Lathe Cutting Tool Height Gage

[Paul Jones]

This lathe cutting tool height gage is based on a design by Hardinge but with the addition of a rectangular base for extending the gage past the edge of a lathe cross slide housing for easy access to the cutting tool. This tool provides a convenient way for setting the correct cutting tool height without the need of first setting steel parallels spanning the carriage aprons to set the height gage. The distance from the top of the lathe cross slide to the center line of the lathe spindle is 3.460” for my 12” swing geared-head lathe. In addition, this height gage has a pair of rare earth magnets embedded in the base that allow the gage to easily extend over the top edge of the lathe cross slide.

The gage is made from 1.1” dia. cast iron round stock and 1.5”x2.5”x0.5” 6061-T5 aluminum. The top surface and bottom surface were machined using the gage cylinder as a mandrel to ensure the base was perpendicular to the height gage body. The Hardinge tool design allows over and under cutting tool touch-off by using a thin cylindrical part that pivots from the top of the cylindrical body (which is 3.460” tall). Two recessed rare earth magnets keep the gage firmly seated on cast iron cross slide. I should have drilled the 10-32 thread hole before parting the thin cylinder part but did not do this step in the right order so instead I used a small hose clamp to ensure the separate parts were aligned during the drilling.

The gage base has a sliding fit and held in place with two 8-32 set screws placed on opposite sides of the aluminum base. A Cogsdill Burraway tool (an eBay buy) was used manually to deburr the threaded holes to ensure a smooth sliding fit of the tool height cylinder. The two side set screws allow minor height adjustments. A future improvement may be to add another 0.375” dia. x 0.188 thick rare earth magnet in between the existing magnets and/or lengthen the 2.5” aluminum based to ensure sufficient extension over the cross slide edge.

[kbalch]

Thanks Paul! I've added your Lathe Cutting Tool Height Gauge to our Height and Depth Gauges category, as well as to your builder page: Paul Jones' Homemade Tools. Your receipt:

Lathe Cutting Tool Height Gauge by Paul Jones

tags: lathe, height gauge

[rossbotics]

Hi Paul
Nice little tool you made there

[Christophe Mineau]

Very nice tool Paul, I need one !

Thanks for sharing, nicely built and documented, as usual !
Christophe

[Paul Jones]

Thank you Doug and Christophe. I made one more modification by adding one more rare earth magnet in the bottom of the aluminum base. Now there are three magnets used to hold the base to the cross slide cover. A very easy change drilling with a letter drill V (0.377") and setting the 0.375" dia. magnet with Loctite 680 (designed for the bonding of cylindrical parts). I like using Loctite 680 for permanently joining loose, sliding and press fit parts because it is very easy to use and wipes off easily in the first 30 seconds. I attached a photo of the improved base that can extend even farther over the edge of the cross slide. Another improvement would be to use aluminum for the vertical cylinder to reduce the weight for long extensions over the side of the cross slide. Thanks again for the feedback, Paul

[crazypj]

I just use a vernier caliper and a fixed point on compound slide. Centre height on my 'HF lathe/mill lathe is 3.496"
As I don't have a QCTP, variations let me know what shim to add or subtract

[Catfish]

Nice job on the tool Paul. I need to make 3 one for each lathe. Thanks Randy

[Paul Jones]

Randy,
You are right about needing a dedicated height gage for each lathe. I like to "set it and forget it" so I don't have waste my time adjusting the same gage for each lathe.
Thanks, Paul

[DIYer]

Those are good improvements on a tool one could easily buy, but get not much pride from.

[C-Bag]

Good one Paul, and excellent documentation. I'd seen a similar design, but I like this one a lot. Glad this got recycled as it was before my time here.