Perfect Fit center band problem

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cdcarter

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I just turned my first Perfect Fit from Berea, and it's probably going to end up being my favorite twist. It's beautiful hardware, has a nice transmission, and uses the Parker, which I like better than Cross.

But first, my center band fit wasn't so perfect. I'm not sure quite how to handle that thin little top band, and the wood ended up pressing over it, ruining the pen. I am assuming the culprit there was that when I cut the tenon (if you'd call it that since it goes all the way to the tube), I didn't go back and check the width of the wood where the band goes. [:I]

But if anybody else has puzzled over this and has any advice, I'm not too proud to take it.

Carl
 
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gerryr

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I've made quite a few of these and also Olympias which as a similar but much smaller centerband. When I turn the cap barrel, I part the wood off when it's still as much as 0.10" too large. I then use my calipers and measure often. I try to get it the same diameter as the CB before applying finish since the finish will add a bit of thickness. My goal is to have the wood no more than about 0.002" oversize after applying the finish. The last thing is be careful pressing on the CB. You want it just tight enough that those two rings don't rotate but not so tight you're driving them into the wood.
 

gerryr

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I neglected to mention the 5th spacer bushing that slips on the upper tube after you part the wood off. Be sure you're using it and it will help quite a bit.
 

cdcarter

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Gerry,

I think you hit on it.

Carl

Originally posted by gerryr
<br />I neglected to mention the 5th spacer bushing that slips on the upper tube after you part the wood off. Be sure you're using it and it will help quite a bit.
 

bjackman

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I used to use that bushing part, but don't anymore. As Gerry said, calipers are going to be your most accurate option. (if you really really want things to be spot on)
With the CB I glue up the various parts of the CB and make it one solid piece before assembly. Also I turn down the tube to give a slightly tight slip fit for the CB on the pen, then epoxy it in place as well.
I think slimline trannys are about the only thing I don't epoxy in place these days. YMMV
 

gerryr

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Bill is talking about removing a small amount of metal from the tube when you cut the tenon. Doing this will allow the CB to slide on more easily, but you have to be careful you don't remove too much metal. Brass is soft so it is easy to overdo it.
 

cdcarter

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Ah. Yeah. That sounds kinda scary. I can see the logic, because thinking back, it was a tight fit. Maybe just brush some sandpaper against the exposed tube briefly while it's turning?
 

gerryr

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If the fit was very tight, you may have still had some glue on the tube. I use my parting tool to remove any glue from the tube at the tenon, just do it carefully. If the CB is a bit loose on the tube, you can use a taper punch from HF for about $1.00, to enlarge just the end of the tube inside the CB. I haven't tried this, but a friend tells me it works great.
 

bjackman

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Sorry, slow getting back to this thread. Gerry is correct (for ONCE!!! [}:)] )ducking and running......
sandpaper should do the job just fine. You would probably be just fine pressing the CB on, I just have this thing about tight press fits vs snug slip fits that are epoxied in place. [:I]
 

cdcarter

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I noticed on the Perfect Fit that the pieces were pretty loose overall. The finial was OK, but I had to put some CA on the nib.

Originally posted by bjackman
<br />Sorry, slow getting back to this thread. Gerry is correct (for ONCE!!! [}:)] )ducking and running......
sandpaper should do the job just fine. You would probably be just fine pressing the CB on, I just have this thing about tight press fits vs snug slip fits that are epoxied in place. [:I]
 

cdcarter

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I've also been known to just give it a quick turn with a countersinking bit, which also works.

Originally posted by gerryr
<br />
If the CB is a bit loose on the tube, you can use a taper punch from HF for about $1.00, to enlarge just the end of the tube inside the CB. I haven't tried this, but a friend tells me it works great.
 

cdcarter

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Wanted to just thank you guys for the very good and well thought out advice on this question. To me, it is what this place is about.

Every reply was helpful in one way or other. I followed Bill's suggestion of gluing up the three pieces of the center band before assembling, as well as Gerry's suggestions regarding use of the fifth bushing and close measurement. It went together just like I knew what I was doing and is nice enough that I'm keeping it for myself.

Yeah, I know ... no photo, didn't happen... but I've been on the road. I'll catch up, if you guys can handle a thank-you note without a picture.
 

bjackman

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Glad it worked out Carl. The PF is one of my favorite kits. Lots of flexibility and it is one of the few twist kits that has a great feel to the transmision. Well worth the trouble of working your way through it's little quirks.
 

cdcarter

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Yep. It's takes me a little more time to turn and more expensive than the others, but if the goal is great pens rather than churning out cheap volume, it's well worth it on both counts. But once I do a few more, I'll get faster at it.

Originally posted by bjackman
<br />Glad it worked out Carl. The PF is one of my favorite kits. Lots of flexibility and it is one of the few twist kits that has a great feel to the transmision. Well worth the trouble of working your way through it's little quirks.
 
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