Flex Shaft Melt Down

[ronboley]

I've read several posts abut flex shaft problems. Today in the middle of a 3 hour carve the outer plastic sheath on my flexshaft melted off!...Oh shoot!...I stopped the carve and let everything cool down. After removing the plastic sheath that was left and the inner core, everything seems ok. I lubricated the inner core, reassembled and completed the carve. The flexshaft (minus the plasic outer sheath) was cool thru the rest of the carve. So the mystery is what was going on to heat up the flexshaft enough to melt the plastic? Did the lube just give out and boom there goes the sheath? Maybe others have had some simillar experience and found what happened in their case. I sure don't know what went on here. The flexshaft has been no more than warm before this and I've done 3-4 hour carves in oak. Things that cross my mind....flexshaft not properly seated in the truck, it seemed ok on disassembly...bit getting dull...maybe...been a while since the flexshaft has been lubed...also maybe...Your input is greatly appreciated. Thanks!

[bergerud]

According to LHR, a common reason for flex shaft heat up is that the core is not "floating". If it compressed between the motor and the spindle, it will heat up. They also say that after such a heat up, the core is toast and recommend you replace the whole flex assembly.

[fwharris]

Just adding on to Dan's comments, make sure the flex shaft has a nice arc from the back of the machine up to the cutting head. It should not have any tight bends..

[ronboley]

The flex shaft is still functioning and not getting any more than mildly warm so I'm still carving with it...ordered a new one this morning anyway. I guess the only conclusion is to lube the inner shaft regularly and make sure it's inserted properly...then hope for the best...Thanks guys for your input!

[Digitalwoodshop]

I had one burn up after doing maintenance. It sat out in the sun and I was too frisky with it when I grabbed it to install. I whipped it and the outer rubber was hot from the sun and it flexed like a wet noodle... I KINKED the Damper Spring and did not know it.. When I started the project the kinked spring was rubbing metal to metal and caused the heat to make it melt and smoke... And YES, the Smoke Detector did it's job.... I was standing out on the deck working and turned around to see the black smoke...

A Smoke Detector above the CW... As Martha Stewart would say...."A Good Thing"...

AL

[radman5506]

I had the same thing happen to me. I did as you did and lubed the shaft, no more overheating. The machine only had approximately 50 hours on it when it happened. I think it is supposed to last longer than that with the factory lube but mine did not. Any way I replaced the melted outer sheath and have had no further overheating problems. Still using the original shaft.

[jmoriearty]

My flex shaft melted down last week too, unfortunately, no smoke detector. I came in to a Z-axis stall, so I guess it stopped turning. We will have to see how much damage I did....uhg. I also have to replace my board sensor, the mounting holes have worried out on it. Looks it's order time for me.

[badbert]

Probably not the kinda advice I should be giving here... When mine melted (after a 40 project marathon) I needed it to finish the project. So I cleaned it really well with WD-40. I used heavy duty electrical shrink tubing. And made a "TEMPORARY" sheath for it. I probably should replace it some day...

[ronboley]

Just to let you guys know...the (now without exterior sheath) flex shaft is still working just fine with about another 8-9 hours of carving time...still not getting any more than mildly warm...I check it regularly now...and I beleive I will lube it more regularly...anyone have a feel for how often to lube the inner core ? I'll still repleace the whole assemblky after the new one arrives, but maybe establishment of a more regular schedule for lubrication of the inner core based on hours of carving is needed.

[dickcash]

About 5 years ago the flex shaft started to heat up and the outer sheath split open around the bend.
I bought a new one to replace it with but kept using it until it failed. That was 5 years ago. The new one is still waiting to be called to duty.
The split in the sheaf acts as a vent to release some heat. It's never run cooler. Might be a feature to add.