[SRT Mike]

My LC40 started dripping hydraulic fluid out of the chuck a few days ago - now it's losing about a gallon every few hours, so I need to fix it. But first how do you get the damn chuck off?

This is my first CNC lathe and this LC40 is new to me. There are three very large hex head bolts on the face of the chuck. Then on the circumference of the chuck there are three small-ish set screws that are only around 1" long - not sure what they are for. Then there are three hex head screws that go in tangent to the diameter of the chuck - they are rounded off on the top so that they match the chuck outer diameter and don't stick out. These only turn 180-degrees.

I have removed the big hex bolts from the front, the set screws seem to be maybe just oil drains or something and dont seem to bear any load, and the half-turning hex nuts I dont know what they are for or what they do.

Can anyone help? How do I get this thing off?

Also, anyone had a hydraulic leak at the chuck before? Is it likely the chuck itself or the connection to it from the machine? Is it a common problem and what should I look for and check?

Its all covered in hydraulic fluid and I am hesitant to climb into the machine and start yanking on stuff and have a gigantic chuck fall on my foot at an unexpected moment, and I'd rather not get covered in oil if there's some magic technique I am missing that makes it easy

Thanks!

[M-man]

The fluid are comming from the cylinder at the end of the spindle, there are no fluid in a hydralic chuck. .. Remove the 3 big hex bolts at the chuck, then the chuck are mounted on the pipe that connects the chuck with the cylinder, just turn the chuck or pipe, until the chuck comes off, we use to put a pipe thru the spindle so the chuck wont fall off..Got a a chuck at work that arent mounted, I could get some pics of it and you will se what I mean.

We always put the c-axis on to hold the spindle locked, you might want to use a pal to hold the spindle if you dont have anykind of break to use.

[SRT Mike]

Ok, that makes sense - thank you!

I have seen the tube moving in and out and I knew the hydraulic actuator was on the back end of the spindle.... so it makes sense that its leaking.

It also explains the 1/2" layer of scum on top of the coolant.

I am surprised at how much oil is going down the tube though... and is it normal for it to leak into the tube instead of just dripping down from the hydraulic actuator?

Any idea what they cost to repair and if it's something I can just buy a rebuild kit for and do myself? Or would I need to send it out?

I really need to try to get the lathe up and running this coming week and I think the only way thats gonna happen is if I rebuild it myself. It works great, just seems to have blown a seal or busted an o-ring or something.

[phx]

hi
you can ask the manufactor of the cylinder for a repair set.
this includes all o-rings, etc.

[M-man]

it is leaking in the front, all oil must come down your tubing then, you prob got a oring that seals between the draw tube and the housing tube, so there will prob be plenty of oil when removing it.Have you had any clamping problems when you have been having this kind of leak, mabe its been a problem for internal clamping? I think you sould do like phx says, it will prob be the fastest way, a normal skilled and hany guy will fix this easy.

[SRT Mike]

it is leaking in the front, all oil must come down your tubing then, you prob got a oring that seals between the draw tube and the housing tube, so there will prob be plenty of oil when removing it.Have you had any clamping problems when you have been having this kind of leak, mabe its been a problem for internal clamping? I think you sould do like phx says, it will prob be the fastest way, a normal skilled and hany guy will fix this easy.

I dug into the machine a bit more - I opened the access panel where the gearbox is, and it's clear there is an internal tube on the drawbar and some sort of outer tube, so I'm guessing the oil is leaking down to the chuck between the two (or at least there is a round sheath where the gearbox is that is larger diameter than the drawtube). I also took all the panels off around the spindle motor and it's a Kitagawa F1768 actuator. I'll call them Monday and see if I can't get a complete seal kit sent right out. I'm sure I can do the job myself, I have rebuilt several car engines and I replaced all the table bearings in our VMC, I just don't know lathes too well (but I'm learning)

I can't say I've noticed any problem with clamping. I paid $6000 for this LC40 lathe from a machine shop next door. It's a 4-axis/dual turret with all the options, OSP5000 control, rear-exit chip conveyor, live tooling, programmable m-codes for robotic part loader, door opener, etc. It also came with probably 50 sets of hard and soft jaws, toolholders, boring bars, inserts, drills, all the live tooling holders, front-cutting live tool adapters, BT holders for the live tooling, floating tap holder, etc. The guy that owned it is really nice and knows his machining, but he's not too hot on the mechanical/repair side. He told me luber started to make a snapping noise, and it was getting tons of oil in the coolant tank, and it was "going through" hydraulic fluid. I think he knew the repair guy would charge him a few grand to come and spend 2-3 days fixing all the issues, and he just figured he may as well get rid of it cheap.

