Lathe Tool Height Gage

[rossbotics]

There are numerous ways to set a lathe tool on center to the lathes axis, the height setting gage I came up with is by no means a new method, but I think it is one of the most simplest and easiest to use gages and by far the most accurate, it consists of only three parts, the base, column, and stylus (plus four socket head cap screws)

The way I came up with the height of the gage was to take a measurement from the top of the cross slide on the lathe carriage using a height gage to the top of a 1/2” dowel pin chucked in the lathe, then subtract one half the diameter of the dowel pin, the measurement I had on my lathe was 4.442” - .250” = 4.192” this is the total height I made my gage from the bottom of the base to the top of the column. (See photo)

Depending upon what manufacturer of lathe you own you may not have a ground flat cross slide, in that case you could lay a couple of parallels across the bed of your lathe and measure from there, however it doesn’t matter where you take your measurement from, where ever you take your measurement from is where you will have to use the gage every time to set the tools height.

I made the gage heavy and ridged enough so it wouldn’t be easy to lift by adjusting the tool bit, in other words you can feel the tool bit touch the bottom of the stylus before it starts to lift the gage, I use a piece of phone book paper (which is .002”) as a shim between the top of the tool bit and the bottom of the stylus, once I felt a drag on the shim I removed it and turned the adjusting screw on the BXA tool holder just a fraction and locked it down, think of it like setting the gap on a spark plug. (See photo)

This height gage will work on any tool holder, those who use a rocker type tool post will find this gage very useful, those using a rocker type are always adjusting the height of the tool every time you resharpen and reinstall a bit.

The entire unit was made from 4140 steel; all parts were hardened and ground, though it could be made from mild steel, however hardened steel is just less easy to ding, scratch and rust, the stylus should be made from a heat treatable steel, reason being that a soft steel stylus would be gouged by the tool bit creating burrs resulting in an inaccurate reading,

I have included two drawings along with multiple photos on the construction of this tool; the height of the column will have to be adjusted to one’s own needs.

As always thanks for looking
And happy Machining

Doug





Calculating the height to make the gage





Grinding in the final height





Checking the height





Setting the height of a 60° threading tool, this method would apply to all cutting tools





All parts made, hardened and ground





Assembled





Another angle





Bottom view





Top view




Drawing 1




Drawing 2

[Christophe Mineau]

Hi Doug,
Beautiful work, as always.
May I suggest a couple of rare earth magnet sunk under the bottom ?
It's what I did in my (much more crude) round version, but obviously, mine was lighter and the base narrower so I needed the magnet, but anyway, I find it useful to be sure the gage is not lifted by the cutting tool.

[rossbotics]

Thanks Christophe
Your pretty darn good yourself
I thought about magnets but I just don't care for them, they seam to be more of a problem than help, the unit is heavy and very stable, thank for the heads up though

Doug

[Carlos B]

I like that, nice work.

[DIYer]

Thanks rossbotics! We've added your Lathe Tool Height Gage to our Measuring and Marking category,
as well as to your builder page: rossbotics's Homemade Tools. Your receipt:

Lathe Tool Height Gage by rossbotics

tags: lathe, height gauge

[Paul Jones]

Doug,

Very nice workmanship and I love the detailing with the hole recesses for less weight and easier tool gripping. The magnets can be useful but can also collect fine chips to distort the vertical dimension. I slightly recessed the bottom magnets on my lathe height gage to allow for the fine chips to slide into the gap and prevent distorting the height distance ( http://www.homemadetools.net/forum/l...8587#post25937 )

Thank you for the advice on measuring off the top of a 1/2” dowel pin chucked in the lathe as a way to determine the exact height gage minus the dowel radius. It is a simple method and something all metal lathe owners should record. Knowing the height comes in handy for many operations on the lathe including broaching keyways.

Regards,

Paul

[Frank S]

I find that the use of magnets around machining operations goes better if you use a thin removable plate under the magnet the plate has to be true parallel to its top and bottom surfaces thin enough to allow enough of the magnetic flux to penetrate and hold and be removed to allow it to be cleaned but thick enough that it does not become distorted or damaged in use. what I really like is to be able to rotate the magnet inside of a sealed base to break the magnetic field for cleaning that way the mounting surface is always true to the post or device it is supporting.

[mklotz]

On my magnetic pickup tools I use aluminum foil or Saran wrap (transparent) on the one that has a built-in light. Simply unwrap in such a way as to include the gathered swarf then discard. My guess is that the thickness of aluminum foil is very uniform so it should work well shielding the base of a height gauge.

I tend to not use the magnetic base indicator holders. Long ago I made a DI-holding block for the QCTP and that handles most of the work requiring indicators.

[Toolmaker51]

Plastic wrap and foil work perfectly and store simply, Marv. And cleaning a magnet is easy; duct or masking tape.
I use a travel indicator frequently on lathe crosslide, especially to monitor shafts and bores for bearing fits. The MightyMag has foil, the touch plate has 3 neodymium magnets mounted sub-flush, sealed flush with discs of brass .005 shim.

[metric_taper]

The way I came up with the height of the gage was to take a measurement from the top of the cross slide on the lathe carriage using a height gage to the top of a 1/2” dowel pin chucked in the lathe, then subtract one half the diameter of the dowel pin, the measurement I had on my lathe was 4.442” - .250” = 4.192” this is the total height I made my gage from the bottom of the base to the top of the column. (See photo)

Thanks for describing this technique. I've only had a height gage for a few months, and only think of using it on the surface plate.