RodLab Penta Dimensions

[StePhDen]

Hi All, but especially Tim M and other RodLab users,

I've been using RodLab for a bit. I'm in the process of building a modified Payne 100. This one is five sided, three piece, hollow, with carbon fiber ferrules. I used the taper comparison tool to tweak the numbers and match the action of the new version to the original Payne 100.

I just finished glue-up and took dimensions and I'm not sure if the dimensions are wrong or if I'm not measuring what I think I'm measuring. First, I guess I am confused about which column I should be planing to in the first place. You have columns for strip height and width. I have a v block so I'm measuring strip height, but in the penta report strip height is larger than strip width (shouldn't that be reversed). I planed my strip heights to the strip width value. After glue-up I measured the rod dimension from flat to the opposite apex and the rod dimension was much larger than it should be according to the report. Is the dimension given in the report different than the flat to apex dimension? I could see the dimension in the report corresponding to inscribed circle (which for hex rods would be the same as flat to flat. If I'm thinking about this correctly the strip height should be the radius of the inscribed circle. I've included my taper below, if the rod dimension in the report is the same as the inscribed circle in this case both the strip height and strip width would create a larger inscribed circle than the rod dimension.

I'm mainly trying to figure out if I accidentally built an 8 wt, instead of a 4wt. the butt section especially is much bigger than I would expect for a rod this size. The first rod I built was a standard Payne 100 and the butt section at the cork didn't seem much larger than a number 2 pencil, This rod is almost half an inch at the butt. Which do I believe? the strip dimensions or the rod dimensions? If the rod dims are right and the strips are too big is there any way to update RodLab so it generates a correct report? I had a similar problem with generating penta reports out of RodDNA, I ended up calculating my strip dimensions by hand.

Thanks,

Stephen

Here are my numbers. the first three columns are copy/pasted from the RodLab MHM report the last two columns are my measurements off the blanks (the tips are still bound up so I haven't measured them)

Rod Strip Strip Rod. Flat 2 Rod
X. Height. Width. Dim. Apex. inscribed

-5, 0.0449, 0.0435, 0.0670,
0, 0.0489, 0.0474, 0.0730,
5, 0.0529, 0.0513, 0.0790,
10, 0.0643, 0.0624, 0.0960,
15, 0.0757, 0.0734, 0.1130,
20, 0.0844, 0.0819, 0.1260,
25, 0.0957, 0.0929, 0.1430,
30, 0.1051, 0.1020, 0.1570,
35, 0.1178, 0.1143, 0.1759,

25, 0.0957, 0.0929, 0.1430,
30, 0.1051, 0.1020, 0.1570, 0.217, 0.194
35, 0.1178, 0.1143, 0.1759, 0.243, 0.217
40, 0.1286, 0.1248, 0.1920, 0.268, 0.240
45, 0.1409, 0.1367, 0.2104, 0.290, 0.259
50, 0.1514, 0.1469, 0.2261, 0.319, 0.285
55, 0.1627, 0.1579, 0.2430, 0.340, 0.304
60, 0.1774, 0.1722, 0.2650, 0.369, 0.330
65, 0.1905, 0.1848, 0.2844,

55, 0.1627, 0.1579, 0.2430,
60, 0.1774, 0.1722, 0.2650, 0.376, 0.336
65, 0.1905, 0.1848, 0.2844, 0.397, 0.355
70, 0.2037, 0.1977, 0.3042, 0.430, 0.384
75, 0.2153, 0.2089, 0.3215, 0.452, 0.404
80, 0.2296, 0.2228, 0.3429, 0.485, 0.434
85, 0.2322, 0.2254, 0.3468, 0.491, 0.439
90, 0.2350, 0.2281, 0.3509, 0.499, 0.446
95, 0.2378, 0.2308, 0.3551,

[TimM]

I just replied to your PM but I'll put the response here in case others also have Q's:

====================================

Hi Stephen,

What version of RodLab are you using? 5.0 is out now and the MHM report looks quite a bit different although it's hard to compare the HTML report to text. I made some report improvements with suggestions from users. The version I see in your text uses some of my old shorthand which is confusing. Here's a quick breakdown of the MHM report columns:

RodX - distance from tip of rod.

X Strp - (now Strip Height) - The normal working dimension you would measure from outside of strip to Apex. Note that this height takes cutter angle into account so the number might not match the end rod dimensions.

Strp Wth (now Strip Width) - This is measuring the corners. If you rotated the strip 90 degrees from the stip height this is what you'd measure. Not a great measurement to take but helps to correlate with Strip Height if you have a crushed apex or other concern.

Rod Dim - The measurement you're targeting on the finished rod measured from flat to point on a penta.

That said I did a quick translation using the Payne 100 with 3 pc, penta and carbon fiber ferrules. I didn't have your hollowing numbers so I used some generic (.020 at tip, .065 at butt) numbers:

https://www.flickr.com/photos/43021860@ ... ed-public/

The numbers I see in your report show 0.355 for "Rod Dim" at the butt end which is not very far out of line with what I came up with in my sample translation but a long way off from the ~1/2 inch it sounds like your rod will measure when complete. It's also a long way off from the 'Flat2Apex' and 'Rod Inscribed' numbers which, I have to confess, I'm not sure what those represent without knowing the version you're using.

I've never used a MHM so I'm not familiar with the setup. A friend helped me create a better report for version 5.0. I hope the poor earlier report didn't send you out into the weeds.

Best regards,
Tim

[StePhDen]

I thought I had 5.0 but I will check and maybe re-download it. Still windows only? I still have a windows machine but I've switched to Mac for most everything else.

Flat to Apex is my direct measurement off the blank but it looks like it is the same as your rod dim. I'm just measuring the rod from one flat to the apex of the pentagon on the other side. The rod inscribed column also from my own measurements. It is taking that flat 2 apex measurement and converting it to the diameter of the inscribed circle of the pentagon at that station. Though based on your descriptions it looks like that isn't as relevant.

I'm still confused about how the strip dimensions result in the rod dimension. I drew up a pentagon in CAD when I make the distance from one edge to the center equal to the strip height I end up with a pentagon larger than what the rod dimension should be. For example, in your taper the strip dimension of the tip station is 0.048, the dimension of that pentagon is 0.108 instead of 0.0704. Am I setting up the pentagon wrong?

[TimM]

Crap - pretty sure you found a bug with Penta reports. The math for tapers is all done with the overall completed rod dim but the report routine takes the rod dim and calculates strip dims. Unfortunately, the strip width calculates correctly but the strip height calculation is wrong.

Going to re-do the math after sleeping on it and check for other dependencies.

Apologies / Thanks !!

[StePhDen]

Cool, let me know when you have an update ready. Thanks!