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Old 08-05-2008, 08:40 AM   #1 (permalink)
 
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Default Mandrels

Looking for feedback on the different type of mandrels people use to make pens, duck calls, bottle stoppers and other small items.
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Old 08-05-2008, 08:44 AM   #2 (permalink)
 
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Not sure what you are asking. I use standard 7mm mandrels on 7mm pens. Those I am using now came from J. collazzo. Larger pens I do with the 'no mandrel' method. Duck calls are also made using the 7mm mandrel and expanding bushings. I made my own screw in holders for bottle stoppers. Some might call them tenons, other might say they are mandrels. I just call them 'screw in things'.
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Old 08-05-2008, 11:00 AM   #3 (permalink)
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Very much like Frank, I use the 7mm for duck calls and slimlines; otherwise, it is the mandrel-less system for everything else. A couple of Frank's posts got me intrigued with the no-mandrel system and I haven't looked back.
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Old 08-05-2008, 12:02 PM   #4 (permalink)
 
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For some reason I just haven't discovered the real advantage of the "no-mandrel" system. Especially if you use the expensive bushing for each different type pen. I do now only turn one half of a pen at a time on a short mandrel. I guess I just feel more secure with a rod going through the blank. If you don't use bushings, I'd be afraid of expanding the ends of the tubes.
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Old 08-05-2008, 12:04 PM   #5 (permalink)
 
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I use mandrell-less bushings and my trusty micrometer.

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Old 08-05-2008, 12:13 PM   #6 (permalink)
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Quote:
Originally Posted by PaulDoug View Post
For some reason I just haven't discovered the real advantage of the "no-mandrel" system. Especially if you use the expensive bushing for each different type pen. I do now only turn one half of a pen at a time on a short mandrel. I guess I just feel more secure with a rod going through the blank. If you don't use bushings, I'd be afraid of expanding the ends of the tubes.

Ditto
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Old 08-05-2008, 12:17 PM   #7 (permalink)
 
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I am using the 7mm mandrel from CSUSA. I also haven't nerved the mandreless technique as of yet.
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Old 08-05-2008, 08:06 PM   #8 (permalink)
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Quote:
Originally Posted by PaulDoug View Post
For some reason I just haven't discovered the real advantage of the "no-mandrel" system. Especially if you use the expensive bushing for each different type pen. I do now only turn one half of a pen at a time on a short mandrel. I guess I just feel more secure with a rod going through the blank. If you don't use bushings, I'd be afraid of expanding the ends of the tubes.
Easy comparison here:
A. You are mounting the bushings on a mandrel that can go OOR from being bent or a tad too much tail stock pressure. Even with this setup you are still mounting the mandrel between the head stock and tail stock with the bushings on that.
Or
B. Mount the bushings directly on the 60 tips of the live center/dead center of the head stock/tail stock - and eliminate the extra part (mandrel) altogether. (Exception - Duck calls and 7mm pens)

Either way, you are "mounting the bushings", but with the no mandrel, you eliminate one step and also one more item that can and does complicate the matter many times.

Other reasons:
Once the size and shape have been achieved, remove the bushings and mount the blank directly between the live/dead center and finish sanding to size.
1. NO Bushing Sanding Dust.
2. NO Stuck Bushings
3. NO CA chipping at the end due to Bushing/blank separation.
4. Under the assumption that every added part increases the chances of OOR or alignment, one part is eliminated.


If you don't use bushings, I'd be afraid of expanding the ends of the tubes.

If you are worried about this, then you would probably be having OOR on mandrels too. The problem you described is that too much pressure would be applied. That SAME amount of (too much) pressure on a mandrel can also cause OOR there too. One note: ON mandrel-less turning - Bushings are used for the turning down with a chisel. Bushings are not used for finish sanding or for sealing, coating and (CA/Lacquer/other) finishing.

You do NOT need special bushings for the mandrel-less turning. You do need bushings that are not OOR, but that applies to mandrel use also. Many order from JohnnyCNC because his bushings are much more precise than OTC mail order tend to be.

In my experience with Sierra bushings over the past 3 years, I have had about 20% to be OOR and two of them visibly so - to the unaided eye. If I had purchased an expensive set from Johnnycnc at the beginning I would have saved money and had better fit on my sierras, even when using a mandrel.

Don't get the idea that you have to have the expensive bushings to turn without a mandrel.
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Last edited by leehljp; 08-06-2008 at 03:43 AM.
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Old 08-05-2008, 09:54 PM   #9 (permalink)
 
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Well I can't say that that doesn't all sound good. I have not experienced some of the problems you speak of yet, but I have experienced the glued bushing when finishing. Wasn't a real problem easy enough to un-stick. Your saying if I finish without bushings the glue will not stick to the dead center and the tailstock center? I'll have to give it a try one of these days. First I need to learn how to turn pens. One advantage I would like about your method is not having to screw on and off the mandrel nut. I'm forever dropping it. Coarse that is better than dropping the pen blank.
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Old 08-06-2008, 03:40 AM   #10 (permalink)
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Quote:
Originally Posted by PaulDoug View Post
Well I can't say that that doesn't all sound good.
Actually, I am not really trying to convince people to move away from the mandrel as a method, BUT I am saying that it is one less step, one less piece of equipment needed (two if you count the mandrel nut), and several problems are eliminated.

My primary purpose in changing was because of the fact that I really liked making pens from oily woods. "Breaking" the CA at the bushing joint with the blank . . often caused a small "lift" of the CA or a chip to come off. I hated that. I waxed my bushings and wiped it off gently with a cloth before using them. I didn't have a problem with "stuck" bushings per se, just chipped ends on oily (ebony) blanks. I even scored the CA at the break line and still had the CA lift about 30% to 50% of the time. I didn't have the problem with non-oily blanks.

I personally have not had a problem with bushing dust, as I learned how to sand without getting to the bushings. But it is difficult for some people. No-Mandrel eliminates that.

I have not had much of a problem with OOR from mandrels either. However, anyone that has been here long will recognize the quarterly discussions of OOR, much of which the blame is from mandrels.

The potential for OOR can be
1. bushings,
2. mandrel bent,
3. mandrel flex and dull chisel, ("A" Mandrel flex is the reason "B" mandrels were introduced, IIRC. I could be wrong.)
4. too much tail stock/live center pressure on the mandrel,
5. unsquared or not precisely squared blanks and overtightened on the mandrel,
6. or tail stock out of alignment from head stock.

Four of the 6 possibilities are connected to the mandrel. So, why go that route unless necessary?

Quote:
Originally Posted by PaulDoug View Post
Your saying if I finish without bushings the glue will not stick to the dead center and the tailstock center?
You _can_ glue them to the live center and dead center for sure. But there is a "step" from the blank down to the LC/DC contact area, and that makes for a much cleaner break than with bushings that are butted up precisely with the level of the blank. Also, with bushings, the bushings have FAR more contact area, making the potential for stuck bushing much greater.
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Last edited by leehljp; 08-06-2008 at 03:44 AM.
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