Caliper search for small mouth hollow form

[robert raess]

I'm looking to make or buy a caliper for checking wall thickness on a hollow form with an opening of less than 5/8".I know Fennell has one, but it is for the area just under the opening.I would like one that feels the whole way down.I saw Ellsworth uses spring steel that he bends to his desired thickness and feels with that..I would like to know what else is out there that has worked well for you besides laser and fiber-optic. Thanks Rob

[Scott Hackler]

Robert, a standard double ended caliper (looks like the number 8 when closed) will work good for that.

You can also do the home made route and bend a circle of a heavy wire until the ends touch, then spread them apart a measurable amount (say 1" or 1 1/2"). Then when inserted into the form and the inside tip of the wire is touching the inside wall, measure the distance between the outside wire tip and the outside of the HF wall. Subtract that off the distance you spread the wire apart and you have the current wall thickness.

[Steve Schlumpf]

I have this version and it does work well: inside/outside caliper (http://www.hartvilletool.com/product/1261/woodturning-calipers)

[Scott Hackler]

I have the same ones Steve linked to, but am craving the figure 8 calipers. I think I would like them better for some reason.

Here is a picture of those.

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[Faust M. Ruggiero]

I made several sets of my own design. They work real well for me. I will take a picture later today and post it for you.
faust

[Bob Hamilton]

These ones are pretty pricey but are the best I have found for measuring wall thickness in restricted access situations: http://www.leevalley.com/US/Wood/page.aspx?p=43201&cat=1,330,49237&ap=1

I have the figure 8 ones as well and they are fine for open forms but the curve on both legs means they cannot get into tight areas through a small hole.

Bob

[Dale Miner]

The bent wire trick works the best. If the one you have won't reach where you want, it takes only a few minutes to make one that will. Getting in a 5/8" opening in a vessel that has a strong shoulder almost requires a bent wire measuring method.

[Jamie Donaldson]

I have never found calipers that work as well as the Ellsworth designed bent wire, and the price is right! I took a class with Ellsworth in 1990 and have been making and using these in all sizes for hollowing since that time. For the miniatures I used to make, the calipers are made from paperclips.

[Jim Burr]

And a quick use of the search function brings us...http://www.sawmillcreek.org/showthread.php?162412-calipers-home-made

[Faust M. Ruggiero]

These are the gauges I made for myself. I use the smallest from the edge of the hole to 1/2" in. Then I move to he next until it no longer reaches and so forth. By the time I am done with the largest I can reach with an 8 shaped caliper or my Kelton Gauge. You know you have to spend the big bucks for good tools. I probably have over $3.00 tied up in these. The ones on the left are 1/8" brazing rod. You insert the #7 shaped piece into the form and slide the other piece into your hand with the straight parts as shown. Make sure both pieces are oriented the same way. The difference in lengths at the bottom of the gauge is the thickness of the form. If you notice the little file marks on each guage, that is how how I make sure both parts of the gauge are in line.
Easy Peasy.
faust

[Harry Robinette]

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These are the ones I posted about 18 months ago that Jim B just reposted. I didn't design them I got a pencil drawing from a book I got from a turner who past away. I then made my first set from 1/8" Baltic birch plywood these are sheet metal. I hope this explains everything. It is done on 1/4"sq graph paper.

[Harry Robinette]

Robert
Now that my other ones are posted. for what your doing I use the same ones Bob H. posted mine are from Veritas I have the large cause I do allot of bigger work but am getting set to order the smaller set.