Custom Brass Checking Fixture | Saga Saturdays Ep 34

[@Driver944S]

You could make a v-block to center and locate the gage under the test indicator for center to center repeatability

[@ElevatedEdge]

Love the idea. Couldn’t you use this fixture as a set up on the Zeiss cmm you guys have.

[@mike-carrigan]

That's a great concept, however have you taken a measurement on your threaded sleeve, disassembled and put the same threaded sleeve back and been able to repeat the same measurement?

[@kenmarapese9085]

You sir practice the art of craftsmanship. I have been enjoying your vids since you were in the garage.

[@kwk8363]

You make great videos. Love the story. It is crazy watching you old videos and today. Incredible journey, congrats

[@DonaldPerreault]

Love my Saga!

[@scorpioreptiles]

Can spring load with balls instead of pins the ball will push in the groove and can get accurate measurements.

[@Squintz45]

Happy Birthday!

[@joshuawentworth7426]

John you own a cmm...

[@kirkbothwell7373]

I could be off base with this, kinda more of a question than anything but is brass the best material for a fixture like this? Is it very thermally stable? Or would we be talking sub tenths of growth in normal shop conditions so it wouldn't matter really?

[@joshuawills5242]

If I understand the fixture correctly, the primary goal is to hold the outer sleeve at a stable height off the surface plate. John didn't specify what type of brass it was, and I couldn't quite tell the size of it, so this has plenty of assumptions (and is based on my untrained but a bit experienced work with thermal expansion): Using Engineering Toolbox's coefficient of thermal expansion for "brass" of 18~19 (10^-6 in. / (in. °F) ). As I understand it (open to corrections), that means that for every inch of material, for every 1 °F of temperature change, the material will change by (18 * 10^-6) = 0.000018". That change would be positive for temperature increases, and negative for temperature decreases. Assuming the chunk of brass is 2" tall for convenience, that means that for every 1 °F increase of temperature (from setting up in the morning and then going into the afternoon, or from holding it in your hand for a short period of time), the total height and thus measured surface of the reference parts would increase in height by 0.000036" . So say the combined change in temperature from when you set up the gauge in the morning is +12 °F, without re-zeroing the indicator with the reference parts, the measurement would drift +0.000432". That's not the complete story - everything else in the system would be changing as well, including the steel base and rods of the indicator stand. Most of the steel types listed on Engineering Toolbox have a lower coefficient of thermal expansion than brass, but not much lower, so the absolute measured difference, assuming ambient temperature change is the only thing changing the temperature of the system (and not heat from the inspector's hands), would be the difference between the two. Because it's a relative measurement, all of this would be addressed by frequently re-zeroing the indicator with the reference part - in this case the threaded sleeve, as the button is already being controlled. That's useful to avoid other sources of error as well - bumping the stand or indicator, wear of the brass from the steel gauge pins, etc. Again, completely open to corrections on any of the details above. And I apologize to the ~90% of the world that uses metric for using imperial measurements here - they were slightly cleaner for the scale, and John was using an imperial test indicator, so keeping everything in that system made sense. Have a good day.

[@kirkbothwell7373]

@@joshuawills5242 wow Joshua thank you for the reply I couldn't have asked for a better one, cheers

[@Hailon]

Buy a Trimos, with the correct probe and part sitting in a Vee block.

[@flagmedownmedia]

Hi Guys, That's a good idea however; It's too fidly, I recommend making a fixture that you could use set of go/no-go gagues. It's wasting way too much time to check each one, I noticed that you cut the video a few times, how long did it take to get back to being under the indictor? Rather than using an optical method for setting the tool offsets for the sub spindle, you could make yourself a reference gague block so you can set the tool offsets in it in the machine.

[@gillisdebilio7086]

I would zero the indicator on the top of the 3 gage pins and measure from there

[@flikflak24]

I find it funny that in some country it's called a "shadow graf" Well in my country it's called a " profile projector "

[@lilchirp4846]

Optical cmm, keyence makes a nice one. You simply lay the part on a plate and it measures the part in seconds..and around here they are just too happy to give you a free demo of their product..

[@3073Sean]

Optical CMM perhaps?

[@SuperstarComponentsLTD]

You need a Keyence. Not because you need it but because they are black magic

[@colormaker5070]

knives and Pens are cool but I could really use the Grimsmo flashlight.

[@clkeck1]

It would be easier to turn up a "master" buttom with a larger flat base. Then flip this whole process over and indicate the 3 holes to the button

[@465maltbie]

The center may not be the best way to measure as you may get a tit from the wear on the tool. This will give you a variation that will not be consistent. Better would be a hollow gage with three points to measure the surface. Mounted in a comparator gage would be quick to measure the difference. Charles

[@CATANOVA]

Looks like a landmine.

[@zbaird3]

John i can tell you're a Robot 🤖.. You eat, live and sleep shop life. Probably don't sleep but that's ok if you are Happy!!! Awesome Video 👍Thx for sharing

[@kevinpotts9583]

using brass as a gauge to soft it will wear out of tolerance

[@kevinpotts9583]

do you sleep at night at the end of the day its a pen

[@dannymaciejewski]

At the end of the day you're a pen