Changing linear guide rails Okuma LT300

[MIKEL12]

Hi

We were going to do a rail/carriage exchange under the subspindle on an okuma lt300 when we ran into a problem. We cant find a way to remove the wagons from the body of the spindle.
There are only 3 bolts accesible for removal and the other 3 seem to be inside the structure.

Our conclusion is that the spindle needs to be lifted and then the bolts removed from the base of the spindle assembly.

Anyone have any tips on this?
On our other machines this operation is easier so we didn't anticipate that this would be such a timeconsuming deal...

[OkumaWiz]

This seems to be a common problem with this series and Okuma is addressing it with new cover kits for these machines...have you had them update your covers? The old covers allowed chips to get under them and build up on top of the linear guide clamp blocks which then tore the bottoms out of the linear guides for ZB and W axes - not good! You REALLY ned to talk to them about this since it is an expensive repair and some machines are being covered under warranty. You also don't want to be doing this again in under a year.

When they update the covers they also add some flushes to the machine to improve chip flow.

To answer your question, the R spindle needs to be lifted off and the B-turret as well in order to replace the rails and trucks. If I remember correctly, once the body is separated from the base, the bolts for the trucks will be accessible.

[MIKEL12]

The machine is from 2007, so warranty could be a possibility. We actually ordered some new covers recently and have yet to install them. I will make sure to check if theese are the new ones and if others need fixing to.

After the scale of the work dawned on us we started to rethink and swaped out some accesible trucks and put the rail in storage until next year. The rails werent that bad after a cleanup, and if the covers have a designflaw as you say we need to swap the rails next year anyway

and lastly a bit of an oddball question:
Our machine guru says to swap the iko guides for rexroth ones, do you have any views on that ? They are cheaper (half price) and promise equal to better performance, but then again I guess all salespeople say that

Thx for the reply, didn't think anyone would be able to answer my questions. And your answer was awesome

-Mikel

[OkumaWiz]

I don't have any experience with the rexroth guides, but am not impressed with the IKO since they seem to be rather fragile on the bottom and the seals get torn off easily. I'd be sure to evaluate the design closely to see if they are less likely to get damaged. Okuma took off our clamp blocks when replacing the guides to try to protect the trucks. Their theory is that in the event of an impact, one rail or the other has machined "L" for backup support, so the clamp blocks aren't really needed and the clearance for chips is needed more. This clearance keeps the chips from getting pinched between the clamp blocks and the trucks which destroys the seals on the bottoms of the trucks and causes them to fail.

Last I knew they were working their way through about 40 of the LT-300's and the Macturn 250's in the USA which share the same bed/cover design. Given it takes about 2-3 weeks to do it, they have a couple years worth of service work to do - Yikes! Bet now they wish they would stick with proven designs and refine them rather than come out with new models all the time!


Good luck with yours!

[Algirdas]

1. you need to take away the spindle. You'll need to align it anyway after rails replacement. Then the bols will be accesible. Other way is to release guideway bolts - while moving the spindle, and to lift railways together with spindle. Not recommended.
2. Rexroth says to me, it's special order for that model - check with Your local dealer and with Your lathe model accuratelly.
3. New design cover kit is absolutelly necessary for that machine.

[MIKEL12]

Thx for all the help,

Currently we are trying to contact the local agent for the cover exchange but everyone is still on vacation.

-Mikel

[Edster]

Was the problem from chips making it past the covers?

Seeing that makes me worry about our captain with a subspindle. Maybe I should take the covers off and check everything.

Good luck, hopefully Okuma will make things right.

[MIKEL12]

Yeah that seems to be the problem, we first thought that the previous owner had accidentally dropped a part on the covers and that had bent them so that chips could get in past them.

But as OkumaWiz pointed out this seems to be a designflaw in the covers themselves, not sure it's affecting the captain though.
Cant hurt to look if you have the time, please report back with findings for future reference