HF Wall Thickness - Which is Better?

[Roger Chandler]

I am looking to get a caliper just for hollow forms.....I find my figure 8 Sorby calipers have some difficulty with some shapes that are wider, and the width of the metal is wider than needed for measuring the shoulder area when the opening is not large, so I am considering both of these and would like the opinions of those who might have them or be familiar with their design.

The first is from CSUSA, and is designed by Mike Jackofsky.

The second is from Packard Woodworks and is also for large hollowforms. Their product page does not give the width of HF that it will measure, but the MJ one from Craft Supplies says up to 18" wide, which is plenty for me. Here is the one from PW...

Opinions and observations are welcome.......I would like to get it right the first time!

[CHARLES D Richards]

Roger, I have the one from Craft Supply (large one) and it is all I use for bowls and HF. At least for me I wouldn't be without it. When turning bowls it is great for getting around the chuck jaws to check bottom thickness

[Brice Rogers]

I have a figure 8 sort of gauge but it won't go in far enough. So my "go-to" gauge is based on the David Ellsworth "design".

It is a ring of stiff wire bent into an irregular "C" shape that allows it to go into the hollow form. I have one gapped at 1" and another gapped at 1/2". They are stuck to my lathe bed with a magnet.

I run the ring around the HF and can determine the thickness from the inverse of the gap outside. It is very simple.

I think that the beauty of the stiff wire approach over the more sophisticated devices is that there will be some shapes that won't work with the commercial units. For instance, a really deep HF or perhaps a real squatty HF.

[Roger Chandler]

Roger, I have the one from Craft Supply (large one) and it is all I use for bowls and HF. At least for me I wouldn't be without it. When turning bowls it is great for getting around the chuck jaws to check bottom thickness

Thanks for your input based on your experience...I am leaning to the large CSUSA one a bit,as I look into them.

[Roger Chandler]

I have a figure 8 sort of gauge but it won't go in far enough. So my "go-to" gauge is based on the David Ellsworth "design".

It is a ring of stiff wire bent into an irregular "C" shape that allows it to go into the hollow form. I have one gapped at 1" and another gapped at 1/2". They are stuck to my lathe bed with a magnet.

I run the ring around the HF and can determine the thickness from the inverse of the gap outside. It is very simple.

I think that the beauty of the stiff wire approach over the more sophisticated devices is that there will be some shapes that won't work with the commercial units. For instance, a really deep HF or perhaps a real squatty HF.

I got to see David's method up close at a two day event he held at our club. I got my first hollowing tools from him at that event. I am going for something a bit more sophisticated!

[Robert Henrickson]

I got to see David's method up close at a two day event he held at our club. I got my first hollowing tools from him at that event. I am going for something a bit more sophisticated!

I've tried various gauges / calipers; I own several. They rarely get used -- I use the stiff wire approach. It can be reshaped to suit what you are working on. And if you need a bigger or smaller one -- it's cheaper and the material is right at hand.

[Roger Chandler]

I've tried various gauges / calipers; I own several. They rarely get used -- I use the stiff wire approach. It can be reshaped to suit what you are working on. And if you need a bigger or smaller one -- it's cheaper and the material is right at hand.

Thanks Robert! I do have a piece of thick guage wire, about 6 feet long that I can easily use at time I wish.....I still want something specifically designed for this task.....my own reasons, and it may not make sense to others, but those reasons are valid to me.

[Robert Henrickson]

Unfortunately, what I have, and don't use, doesn't seem to include what you're looking at. Otherwise I'd sell them.

[Hayes Rutherford]

Its obvious the one in the first photo doesn't work right for the situation. The guage is tilted and the reading is skewed. I like the Ellsworth method because its simple and you can create a gauge for just about any situation that will read perpendicular to the surface. Not for everyone though since you read the remaining gap at the same location you place the gauge, not a created gap in another location.

[Greg McClurg]

I have the Jackofsky one and it works well for me.

[Glen Blanchard]

I have Jackofsky's caliper and use it exclusively for measuring the thickness at the bottom (foot). Works great.

[Leo Van Der Loo]

I have and use the Lee Valley Veritas calipers, I can measure the bottom bowl thickness by using the short bend leg in between the chuck jaws and the large bend goes into the inside.

But the callipers are used most to gauge the equal wall thickness, by sliding the leg over the inside wall, and watching the gap between the end of the leg and outside wall.

With the adjusting speed nut in-between the legs, I can open the legs to go over a thicker rim or else, and when closed again, it will show the gap that was measured.

But like everything, the one size/type does not fit everything/or everyone, so having choices or the thick wire to bend for special shapes, the Lee Valley ones are my goto ones.

Lee Valley calipers info.jpg

[Jay Mullins]

Roger,

I have the MJ style, the bent wire type and the Reed Grey method of determining the thickness of the bottom. I use them all. They work for me.

Jay

[Roger Chandler]

Great comments from you all.....much appreciated! After reading the responses, I went ahead and ordered the Mike Jackofsky ones fron CSUSA....it also did not hurt that I had a couple of their gift certificates that I won at last month's club meeting that I was able to apply to the purchase!

[Roger Chandler]

I just received the Mike Jackofsky calipers in the mail, and currently have a hollow form in the chuck on the lathe with the steady rest and Monster Articulated hollowing rig all setup where I was doing the hollowing. The calipers came at an opportune time, and I used them to check wall thickness. I have the top of the form near the opening at 1/4" thick now, and the calipers gave me good indications on how much further I need to go at the shoulder and down to the bottom, to finish up at the 1/4" thickness all the way down. This is a fairly good size form at about 9.25" tall and 7-5/8" wide, and is ambrosia maple.

Based upon my use a few minutes ago to get a good snapshot at where I am at present, I can tell you that I am glad I got them. They are a simple yet very accurate design, and of course I would not have expected any less from someone with the renown that Mike has related to hollow forms. Two thumbs up here!

Once I get the form completely hollowed and finished, I will likely add a finial. I will probably post a pic or two of it when done. I have not posted many turnings in the last couple of years, but might post this one, just cause it's got nice ambrosia markings and figure.