Now 6.345 was too little in my test case so I guessed at 6.349 and it is a marked improvement.
Maslow thinks it is closer together than reality because the chain is actually a bit shorter than it is using to calculate right? I also note that I’ve never seen my top bar flex like in practical use like it does when measuring with the chain.
So when I had my numbers I then did the triangle cut pattern again to finish the calibration.
Yes, I think @Jon used 6.349 mm I mistakenly said that was my magic number, mine is actually 6.359 mm. In your case your case and mine, Maslow thinks your motors are closer together than they actually are so your chain pitch must increase. In @Jon’s case his Maslow thinks they are farther apart.
There are two ways to adjust this value in the settings, in 1.11 you can actually use a percentage error for the right and left chains independently or you can manually change the chain pitch.
To be honest, I have never actually measured my right side chain so I don’t know for a fact that it has the same error as my left side chain (that you use for the stretch measurement). It is something I need to test.
Thanks for that @arnoldcp… I was definitely confused. Maybe I still am.
I guess I should Maslow measure both sides as well. To be clear, in our case, with the chains longer than the Maslow thinks, the percentage error would be actual dim / Maslow dim, in my case 3009.9 / 3001.9, or 1.002365. Is this the value that would be entered for percentage error? Or the opposite?
That calculation is correct. I will say the difference between your measurements and the resulting error percentage seems high. The published spec I have seen on #25 is +0.15% which should give you a maximum chain pitch of 6.359525 mm.
You said you planned to measure again, that’s a good idea. Because it is so hard to measure center of shaft to center of shaft another member determined that if you measure from the outside of the gearbox to the outside of the gearbox and the subtract 40.4 mm. You end up with the proper distance between the shaft centers. You may want to attempt that as well.
OK. I remeasured the motor spacing to the outside of the gearboxes. Assuming that the 40.4 mm correction is correct, my spacing is now 3006.012. Previously I measured from the right side of the R chain gear bushing to the right side of L chain gear bushing. I will try the new calculation.
Also, for yucks I entered the 1.002365 value into the Left and Right chain tolerances. I then needed to do the 12 o’clock routine due to loss of chain length error… The gear rotation adjustments were all screwed up (Large distances, wrong directions) until I returned to the 0 settings.
I also measured the left and right chains using the Maslow chain tightening, and got the following:
L - 3001.8
R - 2997.15
So, it’s Duck Soup to me…
I will try the 3006.012 distance number and cut a circle, and then, if necessary, try fiddling with the pitch settings.
Used the 3006.012 top measurement, ran through the calibration and the triangular cal cuts. My 6" circle was 6" wide x 5 7/8" high. Made several adjustments to the chain pitch, ending up at 6.368 mm, which yields some perfect 6" circles, and several that are either 6" wide x 5 31/32 - 5 15/16" high or 5 31/32" w x 6" h. Maybe this is as good as it gets? I have just run the Benchmark Cal cuts, and we will see what that yields.
Regarding the separate chain tolerances, how would that be calculated? For instance, on the left side, the ruler-measured distance is now 3006.012, with the Maslow measurement at 3001.8 I am assuming the value would be entered into the Chain Tolerance section for the left chain. And, what value should be used for the motor spacing? Seems like it would need to be the actual number.
Note that I tried dividing the Maslow number by an earlier slightly larger ruler measurement, using the Left side value for both chains (1.002365). This change made adjusting the 12 O’clock position impossible (large movements, often in the wrong direction.)
Regarding the separate chain tolerances, how would that be calculated? For instance, on the left side, the ruler-measured distance is now 3006.012, with the Maslow measurement at 3001.8 I am assuming the value would be entered into the Chain Tolerance section for the left chain. And, what value should be used for the motor spacing? Seems like it would need to be the actual number.
do the motor spacing measurement twice, once with each chain. Each time you also
measure manually (the manual measurement should be the same if everything is
going right )
Then you calculate the error between the measurement-by-chain and
measurement-by-tape for each chain, enter the tolerance for each chain.
Then if you re-run the motor spacing measurement, you should get the same result
by chain as you do manually (using the tolerance for the appropriate chain)
That is the motor spacng measurement you should enter.
This change made adjusting the 12 O’clock position impossible (large
movements, often in the wrong direction.)
Explain this more, tolerance values should have no effect on rotating the
sprocket to the 12 o’clock position.
Regarding the “12 O’clock” adjustment problem, I entered the error percentage calculated as the first physical measurement (3009.9) divided by the Maslow measurement of the left chain (3001.9), getting (1.002365)… Used this value in the chain tolerance section for both left and right chains. After doing this, when trying to rotate the gears to get to 12 o’clock, they moved several inches with each click, even with the 1 degree buttons. When I reset the chain tolerances to 0, this problem was fixed.
David, how is the tolerance expressed? For instance, if the Maslow says the spacing is 3001.8 for the left motor, and I measure it as 3006.02, the error is 4.94mm… As a percentage, 4.94 / 3006.02 = .00164337
.1643%? because the Maslow is less that the measurement, I am thinking it should be positive?!?
If it were the other way around (Maslow larger than the measurement), would it be negative?
Correction… the man-measured motor spacing is 3006.012
3006.012 - 3001.8 = 4.212
4.212 / 3006.012 = .00140119
1.00140119 x 3001.8 = 3006.0061, pretty close to 3006.012
So, for the left chain, use the 1.00140119 (or just .00140119?) as the left chain tolerance, and use the Maslow to remeasure this chain, hopefully getting the correct number.
Doing all of the above, the chain pitch would be returned to the default 6.35, right?
No, I am not measuring while the system is under tension. I imagine there might be a slight change, but I see no flex in the 2x4. When I built the frame, I attached a 8’ x 6” x 1/2” piece of particle board across the top edge of the 2x4 to keep it from flexing. In the interest of precision, I see your point… how long do you think the system can sustain the tension. Not sure I am comfortable messing with the tape while all this is going on. Have you done it?
I have not tried it. I am in a similar boat as you and wondering the optimal way to measure. On an 18" circle I am measuring 17 7/8in horizontal and 17 27/32in vertical
I’ve not been involved in the development of this, but based upon my read of the code, you would enter it as a percentage. So for 0.00140119, you would enter 0.140119. The code divides the value you enter by 100 and adds its to 1 to become a multiplier. So 0.140119 would become 1+(0.140119/100) = 1.00140119.
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