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Wondering if Okuma DC drive lathes are to be avoided or is my tech off base?


Cast Iron
Sep 12, 2008
Eugene Oregon
I've asked about whether to consider an LH or LB series lathe if the chance comes up and I got a stern opinion to stay away from the DC drives these machines use. I'd like knowledgeable people's thoughts on this maybe his personal preference that follows his dislike for the encoder style, or is this a known problem area and I'm prone to certain financial ruin if I don't follow those words?
I've never heard of this and I've been working around Okuma lathes for like 20 years. There are a gagillion LB10/LB15/LB25 lathes out there going all the way back to the early 1980's still pounding accurate parts all day every day.

Old machines (like 20+ years) will, at some point, experience a drive failure simply because components don't last forever.

Occasionally I'll have drive faults and I bring in a local industrial electroinics guys. He'll take the whole drive home and go over it. Normally he'll find a couple bad capacitors and replace those along with any others that look iffy. A few days and few hundred $$$ and I'm back in business.

I'm pretty convinced that the LB series from Okuma will still be running after a nuclear strike.
Good DC drives are fine. There are few components in a 1980's Japanese cnc that are built poorly and cannot be repaired or updated, usually very economically.

DC spindle drives can be problematic to repair or retrofit.

Resolvers/tachs can be hard to retrofit, but are usually very available used.
Okuma ever used DC spindle drives on LB lathes??
Afaik, DC spindle drives were mostly a Gildemeister thing, early NEF CT40 and similar had them.
Also common on early Maho-C and Hermle milling machines, better Okuma/Fanuc machines switched to AC spindle drives quite early on.
My Okuma ACT4 from 1982 already used AC spindle and DC servo, Puma8/Fanuc10T from around 1988/1989 is aready full AC-Spindle/Servo.

DC-Servo are OK, AC servos usually run smother, DC-spindle is a thing that I usually avoid, due to brush/commutator wear, already fried a couple of DC-motors on my washing machine, don't need that on my machinery if there are other options/a second hand market filled with old iron ;-)
I remember he was talking about DC and the spindle so maybe the whole topic was about the dc drives for them. Hard to follow a conversation when you have limited knowledge. Is there a simple way to tell if they are a DC drive when shopping for machines on the interwebs?
If it has a crt display it probably has an ac spindle motor.

DC spindle drives were unpopular past early 80's.