3D Printed stimpmeter

It’s pretty easy to make a ramp with 2 one piece cues. The longer the ramp the less deviation from variations in how the ball is released too. I had already done this to check rebound angle and response on both SS and Artemis cushions on one table using a fixed ramp. The only factor that changed was the end rail was swapped. Both rails performed very close in both rebound angle and speed. The Superspeed equipped rail was actually slightly faster, but that could have been the difference between a Mark Gregory rail and a stock Brunswick. The MG rail is quite a bit more substantial than the stock rail. It probably weighs 25% more.
 
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Bob Jewett said:
Is the main point to measure the bounce off the cushions?
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Maybe. This particular design I drew a year or more ago and just got around to printing it. Testing the cushion was its basis, and the original CAD actually had the ball against the cushion as the starting point. I had thought of a pendulum design before with an encoder to measure the rebound. I think it might have been you that suggested a phone recording in slow motion might be better. I've always been looking for something in pool to 3D print.

But besides that, I know we've talked about stimpmeters on here over the years. Usually made of wood with a groove in it. 3D printing offers a lot more options that once designed, are hands-off to make. Maybe some people would want them and find useful for cloth speed?

I'm also working a 3d printed 4 piece travel cue:) I have no idea if it will work. The density of the PLA plastic material is a bit more than maple, so I think I can get the weight and balance good by leaving strategic hollow areas. I'm thinking a carom cue style joint between each piece. And the piece closest to the tip would be a real predator wood shaft, cut and threaded into the rest of the cue that would be 3d printed.
 
I also sketched some designs where there would be a second ball at the bottom, that the ball at the top would collide with. This bottom ball would be the one that hit the rail. If close to the rail, it should have no spin on it, and see how the rail reacts that way.

Then another idea was to impart side spin with a collision.

What I noticed though, was the ramp has to be quite high to get enough speed to test sliding conditions.
 
I think the slope has to be shallow enough or the material sticky enough that the ball does not slip on the ramp. If the ball slips a variable amount as it goes down the ramp, the results are likely to be inconsistent.
 
Bob Jewett said:
I think the slope has to be shallow enough or the material sticky enough that the ball does not slip on the ramp. If the ball slips a variable amount as it goes down the ramp, the results are likely to be inconsistent.
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On my 7 foot table, bouncing off the end rail, a simple printed ramp will produce results that are within about 2 or 3 inches of each other (marking each result with a dot on the cloth). The big variable is how the cue ball is released from the ramp.

Certainly not precise or able to convert
to proper units, but enough to visualize the difference between two tables (or in different directions on the same table).
 
iusedtoberich said:
Any ideas what you'd like it to do? 3D printing means features are free. Just design time, not building complexity.

I was going for maybe testing table straightness, testing cloth speed, testing rail rebound angle, testing rail rebound speed. Any other ideas?
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Those all sound great. I do like the idea of a spring loaded staring gate to get consistent release position and velocity. This would most likely add to the complexity of the design, though.
 
I uploaded the STL of my simple stimp meter to Thingiverse:

www.thingiverse.com

Stimpmeter for Pool Ball by oz1051

Very simple stimp meter for American-sized pool balls (2.25in diameter).
www.thingiverse.com www.thingiverse.com

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One of the things you discover if you use a ramp repeatedly in the same place is that the table gets faster along that line, presumably from the cloth being smoothed down or compressed.
 
iusedtoberich said:
Here is version 2, with a 50 sec video.

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I think there is still an issue with the maximum slope. If the ball slips on the ramp the velocity/spin as it leaves the ramp will be somewhat random depending on the particular slipping on that trial. Do you get different results with rubber tracks?
 
Jack Koehler did a lot of testing for his physics of pool book with ramps. Here are his. He also had a long chute/box that could set the direction of the ball very accurately. The parallel sides had only 0.003" extra space for the ball to pass along.

I had remembered him saying he could add a known amount of side with his fixtures but there is nothing about fixtures for side spin in his book, so I guess I misremembered. That could be achieved with a (sticky) rubber wall that's maybe flat or C-shaped. The more oblique the collision, the more the spin/speed.

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Bob Jewett said:
I think there is still an issue with the maximum slope. If the ball slips on the ramp the velocity/spin as it leaves the ramp will be somewhat random depending on the particular slipping on that trial. Do you get different results with rubber tracks?
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I haven't redeisgned it since reading your slip comments. My printer was broken, and I just fixed it yesterday, so printed v2 as-is for further learning.

I was thinking to cut a groove on each face of the ramp for o-ring stock.
 
Bob Jewett said:
Jack Koehler did a lot of testing for his physics of pool book with ramps. Here are his. He also had a long chute/box that could set the direction of the ball very accurately. The parallel sides had only 0.003" extra space for the ball to pass along.

I had remembered him saying he could add a known amount of side with his fixtures but there is nothing about fixtures for side spin in his book, so I guess I misremembered. That could be achieved with a (sticky) rubber wall that's maybe flat or C-shaped. The more oblique the collision, the more the spin/speed.

View attachment 721931
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I had thought about a way to apply deliberate spin a year or so ago. That if there is a ramp with side walls, with rubber on one side only near the bottom, the ball would grab some spin. My finger was basically doing that when releasing the ball from the side. However what I noticed on these limited tests, is if the ball has spin starting from the top of the ramp, it will masse when hitting the cloth, even though the ramp hits the cloth tangent. I guess the axis of the spin remains (or does not shift completely vertical), by the time the ball hits the cloth.
 
I'm also noticing for doing collision tests, the 3d printed ones are way too short. I guess that's why the Kohler ones are so tall.

I also ran into a lot of difficulty aligning the ramp perfectly normal to the cushion. Even with the wider back on v2, it still compressed the cushion and was easy to misalign a few degrees. I'm wondering if that's why Kohler was describing a direction box.
 
What was your release mechanism Bob? I can't quite make it out. Is it a pin in front of the ball that you simply lifted straight up?
 
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