Lathe Tool Height Gage

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



Attachment 17939

Calculating the height to make the gage



Attachment 17940

Grinding in the final height



Attachment 17941

Checking the height



Attachment 17942

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



Attachment 17943

All parts made, hardened and ground



Attachment 17944

Assembled



Attachment 17945

Another angle



Attachment 17946

Bottom view



Attachment 17947

Top view


Attachment 17948

Drawing 1


Attachment 17949

Drawing 2

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.

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

I like that, nice work.

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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

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.

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.

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.

Quote:

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Originally Posted by rossbotics

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)

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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.

Well metric_taper
you can use your height gage on any machined surface to measure anything, I wouldn't advise using it on a concrete floor though, just make sure your machined surfaces your measuring from are burr free and rust free.

Quote:

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Originally Posted by rossbotics

Well metric_taper
you can use your height gage on any machined surface to measure anything, I wouldn't advise using it on a concrete floor though, just make sure your machined surfaces your measuring from are burr free and rust free.

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I guess I fall back on my methods previous to having the gage. Typically, the datum is the surface of what ever the "sacrificial" material is. And your 'carving' away relative to that surface.
I can't think of to many operations where I would measure height (or distance) where the HG would be efficient. But lathe center to some carriage surface clearly is a proper usage of the tool. My main use of the HG has been with an adapter that replaces the carbide scribe that holds a test or dial indicator, on a surface plate. I've made parts for years without using a plate, so I'm in learning mode, and it's a new world of much more accurate measurements.

Your doing just fine sir, hope this was a learning experience for you, cheers

Quote:

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Originally Posted by rossbotics

Your doing just fine sir, hope this was a learning experience for you, cheers

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Going from 'thousands' to 'tenths' is the biggest change in the hobby moving forward. Life is at its best when I learn new things. And this is an unexplored machine shop 'space'.
Thanks for passing your knowledge to others.

Quote:

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Originally Posted by metric_taper

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.

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Don't forget that the height gauge can be used as a very large capacity calipers allowing precision measurement over lengths that most calipers could never accommodate.

Typically this requires clamping the part to a right-angle block and then using a square to ensure that it's held perpendicular to the surface plate.

Fitted with a DTI they can also be used to check squares for perpendicularity.

Quote:

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Originally Posted by mklotz

Don't forget that the height gauge can be used as a very large capacity calipers allowing precision measurement over lengths that most calipers could never accommodate.

Typically this requires clamping the part to a right-angle block and then using a square to ensure that it's held perpendicular to the surface plate.

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This is a setup I would never think of doing.
Luck has it I have a 24" Mitutoyo dial caliper. It's a dual beam design. I got it from my companies 'inventory disposal' sale. It was broken. Some smart guy, ran the moving jaw up and down many times and fast, that it caused the pointer needle shaft to fail on the bearing just below the scale. So the pointer was sitting under the crystal with what was left of the eroded shaft. This shaft was the same shaft of the gear that was part of the rack and pinion drive. I think I was able to grind a new shaft from some O1 drill rod, and then machine this in a spin indexer on the surface grinder. It's not perfect, but within .001". It was way beyond my skill when I did the repair..

Quote:

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Originally Posted by mklotz

Fitted with a DTI they can also be used to check squares for perpendicularity.

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This setup I've seen, but have not done. I know this is for a cylindrical square. That's one of the projects I want to make. Seems it's good check of the lathe, and machinist.

I just got a granite square last week (triangle 1" thick, 10" on long side), damn their pricey. Even a cheep import.

Wow, a 24" Mitutoyo caliper! That must have been a pricey bit of kit to buy initially. Since most hobbyists couldn't afford it or have the space to store it for that matter, I'm glad I mentioned the height gauge approach. Future readers may not think of it so a written reminder is in order.

The height gauge can be used to check conventional as well as cylinder squares for orthogonality. Angle plates too. With its accurate measurement of height, one can mathematically verify shallow angles as well.

It does often require some sort of protruding foot on the base of the gauge to space it a fixed distance from the object to be checked but that's a lot less work than making a purpose-built device.

Quote:

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Originally Posted by mklotz

Wow, a 24" Mitutoyo caliper! That must have been a pricey bit of kit to buy initially. Since most hobbyists couldn't afford it or have the space to store it for that matter, I'm glad I mentioned the height gauge approach. Future readers may not think of it so a written reminder is in order.

The height gauge can be used to check conventional as well as cylinder squares for orthogonality. Angle plates too. With its accurate measurement of height, one can mathematically verify shallow angles as well.

It does often require some sort of protruding foot on the base of the gauge to space it a fixed distance from the object to be checked but that's a lot less work than making a purpose-built device.

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It is a monstrous size item to store, very heavy. It came with it's original Styrofoam packaging, that used to have a cardboard sleeve, thus making it larger to store, but it acts as a dust shield. It's buried on a shelf over the lathe, under bore gauges and Clover brand lapping compound cans. Clearly not a very often used item in the shop. I have a 500mm digital caliper (Harbor Freight) that is typically what I use for large measurements, as I can hold it in one hand.

