# Thread: How much Gross Grain is left on the roll

1. Originally Posted by WV
You can also work backwards: weigh a short length and calculate from that. It's surprisingly accurate.
with a note of caution on the accuracy of the scale used. I whack off 1 ft, and on a scale that is accurate to 0.5 grams (like mine) I come up with w grams. If w is large compared to 0.5, no problem. But if it is small, and I weigh a roll and it comes out at N grams, my error can be large.

To wit, if the true value is between w-0.5 grams and w+0.5 grams (depending on your definition of "accuracy to within 0.5, but just go with this), then if you weigh the roll and come up with N grams the true value is between
N/(w-0.5) and N/(w+0.5) ft. If w were, say 2 grams, the range is N/1.5 to N/2.5 feet, very roughly error on the order of 25%.

Not sure what a foot of grosgrain weighs, just used 2 g for illustration.

2. Originally Posted by GrizzlyAdams
with a note of caution on the accuracy of the scale used. I whack off 1 ft, and on a scale that is accurate to 0.5 grams (like mine) I come up with w grams. If w is large compared to 0.5, no problem. But if it is small, and I weigh a roll and it comes out at N grams, my error can be large.

To wit, if the true value is between w-0.5 grams and w+0.5 grams (depending on your definition of "accuracy to within 0.5, but just go with this), then if you weigh the roll and come up with N grams the true value is between
N/(w-0.5) and N/(w+0.5) ft. If w were, say 2 grams, the range is N/1.5 to N/2.5 feet, very roughly error on the order of 25%.

Not sure what a foot of grosgrain weighs, just used 2 g for illustration.
Thanks, Griz. I was thinking of "a short length" as a couple of yards. I have also used longer "short lengths" (5 or 6 yards) and weighed them without cutting them off the main roll. Of course, there's some error in weighing with the main roll attached, but by watching the scale and lifting and lowering the main roll next to it I can see the range of error + or - and interpolate my usual SWAG. (I have actually only done this with amsteel, but it should work equally well - or badly - with gross grain.)

3. Originally Posted by GrizzlyAdams
with a note of caution on the accuracy of the scale ...
Precisely!

...er, I mean, Right on!

4. When I run out I order more.

5. This came about b/c I was selling some grosgrain rolls and wanted to provide an approximate yardage so folks could see what a good deal (or not) it was.

I also have run out once when binding a tarp. Fortunately, I had another roll waiting of the same color.

All of the weight formulas would work if you know the weight of the core it comes on, which you could determine once empty. From experience, you don't wan't to ever pull it out because gg (like amsteel) has a super ability to knot itself itself if not tightly bound and guarded.

6. Originally Posted by nacra533
This came about b/c I was selling some grosgrain rolls and wanted to provide an approximate yardage so folks could see what a good deal (or not) it was.

I also have run out once when binding a tarp. Fortunately, I had another roll waiting of the same color.

All of the weight formulas would work if you know the weight of the core it comes on, which you could determine once empty. From experience, you don't wan't to ever pull it out because gg (like amsteel) has a super ability to knot itself itself if not tightly bound and guarded.
yeah, I thought of the possibility of a core too, but have never purchased enough at once to see one If you save a core from one roll and weigh it, then I'd go with the weighing method. For all but the shortest pieces that will do the job well.

7. If it comes loose I rewind gross grain on the 99 cent plastic winders for extension cords.

By the way, what's the correct spelling, if any? I got mine (the spelling) from the OWF site, but "grosgrain" somehow looks better.

8. My 100 yard rolls of grosgrain weigh 18.8 oz. The core weighs 0.2 oz, which is the weight of one yard. Therefore, ignoring the core give a 1% error, so that, at the end, you would have one less yard of grosgrain than your scales indicate.

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