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Need Help with LeBlond Electric Spindle Brake

Slash

Plastic
Joined
Oct 12, 2005
Location
NW Ohio
I have an older 13" LeBlond lathe, and the brake has never worked for me. I'm not sure of the exact year of manufacture, I'm guessing that it dates to the 1960's. (Serial number is 4B1166 - Is there somewhere to look it up?) It is a manual shift model not a servo, if that makes a difference.


Here is a photo of the diagram for the brake system:
LeBlondBrake.jpg


I have a little experience with electrical work, probably just enough to get me in trouble
. I've done a little snooping around, but I didn't find anything obvious and this stuff is a little over my head.

So far, what I've found is that there is 53 VAC at both terminals on the brake, and 230 ohms resistance across them. With the lever in the run position, the voltage increases to ~65 VAC.

I read in another thread that loose/broken wires at the drum switch are common, but I don't see any issues there. The switch closes across 4 & 5 in the off position, so I don't think that this is the problem.

At the transformer, I'm getting 120VAC on 1 & 2, but zero volts across the two, instead of 230. I'm using a static phase converter. Could this be the cause of my troubles?


If anyone has any suggestions, I'd sure appreciate hearing them. Thanks.

[ 06-30-2006, 01:20 PM: Message edited by: Slash ]
 
Is your brake coil good? Unhook one wire and check the resistance across the brake coil. If you didn't unhook one wire, the 230 ohms could be the value of the variable resistor.

I think the resistance on my coil is about 50 ohms. I'll try to remember to check tomorrow.
 
You need 115 VAC at X1 and X2. If you don't have that do whatever it takes ahead of the transformer to get it.
It is a nominal 90 VDC brake. You should be checking for DC voltage across the brake. If you only have AC the rectifier is probably bad. The voltage across the brake may be less than 90 VDC depending on the pot setting. The pot is to be adjusted to make it stop nicely, the full 90 VDC might stop it like hitting the wall.
 
We just fixed the brake on our old Leblond Tool and Diemaker. Take a look at the little carbon brushes that supply power through a commutator into the brake coil. These wear and get loaded with oil and carbon dust. The holder for the brushes is on a funky arm that can move away from the commutator if the screw loosens. The brushes are cheap from Leblond.

Good luck.

Tom Lipton
 
Hey Slash!

Didn't see this post till after I got your PM about the DRO's.

A search on "LeBlond brake" turns up a few hits, this one was mine:

http://www.practicalmachinist.com/ubb/ultimatebb.php/topic/1/9064.html#000000

I agree with everyone about calling LeBlond. I had to laugh when they sent me a copy of "my brake don't work". The troubleshooting help was dead on. Mine was the simple broken wire at the drum switch.


I'm using a static phase converter. Could this be the cause of my troubles?
I don't know for sure on that one (how the brake would be affected), but I had a problem actually running the lathe on a static. Running problems went away when I went to a rotary. Mine is a 15", too (if that matters).

Good luck with yours!

Mark
 
I am not sure what you mean when you say the voltage goes up when the lever is in the run position. There shouldn't be any voltage at the brake then. Make sure the switch is OK.

I have a similar aged 14" that I just completed rebuilding. The brake coil is stationary and has no brushes. Like gbent said, check the coil resistance by removing one wire. If it isn't open, it is probably good. Mine was caked up pretty good with grease and grime. Have you removed the pulley and cleaned all of the junk out?

The voltage on the third leg on a static phase converter will change under load. It will actually be much more stable when you have a motor running - the motor acts as a buffer. A rotary phase converter is a static with an idler motor (and slightly different capacitance values).

The brake system only uses a half-bridge rectifier, so the voltage will show up both DC and AC scales (depending on the meter).

You can check the rectifiers by measuring the resistance in both directions (power OFF!!, one end of the diode disconnected). One direction should show low resistance, the other very high resistance.

Let us know how you make out!
 
I've had several Leblond dual drives with the eaton electronic brake. About the only problem I ever had was "less than ideal" commutation betwixt the brushes and the slip rings.