Turns out the problem on the lube tank was just a cracked line from the pick-up to the connector on the housing, and since there was no restriction to the pump, it would raise the plunger which would then smack down (the noise he heard) and squirt the lube right back into the tank. Paid $60 for all new fittings and filters for the luber. I *thought* that was the problem with the oil in coolant also, but theres a LOT of oil in the coolant. The hydraulic pump in the tank out back made a starving noise so I shut it off right away - it took 5 gallons of hydraulic fluid to come up on the level to low (it holds 10 gallons I believe). I had also noticed the chuck was literally drenched in oil if the machine sat for more than about 10 minutes. If I rotated the chuck by hand the entire outside was covered and oil was dripping down between the jaws. I put 2 and 2 together and figured that's where the leak was.

I have really only been running the machine maybe a total of 3-4 hours of actual cut time since I got it a couple months ago (had to learn to program it and all), so I probably wouldn't have noticed a chucking problem. I am also using custom soft jaws to hold my parts, which are small 1.5" to 2.5" aluminum parts, so I probably wouldn't have noticed a problem anyway with such light duty work.

On a side note, its very interesting to "get into" this machine. The spindle motor is 60hp, and the DC motor that runs it is around 30" in diameter and about 3 feet long with giant eye-bolts on top to lift it. It has a seperate 1/2hp or so motor that drives a fan that ducts air into the main spindle motor. I laughed at that! My little hobby lathe has less power than the motor that cools the spindle on the CNC lathe I pulled the panel housing the gearbox - what a beautiful sight. The gears are very precise, clean, pristine. The load-bearing shafts are perfectly polished - like chrome. Very interesting, and very cool.

So hopefully I can get the actuator rebuild done this week. When I removed the two lines going to the actuator, there was no fluid in there - zero. I wonder if the main hyd. pump is filling the actuator every time I turn it on, which then just leaks the fluid into the tube and out the chuck. Maybe there won't be too much fluid coming out when I pull the actuator - but we shall see!

Thanks guys!

[Geof]

I had a thought which is turning into a suggestion. Before you going ripping things apart found out whether that hydraulic cylinder has a drain line on the seals.

We had a hydraulic leak on a SL10 recently just after installing a new pump. The leak was from the drain line returning seal leakage to the tank. High pressure high speed rotating seals are often designed to be leaky. This is for a couple of reasons: If they do have components actually in contact the contact forces from the pressure combined with the high speed makes things hot so the leakage provides a cooling flow. The other reason is that sometimes these seals do not have any sealing surfaces in contact; they have what is called a labyrinth which is sort of mini-size interlocking grooves and ridges with very small clearances but no actual contact. The fluid can escape through the small clearance but it has a tortuous path and when the seal is rotating this enhances the turbulence in the leakage flow so it is quite small. All that is needed to maintain pressure is a pump large enough to overcome the leakage flow. And naturally there has to be a system to collect the leakage and return it to the tank.

[Big_d]

We always put the c-axis on to hold the spindle locked, you might want to use a pal to hold the spindle if you don't have any kind of break to use.

On some machines you can get away with this, but you are taking a BIG risk as if the spindle is powered whilst holding it could take off if you manage to move it a little. PLEASE don't do this!

[Big_d]

Wow a LC40 a lot of machine for that kind of money. They are very solid and quick if you use both turrets at the same time. Hence the 60hp DC motor (About equal to a 25-30hp ac motor). We used to spin a 110kg chuck and a 16kg part at 1700rpm on ours for many years before it was retired about 15 years ago. Does this one have the brake option on the spindle motor? It makes it a real pain to change the belts. Make sure the filters are in good order on the cooling fan as this is the quickest way to cook one of these big DC motors. I retro fitted an even larger blower and several paper element filters on ours it helped drop the motor temp quite a bit. Ours was finally retired due to it catching on fire in the control box. It was sold as scrap iron and I believe we got 2200 as you probably know they are around 9 tons.

