Turn between centers..... to where?

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MatthewZS

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Jul 22, 2010
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So to those of you who don't use bushings.... or I guess even those that do....... and who use a CA finish..... do you turn RIGHT TO the bushing or a TEENY TINY TATER TOTS bit more to compensate for your ca finish? Or is even the thickest of CA finishes not enough to throw that measurement off?
 
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I still use a mandrel for most pens. But when I turn between centers I go just barely below the bushings and rebuild with CA.
 
I turn smaller by 3 - 5 thousanths, build up bigger, then take it back down to the size I want. I use a micrometer and go for 1 - 2 thousanths over the size of the mated part. Before I started doing this I regularly got sand through.
 
PenMan1 said:
10 thousandths takes a LOT of CA to build back up! DAMHIKT.
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Yes - especially with thin and a paper towel. Not so bad with Medium using a plastic bag applicator. I've successfully built up .03 using medium, plastic bag, generous squirts and accelerator - but that was obviously an exception and the large ridges had to be turned off (I used a woodchuck) before final sanding/pilishing. At this point it finishes a lot like an acrylic blank.

My current preference is to turn .003 small, build to .002 over and end up .001 over, leaving me with a .004 film build. BUT.... I'm not that good, so rarely hit this. Much less frustrating for me to build it thicker than to have to re-do it.
 
It's ALWAYS better to go a bit oversize than under. I turn to about .010" over and sand down to the exact diameter of the hardware. After I add my CA finish it's just a tad over, but like I said, under is a no no. I don't want to feel the edge of the hardware when I slide my finger over the pen.:wink:
 
MatthewZS said:
So to those of you who don't use bushings.... or I guess even those that do....... and who use a CA finish..... do you turn RIGHT TO the bushing or a TEENY TINY TATER TOTS bit more to compensate for your ca finish? Or is even the thickest of CA finishes not enough to throw that measurement off?
Click to expand...

I use a slightly different approach than most. If you visit the home page and look on the right side, you will see a tutorial on turning between centers. If you look on page 14, you will see .551" on the caliper, this is the diameter of the blank after final sanding, just before applying the CA.

Page 18 shows the blank after applying the CA, note the diameter on the caliper!

I like applying a thick coat of CA then turning it down and on page 20 you will see me smoothing the CA back down to the final thickness to mate with the kit parts. Some say using a skew to smooth CA is nuts but to those I have demonstrated this to agree that it is a nice way to get a super smooth finish with no ridges or ripples.

If memory serves the final diameter of the blank was .560" so in this case the blank was cut down .009" under, built up with CA to .002" over then finished to match kit, so that's .011" of CA.

Just another way! :wink:
 
Am I missing something here. The instructions I got when I ordered the bushings is to remove the bushings and turn between the dead center and live center for finishing. Works just fine.
 
wb7whi said:
Am I missing something here. The instructions I got when I ordered the bushings is to remove the bushings and turn between the dead center and live center for finishing. Works just fine.
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I don't think we're missing anything, that's what I do also. CA hasn't touched my bushings in a long time! Without bushings, the CA has a tendancy to roll over the edges and coat the ends of the blank too. I like that!
 
Texatdurango said:
wb7whi said:
Am I missing something here. The instructions I got when I ordered the bushings is to remove the bushings and turn between the dead center and live center for finishing. Works just fine.
Click to expand...

I don't think we're missing anything, that's what I do also. CA hasn't touched my bushings in a long time! Without bushings, the CA has a tendancy to roll over the edges and coat the ends of the blank too. I like that!
Click to expand...



Same here too. The CA on the ends helps keep water from soaking in to the ends and getting under the CA finish when I wet sand with micromesh.
 
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