pool table speed guage

driven

AzB Silver Member
Silver Member
In response to Side Pockets felt too fast thread...

I made a guage to measure the speed of the cloth.

My cloth is 860, about 3-4 years old and hasn't been cleaned for at least 2 months.
I am going to play on 760 tmrw that is very well maintained and will get you the numbers for comparison.
enjoy.

This thing is very easy to make using scrap 3/4 inch wood. Make very accurate cuts.
If enough people decide to make one we can get a pretty good idea how
fast different cloth is.


I should mention at the time of filming the temp was 68 degrees with humidity at 31%

http://vimeo.com/108514470

steven
 
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Side Pocket

AzB Silver Member
Silver Member
I think this will be good if enough people will do it. I will build a gauge here in the next couple of days.

Thank you.
 

Bob Jewett

AZB Osmium Member
Silver Member
It is also possible to measure the speed of a table with a stop watch. If you time a lag shot from far rail to stopping just before the near rail, the time in seconds squared times 2 gives you the reciprocal of the effective slope. So, 7 seconds for a lag to travel the length of the table gives:

7*7*2 = 98

slope = 1/98 = 1.0% more or less

On a carom table, it is not uncommon for a lag to take 10 seconds for the last lap of the lag:

10*10*1.8 = 180 (1.8 factor for a 10-foot table)

slope = 1/180 = 0.55%

Since most people can do lags and have stop watches or stop watch apps, this is a pretty simple and accurate way to measure table speed.

Also, if a video has a lag, you can pick the speed of the table off the time of the video.
 

Side Pocket

AzB Silver Member
Silver Member
It is also possible to measure the speed of a table with a stop watch. If you time a lag shot from far rail to stopping just before the near rail, the time in seconds squared times 2 gives you the reciprocal of the effective slope. So, 7 seconds for a lag to travel the length of the table gives:

7*7*2 = 98

slope = 1/98 = 1.0% more or less

On a carom table, it is not uncommon for a lag to take 10 seconds for the last lap of the lag:

10*10*1.8 = 180 (1.8 factor for a 10-foot table)

slope = 1/180 = 0.55%

Since most people can do lags and have stop watches or stop watch apps, this is a pretty simple and accurate way to measure table speed.

Also, if a video has a lag, you can pick the speed of the table off the time of the video.



Thanks Bob. Here is my lag on my 10 foot table. This is with Gorina M cloth.

https://www.youtube.com/watch?v=Dc76hej5WZI&feature=youtu.be
 
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driven

AzB Silver Member
Silver Member
I think this will be good if enough people will do it. I will build a gauge here in the next couple of days.

Thank you.

And now I know how to spell it.
thx
The az machine won't let me fix spelling in the title.
steven
 

Bob Jewett

AZB Osmium Member
Silver Member
Thanks Bob. Here is my lag on my 10 foot table. This is with Gorina M cloth.

https://www.youtube.com/watch?v=Dc76hej5WZI&feature=youtu.be
I measure the time as 10.05 seconds but it would be much better if the lag just barely didn't get to the second cushion. The bounce makes it complicated. In any case, 10 seconds for a lag on a 10-foot table puts the effective up-hill slope at 0.55% which is fast for a carom table and very, very fast for a pool table.

It's a little strange that we call the table "fast" but things like the ball stopping happen a lot more slowly.

If you have some good video editing software, you can get the time of each frame down to 1/30th of a second. That is more accurate than trying to pull it off YouTube with a stopwatch.
 

neonlight

Registered
I'm really surprised the BCA does not maintain speed standards. A measurement system would be easy. It is done all the time on golf greens. A similar sloped apparatus would offer consistent measurements.
 

Dave

AzB Silver Member
Silver Member
cushions too

A similar approach could be used to gauge cushion rebound.

I feel that I've seen another version of this several years ago.... could it have been Dr Dave?
 

Bob Jewett

AZB Osmium Member
Silver Member
I'm really surprised the BCA does not maintain speed standards. A measurement system would be easy. It is done all the time on golf greens. A similar sloped apparatus would offer consistent measurements.

As mentioned above, you don't need any apparatus other than a stop watch and the result is a number that is easy to interpret.

The bounciness of the cushions is a little harder to interpret because it depends a lot on the cloth on the nose of the cushion. Sticky cloth tends to give a bouncier cushion.
 

dr_dave

Instructional Author
Gold Member
Silver Member
In response to Side Pockets felt too fast thread...

I made a guage to measure the speed of the cloth.

My cloth is 860, about 3-4 years old and hasn't been cleaned for at least 2 months.
I am going to play on 760 tmrw that is very well maintained and will get you the numbers for comparison.
enjoy.

This thing is very easy to make using scrap 3/4 inch wood. Make very accurate cuts.
If enough people decide to make one we can get a pretty good idea how
fast different cloth is.


I should mention at the time of filming the temp was 68 degrees with humidity at 31%

http://vimeo.com/108514470

steven
Joe Waldron has also proposed a fairly-simple-to-make "stimpmeter" to measure and compare table "speeds." Here's his article for those interested.

Enjoy,
Dave
 
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driven

AzB Silver Member
Silver Member
I measured my friends table a couple days ago. It now has 860, not the 760 I advertised. I forgot he had it redone.

The table was set up by an actual pool table mechanic.

Up table the balls rolled to the spot. 25 inches from the rail.
Down table they rolled an extra 2 inches to the 23 mark.
average roll out 24 inches from the rail, or 76 inches from the starting point.