I digress, I believe there is only a couple of things that it would be. Most cnc chucks are mechanical and are operated with a hydraulic cylinder at the rear. This chuck cylinder spins with the spindle and doesn't have to swivel, it should be attached to the centre of the mechanical chuck and retract to close. Look at the centre of the chuck and see if there is a bolt/cap screw holding its rod to the rear? If so undo this. The cylinder and swivel joint should then be able to be removed from the rear of the spindle. Just undo the bolts from the flange if fitted (It may be screwed I don't remember) and the whole assembly should come out the back (Be careful it's not light). The cylinder should only be sealed with O rings so it will only cost a few dollars to reseal. The swivel joint could be the culprit of the leak but most of the time it will only be the the static O rings leaking. Use 90 duro O rings and make sure the areas they sit on are smooth, if not polish them or get it hard chromed and ground. Treat this assembly like a crankshaft, be careful not to bend it or mark any of the labarinth areas and contact areas.
Geof is on the money with the labyrinth seals and if the bearings haven't failed in the swivel they will be fine. How are the bearings on this joint? When they get tired they are normally the cause of excessive leaks out of the labyrinths. This happens well before they make contact.
Good luck with the old girl let us know how you go.
Cheers
Daza

[RODMAN]

Mike,
That machine originally had a drain line (about 1" ) connected to a sheet metal collector near the back of the cylinder draw tube. The other end is routed to the hydralic tank. If the machine is somewhat level then oil leaking out of the cylinder will be returned to the hydralic tank. It was normal for these drain lines to get knocked out of place when moving the machine. Small leaks are normal, BIG leaks need to be fixed.

Rodman

[SRT Mike]

Thank you everyone for the tips so far! I got overloaded with work yesterday but today I had more time to work on this.

I did check the drain line at the bottom of the assembly under the labyrinth seals and it was not blocked at all. When I removed the line and stuck my finger in the resultant hole, there was no debris or restrictions I could feel. So I don't think it's as simple as a blocked drain line (although I was hoping it was). I managed to get the chuck off (and ruptured my colon catching it when it started to go - THANKS for the tip to put a bar in the spindle to prevent it falling - that sucker must weigh over 200lbs!).

I also removed most of the parts surrounding the hydraulic actuator. When I look into where the chuck was, it appears the inner tube is now free to slide around and that means it should be able to come out from the back along with the cylinder (if it needs to come out that is - see below).

However, do I need to remove the hydraulic actuator AND the drawtube together? Or should I be unbolting the actuator and just removing that? Please see the pics I posted below...

There is a metal ring held on with clips at the back of the cylinder. This is connected to a pair of microswitches that will just be to detect whether the chuck is open or closed, so I will get a clip wrench bit enough and get that off.

On the cylinder itself, there is the actuator itself that looks like a motor, this spins freely with the mount, hydraulic lines and drain line removed. Then right in front of it is a large metal cylinder slightly larger in diameter than the actuator - this has a big set of bolts on the front and some hex socket bolts recessed in the rear. Then there is a brake rotor (may be one big piece that's also the front of the cylinder - I can't tell) then another set of large hex head bolts right before the tube disappears into the casting of the machine and re-appears about 3' to the right inside the machine where the chuck is.

It appears I can either remove the brake calipers and try to slide the whole thing out, actuator, cylinder, and drawtube all in one. OR, I can unbolt it somewhere along the way and just remove that part.

I'm guessing I want to do the latter? But before I start can someone confirm that? I am guessing that in the cylinder part on the front of the actuator will be some connection mechanism to the drawtube, and that's where the seals and o-rings will be. But if I have to unbolt it at the right-most (closest to chuck) set of bolts I will have to remove the brake system from the spindle to get the rearward part off the machine.

