Making a CI surface plate

[Bented]

I have a very small yard, after cutting the grass each blade is measured then trimmed if out of tolerance, this is a laborious process at best.
The little bastards keep getting longer and going out of spec.

In order to achieve repeatable results place the entire mower on a surface plate and measure the blade height.

[J Tiers]

Bented, you do not understand marketing.

Don't try to, it would only bend your head.

But, the idea here is to go top-notch... The product does obviously need to be good. But once it IS good, you can add a LOT of "value" (price) by making sure that everyone knows it is the best because it looks like it is the best, and in fact "screams" that it is the best to anyone who sees it.

At that point, it becomes a "brand" known all over..... " How do you set your mowers?" answer: " I use a Mcphearson gauge, of course." ....

[Bented]

Bented, you do not understand marketing.

Don't try to, it would only bend your head.

But, the idea here is to go top-notch... The product does obviously need to be good. But once it IS good, you can add a LOT of "value" (price) by making sure that everyone knows it is the best because it looks like it is the best, and in fact "screams" that it is the best to anyone who sees it.

At that point, it becomes a "brand" known all over..... " How do you set your mowers?" answer: " I use a Mcphearson gauge, of course." ....

You do not appear to understand parody or sarcasm, I fully understand the effects of marketing.
Can you say Prada©®™
https://www.prada.com/us/en/women/ba...002_V_OOO.html

[J Tiers]

You do not appear to understand MY ODD FORM OF parody or sarcasm
.....................

There, I fixed it for you............

[boslab]

Was thinking about grass length myself, I suppose a centre line average would quantify it, very much like surface texture where centre line average is a median line drawn and the CLA is sigma, area above the line divided by area below the line or for grass sigma av length above the line divided by av length below,
mark

[A.K. Boomer]

Bented what is the weight of that thing? that's massive!!! It looks like it could buckle those legs...

[nickel-city-fab]

Bented what is the weight of that thing? that's massive!!! It looks like it could buckle those legs...

Looks like a good spot to wear steel toed boots
[/sarcasm]

[A.K. Boomer]

I wonder how well those legs would hold up in an earthquake ?


"Hey Wally --- did Dad say hide under the table in case of a tornado or was it an earthquake"?

(famous last words) Geeze Beave I dunno --- lets flip a coin...

[mikey553]

Thank you Mikey553, your insight is helpful. I didn’t think about flex. I don’t see a thick custom casting in the cards. I’m going to try to measure the amount of flex I get with the 3/4 prototype. Maybe the flex can be minimized with a “smart” 3 point support rig. Spent all day researching scraping, airy and bessel points etc. Came Across this video below. I didn’t realize scraping was used for liquid tight seals. Doesn’t apply to me but it’s interesting.

https://youtu.be/k4lUmE945js

Roland, the flex is very important for precision parts. Yes, it can be minimized by a 3 point support, but you should also think about how difficult it is to make a precision part if it is flexible. For example, I have a cast iron straight edge. It has one flat surface 2 x 24", but it is 4" high for rigidity. It is not a solid piece, but a casting with multiple ribs to reduce the weight, but maintain the rigidity. It weighs only 18 lbs. Your gauge is not in the same accuracy category as a straight edge, so maybe you can reduce the height to 3", but definitely not less than that.

I recommended to go a casting route because it is the best way for 100 plus parts from all points of view - cost, weight, looks. Gray iron is easy to cast and it is cheaper than steel bar of the same weight. If you are willing to learn scraping for this project, you can learn casting as well. Scraping is an interesting skill and I want to learn it too, but scraping 100 parts of this size may take a few years of your life. Think again if you want to do this. Look at this video by Stefan Gotteswinter to get a better understanding of the process.
https://www.youtube.com/watch?v=jG5mOnjrd2Q

I believe your gauge can be finished to .001" flatness on a good milling machine using a face mill and "smart" clamping to prevent warping. If machine is properly trammed, it will leave a nice checkered finish. It can be ground too, but it may be difficult to find a shop with a big enough grinder and sufficient skill level to produce a flat part.

[rmcphearson]

In order to achieve repeatable results place the entire mower on a surface plate and measure the blade height.

Placing the mower (cutting units) on a granite plate is how we parallel the rollers, not adjust the height.
https://youtu.be/USnfj4ikwVk

I haven’t suggested anyone is gauging grass height. What is being gauged is the mower height. And there is a demand for a tool to calibrate the gauges.

[Bented]

Bented what is the weight of that thing? that's massive!!! It looks like it could buckle those legs...

The tag says 6400 lb's, not terribly heavy considering that a modern US pickup truck can weigh that much and sits on 4 pneumatic tires.

[A.K. Boomer]

Wow that's still a chunk of stone... thanks for letting us know, by all the staining it looks like it gets it's fair share of use...

It almost looks regulation billiard table size --- you thinking what im thinking? little bit of felt and some rails and you have the worlds most precision pool table....

[nc5a]

At that point, it becomes a "brand" known all over..... " How do you set your mowers?" answer: " I use a Mcphearson gauge, of course." ....

This comment by Jerry got me to thinking. If you want to go first class and your idea is truly unique and worth the expense and effort look into having ceramic master gauges made. Building a brand these days is difficult but can be done. Ceramic masters are expensive but they are very stable, light weight and have a bit more class than say a granite or cast iron gauge. Google ceramic masters or precision ceramic products and you'll be on your way.

Jerry's comment has a bit ring to it. Who knows, this could be the start of the Mcphearson Gauge.

Go for it with everything you've got and don't worry about the torpedoes maintain full speed ahead.

I've been where you are right now. Good Luck, Ron

[rmcphearson]

https://youtu.be/0PqFFPVxjXI
This shows just two of many brands of gauges. There is a market for a tool to calibrate them accurately.

I’d like to discuss home shop machinist stuff relating to my plate…

Thank you to those of you helping.

[rmcphearson]

Thank you nc5a. I’ll look into ceramic.