Flight B/C

[Sapphire]

Even with a rubber stripper, we have a lot of trouble getting the exact densities we want. Is there are way better than just mass producing rubbers and calculating all of their densities to build up a range? It feels a bit inefficient, but to be fair the yield is way better than not using a rubber stripper.

[coachchuckaahs]

Saph:

Yes, there is. It takes careful record-keeping, and repeatable processes in using your stripper.

Basically, you cut blanks, which are equal lengths of stock rubber, with the length a bit longer than the longest you expect to be useful. Then you carefully weigh each blank, record these weights, and sort them by mass. The sorting is not entirely needed, but it does allow a more systematic approach to adjusting your stripper.

In addition to the blanks, you can cut a handful of shorter blanks, typically 3" long.

Start with the 3" blanks and get your process and stripper dialed in. Then you can go to the full blanks.

The process is basically figuring out what fraction of the blank you need to get the desired density. One way to do this is to determine the desired mass of the cut strip (your density times the length of the blank), and divide that by the mass of the blank, to get a decimal fraction number. Once you have gathered some data, you can use this fraction to set your cutter width. After cutting, you measure the actual mass of the cut strip and record that as well. The difference between that and the goal is your error. For the next strip, you adjust for this error, as well as for the difference in blank mass. You can fit a line through the cutter setting vs fraction of blank to determine how many thousandths to adjust the cutter. Or you can calculate it. For example, if your blank width is 1/8" (0.125") then each thousandth adjustment should change the fraction by 1/125.

I have a spreadsheet that does this, and calculates the adjustment based on the previous cut. Obviously that takes some care, because if the previous cut was wrong for any reason (say the mass was off), then that error propagates. It would be better to have a large amount of cutter data, perform a robust least squares fit (so that outliers do not skew the results), and use that to predict the right cutter setting.

Everybody ends up making a spreadsheet and doing the math their own way. It is instructive to do that so you understand the process. My spreadsheet has a lot of extra columns due to trying things at one time or another, bad scales, and other artifacts.

Perhaps I need to put together a simple spreadsheet, taking out all the excess info.

Also, there is an art to this. Especially with the Harlan cutter, where each side has to be adjusted, whereas on the Johnson you set the "gate" once for the stock width, and then just set the width you want. You will find that the feel of the rubber in the gate is critical, as getting the gate too tight or too loose will affect the end results.

I hope this helps! I will try to put together a simplified spreadsheet in the coming weeks and make it available. But I do encourage you to do the same.

Coach Chuck

[jgrischow1]

I've seen various mentions in the discord, but I was looking forward to Coaches Brian and Jeff doing a Nationals Flight wrapup with top times and general comments.

[jander14indoor]

Sorry for late report, but for some reason Scioly has been ignoring my attempts to log on. Not sure why it let me today, so here goes.

Div C National Tournament overview (times with no bonus, top teams all had full logs)
Top team, West Madison, WI 2:48.37, very good in that venue.
Second, Ann Arbor, MI 2:44.8, very close
Third, Albuquerque Academy, NM, 2:37
Fourth, Mason, OH, 2:35.29
Fifth, Syosset, NY 2:29.72
Sixth, Solon, OH 2:27.54
Beyond that, 21 teams were above 2 minutes
another 24 teams above 1 minute
Only 4 incomplete or no logs
Only 4 teams tiered this year, typically last minute or travel damage.

Overall, I'd say the level of competition this year is as good or better than I've ever seen. Congratulations to everyone!

Jeff Anderson
Livonia, MI

[jgrischow1]

Sorry for late report, but for some reason Scioly has been ignoring my attempts to log on. Not sure why it let me today, so here goes.

Div C National Tournament overview (times with no bonus, top teams all had full logs)
Top team, West Madison, WI 2:48.37, very good in that venue.
Second, Ann Arbor, MI 2:44.8, very close
Third, Albuquerque Academy, NM, 2:37
Fourth, Mason, OH, 2:35.29
Fifth, Syosset, NY 2:29.72
Sixth, Solon, OH 2:27.54
Beyond that, 21 teams were above 2 minutes
another 24 teams above 1 minute
Only 4 incomplete or no logs
Only 4 teams tiered this year, typically last minute or travel damage.

Overall, I'd say the level of competition this year is as good or better than I've ever seen. Congratulations to everyone!

Jeff Anderson
Livonia, MI

Thanks!