Q4U Machinists: Height Gage as Thickness Gage?

[Doug Shepard]

I've been eyeballing some machinists height gages on eBay and wondering if it's possible or feasible to use one as a thickness gage for checking the center of a panel - places where calipers cant reach. Could one of these be rigged up with a longer arm that had a downward pointing tip on it? Here's example pics of one.

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[Frank Guerin]

They can be but its trouble. Since were wood working you really won't have to taker into consideration sag if you have a stiff enough extention. Keep in mind that what ever your measuring will have to be on the same plane as the bottom of your heigth guage. You will also have to have something (jo blocks ) of a given heighth to zero off of to start with. You can buy ( I forget the name ) that is a indicator thickness guage that will reach as much as 6 inches. Hope this helps.

[Bruce Page]

Well, you could. I’m not sure why you would want to go to that much trouble.
I just took a pic of the setup using a 20” rod which would get you to the center of a 40” panel. I used a small indicator but you could just as easily use a pointer of some sort. This would be a crude flatness/thickness measurement, i.e. if the panel is not flat to begin with, the measurement you get at the center will not be accurate. There is a methodology to checking flatness/thickness based on a three point system but it is somewhat complicated if you are not familiar with the metrology world.
P.s. I wouldn’t go after the height gage that you have pictured. Note the clamp arrangement on my gage, this allows you much more flexibility. The one you show is very limited on what it can do.

[Mark Singer]

Doug,
A really handy tool in the shop is a digital caliper....it will measure and match sizes really well...machine settings....heights of blade to match rabbet...just really hanfy and about $30 or less! Depth of mortice...router bit height...distance to a fence... I have a Starette height gauge and never use it..