Turning using calipers

[Blind_Squirrel]

This question is for those of you that use calipers to gage the final diameter of a pen.

Do you leave the blank "proud" to account for sanding? If so, how much do you leave to account for the sanding process?

I guess I should also ask what grit do you start at? Personally, I start at either 320 or 400, depending on how aggressive I was.

 

[Paul in OKC]

Well, I do not use calipers, but you still have to leave things big to allow for sanding. How much? Depends on how much you sand. If you start with the grits you've said, I wouldn't think you need more than about 10 thou (.010). Do a test turn and see how much comes of with a little sanding of each grit. That should put you in the ballpark. Of course the density of the woo will also make a difference.

 

[bonefish]

At best, leaving the wood proud to compensate for sanding is guesswork. The hardness of the wood will have something to do with it, too. Some material sands easier and faster than others, and the length of time you sand can vary.

I try to leave about .004, depending on the grit and the type of material. If the turning is not smooth, and I have to start with 220 grit, I might leave more than .004. Like you, I try to begin with either 320 or 400, preferbably 400.

Precision measuring with calipers is guess work, too, unless you are using micro calipers.

Bonefish

Bonefish

 

[Firefyter-emt]

Yes, you have to leave it proud or you will be too small when you are done. Just how much like said depends on the wood. Cocobolo is going to sand down a lot harder than say spalted maple.

FYI, I use digital calipers. I measure the pen part and reset the caliper to zero at that size. Now my "goal" is just a little bigger that zero. No messing up what size it was and no guess work.

 

[DocStram]

I'm a caliper convert. Speaking of getting the blank "right down there" ..... the point was driven home to Skye and me last Saturday at Bubbasville SE. The two of us stood there for about 30 minutes just picking up Chigdon's pens and handing them back and forth to each other .... and feeling the smoothness of the transition from metal to wood. Talk about craftsmanship. Dang!

 

[Blind_Squirrel]

Originally posted by Firefyter-emt
<br />FYI, I use digital calipers. I measure the pen part and reset the caliper to zero at that size. Now my "goal" is just a little bigger that zero. No messing up what size it was and no guess work.

Thanks for that great tip! []

 

[Firefyter-emt]

One more thing to remember, your finish will add slightly to the overall diameter. Measure a pen after it is finished and you will have an idea on how thick your finish is.