From McMaster Carr, commutator dressing sticks, and a 200 proof alcohol soak of the brushes to get rid of oil.... all was good.

Cyclotronguy
 
Update:
I just received a fax from LeBlond, but it isn't what I was hoping for. It doesn't give much info that will be helpful. I'm not sure that they sent the same page that several of you have mentioned - It is titled "Regal Lathe Brakes", not "My Brake Don't Work". :confused: The rep did state that the rectifier is a common problem, and that they don't stock the part.

Scott R - Yes, I pulled the pulley off yesterday. It looks like I might have a small leak at the oil seal. There was quite an accumulation of oil/dirt/grease/gunk. I don't have it all cleaned out yet, but will finish doing so today.

gbent & John Michael & Scott R - Thanks for the tips. It really helps knowing what to look for. I wish I understood more about how the electrical system works.

tlipton & Cyclotronguy - I'm not sure what you are referring to on the brushes. All I see is a fixed coil, maybe I'm missing some parts???


Thanks toeveryone who has replied. I'm going back out to the shop to see what else I can discover...
 
I think tlipton was referring to the zero speed switch on a Leblond with servo-shift. IIRC it's a mercury switch. They sometimes leak.

Your schematic shows no switches. I don't know what turns it on.
 
I'm not sure what the 750 ohm 25w rotary(?) does but check diodes, one has a hole in it


Seriously, if all your voltage inputs measure good at the xfmr input, swap AC to DC meter function. Check the diodes first. No help there, check the bypass cap.

Dobber
 
The 750 ohm rheostat varies the voltage applied to the brake. With the rheostat off, the brake applies hard & fast, quickly stopping the spindle rotation.

As the rheostat is dialed into to the circuit, the brake slips in varying amounts, allowing a coasting stop.

If you were turning a flywheel that close to the maximum swing of the lathe and it was mounted on a mandrel between centers, for instance.

The inertia built up in the flywheel could overcome the grip of the mandrel and the flywheel could spin on the mandrel if the brake locked up quickly.

Later model LeBlond lathes had three rheostats: one for the brake, one for the clutch and one for the jog; to prevent similar occurences at spindle start-up.

Mike
 
UPDATE:
The brake is working! The braking action isn't instantaneous, but at least it works. I've been running for ~5 years with no brake.

It turns out that the static converter was the culprit. I was not getting correct voltage to the transformer. I simply moved one of the input leads to a different 'leg', and that corrected the problem. Well, maybe it wasn't so simple, but I finally figured it out, and I didn't electrocute myself in the process. :D


I really appreciate everyone's assistance. I was honestly expecting to either get flamed or just be ignored.

You folks have been nothing but cordial and helpful. In addition to the responses here, I've received multiple PMs & emails, and one member faxed me his copy of the LeBlond troubleshooting proceedure.

I must admit, I'm taken aback by your response. I hope that someday I can return the favor.
 
My break don't work

Slash,

If it can wait till late Sunday, I can fax you "my brake don't work". You have my email, let me know.

Mark

Could I please bother you for a copy of my break don't work I have a 13" leblonde that I'm converting to vfd and having trouble finding any elect diagrams Thankyou in advance . Mick
 
I know this is a old thread but could I trouble you u for a copy via email of my break don't work ? I have a leBlone wth break issues Thankyou in advance if not I understand .
 
I know this is a old thread but could I trouble you u for a copy via email of my break don't work ? I have a leBlone wth break issues Thankyou in advance if not I understand .
If you received a copy, could you please send one my way, I have a 15" Leblond Regal lathe and the brake has stopped working to my email address.
Thank You,
Bob
 
If you received a copy, could you please send one my way, I have a 15" Leblond Regal lathe and the brake has stopped working to my email address.
Thank You,
Bob
No need, LeBlond was gracious to send me a copy.

Thank You
Bob
 
I am looking for the rest of this wiring schematic I have, could not find the entire schematic.
Thanks, Bob
 

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