Any tips so far? I'm planning to get it off tomorrow or on the weekend and hopefully have the beast up and running again next week. Hopefully being the operative word here

[SRT Mike]

Wow a LC40 a lot of machine for that kind of money. They are very solid and quick if you use both turrets at the same time. Hence the 60hp DC motor (About equal to a 25-30hp ac motor). We used to spin a 110kg chuck and a 16kg part at 1700rpm on ours for many years before it was retired about 15 years ago. Does this one have the brake option on the spindle motor? It makes it a real pain to change the belts. Make sure the filters are in good order on the cooling fan as this is the quickest way to cook one of these big DC motors. I retro fitted an even larger blower and several paper element filters on ours it helped drop the motor temp quite a bit. Ours was finally retired due to it catching on fire in the control box. It was sold as scrap iron and I believe we got 2200 as you probably know they are around 9 tons.

Thanks Daza, great info!

It does have the brake on the spindle - I didnt know that was an option! As far as I can tell it has almost every option. The original owners used it to run parts for I believe the oil industry. It was just one part, over and over, all day long. So they got the options to open the door through an M-code, and the option to clamp/unclamp the chuck. Then they had a robotic loader (which can be fed with codes from the control, as far as I can tell) and they just let the thing run all day and all night. Then it was purchased by a guy who used it for turning large parts as-needed. He sold his shop to his brother and I bought it from the brother who wanted to move it to make room for a 2nd Mori (since he liked his first one so much and the LC40 took so much room, and he no longer wanted to do big parts to limit liability for material costs if he screwed one up!).

The more I use this machine the more I like it. I am quite amazed it had so much capability considering it was made in 1986 I believe. I can program a profile and just let the machine figure out how to cut it, and it cuts beautiful threads and will take gigantic cuts without so much as batting an eye.

Good tip on the filters - while I had the cabinets off I looked at them and they are absolutely covered with dirt and greasy oily goop. The outer one was anyway, inner one was OK. Did you ever need to change the brushes on the motor? This one runs like a champ - all the belts look almost new. For some reason I can't clamp/unclamp tooks in the live tooling on the A turret. There is a pressure gauge right behind the Z axis servo and it reads zero. I believe this gauge is hydraulic pressure for the live-tooling part of the A turret, and I haven't looked into why there is no pressure. I also have a controller board problem that gives an error when the 2nd turret tries to move in the X-axis, but I do electronics design and I am going to try to fix it myself - I was able to repair the TRS-50B servo driver from our leadwell mill so maybe I'll get lucky again! If I can't fix it I will just send it out to get R&R'ed. I work with the A turret now and its pretty quick, so I can imagine doubling throughput having 2 turrets - would be very cool.

If you have any more tips or comments on these machines I'd love to hear them. It was funny when they moved it in here. We told the rigger it was 25,000lbs and they brought a 25,000lb forklift. Well, that may lift 25k lbs but probably only when the weight is right back against the rear of the forks. So of course the forklift went up in the air when they tried to pick it up. They put a 5k-lb forklift on the other and and still no luck. They ended up bringing in a 2nd 25k-lb forklift and putting one under each end and being very careful to sync their movements. I shudder to think how it will be when we end up moving out of this place!

[Big_d]

Ours was a 78 from memory? We had a different brake on the end of the spindle motor. The spindle brake is part of the live spindle option and we didn't have this on our machine as it was only used for turning. I maintained it for about 5 years doing the mechanical side of things. The brushes we used to change every 12 months regardless of condition and they were checked every 3 months. They probably had 9 months left in them from memory but our machine was run very hard with the maximum acceleration curve used at all times. Always in top gear. You only have a small chuck so I don't think you will be wearing these out like we used to.

The second turret problem would be cable related, I would be checking that before starting on drives. They are a real pain to rewire so I hope im wrong. It is common with these when they start getting on. Being Okuma all the electronics, motors and encoders are in house units and are normally only marked with Okuma part no's, you will need to know what you are doing if you don't have the correct service documentation.

The biggest problem we encountered was deflection when using 2 turrets and would always work with the bottom turret roughing the outer and the top doing the bore and finish the outer.

