Pinewood Derby Wheel-Axle Friction

by Bob Barga

Goto "Data collected and statistics"

The Tests

P#10: Purpose is to devise a way to test different wheel hub and axle treatments as well as various lubricants. The testing procedure has to be done in such a way that the conditions are equal for all tests and the results are repeatible. I used a method that was devised by Stan Pope and posted on his website. My weighted ring weighs 1.98 oz. with a wheel inserted. The string ended up being 47 inches long from tip of the loop to the attachment point of the weights. I used two 1/4 oz. fishing sinkers for weights tied on the string. For the string I used a piece of 4lb test extra limp fishing line. My ring is not perfectly balanced but I believe it to be sufficient considering that I am using the same ring for all tests. Also I should mention that I wind up the string until the weights touch the eye screw for each test, that way the drop length is identical on every test. Also the axle is installed in a horizontal orientation. I do this by eye to start with and then I adjust it within the first couple spins. Ultimately the axle is adjusted so that the wheel spins approxiamately in the middle of the axle and does not migrate to the head or against the holding fixture. The way I see it there is only 2 possible variables per test. The first is that I do not have a positive stop so that the wheel is inserted in the ring to the same depth each time. For the depth I insert it to flush on the back side. For lateral alignment I also eye this operation and adjust accordingly, within the first couple spins to eleminate any sideways wobble. The second variable would be amount and method of lubrication application. As you will see in the following paragraphs I have tried to minimize that variable as well.

Test Subjects

P#20: I am testing oversized axles (.091) polished with mothers polishing compound, oversized axles cut with a single groove 1/8 in wide and polished with mothers, and oversized axles cut with 4 grooves the width of a cut off wheel for a dremel and polished with mothers. Also testing standard BSA axles (.086) in the same configurations. I have 2 axles per set of each treatment. The axles will be labeled A and B of each set, they are identical except for that B axles were polished with micro-mesh cloth after the mothers. Micro-mesh, for those that don't know is supposed to be finer and therefore better than polishing compound. After establishing my baseline numbers I am not sure it is any better.

P#30: I am also testing different sets of wheels with different hub treatments. All wheels initially were worked on a pro hub tool per the instructions and then had a pipe cleaner spun in the hubs with a drill for 15 seconds then the treatments were applied. The first wheel is for my baseline times and had nothing more done to it. The next set had the hubs burnished with a piece of 3/32 rod while rolling wheel back and forth across countertop. The theory is that burnishing in this fashion will melt any small imperfections back into hub and make it super smooth. I also ran the pipe cleaner back through these hubs after this operation. The next set was polished and then threaded with a 4-40 tap. The next set was polished and then undercut with a dremel bit so that only approxiamately 1/16 in of contact surface remains on each end of hub inside diameter. There are 2 wheels in each set. Both wheels in each set are marked and I have been using 1 wheel for graphite tests on all axles and the other wheel for Nyoil tests on each axle as well as any following tests that I may do with other liquid lubes.

Lubes

P#40: I was initially only going to test Hob-E-Lube brand graphite with moly. But with the emergance of Nyoil I decided to test that also.

P#45: To apply the graphite with moly lube I will put 2 puffs of graphite into hub. I will then insert axle through wheel with the ring assembly still on it. I will then spin the wheel assembly with my finger and let it come to a complete stop, 3 times. I will then relube and respin following same procedure 2 more times. This should ensure plenty of lube with some breakin as well, considering the approxiamate 2 ozs of weight on wheel.

P#50: In beginning the tests I found that the slightest difference in the method or amount of lubrication applied will have a substantial difference in spin times, especially the liquid lube. At first I applied the Nyoil as directed by the enclosed instructions (obtained from Maximum-Velocity). For those that do not have access to the instructions they say to put 1-2 drops on a pipe cleaner and then insert the pipe cleaner into a wheel bore. Rotate the wheel one complete revolution and remove. Then put 2 drops on the axle, then wipe off with a lint free towel. After having most of the baseline tests done I realized that they were not very consistent between the 2 axles of the same sets. I realized there was pipe cleaner lint in the bore so I switched to a much stiffer pipe cleaner. The numbers were still very inconsistent so I switched my method a third time. Now I simply put 1 drop on axle and let it flow to the end. Then without wiping the axle off I insert it into wheel (notice I did not lube inside wheel bore) and begin tests. This way I am sure there is the same amount of lube (Nyoil) per each test cycle.

Cleanup Between Tests

P#70: Next I had to figure out a sufficient way to remove the residual lube from each test before I start the next test. I found some solvent that works excellent and does not harm plastic. I will also be using this to clean between each graphite test as well.

P#80: To remove residual lube from previous test I dip the axle into solvent and then wipe with paper towel. I then dip axle into solvent again and swirl it around, this time letting it air dry to be sure there is no paper towel lint on axle. To clean the wheel I dip a pipe cleaner into the solvent and then run it back and forth through the wheel hub. Then use another piece of pipe cleaner and do it again, this time I blow through hub to remove any pipe cleaner lint, and let it air dry. The solvent I am using evaporates fairly quickly so it does not take more than a minute or so for it to dry.

Results

P#100: I should mention that a test cycle consists of 20 spins per test that are lubed once at the start and then not again. The spin is timed from the drop of the weight until the wheel comes to a complete stop.

