Mandrel Problems???

[kmccolly]

I recently purchased a Pro Pen Mandrel (145997) from Woodcraft. On the same order I received pencil kits (123850) and pen kits (123108). The pen kits call for 2-3/8" blanks, and the pencil kits for 2-1/8" blanks. Even with adjustment the mandrel appears to be too short for the pen blanks. The pencil blanks fit with the brass nut flush with the end of the mandrel shaft.

Questions: 1. Is this an operator problem?
2. Must I find a source for a longer mandrel shaft?
3. Did I purchase the wrong mandrel altogether?

Thanks for your assistance in advance, and Happy New Year!

Ken

 

[TellicoTurning]

Ken,
I don't use this particular mandrel, but it appears to be an adjustable mandrel... can you loosen the nut at the taper and slide the mandrel in or out in length... the shorter mandrel allows for a more ridged and less flex in the rod....

 

[kmccolly]

Re: Pen Mandrel

Chuck - I understand the adjustabiity of the mandrel. The problem is that with both halves of the blank and 3 bushings installed leaves the mandrel shaft too short for installation of the nut, even with a minimal amount of the shaft in the collet.

Ken

 

[TellicoTurning]

Ok, that's unusual... so I'm lost now.... I thought I was being clever looking it up to see the adjustability... those aren't overly long blanks... you may have to add enough spacers and shorten the mandrel and just turn the blanks one at a time... kinda like you are doing between centers... I have a mandrel that I've cut in half and put the half with the threads in a jacobs chuck to do single blanks... works okay, but I do mostly TBC now since I got my dead center from Johnnycnc.

 

[johnnycnc]

Ken,
I think I may see the issue..the instructions call for 2-3/8" long blanks,
but they probably padded the length. You will cut them down to the length of
the tubes after you glue tubes in. Measure your tube lengths, you can try the bare
tubes and bushings alone on the mandrel to check your assembled length issue.
I can see where the 2-3/8" length is (hopefully for you) initially misleading.
BTW, sorry about your mandrel.

 

[leehljp]

How long are the "bushing" spacers? Some are 1/2 to 3/4 inch long, IIRC. If so, that is the problem. Most "normal" spacer/bushings are 1/4 inch from most places. On the WC website, most pictures show the "longer" spacer/bushings. You need on the 1/4 inch ones in between and even on one end or both ends. This will save you some space, if it is the problem.

 

[kmccolly]

Re: Pen Mandrel

John - I will try just using the tubes and bushings tomorrow to see if that is the problem. Thanks......

Hank - Yes, my bushings are at least 5/8" if not 3/4". I just ordered the bushings listed in the instructions. I may have to purchase some shorter ones. I appreciate it.

Ken

 

[leehljp]

John - I will try just using the tubes and bushings tomorrow to see if that is the problem. Thanks......

Hank - Yes, my bushings are at least 5/8" if not 3/4". I just ordered the bushings listed in the instructions. I may have to purchase some shorter ones. I appreciate it.

Ken

5/8 to 3/4 - That is your problem! Three of those will take up about 2 full inches by themselves.

Those long bushings come in handy when turning single blank pens, but cause problems when turning two long blanks like you are asking about. It is always good to have both kinds on hand. When ordering the short bushings, always order an extra pair. When you have only one set, one is sure to jump off the mandrel and into a corner under a heavy table and attache itself to glob of sawdust! :wink::biggrin:

If nothing else, use a long bushing on each end and a short one for the middle - that will give you 3/8 inch of threads at the least.

 

[Mr Vic]

I use the WC adjustable with the long bushings all the time. Never had an issue. Loosen up the jam nuts and tighten the brass nut till you have some thread showing on the tail stock end. Then snug up the jam nut. Should work...........

 

[JakeAB]

I have the same mandrel, and had the same problem. Adjusting the mandrel to give enough thread for the brass nut resulted in not enough mandrel for the jam nut to hold securely. Got shorter bushings and the problem went away.

More often than not now, I shorten the mandrel and turn one barrel at a time. Less tendency for the mandrel to flex if I get overenthusiastic and tighten the nut too much.

I just started experimenting with TBC, which would make all these problems go away.

 

[kmccolly]

Re: Pen Mandrel Prolems

Gentlemen - I greatly appreciate your collective wisdom. Although I have not eliminated the problem, I have developed a way to work around it with your help.

John - You were spot on about the blanks. Although the kit directions called for 2-3/8" blanks, the tubes were only 2". I cut my blanks down to 2-1/8" (which is what the matching pencil kit called for) and everything worked.

Hank & Jake - The length of the bushings was definitely an issue. Even though we developed a solution for this particular kit, I can see where I may come across a situation in the future where that may not be possible. Hank, what was your source for the short bushings?

Chuck - Thanks for the idea of turning a single blank at a time.

I may also get a machinist to make me an inch longer mandrel shaft as a reserve.

Thanks again!

Ken

 

[Paul in OKC]

I can see if I have any drill rod that size left. Let me know how long you need it. I assume the adjustable mandrels are just threaded on one end, correct?

 

[kmccolly]

Re: Pen Mandrel

Paul -

8-1/2" would be great, threaded one end. If you can do it, just add it to the bill for the vise and press you are doing for me. Thanks.........

Ken McColly

 

[chugbug]

Why not turn the two separately?

Hi Ken,

didn't see it mentioned, but... why not turn them separately? I know the norm is to turn the two tubes at the same time, but just turn them separately.

I have the same mandrel as you noted, and I did have an issue with a pen a while back (don't remember now which one it was), but as you said, the mandrel shaft is a tad too short even extended all the way out for the two blanks and three bushings for a few kits. I actually almost ruined mine trying to get the length to fit.

In the end, I just turned the two blanks separately, reducing the size of the mandrel shaft, and adding a length of lamp rod (threaded or unthreaded) long enough to fit my tool rest in. The hole in the rod is just the right size to slide over the mandrel shaft and not wobble. If you don't have that, just use a bunch of 5/16" nuts. They fit snug on the shaft too.

Hope this helps...Chugbug

 

[kmccolly]

Chugbug -

Jake also suggested this and I may try it on my next go around. Thanks for the help!

Ken

 

[leehljp]

Hank, what was your source for the short bushings?

Thanks again!
Ken

I am fairly certain that I got mine from Ernie at Beartoothwoods. There are other vendors that sell the short ones though. It seems like I ordered maybe two sets from him when I ordered a mandrel for my newly purchased Rikon lathe that I bought in '06.

Click here for a list of his bushings. I purchased the ones for the slimlines - you will need to scroll about 1/2 to 2/3rds down the page.

I haven't used a mandrel in a couple of years, so I might be rusty on some of the details.

 

[Randy_]

Have you called or emailed Woodcraft to see what they have to say??

 

[Paul in OKC]

Oops, forgot to check. Will do tonight.