# "B" Mandrel



## wood-of-1kind (Mar 23, 2007)

For those members that use the BEALL CHUCK to turn pens. What size of ER collect do you use? The "B" mandrel (0.290") that I use has been giving me problems in terms of matching to a proper collet size. The closest match so far is a size 8 mm (8-7 or 5/16"). In order to get a good grip I have to wrap some masking tape to build up on the diameter of the "B" shaft. Would be interested in your comments in terms of what you are doing to use the Beall chuck the way it was meant to used.

Thanks in advance for your input.

-Peter-


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## Mikey (Mar 23, 2007)

I was told it was 5/16". I do know you can get the metric collets on eBay for as little as $10 each plus shipping. I have been looking at a set of like 10 for about $110 plus shipping.


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## Mikey (Mar 23, 2007)

That's good to know since I have the B mandrel and have been trying to get the 5/16" from a member here.[]


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## Paul in OKC (Mar 23, 2007)

If the collets come in 1/64th sizes, I would try a 23/64, an 11/32 would be at .281, the collet should expand a little for that.


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## alamocdc (Mar 23, 2007)

Pete, if I have time tonight, I'll see which collet fits my "B" mandrel best and get back to you. I believe all of mine are by 1/32" sizes. If you don't have that, you can make your own collet insert using a scrap of good dense hardwood. James (Fangar) showed such an example that he uses for casings. I've copied his technique for a number of things now, and it works very well. Essentially you drill a hole just large enough for the mandrel through the scrap. Then turn it round (I do this on the mandrel, but between centers should work too). Then use the band saw (or coping saw) to make a cut right down the middle (lengthwise down the cylinder) about half the length. You'll make 4 cuts in all that will yield 8 slots. Maybe these graphics will make more sense.




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Note that on the end view below, the dashed line represents the opposite end of the cylinder, and that the cuts are offset 45 degrees so that the cylinder remains in one piece, but has a fair amount of flexibility.



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## Fred in NC (Mar 23, 2007)

In the past I made a few shafts for B Mandrel.  On some of them I turned one end to 1/4", the other was threaded as usual.  I will see if I have any left.  Please email me if interested.


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## Tea Clipper (Mar 23, 2007)

Peter, I use 5/16" and haven't noticed any grip problems.


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## Randy_ (Mar 23, 2007)

I agree with Ron.  I use a 5/16" collet and it grips just fine.  I suspect there is some other problem working here.  Collets are designed to hold the labeled diameter and up to about 1mm smaller.  You should not try to squeeze a larger rod into a smaller collet.  

Berea "B" mandrel = 0.291"
5/16" Collet = 0.3125" - 1mm(0.039) = 0.273"

As you can see a 5/16" collet should work just fine.

Since you are trying to grip a "B" mandrel, I will assume it is one from Berea.  That being the case it most likely is threaded on both ends and both of the  threadings are 1/4" threads.  If you are trying to grip the threaded portion of the mandrel, a 5/16" collet will, in fact, be too big to grip properly.  Drop down to a 1/4" collet and things will be just fine although you may distort the threads somewhat.  I tried Bruce's suggestion when I first got mine and you "CANNOT" force a true 5/16" diameter rod into a 1/4" collet.


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## Tea Clipper (Mar 23, 2007)

Oh yeah, good point Randy.  I grip the rod as I do one barrel at a time.  I do not try to grip the threads.


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## scubaman (Mar 23, 2007)

5/16" = .3125".  This collet grips down to .273" = the B mandrel at .290" is right in the middle of its grip range.  If you can't grip it, make sure all the surfaces that need to slide against each other as you are tightening the nut are clean and actually do slide - on the nut, the collet and the chuck.  Make sure the collet is seated properly in the nut - snap it in the nut before you screw the nut on the chuck.  Note that there is an eccentric lip inside the nut that has to catch the lip of the collet or it will not release properly.  If the collet and nut do not meet properly, you may experience binding, inability to tighten, etc.


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## wood-of-1kind (Mar 23, 2007)

> _Originally posted by scubaman_
> <br />5/16" = .3125".  This collet grips down to .273" = the B mandrel at .290" is right in the middle of its grip range.  If you can't grip it, make sure all the surfaces that need to slide against each other as you are tightening the nut are clean and actually do slide - on the nut, the collet and the chuck.  Make sure the collet is seated properly in the nut - snap it in the nut before you screw the nut on the chuck.  Note that there is an eccentric lip inside the nut that has to catch the lip of the collet or it will not release properly.  If the collet and nut do not meet properly, you may experience binding, inability to tighten, etc.