It's a mindset change to use the height gage. Thinking about it, it is a caliper that measures from an inside edge (surface plate, angle plate; reference datum) to an outside edge.

I purchased the granite square to calibrate a test indicator setup for measuring orthogonality.

My company (former Collins Radio and where I got the caliper from) had a world class manufacturing shop. They produced everything in house during the moon mission. They have sold off most of the machinery, long before I retired, to where engr. prototypes had long lead times. It's all outsourced CNC shops now. I never could get my hands on a large lathe (16X60) when they were being auctioned off. There were rows of them. They all went to a Chicago machinery dealer. The machines were in pristine condition from only running aluminum their whole life. That was in 96, and $15K was out of my budget. I recall LeBlonde and other mainstay manufacturing names. they all had DROs. They were mid 50s to 60s age.

Quote:

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Originally Posted by metric_taper

It's a mindset change to use the height gage. Thinking about it, it is a caliper that measures from an inside edge (surface plate, angle plate; reference datum) to an outside edge.

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Indeed. And mindset changes are what "thinking outside the box" is all about.

Little mental exercises such as thinking of a linkage as a device to hold two holes a fixed distance apart can really help to develop the sort of mental flexibility needed to originate new and improved tools.

Quote:

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Originally Posted by mklotz

Don't forget that the height gauge can be used as a very large capacity calipers allowing precision measurement over lengths that most calipers could never accommodate.

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Even better when you need to take several measurements on a complex object is a mill with a DRO, and an edge finder or probe. That is, if like me your budget doesn´t run to a CMM.

Not to hijack this thread but look at this one found but $25.00 plus depending on where you get it. Build it for about $2.50.
Take a look:
Pro Lathe Gage 02-000 - Edge Technology

Nelson,

I finally bought this type of lathe height gage last year after seeing Adam Booth (Abom79) use it several times in his YouTube videos. I wanted to see how well it worked. It is extremely accurate but it requires using the lathe chuck to locate the precision gage pin about which the level rotates. The problem I have is most of the time I have a part already being machined in the lathe chuck when I discover one of my lathe cutting tool is slightly off center. Most of my machining operations require swapping out QCTP tools and sooner or later one of the tools is slightly off center. In this situation removing the partially machined part to use the chuck for this type of gage will probably result in not putting the partially machined part back in exactly the same position in the chuck and depending upon the chuck TIR, the remaining ODs and IDs won't machine concentrically.

The Pro Lathe Gage is great for initially setting up the lathe cutting tool heights before starting the machining. I still prefer the lathe tool height gage like the one presented here by Doug or the Hardinge Lathe-style height gage I made ( see http://www.homemadetools.net/forum/l...8587#post25937 ) for making adjustments anytime during the machining operation without disturbing the partially machined part by removing it from the chuck to use the Pro Lathe Gage. These lathe height gages work well but it depends on when in the machining process the adjustment is made.

Regards,

Paul Jones

Quote:

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Originally Posted by ncollar

Not to hijack this thread but look at this one found but $25.00 plus depending on where you get it. Build it for about $2.50.
Take a look:
Pro Lathe Gage 02-000 - Edge Technology

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I don't like this type of gauge because there are so many situations for which it is not suitable. Paul mentioned the case of having a work piece mounted but there are several other cases.

* You might have a 4 jaw chuck or face plate mounted.
* Wrong size collet.
* It relies on the cross slide motion being horizontal. Many home machinists have lathes which have not been levelled but it can be even worse for lathes mounted on a mobile platform such as a ship or service truck.

I could go on but you get the idea. On the other hand, the type of device in this post by Doug (Paul mentioned his and I also posted my version of the same principle http://www.homemadetools.net/forum/a...8027#post86660) will work under all conditions and made to appropriate dimensions will also be good for setting upsidedown tools.
Marv also posted his very simple setting device which always works.

Adhere to the KISS principle.

Nice work! I obviously missed it the first time around.

Quote:

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Originally Posted by ncollar

Not to hijack this thread but look at this one found but $25.00 plus depending on where you get it. Build it for about $2.50.
Take a look:
Pro Lathe Gage 02-000 - Edge Technology

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I have one of this style...

https://www.amazon.com/center-height...l+height+gauge

though not that exact model. While it eliminates the need to remove the work from the chuck in order to use it, I find that reading the tiny level with any accuracy is far more difficult than using one's sensitive finger nerves to detect alignment as with this one I made...

http://www.homemadetools.net/forum/d...ht-gauge-57996

In fact, I think the style with a level is less accurate than the age-old dodge of trapping a scale between the tool and the work and adjusting until said scale is held vertically without a tilt.

I once restored a Harrison 280 gap bed trainer lathe that had degree indicators around the perimeter of the chuck y could lock the chuck at the 0° mark then move the tool post and cutter next to the chuck and read the line at the 90/270° mark. Quite accurate since the chuck were 200 mm in diameter there were also marks in the D4-1 spindle nose that could be used if collets were to be mounted in the spindle.

Nice work doug, i need to make one, the ol' eyes ain't what they used to be, thanks