My table is quite a bit faster even though I rarely clean it. I could be the age factor, mine being older. Not sure about that. It could be I stretched the cloth a bit more.
At first I thought because my table was so far off level the results must be wrong, but I had more roll uphill as well.

I never noticed the speed difference on Friends table. I am thinking any table that plays within 2 inches in either direction should be deemed level

I knew my table was much faster towards the foot end, a 14 inch difference in speed is no small difference. Someday I will even it out.

I am wondering now how many tables roll equal in both directions.

That is a very cool gauge there, rexus31.
Do you notice any difference in speed up table vs. down?

Your gauge and the one from Joe Waldron is clearly the way the thing should be made. I might add a slight curve near the bottom to smooth out the transition from device to table. Much like a bowler should release the ball.
steven
 

app4dstn

AzB Silver Member
Silver Member
It is also possible to measure the speed of a table with a stop watch. If you time a lag shot from far rail to stopping just before the near rail, the time in seconds squared times 2 gives you the reciprocal of the effective slope. So, 7 seconds for a lag to travel the length of the table gives:

7*7*2 = 98

slope = 1/98 = 1.0% more or less

On a carom table, it is not uncommon for a lag to take 10 seconds for the last lap of the lag:

10*10*1.8 = 180 (1.8 factor for a 10-foot table)

slope = 1/180 = 0.55%

Since most people can do lags and have stop watches or stop watch apps, this is a pretty simple and accurate way to measure table speed.

Also, if a video has a lag, you can pick the speed of the table off the time of the video.
that's a good practical and simplified test. :thumbup:

i tried this last night. rather than film it, i went to a metronome website and got a 120bpm cadence into my head. using the sound off the far rail to trigger the counting, the return lap on succesful lags were consistently around 12 beats (never 11, never 13), rough estimate 6 seconds.... 8 foot table (2.25 factor)


6 seconds -> 100/(6*6*2.25) 1.23456790123.... 1.23%
5.5 seconds -> 100/(5.5*5.5*2.25) 1.46923783287 ...1.47%
6.5 seconds -> 100/(6.5*6.5*2.25) 1.05193951348....1.05%

i know it's sloooooow. slow like pancake syrup? pancake batter?

anyone care to post up their (approximate) slope measurements? and the cloth they're using?

(i got my table on CL a couple of months ago. if i had to guess, the cloth that came with it is no-name/economical via ebay. i see it starting to develop fuzzies that weren't there when i got it.)
 

jviss

AzB Silver Member
Silver Member
Resurrecting an old thread...

It's a shame the videos and pics are no longer available!

I'm interested in this topic for my scale pool table project.
 

Bob Jewett

AZB Osmium Member
Silver Member
It's a shame the videos and pics are no longer available!

I'm interested in this topic for my scale pool table project.
I think no picture for the timed method of measuring pool table speed is needed. Were the instructions not clear?

Cushion rebound is harder to measure in part because it depends on how new the cloth is, as mentioned above.
 

jviss

AzB Silver Member
Silver Member
I think no picture for the timed method of measuring pool table speed is needed. Were the instructions not clear?

Cushion rebound is harder to measure in part because it depends on how new the cloth is, as mentioned above.
Thanks, Bob. Yea, I guess your method doesn't require pics, but it's generally disappointing when threads age and pics and videos evaporate.

I'm interested in various methods. Have you ever run statistics on your method to determine the repeatability, the 'resolution,' so to speak?

I must say that I'm reading and re-reading your article from April 1995 on this topic, and I haven't completely wrapped my head around it yet. I though it produced an absolute speed number, but then I saw that there's a correction factor for 10' tables, which hints that the method is actually calibrated to 9' tables, which I didn't think was the case. For example, for a ball to make it the length of a 10' table the initial "launch velocity" from the foot rail would have to be higher than on a 9' table. Similarly, it would be slower still for an 8' table. One would expect that if we measure the 10', 9', and 8' total distances for the same ball on the same table, that the times should be the same, leading to the same cloth speed.

A nice aspect of your method is that it doesn't require any special tool, and every smartphone has an excellent stop watch!

Very interested in this topic, thanks.
 

Island Drive

AzB Silver Member
Silver Member
Bottom Line

I'm really surprised the BCA does not maintain speed standards. A measurement system would be easy. It is done all the time on golf greens. A similar sloped apparatus would offer consistent measurements.

Mfg, could care less, that has been the norm for decades....the home market is their target.
 

Bob Jewett

AZB Osmium Member
Silver Member
... but then I saw that there's a correction factor for 10' tables, which hints that the method is actually calibrated to 9' tables, which I didn't think was the case. ...
The number that is multiplied by the square of the rolling time in seconds is related to the rolling distance from the last cushion until the ball stops. For a table 100 feet long but with normal cloth, you would expect about a 25 second lag time if the ball stops just before the cushion and the multiplying factor would be something like 1/6 instead of 2 since the lag is 12 times longer than a "normal" lag.

On the other hand, if your lag only comes back 60 inches (on any table) and it does it in 6.0 seconds, the multiplying factor is about 3.333 (due to the short length) and the nominal speed of the table would be 6*6*3.333 = 120.

The speed of the cloth has nothing to do with the length of the table. It is only related to how fast the rolling ball slows down. The different factors quoted for different lengths of table just save you from having to do the math like in the 60-inch lag -- the lag length is built in to the factor.
 
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