That chuck cylinder is a piece of cake to rebuild just remove the bolts (Heads facing the turrets next to the brake rotor) and remove the swivel, alloy barrel and draw bar out the back. You could strip it mounted to the machine but I normally do this back in the workshop to keep any stray swarf out and pressure test them before re installation . No extra work but cleaner? I do these without assistance but they are not light. I would guess that the front/rod seal on the clamp cylinder is the leak. Not common in my experience but if you had oil streaming out at the chuck end that would be it. The rest is obvious but if you get stuck PM me.
Cheers
Daza

[SRT Mike]

Ours was a 78 from memory? We had a different brake on the end of the spindle motor. The spindle brake is part of the live spindle option and we didn't have this on our machine as it was only used for turning. I maintained it for about 5 years doing the mechanical side of things. The brushes we used to change every 12 months regardless of condition and they were checked every 3 months. They probably had 9 months left in them from memory but our machine was run very hard with the maximum acceleration curve used at all times. Always in top gear. You only have a small chuck so I don't think you will be wearing these out like we used to.

The second turret problem would be cable related, I would be checking that before starting on drives. They are a real pain to rewire so I hope im wrong. It is common with these when they start getting on. Being Okuma all the electronics, motors and encoders are in house units and are normally only marked with Okuma part no's, you will need to know what you are doing if you don't have the correct service documentation.

The biggest problem we encountered was deflection when using 2 turrets and would always work with the bottom turret roughing the outer and the top doing the bore and finish the outer.

That chuck cylinder is a piece of cake to rebuild just remove the bolts (Heads facing the turrets next to the brake rotor) and remove the swivel, alloy barrel and draw bar out the back. You could strip it mounted to the machine but I normally do this back in the workshop to keep any stray swarf out and pressure test them before re installation . No extra work but cleaner? I do these without assistance but they are not light. I would guess that the front/rod seal on the clamp cylinder is the leak. Not common in my experience but if you had oil streaming out at the chuck end that would be it. The rest is obvious but if you get stuck PM me.
Cheers
Daza

The thing abou the 2nd turret is the guy who owned the machine before me had called in his Okuma tech (he has all Okumas) who said the controller board was bad. He wanted to replace it - for $3.5k! The guy said "no thanks, I'll just use turret A!". I will try to fix it myself... I can index it and move it in X, just can't move it in Z.

Also when the electrician was wiring the machine, he knocked the control panel and busted several of the switches. There is a button marked "tool clamp/unclamp" that I think you must use to load toolholders into the live tooling, but it isnt working. But also there is no pressure showing on the gauge on the live tooling area in the cabinet, so I'm guessing either there is a problem or it may just be that the former owner turned the pressure all the way down to zero on that because he never used it. I'll probably take a stab at fixing that servo controller on the Z axis of turret B. I can swap controllers for X and Z axes to check if it is the controller, and if it is I can hopefully do a component-level test on each part to figure out whats wrong

But I guess for now if I can just get the spindle to stop leaking I can get back to making parts.

I really like this machine - it's so solid and capable and the more I dig into it and take parts off the more I can really appreciate the engineering and "no expense spared" approach to building it. It is designed very intelligently and robustly!

I PM'ed you also about the actuator - trying to get the cylinder body apart - not sure if its supposed to come apart from the drawtube end or the rear (furthest from the chuck) end!??!?!

[Big_d]

Check the cables they have been the cause of many a drive failure on these.

[SRT Mike]

LC40 is fixed and back up and running with no leaks!

It was the seal between the piston and the cylinder housing, letting fluid leak into the housing that goes around the drawtube, which then worked its way down the drawtube into the chuck.

I never worked on a lathe before, so it was all new to me. When I put it back together I made a mistake on the cylinder, had to rip it all apart - still didnt work, then I realized I had put a broken spring back in (looked like 2 springs to me!). Its all working now.

I guess the bottom line is this - to remove chuck from an LC40...

1) Put a piece of stock as close to the bore size as you have into the bore to "catch" the chuck

2) Remove Jaws, turn the flush-style allen head bolts around the outside which will release the master/inner jaws

3) Remove the 3 huge hex head bolts on the chuck face

4) Have someone brace the spindle at the cyliner end, put a hefty bar of something soft (like AL) into the chuck and unscrew it



It wasnt going back on right, until I looked close at how exactly the mechanism works. Its all back together and working now... I had a couple parts not quite lined up.

Happy to have my LC40 up and running again!