Quoted from Procrastinator:Updated with more pins:
Not all the way finished, but using a rebound tester, and configuring for somewhere between hardwood and bronze, I got some interesting results. The problem is trying to get a reading through the clear, which is obviously changing the hardness of the material.
Average of 5 readings just above the valley on the shooter lane. HB is the unit of measurement, but it a complicated answer as to what the scale exactly is.
MMR: 119 HB
LOTRLE: 178 HB
TSPP: 138 HB (mini playfield was 153 HB)
TH: 163 HB
WOZ: 184 HB
I will do a GB and a MET On my way back from dinner and will update the results.
Updated list with more games:
MET: 157 HB
GB PRO: 92-104 HB (92 was at shooter lane, 104 was highest result elsewhere on the untouched portions of the playfield, 3 ghosted inserts)
NGG: 181 HB
TOM: 170 HB
AFM: 177 HB
TRON: 155 HB
GB PRE: 133 HB
ST PRE: 161 HB
Updated: With the updated results, especially with the ghosted one, it's pretty clear whatever they are doing with the wood has an effect. I checked the GB PRO all over, just to make sure I wasn't getting an erroneous reading. There was also a visible difference between the softer games and the harder games as far as playfield quality and condition. I don't really know what the fix is or what any of this really means as far as a solution, but at least their is verifiable data from a calibrated test device that we can go off. Also, we do rent this gear out, so stern is more than welcome to grab some equipment for their QC shop if so desired.
So far I was really surprised by the vast differences in hardness, as a typical steel pinball would be in the 450 HB range the way the unit is configured. Keep in mind, these were the average of 5 readings from the same spot (I did some reference checks around the playfield and all results were within 5%). I always thought my MMR had some funky looking dimples, but nothing out of hand. I do Now know why my LOTR has always looked perfect, even after hundreds of plays, and it has something to with it being "harder" would be my guess. Either way, take what you will from the data, but it's not everyday you can use a $10k hardness tester for a god damn pinball playfield (I think I crossed a line of being "too into" the hobby and need to step back. Haha)
Dear Procrastinator.
Hi, I would be interested how you have perfomed this HB testing as the level of your results seems unfamiliar to me (I'm working in aeronautics into a machining domain)...
In fact if you google Wikipedia and Brinnel, in general a ball of 10 mm is used (around 3/8") under a charge of 29.430N for a period of 10 to 15 seconds. The scale of measure for a steel ball is HBS (HBW if a ball of tungsten is used, but this is for hardest metals).
Soft wood (pine) = 1.6 HBS
Hard wood = 2.6 to 7.0 HBS
Aluminium (not heat treated) = 15 HBS
Copper = 35 HBS
Soft steel = 120 HBS
Stainless steel = 250 HBS
Hard steel = 650 to 700 HBS...
When I see you have measured a minimum of 92 HB and a maxi of 184 HB (for maple plywood) then I'm wondering about the method you have used... Could you please make a clarification?
Marseille