Data collected and statistics

Oversized axle A = polished with Mothers polish
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil lube		37.98	4.25	26.88	43.19	16.31	26.88	42.16	Increasing spin times
Hob-E-Lube		29.97	1.85	26.59	33.62	7.03	26.59	30.31	Increasing, peak late
Undercut hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil lube		33.38	3.38	23.94	37.06	13.12	23.94	37.06	Increasing rapidly to plateau
Hob-E-Lube		22.77	1.81	18.75	24.87	6.12	20.75	24.87	Increasing, plateau late
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		32.88	1.32	31.06	35.25	4.19	31.72	32.13	Small, broad central peak
Oversized axle B = polished with Mothers polish and then micro-mesh
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil lube		36.35	1.44	33.77	38.48	4.71	34.28	38.48	Somewhat increasing spin times
Hob-E-Lube		29.01	1.17	26.94	30.78	3.84	27.72	26.94	Steady
Undercut hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil lube		40.33	2.47	30.56	42.31	11.75	30.56	40.84	Increasing rapidly to plateau
Hob-E-Lube		26.60	1.96	21.31	29.53	8.22	21.31	28.53	Increasing, plateau late
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		34.06	2.04	30.09	37.19	7.1	31.21	34.54	Increasing rapidly to plateau
Oversized axle with single wide groove A = polished with mothers
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		40.93	2.90	32.03	44.19	12.16	32.03	43.90	Increasing spin times, peaked early
Hob-E-Lube		24.15	1.33	21.75	26.91	5.16	22.15	25.68	Increasing
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		27.50	1.68	25.12	30.57	5.45	30.40	25.12	Stable
Oversized axle with single wide groove B = polished with mothers and micro-mesh
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		36.79	1.99	30.60	38.59	7.99	30.60	38.16	Increasing spin times, peaked early
Hob-E-Lube		27.81	1.79	25.50	31.22	5.72	31.00	27.81	Decreasing, level off quickly
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		31.68	1.44	29.31	34.60	5.29	34.60	32.50	Gradually decreasing
Oversized axle multi grooves A = polished with mothers
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		33.58	2.27	28.87	37.12	8.25	29.00	35.57	Increasing spin times
Hob-E-Lube		26.17	0.92	24.25	27.72	3.47	25.59	26.53	Steady
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		32.95	1.72	28.38	35.22	6.84	33.44	34.09	Variable
Oversized axle multi grooves B = polished with mothers and micro-mesh
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		32.71	2.07	26.87	34.91	8.04	26.87	34.25	Increasing spin times, peaked early
Hob-E-Lube		23.47	0.84	22.22	25.06	2.84	23.82	22.50	Steady
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		31.51	0.78	30.66	33.72	3.06	31.37	31.40	Gradually decreasing
BSA axle A = polished with mothers
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		35.85	3.00	27.31	40.75	13.44	27.31	40.75	Increasing spin times
Hob-E-Lube		35.58	1.42	33.53	39.18	5.65	36.13	33.65	Steady
Undercut hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil II Lube		43.54	3.91	31.85	48.22	16.37	31.85	46.18	Rapidly increasing to plateau
Hob-E-Lube		28.88	2.03	26.50	33.81	7.31	30.97	26.75	Unevenly decreasing spin times
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		37.00	2.10	33.12	41.06	7.94	33.12	34.88	Broad central plateau
BSA axle B = polished with mothers and micro-mesh
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		38.73	2.41	32.53	42.62	10.09	32.53	42.19	Increasing spin times
Hob-E-Lube		35.65	1.94	32.65	40.10	7.45	39.54	35.81	Unevenly decreasing spin times
Undercut hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil II Lube		43.32	2.45	36.07	46.69	10.62	36.07	44.78	Gradually increasing
Hob-E-Lube		32.90	2.20	28.78	36.72	7.94	35.09	28.78	Unevenly decreasing spin times
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		31.07	1.67	27.75	34.60	6.85	32.71	32.75	Stable
BSA axle single wide groove A = polished with mothers
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		43.12	2.70	32.75	45.25	12.5	32.75	44.56	Increasing spin times, peaked and leveled off
Hob-E-Lube		28.14	2.28	24.00	34.15	10.15	26.35	28.31	Unevenly increasing spin times
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		30.81	1.72	28.03	33.44	5.41	30.59	30.65	Gradually decreasing
BSA axle single wide groove B = polished with mothers and micro-mesh
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		44.35	2.72	36.66	46.90	10.24	38.68	46.90	Increasing spin times, peaked early and leveled off
Hob-E-Lube		30.64	1.02	28.81	32.59	3.78	31.53	28.81	Steady spin times
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		32.02	1.29	28.91	33.65	4.74	28.91	31.66	Stable
BSA axle multi grooves A = polished with mothers
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		44.75	2.33	37.32	46.57	9.25	37.32	46.06	Increasing spin times, peaked early, leveled off
Hob-E-Lube		32.83	0.92	31.07	34.19	3.12	32.06	33.91	Steady
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		30.19	1.26	27.75	32.06	4.31	27.75	31.72	Stable
BSA axle multi grooves B = polished with mothers and micro-mesh
Baseline Wheel = polished hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Nyoil		43.99	1.38	41.37	45.60	4.23	42.35	45.53	Increasing spin times, peaked early, leveled off
Hob-E-Lube		28.86	1.99	24.81	32.63	7.82	24.81	28.59	Unevenly increasing spin times
Threaded Hub
Test Condition	Show Data	Avg. Sec.	Std. Dev.	Low Time	High TIme	Range Sec.	First Time	Last Time	Trend
Hob-E-Lube		33.00	1.74	29.35	35.81	6.46	33.53	30.56	Stable