Ron Stadler]

Yes I like everybody's idea on here I'm probably going to do something more simple like hanging a sign on it though as mentioned, it sounds like a good idea, maybe big red or yellow signs saying STOP! right over the switch.
Sure wish powermatic would have put a little more thought into this feature though

[Joe Meirhaeghe]

Some how this doesn't seam to me like it should be a big problem. The only time I've used the spindle lock was to remove the chuck. Lock it remove chuck unlock it, move on. I've had my 3520 b for some where between 8 to 10 yrs now ( I can't really remember what yr I got it) but I bet I haven't taken the chuck off it more than 4 or 5 times since I've had it. I guess I don't understand why you would lock it and walk away from it.

[Steve Mawson]

I almost always give what ever is on the lathe a spin by hand before I turn it on. A good habit to get into to make sure the piece will not hit the tool rest, not spinning too fast, spindle lock not engaged, etc. No electronics needed

[John K Jordan]

Some how this doesn't seam to me like it should be a big problem. The only time I've used the spindle lock was to remove the chuck. Lock it remove chuck unlock it, move on. I've had my 3520 b for some where between 8 to 10 yrs now ( I can't really remember what yr I got it) but I bet I haven't taken the chuck off it more than 4 or 5 times since I've had it. I guess I don't understand why you would lock it and walk away from it.

Some people use their lathes in other ways. For example, I often locked the spindle with the indexing pins, sometimes to keep a square edge in a good position for shaping, sanding, or carving. (I use a carving stand now.) I don't know about walking away but I know I've had my spindle locked in one position for 10 minutes or more.

As for chucks, depending on what I'm turning I might take one off 4 or 5 times in one turning session, switching between centers, chucks, etc. We obviously work in different ways and do different types of turning.

As mentioned, I've never forgotten to release the lock but I can imagine someone getting distracted and forgetting. It's nice to know what JohnL. mentioned that it shouldn't hurt the VFD or motor if that happened.

Steve's method seems the best - always test-spin by hand!

JKJ

[Jeffrey J Smith]

I change chucks often - going from chuck to chuck or to the vacuum chuck - and use the spindle lock (it is the persistant variety) every time when loosening the chuck. My lathe has a power lock out that locks out power when the spindle lock is engaged. After 6 years of turning on it, it is now second nature to reach over to the handwheel and give the piece a spin before turning the power on.
The other aspect is that when replacing the chuck, I always like to hear the chuck seat all the way back to the shoulder/face of the spindle with an audible clunk - that requires spinning it using my right hand while turning the handwheel with my left.
Can’t be done with the spindle locked...

[robert baccus]

The spindle lock and rpm thing quit on my B model years ago. I use a cut-off screwdriver in the spindle, handle up for a lock--a screeck reminds me if I forget and the red handle is a reminder.

[JohnC Lucas]

If your spindle lock doesn't work on you 3520B it's just that the locking ring on the inside has come loose. The set screws do come loose occasioanally. Just repositon the ring in the right position and lock the set screws down. I would have to look and see where the spindle rpm sensor is to answer the rest but guessing that it might be tied into the position of the spindle lock ring.

[Ron Stadler]

Well I can tell you this, it does not shut off on its own and was trying to overcome the the tension of the belt on the pulleys as they started squealing, I have had a sleep deprivation problem for many years and some days I have to admit I'm quite slow on my reaction time and can be quite forgetful so this is kinda serious for me, but I am gonna try just hanging a sign on it when I lock it as long as I don't forget that, lol.

[JohnC Lucas]

Well that's interesting. That would mean the C series must be programmed differently. I'll try to call my friend tomorrow who just got one. If she has it all wired up I'll ask her to test it. On my A series if you have something blocking the spindle from turning it simply won't start. It senses that resistance and simply stops. I'm pretty sure our Club's B series is the same but might have to call the owner and verify that. My memory isn't as good as it used to be.

[robert baccus]

Thanks for the advice, but I really never miss either one a bit.