Friday, 9 March 2018

Low Cost Surface Firmness Tester

If you're a broke datahead like me you probably have always wanted to measure your putting green surface firmness but haven't been able to justify the $1000+ expense to buy one of the fancy testers available on the market. The problem I have had is that I just wasn't sure if it would be a metric that would make a difference in the way I managed my golf course.

It was easy for me to justify the expense of a moisture meter almost 10 years ago because I could see how it would improve my operation. I'm still on the fence about the firmness tester so I asked twitter how I could make one for myself and as usual, was pleasantly surprised.

This rather simple firmness tester was brought to my attention but it was still out of my price range at around $500.

Dr. D made a great little video outlining these various devices and how they work.

I decided to make an even cheaper version than what the PGA currently uses, again, because I am not sure if this is something that is valuable to me.

I bought 2 steel balls that are close in size to a golf ball which is 1.68" in diameter. My steel balls are 1.5" but you could also use 1.75" balls. You can get these on Amazon.

My version uses your HOC gauge to measure the depth of the impression on your green. Don't tell your mechanic.

Instead of a washer I used an old bedknife that is the same thickness as the little knob below the HOC gauge.

center the hole with paint over the indent

Find a bedknife that is a similar thickness to the tab on the bottom of your gauge.
In order to get consistent data you need to drop the balls from a constant height. I use a flag stick (assuming all of your flags are the same height). I drop the balls from the bottom of the flag because no one else on my crew can reach the top!

This version requires you push down on the gauge to test the depth. This obviously introduces some error so be as careful as possible to not push too hard.

I take a few measurements then log them in my firmness tester spreadsheet found here.

I've been asked a lot about how much the balls should weigh. I don't think it matters much as long as all your balls are the same mass and size. The only reason to have a standardized ball would be to compare to other courses which isn't what this is for.

In time I expect to build an understanding of what this data means. What is firm and what is soft and if it's something that I care about enough to measure or invest further in one of the fancy units.

For now I've pulled this data into my maintenance HUD to see how important this data really is.

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