Z-axis lead screws maintenance

[Mary Anne de Jong]

Having some trouble with my universal laser (vl200) so I want to clean the z-axis lead screws.

Would like to know...

1. What do I clean them with to get rid of the old grease?

2. What kind of grease can I apply that would be suitable?

I read somewhere I should use white lithium grease but it's a bit hard to source locally..can only get spray cans....not tubes. Looking for a suitable alternative. Don't want to apply the wrong thing and end up with a bigger problem.

TIA

[Gary Hair]

Denatured alcohol will work fine to clean it and, yes, you do want lithium grease. Not sure where you are located, but you can buy lithium grease at most home improvement stores or even online. Go to amazon and search "white lithium grease" and you'll get hundreds of results.

[Doug Fisher]

If Gary's suggestions for sourcing a tube of white lithium grease don't work, try calling around to well stocked bicycle shops. That is where I bought my last tube.

[Jerome Stanek]

I bought a tube from a mower shop that sells lawn boy that is what they use in their gear box

[Mary Anne de Jong]

Thanks for the ideas...hadn't thought about bike shops or mower shops. Unfortunately home improvement stores only stock the spray cans....

[Bill George]

Thanks for the ideas...hadn't thought about bike shops or mower shops. Unfortunately home improvement stores only stock the spray cans....

I thought your husband took the entire machine to be serviced and they cleaned and lubed those screws last week? Unless your doing a lot of dirty cutting or Corian engraving they should not need cleaning every week. I have used dry spray lube on CNC machine screws in the past and it lubes but no sticky grease to attract dirt and grit.

You can find the maintenance manual here > http://www.engravingsys.com/equipment-support/universal-laser-systems-support/
No mention of lubing the Z screws that I could find. But they do stress the table needs to be the same height on all 4 corners or it would bind. This would be something you need to measure.

[Matt McCoy]

...the table needs to be the same height on all 4 corners or it would bind. This would be something you need to measure.

I think Bill is on to something.

[Mary Anne de Jong]

Thanks for that Bill....yes he did bring it in to be serviced and they said they had to clean and grease the lead screws and it was working fine however after returning home and starting the laser up the following day the table was still stuck. Tried to get some help from the technician who said he fixed it but didn't get anywhere. He just told us to check the table level but that was ok.

It would jamb up about 1 cm from the top or the bottom so haven't been able to use the machine at all.

Decided to do some more research and try to fix it ourselves. Found an extensive service manual online and had a lot of good advice here in the forum as well which has been great. I rang a different laser supplier and spoke to their service technician and he confirmed the white lithium grease is what they use. We purchased some online from an archery shop of all places.

After a lot of cleaning and re-greasing have the table moving up and down better but still slightly sticking at the top..I will do a bit more cleaning tomorrow.

[Bill George]

I am just wondering if its binding up because of a twist or something out of alignment in the frame? By now it should be the cleanest machine on the Forum! If as some suggested you can get the belt loose and try running it up and down by hand. It has to be frustrating!

[Joseph Shawa]

So one problem I have had is that one of pulleys on the bottom slipped when I over raised the table and went to the end of the screw at the top. This too my table out of alignment. I have since purchased limiters for the top(yet to install).
As the long screw/bolt that runs through the nut has some freedom in the X Y plane the only binding that could or even MIGHT happen should be at the bottom near where the pulleys are mounted to the floor of the frame.
One suspicion is that one of the threads is messed up near the top. You can check for freedom of rotation at the time of binding by disconnecting the belt when the table gets stuck.
Another thing that has happened to me (what hasn't?) is that somewhere along the way I changed the setting for the Z stepper motor and it tries to move too quickly and grinds to a halt- a terrible sound. In conjunction with a binding screw this might happen at the same place on the table. The motor and table should operate rather quietly with only a small amount of grease and as this is a slow moving part I would say any kind of grease should be fine.

Good luck

[Kev Williams]

On thinking like Bill's thinking, only I don't think the frame is twisted, I'm leaning more towards one or two corners are high or low, most likely just one-

-- if the table is nice and level to the machine, then all the screws will be 'relaxed' within the threaded females. The females on my GCC are about an inch thick, on the LS900 they're well over an inch. That's a lot of threads the females are covering.

So-- suppose one screw is 1/8 to 1/4 turn out of sync with the other 3-- the table is going to be higher or lower on that corner. But it doesn't WANT to be! The table is pretty rigid, and pressure exerted by the table wanting to spring back to it's relaxed flat state, is directly applied to that lead screw and nut, AND to the diagonal corner to some degree. What should be a relaxed fit is now an interference fit...

Now, notice her pics in the other thread, of where the stoppage takes place; at near full up, and near full down travel-- where the screws are anchored...so, while the table is hovering around the middle of the travel range, the screws are flexible, free to bow in and out a bit, allowing for enough operational free-play. But move the females towards the top or bottom where the screws are anchored, and the screws are rigid with no give at all- and the stepper motor may not have the oomph to overcome the thread interference...

That's one theory ;)

[Bill George]

Kev that one that has been suggested over and over by several posters. The OP seems to think its all in the cleaning and lubing.

[Kev Williams]

sorry if I'm being redundant, I haven't had time to read all the 'in retrospect'... ;)

[Bill George]

sorry if I'm being redundant, I haven't had time to read all the 'in retrospect'... ;)

Not redundant but Correct!! :) Like you usually are.