using caliper points to mark dia. on turning piece

John O'Toole wrote:I saw a video where Chriss Stott uses the interior diameter points on calipers to mark the desired diameter (clip) ^^^^^^^^^^^^ I havn't seen the video, but I doubt that he uses ID calipers. You should use a pair of dividers. Place the toolrest close to the surface, and rest the points of the dividers on the toolrest, not quite touching the wood. By eye, position the points so they appear centered. Assuming the lathe is turning in the normal direction, GENTLY apply the point closest to you to the wood, making a faint circle. Observe where the other point is in relation to the circle, and adjust the position of the dividers accordingly, and increase the pressure. Both points should be running on the circle.

If you wind up with a circle which is off a little, carefully apply the other point to the wood also, and you will wind up with two circles, with the correct position halfway between.

Have at it. It's actually easier to do than describe.

If you're squeamish about touching the wood with the tips of the calipers, do the following:

Hold the calipers as near to the spinning work as possible visually center the caliper, the transfer the location of the left point to the base of the work using a sharp pencil, move the caliper until the right caliper point and the pencil mark align. The main benefit of this method is that you don't mar the work piece and you can erase the pencil mark if necessary.

Juergen

John O'Toole wrote:

While I'm by no means as experienced as other posters, this is the way I do it: set toolrest as close as possible use a pencil to mark the center of the spinning piece. If I'm off, I erase it and try again until I have a neat point set the calipers to the radius of the piece with the lathe running and hte calipers flat on the rest, dig one point of the calipers into the center, just far enough for it to hold still then slowly push the other point into the work.

If you're just making an approximate mark, you can skip the pencil stage, the first dig into the wood as close to the center as possible by guesswork will hold the point in place.

Incidentally, any way you do it, this practice vibrates the calipers. If you're using calipers with one of those tiny set screws, make sure you tighten the screw hard every time, or you'll be looking for it among the shavings on the floor.

Only one P in my real address/ Un seul P dans ma véritable adresse

Peter Wells wrote: (clip) set the calipers to the radius of the piece (clip) ^^^^^^^^^^^^^ This is a good method if you KNOW the radius of the required opening. But, usually, it is easier to caliper the diameter of the insert to the hole, so the earlier described methods are more direct.

Hi John,

I use a pencil to mark the center point then lay my rule along the top of the toolrest and use the pencil again to mark the circle. I'm a feared of sharp pointed objects you see! ;)

Dan "Eccentric by Nature"

Just the one point touches the timber. When the other point is aligned with the mark created then you have your required diameter.