Daewoo Low Chuck Pressure

shortbusdriver · Oct 24, 2019

Im looking at buying a Daewoo Lynx 200 cnc lathe. Machine looks to be in pretty good shape but the owner says it has low chuck pressure. He has not looked into it as he is not using the machine lately.

As far as I know it is not throwing a low hydraulic pressure alarm so I do not think that is the issue.

Any ideas to look into first? I am a self taught manual machinist so I do not know much about these machines. I would like to see if I can find the issue before I either buy this machine, or move on to something else.

TeachMePlease · Oct 24, 2019

Well, hello, Buddy.

Guest · Oct 24, 2019

Not familiar with that model but it should not be any different than any other lathe of similar construction using hydraulics. What items are operated by hydraulics? Chuck, turret, tail stock, part catcher, or ???. Is the pressure on the main pump good? Do all items operated by hydraulics have adjustable pressure? I honestly would only be concerned if the main pump pressure was low and can't be adjusted up as it could be worn out. Honestly the problem could be so many things. If the main pump looks good I would just start at the chuck and work my way backward. Something is probably plugged up or a valve or the like isn't functioning correctly. If the main pump needs a rebuild that could be an issue, anything else is probably a cheap fix.

Ox · Oct 25, 2019

Hydro pumps are available for cheap as they are more plentiful than small block chevy's. (anymore)

I would think that the only component that would be expensive would be the actuator if there would be some reason that needed replaced, and I doubt that you would be able to diagnose that upon inspection.

If I liked the machine otherwise, and I could pick it up cheap doo to the [semi unkown] issue, I would prolly jump at it, keeping in mind that a new actuator is likely the most expensive possibility.

Heck, who knows, maybe the draw tube needs beat out with a sledgehammer and the whole thing cleaned out real good is all?

------------------------

Think Snow Eh!
Ox

Guest · Oct 26, 2019

Ox said:
Heck, who knows, maybe the draw tube needs beat out with a sledgehammer and the whole thing cleaned out real good is all?

------------------------

Think Snow Eh!
Ox

I now think I misinterpreted the original post. By low pressure I assumed he meant the hydraulic pressure to the chuck was low. By reading your comment and re-reading the first post he could have well meant clamping pressure.

Ox · Oct 26, 2019

Yeah - IDK.
I read it both ways, and figgered that he actually meant clamp pressure, but who knows.

I'm going with the worst case scenario and be happily surprised later.

On the other end of the spectrum, maybe someone turned the chuck pressure down for a light weight job and nobody there anymore realizes that _ that is even an option? Find the pressure reg and just turn it back up? But again - even if that is the case - you doo NOT want to test it on the current owners floor!

-------------------------

Think Snow Eh!
Ox

Guest · Oct 26, 2019

Didn't Toolcat sell one of those machines recently?

DouglasJRizzo · Oct 26, 2019

Usually, the pressure adjustment is set too low and someone doesn't know where it is. I was their training guru for years and found the pressure adjustments moved a few times to differing places. Barring that, a variable vane pump that has some wear (easily replaceable) can cause it, incorrect voltage phasing can do it, low fluid level (usually a buzz saw noise indicating cavitation of the pump), or a clogged strainer. None are fatal. The Lynx is a great machine and a money maker. Parts are readily available and I have training materials free of charge for the asking.

shortbusdriver · Oct 28, 2019

The chuck itself has low holding pressure according to the owner.

DouglasJRizzo said:
Usually, the pressure adjustment is set too low and someone doesn't know where it is. I was their training guru for years and found the pressure adjustments moved a few times to differing places. Barring that, a variable vane pump that has some wear (easily replaceable) can cause it, incorrect voltage phasing can do it, low fluid level (usually a buzz saw noise indicating cavitation of the pump), or a clogged strainer. None are fatal. The Lynx is a great machine and a money maker. Parts are readily available and I have training materials free of charge for the asking.

How do you check/change chuck pressure?
How much would a replacement pump be?
I would be interested in training materials if I get this machine. I am just very scared to dive into another project as the last 3 machines I bought I ended up getting lied to/screwed over on.

Vancbiker · Oct 28, 2019

My thoughts are kinda in line with Ox's. I've seen more than one chuck that used up most of the force from the actuator just to overcome the internal friction in the chuck. Lots of places never grease or clean the internals of a chuck. Crap builds up, sliding surfaces get a bit galled, and before you know it the chuck will hardly grip anything despite cranking up the hydraulic pressure.

SIM · Oct 29, 2019

I've also had a clogged hydraulic filter use up alot of the pressure exerted by the pump.

Dirty chuck...

Too low a setting on the pump.

Where to find setting....usually by the hydraulic pump...but not always. however lines will come fromt eh pump...trace them to a knob...usually around a dial gauge.

Hoss710 · Oct 30, 2019

4 thinks come to mind. the chuck itself could be bound up with chips . a bad suction filter. bad regulator( broken internal spring, or bad seat) . last a blown draw tube cylinder seal. I have seen all of these cause this type of problem. if it were me, I'd buy it knowing what worse case scenario would cost and deduct from asking price. if its something simple then its money in your pocket. if it's worse case, you are prepared to pay the piper.

DouglasJRizzo · Oct 30, 2019

shortbusdriver said:
The chuck itself has low holding pressure according to the owner.

How do you check/change chuck pressure?
How much would a replacement pump be?
I would be interested in training materials if I get this machine. I am just very scared to dive into another project as the last 3 machines I bought I ended up getting lied to/screwed over on.

There is a small door where the pressure valves are located. Check where the pressure gauge is and you'll find the adjusting valves very close. Not sure how much a pump would be. If you get the machine, PM me, and I'll send training manuals.

shortbusdriver · Nov 6, 2019

DouglasJRizzo said:
There is a small door where the pressure valves are located. Check where the pressure gauge is and you'll find the adjusting valves very close. Not sure how much a pump would be. If you get the machine, PM me, and I'll send training manuals.

What should the pressure be?

Mike1974 · Nov 6, 2019

shortbusdriver said:
What should the pressure be?

Really depends on what you are doing, but a WAG is 150-250. Not sure on that model but the older Haas SL lathes would alarm out around 60-70...

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