Height Gauge Depth Arm

In the shop I have a 2 beam dial height gauge that I use a lot for measuring and general layout work.  As far as measuring equipment, it is my favourite tool to use, even though I would want a micrometer and a caliper before a height gauge.  Once you get one you’ll wonder how you got by without one.

Most height gauges come with a tool for measuring flat surfaces, and for scribing.  To get the most out of the gauge you need a depth arm – basically a pin in an arm, for measuring depths.  I needed one to measure up a motor face so I can get a 3 phase motor mounted on my lathe – one of those projects to complete a project sort of deals.  I decided to make one up instead of buying it:

I made most of the arm on the shaper and used a gift from Max over at the Joy of Precision to bore the hole for the pin.  The boring head Max made is the star of this show.  It is the perfect size for the mini mill.  It is one of the best designs for a small boring head I’ve seen, and used.  The adjusting dial is a tad small but once you get a feel for it adjusting it is easy.  It’s also great because you can bore small holes – saving you from buying a lot of reamers.

The pin was turned between centers and was within .0004″ over the length – something I was very happy with.  The deviation was in the centre of the pin.  The pin sprung between centres a bit when I was cutting – aside from using a traveling steady there isn’t much you can do here about that.  The beginning diameter and end diameter were essentially the same within .0001.  I probably didn’t need  that much precision but I wanted to dial in my tailstock anyway.  At the end of the pin you can screw in standard dial indicator ends using a #4-48 thread.

I made the screw out of brass because it looks nice, and doesn’t mar the pin.  I usually don’t turn that much brass so I was reminded how easy it is to work with.

Here is the drawing for the height gauge arm.  I will be sharing all the projects in Fusion at some point and I’ll post a link.

Height Gauge Arm (Revision 01)

If you are looking to get a height gauge, do yourself a favor and go a dial one instead of a digital one.  Even though the dial on mine is graduated to .001″, you can actually measure much closer in the home shop with it.  Notice I didn’t say in the shop – in a professional environment I get that you need hard numbers and ‘guessing’ at the measurement is very poor practice.  Verniers are also good but I find them slow – probably because I don’t have enough practice.

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