Overheating Shaft

[gumbo]

I bought my machine in Feb. 2009 as a "factory refirbished" with 20+ hours on it. I soaked the flex shaft in the chain lube with moly around April and now have about 100 hours on it. While doing a carve tonight I noticed a mark on the shaft and sure enough it was a melt spot. After about 15 into the carve I felt the shaft was hot I stopped the carve took the shaft apart and resoaked it for about 40 min. I then restarted the carve and after about another 15 min felt the shaft again and it was hot. Any one with any suggestions of what may have happened and or what I could or should have done? I know I am going to need to order a new shaft but just looking for some advice. One thing that I was thinking was that I replaced the QC with the rock chuck (great move by the way) around xmas time and I oiled the bearings in the z truck pretty heavely and was thinking that maybe some of the oil worked its way up the shaft and caused a problem. What do you guys think?

[dbfletcher]

I bought my machine in Feb. 2009 as a "factory refirbished" with 20+ hours on it. I soaked the flex shaft in the chain lube with moly around April and now have about 100 hours on it. While doing a carve tonight I noticed a mark on the shaft and sure enough it was a melt spot. After about 15 into the carve I felt the shaft was hot I stopped the carve took the shaft apart and resoaked it for about 40 min. I then restarted the carve and after about another 15 min felt the shaft again and it was hot. Any one with any suggestions of what may have happened and or what I could or should have done? I know I am going to need to order a new shaft but just looking for some advice. One thing that I was thinking was that I replaced the QC with the rock chuck (great move by the way) around xmas time and I oiled the bearings in the z truck pretty heavely and was thinking that maybe some of the oil worked its way up the shaft and caused a problem. What do you guys think?

Ummm.. what bearings did you oil in the z-truck? The bearings undr the top hat should not have any lubrication put on them at all... that why you have to make sure the flex cable doesnt have any excess lube on it when putting it back.. you dont want any to work its way down to the z-truck.

Doug Fletcher

[c6craig]

Yup, you are doing it backwards. Soaking the Flexshaft in the proper lube is great, but you have to let it drip off the excess or wipe it down before you put it back in. The goal is to keep oil OUT of the top hat and bearings, or else you will burn up your Z Truck...plus I have been told that too much oil on the Flexshaft is as bad as too little...

Craig

[rjustice]

Doug is correct... these are sealed bearings, and in fact if overlubed, will cause the spindle to turn harder at high RPM, creating heat, and in turn could cause the flexshaft to work harder, and heat up as well...

[gumbo]

Ok great now what if anything can I do to clean up the mess I created for myself?

[dbfletcher]

Ok great now what if anything can I do to clean up the mess I created for myself?

My understanding is that if the bearings in the z-truck get fried, you must replace the entire z-truck. I'd take the tophat off and inspect them. Hopefully someone will chime in on what exactly you can look for to determine if they are damaged at all.

Sorry to be the bearer of bad news....

Doug Fletcher

[DocWheeler]

I just did that search and found a ton of posts, reading through them might help.

[c6craig]

One of the easy ways to tell...when you are carving, if your Z Truck is getting too hot to touch comfortably...you are screwed - new Z truck in your future.

If it is not heating up too bad you may be able to pull the top hat off and wipe it out as best as you can...

Ask me how I know... :rolleyes:

Craig

[cnsranch]

FWIW, I keep an eye on the z truck constantly with an infrared thermo - LHR told me that 120 degrees is acceptable, higher is bad.

[gumbo]

Well I think that you all hit the nail on the head, so I bit the bullet and ordered both the flex shaft and the z truck. What should I do should I wait to run the machine until the parts come in, or should I run the old parts until they go? Could this do any other damage?

[cnsranch]

gumbo

Seems like you're asking for trouble if you continue to run the machine - if the z starts to seize, I gotta believe that the motor will work harder and harder....

I could be way wrong - I'm sure Al will chime in soon.

Re the flexshaft - when I first got my machine, I couldn't keep the shaft cool enough for my taste - the chain lube with moly wasn't working for me. I was also really concerned about the lube getting into the top hat - the stuff is like water, and I felt that it running into the hat was a "sure thing" (for me, it's one thing to repair something that wears, etc., it's another to have to replace something I caused to go).

I had less than 10 hours on the machine when I found a lube with moly that was paste-like, rather than runny. Thanks to Chris Alb, I got some CraneCams (sorry, not made any longer) I lubed the shaft with that, have over 250 hours on the machine since, and the shaft NEVER even gets warm - infrared thermo shows it always around 95 degrees, and I've done a couple of 9.5 hour carves.

Here's just one link when you Google "lube paste moly".

It's not cheap, $33 for an 8 oz jar, but the CraneCams was $10 for two 1oz. packets.

FYI, I used much less than 1/10th of the packet to lube the entire shaft - the two packets will last my lifetime.

http://www.tsmoly.com/catalog/product_info.php?cPath=1_7&products_id=84

[gumbo]

Hoe about using the flex shaft after I change out the z truck, do you think that the overheated shaft is still ok to use or should I put the new one on asap?

[cnsranch]

gumbo

It depends on whether you can keep the shaft cool, and it won't melt the outer sheathing further.

Pull it apart, and see if the inner spring has been kinked or otherwise ruined from the initial overheating.

[AskBud]

If the outer casing and spring are still OK, you should be good to go. You could be in a position to just change out the 2nd, pre-lubed, inner flex whenever the current one begins to heat

[gumbo]

there is a small melted spot on the lplastic casing but everything else looks fine,

[gumbo]

My parts finally arrived but I need some advice. Do I use my old flex shaft it has a small melted spot where you can see the sheath, or should I put the new one on. I have already replaced the Z truck but I am not sure what to do about the shaft.

[earlyrider]

I'd clean out the sheath with mineral spirits (and maybe a piece of rope) and the spring, first, then lube the shaft. Check for heat on the next (trial) run. If the flex gets hot, then switch it out with the new (lubed) assembly.
Ron