An idea about hollowing and wall thickness

[Scott Crumpton]

I’m new to turning and have yet to turn a hollow form. Maybe this idea has already been considered and rejected. Recent threads involving hollowing tools along with the concern for wall thickness got me thinking. I’ve seen the laser systems in the catalogs, but thought there must be a simpler way.

<o =""></o>My goal was to come up with a simple mechanical way to determine the wall thickness while hollowing. My first idea was a set of dual ended calipers as a cutting tool. Too bulky. Then I came up with the tool in the attached drawing. It simply follows the outside of the form (it will need a spring at the pivot) and indicates the wall thickness by how far the pink bar extends beyond the blue bar. I can think of several problems, marks on the outside of the form and the potential for a catch on the outside. But all of that can be dealt with by proper design and/or a little sanding.<o =""> The design assumes a captive tool rest system.

</o> So why don’t I see this in catalogs? Or, put another way, what's wrong with this idea?

<o =""></o>---Scott.

<o =""></o>P.S. I’ve added the copyright only because if this is a new idea and someone decides to build and market it, I want my cut. :)

[Glenn Hodges]

Scott, I am always open to new ideas, and as far as I can see this is a good one. I would have to see it in operation to find out if it would be practical, but on a first look I would say very inventive and it shows creative thinking. Good show old chap! Hope you make some money out of this.

[Carole Valentine]

Robert Sorby makes a hollowing tool with an attached wall thickness gauge. Don't know if you have seen that one or not. I would post a link, but I don't think it is allowed? Just go to their site and look under hollowing tools. BTW...am I the only one that does not see a pink bar in your drawing? I see blue, green and black.:)

[Richard Allen]

The laser works easly in a captive system. The catching part is the big issue I see with your system. There has been a small hollower with a spring loaded thickness guage made by Sorby.

http://www.robert-sorby.co.uk/graphics/hollowing_tools.jpg

Copywrite is automatic in the USA. Putting the word "copywrite" gives you no more rights than you would have without the word. You can register your copywrite. Mind you a copywrite isn't a patent. And collecting money for an idea has almost nothing to do with a copywrite, patent or trademark.

Good Luck

[Scott Crumpton]

Pink was a typo. :) I can't tell for sure from the picture, but the Sorby tool appears to work like a springy caliper where you set the wall thickness and when the outside quits rubbing you're there. That's probably the better, and simpler, design since it's only the last 1/4" or so where precision is needed. Thanks for the input, I doubt I be making my design anytime soon as I have a long way to go before I'm ready for hollow forms.

[Jim Becker]

Measuring by contact requires that the lathe be turned off...it would be dangerous to use a physical device while the workpiece is spinning. That said, your device would likely work find for spot measuring as it essentially duplicates the same kind of function that many folks use to measure thickness as well as commercial calipers. You do need to insure that the measuring point is also adjustable so that it is always exactly in line with the portion of the cutting tip doing the work. (Same as adjusting a laser) My big concern is that your long outrigger could interfere with some kinds of turnings as well as cause damage should you accidentally move the whole tool assembly to the left suddenly.

I generally use my fingers for measurement (human fingers are quite accurate in detecting such things) when they can fit and occasionally turning calipers. I have a laser setup for my Jamison system, but am not pleased with the sturdiness of the mounting system that was supplied...I need to build a replacement that doesn't flex as much.

[Ernie Nyvall]

...am I the only one that does not see a pink bar in your drawing? I see blue, green and black.:)

What blue, green, and black?
;)

Ernie

[Jerry Clark]

It is pink with my 3-D glasses-- ;)