Serious Problem(s)

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Mapster

Mapster

Member
Joined
May 21, 2010
Messages
505
Location
Orlando, Florida
I have a debilitating problem at the moment. Everytime I turn a pen my mandrel unscrews from itself. I have the mandrel that screws onto the headstock and it is two pieces (as most are). It has the threaded part that screws onto the headstock and the rod. The rod keeps unscrewing from the part that screws onto the headstock :confused:

I thought it was just loose, tightened that rod as hard as I could and within a minute it was loose. Makes all kinds of screechy annoying noises. I then thought it was from cutting the blank, but it still came off within a minute while sanding. I made a pen and despite all of my desperate attempts it is horribly out of round.

I would greatly appreciate any ideas. I realize I will most likely need a new mandrel, but I don't see how that can be the problem. The way the lathe turns would tighten the rod, not loosen it, so I don't understand how it can turn the wrong way and unscrew while the lathe is tightening it at 3200 rpm. Turncrafter pro with mandrel saver. Thanks in advance
 
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Mapster said:
Everytime I turn a pen my mandrel unscrews from itself. I have the mandrel that screws onto the headstock and it is two pieces (as most are). It has the threaded part that screws onto the headstock and the rod. The rod keeps unscrewing from the part that screws onto the headstock :confused:

with mandrel saver.
Click to expand...


Marshall; The last quoted line is the most important. The Mandrel Saver puts the compression on the bushings and blank, not on the mandrel so there isn't anything to keep the mandrel from unscrewing.

My second thought, is that the rod may be threaded opposite to the headstock.

Suggestion that occurs to me is to use CA on the threaded rod. That is assuming you don't need to unscrew the rod. You could break the CA bond with heat if necessary.


Hope this helps.
 
I'd see if I could test a different mandrel or test that mandrel on a different lathe. The OOR usually indicates some kind of wobble, which normally comes from over-tightening or under-tightening the tailstock. I propose it could be if the tailstock is moving and/or undertightened, it could be causing the OOR and letting the mandrel vibrate itself unscrewed (it's totally possible, believe it or not).
 
Yeah, I thought about CA, but I did that on a tailstock I had that kept unscrewing and it broke the CA bond. I think I will try that. Even with the mandrel saver there is no reason the mandrel should unscrew, it makes no sense. The rod is threaded the same as the headstock, so I don't believe that could be the problem. Thanks for the idea though, CA will be next in line if there isn't a bigger problem.
 
Well, there is not much oor from the mandrel itself. The lathe runs fairly true also. It could be part of the problem also though, it shakes slightly right when it starts or when it is about to stop. Loctite is a good idea, I think I might try that.
 
Is turncrafter pro a Penn State Ind. product? (Just asking.) If it is, I would call their toll free number and talk to their technicians. Someone can tell you what the problem is and how to fix it. (Probably!)
 
I also use the mandrel saver, and I have never had this problem. If I recall, the mandrel is threaded in the opposite twist as the lathe runs, so it should not untwist. I know this sounds weird, but does you lathe turn in the same direction as the threading? Might have a wiring issue. Just throwing out thoughts...
 
Chuck, that is going to happen soon, it is on my list, but I don't quite have the $ca-ching to make the switch at the moment. I will try some loctite or Ca for sure then, thanks for the help. And no, my lathe does not turn in the same direction as the threads, it was a very valid question though. Thanks for the help all
 
Mapster said:
Chuck, that is going to happen soon, it is on my list, but I don't quite have the $ca-ching to make the switch at the moment. I will try some loctite or Ca for sure then, thanks for the help. And no, my lathe does not turn in the same direction as the threads, it was a very valid question though. Thanks for the help all
Click to expand...

I see this comment often when it comes to turning between centers. The cost is much less than you think. All you need is a dead center and a live center. I bought both for less than $20. Use the same bushings you currently use. I know many people like to buy the special bushings from some of the members here but it is not required. They may be better, but not required. It's like saying you can't turn a pen because you can't afford a Oneway lathe.
 
That is true, I didn't think about using my existing bushings... Also, making them would be pretty easy. Definitely a project to start, but after the holidays. For now I bought some loctite and have that drying as I type, so I can get back to my holiday pens I need to finish tomorrow
 
Red loctite instructions say to loosen thread lock, heat to 450 F for 5 minutes. Blue will simply loosen with pliers. You can always use blue, then followup with red if blue does not solve the problem.
 
Do you have a brass nut that hand screws onto the end of the mandrill? Mine does and if my tail stock is loose I get a screem and the hand nut backs off. I reset my tail stock and make sure the setscrews are tight
 
That sounds like one of those Turncrapper mandrels that I used to own. Loctite will fix it, if not, an 8 pound sledge hammer will!
 
If you're using the Mandrel Saver double check the alignment of the headstock to the tailstock. I was having this problem with my mandrel and sure enough the alignment was just a tiny bit off. Once I fixed the alignment, the issue went away.
 
Live2Dive said:
I also use the mandrel saver, and I have never had this problem. If I recall, the mandrel is threaded in the opposite twist as the lathe runs, so it should not untwist. I know this sounds weird, but does you lathe turn in the same direction as the threading? Might have a wiring issue. Just throwing out thoughts...
Click to expand...

Yes, I was thinking the same. Haven't flipped the switch to reverse by accident, have you?
 
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