The collet is seating fine with the head of the chuck (they're flush) and no gaps. I've checked the Berea "B" mandrel and it is at spec at 0.290" but the 5/16" collet just does not close (to bite) and hold the mandrel tight. The only way that I could get the mandrel not to 'spin' freely is to build up the mandrel by wrapping masking tape. The tape does allow the collet to 'bite' and keep the mandrel from spinning but I don't like this solution. And yes, I have been gripping the mandrel on the non-threaded part of the shaft.

Billy, thanks for the wood dowel insert but it just doesn't seem right to spend all that money on the Beall and the collects and still come up with a makeshift idea.

I will try another 5/16" collet and see if the jaws lock in and grip the shaft better. Perhaps I may have a defective unit.The one that I purchased is marked 5/16" but also has an 8-7 designation (metric equivalent I'm guessing).

Thanks for all the input that has been received so far. I really want to find a proper sized collet and use the Beall as it was intented to be. It's a better way of turning versus the sliding MT2 mandrel that has served me well up to now.

-Peter-


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## arioux (Mar 23, 2007)

Peter,

I would definitely suspect a defect somewhere.  I use a 5/16 as well and everything is fine .

Good luck.

Alfred


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## wood-of-1kind (Mar 23, 2007)

> _Originally posted by arioux_
> <br />Peter,
> 
> I would definitely suspect a defect somewhere.  I use a 5/16 as well and everything is fine .
> ...


Thanks Alfred. That's another confirmation that the 5/16" collet is the correct one to use.
-Peter-[] until I get a good collet.


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## Rudy Vey (Mar 23, 2007)

Using a 5/16 for years on my "B" mandrels with no problem, they hold fine. Check out if your 5/16 collet is a 5/16 collet or larger. I would advise against wrapping masking tape around the mandrel, this might toss your "roundness" off a bit, since the tape is overlapping somehow.
Also, did you check the diameter of your "B" mandrel?


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## scubaman (Mar 23, 2007)

Check the correct nominal size with the shaft of a 5/16" drill bit.  Carefully inspect all the slots that they are open.  8mm is .315" - just a tad over a 5/16" and effectively interchangeable


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## Randy_ (Mar 23, 2007)

> _Originally posted by wood-of-1kind_
> <br />.....The collet is seating fine with the head of the chuck (they're flush) and no gaps. I've checked the Berea "B" mandrel and it is at spec at 0.290" but the 5/16" collet just does not close (to bite) and hold the mandrel tight.



A couple of additional things occur to me.  One is simply that the collet is mislabeled and it is not a 5/16" collet.  Peter, you are correct that the 8-7 designation is the equivalent metric designation.  Try measuring the ID of the uncompressed hole in the collet.  I just measured mine and it is 0.308".  If yours isn't close to 0.312", then the labeling is probably incorrect.  Another possibility is that there are metal chips or other debris in the compression slots in the collet.  You might tighten the collar on the collet and see if all of the little slots compress properly and all compress to a uniform width.  If that doesn't happen,  maybe you can try to clean out the slots with compressed air or whatever method is available to you.


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## Randy_ (Mar 23, 2007)

For reference, the slots in my collet are about 3/4 of a mm wide when the collet is uncompressed.  With the collet in the chuck and the collar tightened as tight as I can get it by hand, the slots narrow down to a little less than a half mm.


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## scubaman (Mar 23, 2007)

Over the grip range of a collet, each slot narrows by .015" - .020" depending on the type - some collets have 4 slots, some only 3.  If they are filled with metal filings, the collet will not behave.  DAMHIK.  Also inspect for burrs.  If it's seated properly, and the size is correct, there has to be some sort of defect - 5/16" (or 7-8mm) *IS* the correct size.


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## wood-of-1kind (Mar 23, 2007)

Thanks for all the good advice and all the measurements that I can check to make sure that everything is in order. If I get nothing else out of this posting, it certainly has been clearly stated that the 5/16" collect is the correct match and mate for the "B" mandrel.

-Peter-[]


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## wood-of-1kind (Mar 29, 2007)

I have replaced(exchanged) three 5/16" collets and the third one was of proper fit. Long story short: careful of the quality of the ER32 collets that you purchase, they're NOT all built alike and they certainly are not all of equal quality."Caveat Emptor" - buyer beware.

-Peter-[]


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## Randy_ (Oct 9, 2007)

Peter:  Just curious??  Was the problem collet a Beall collet or something you purchased on eBay?  There is another thread running right now and the guy is having trouble with with his Beall chuck.


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## LanceD (Oct 9, 2007)

When using my B mandrel on my Beall collet chuck I have to take it off of my lathe and put the chuck in my vice then tighten down the collet with the collet wrench as tight as I can. My set was purchased as a set from Charles. I have no problems with the 1/4, 1/2 and 3/4 collets, only the 5/16 size.


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