User:Jstapko/EngLab/WimshurstBelt

Wimshurst Belt

Introduction
This project is to find a new belt for the small Wimshurst machine in CL-158.
 * add pic
 * add link to Wimshurst machine

Belt Size Calculation
Per Mr. Plotnick's measurements, the dimensions of the pulleys are: large pulley I.D. calculation: 3.925 - (2 * .201) = 3.925 - .402 = 3.523 = LARGE PULLEY DIA.
 * 1) Small pulley: 0.875" Inside Diameter
 * 2) Large Pulley:
 * 3) *3.925" Outside Diameter
 * 4) *0.201" groove depth*
 * 1) 5.101" center to center

 *  Did not have the right tool to properly measure groove depth. Caliper did not bottom out in groove. Using string-around-plleys method might solve this problem.


 * UPDATE, 9/13: Did string test for open belt; found length to be closer to 17.5" than 17". Have not done string test for crossed belt, but have determined there is at least 1/2" difference in center-center distance between open and crossed.

Belt Size Calculation Links

 * 1) LINE SHAFT PULLEYS and BELTING Tells how, including associated geometry and drawings, to exactly calculate the length of belt needed for pulles of different diameters
 * 2) Audel Millwrights and Mechanics Guide Page 305 and later covers belt calculations and adjustment
 * 3) web based V-belt size calculator (returns 17.45" belt length for above dimensions)
 * 4) Dura-Belt belt length calculators (suggests using string wrapped around pulleys, I like this idea)
 * (actually, this also gives me an idea of using string or rope drive, like old radio dial belts)
 * 1) MSC animated belt calcualator (MSC is a possible source for Wimshurst belts)
 * features of this calculator include:
 * 1) belt length calculation
 * 2) Pulley RPM calculations, given pulley diameters
 * 3) Belt surface speed
 * 4) animated graphic that is supposed to simulate pulleys turning and distance approx. to scale
 * main drawback is that the finest pulley diameter measurement is1/32", not .001".
 * 1) Freson's Hardware belt calculation method (approximate only, adds diameters before multiplying)
 * 2) Calculation of belt length", by BEHA Belt (Germany)
 * Major points include:
 * 1) Shorten your calculated belt length by 1-8 % to pre-tension it
 * 2) Includes formulas involving contact angle for unequal pulley diameters, but I don't understand the math.
 * 3) Tells how to measure belt pre-tensioning (make marks on belt and measure them on and off pulleys)
 * 4) B&B manufacturing belt calculator For toothed belts (They sell toothed belts; this might be useful info in the future.)
 * 5) engineeringtoolbox.com belt size calculator
 * 6) * Uses (D-d)2/4L (center dist) in calculation, not sure how or why this works
 * 7) * Returns value of 17.5" length (not compensated for pretensioning as in link (7), above) with dimensions given above.
 * 8) * Includes formulas for RPM, belt power transfer, etc.
 * 9) csgnetwork belt calculator(returns 17.455" with dimensions given above, no pre-tension compensation)
 * 10) Google Book: "Belt Selection and Application for Engineers" by Wallace D. Erickson. Pages 90-91 help to explain derivation of belt length formulas, although does not give a complete explaination.

Belt Supplier Possibilities

 * 1) Sci-Supply.com 18.5" belts NOT SOLUTION - these belts are 18.5" circumference, while our machine should have a belt no longer than 17.5", as noted in section 3, links (3), (9), and (10), above.
 * 2) Sci-Supply.com "Economy Wimshurst Belt" POSSIBLE SOLUTION - features include:
 * says belt is 17.5" circumference, very close to what we need
 * says it's for a Wimsurst generator "P/N SS2310" (is this what ours is?)
 * price is $4.79 for set of two
 * part number of related machine matches that for link (4) below, but belts in link (4) are 1/2" shorter.
 * 1) Abra-Electronics.com Wimshurst belt POSSIBLE SOLUTION- can't tell from this page what the belt length is, but the machine it goes to looks exactly like HCC's. Other points include:
 * Machine part number in pic is Ginsberg Scientific 7-509
 * Belt part # is 7-509-2
 * Might be OEM part
 * Price is $5.00 for set of two
 * Might be able to confirm make/model of machine with Scott or Keith
 * 1) Amazon.com 17" Wimshurst belt GOOD POSSIBLE SOLUTION - 17" belt, which would give 2.9% pre-tension if our machine is supposed to take a 17.5" belt. Other points include:
 * Intended for Lethan Model SS2310, which looks very similar to HCC's unit
 * Price is $5.99 for set of two
 * Claims to fit same machine as belt in section 4, link (2), above, but this belt is 1/2" shorter circumference (what gives, 2 belt sizes fit same machine?)
 * 1) Makezine Wimshurst Project suggests to use Mcmaster-Carr "Neoprene O Rings." The one closest to the size of our belt is McMaster # 94115k283, 16.955" I.D.
 * 2) Repairs - Wimshurst Machine Regional Technician's Group guide to repairing Wimshursts. Major points include:
 * make sure leyden jars aren't cracked
 * original belts were made of leather (mabye Sewing Machine belts)
 * troubleshooting tips might be useful later
 * Says to use Neoprene belting, and tells how to splice it after cutting to make the crossed end (this raises new possibilities)

New Information Based on Finding Model Number

 * 1) HCC's wimshurst is an American Educational Products Co. model 7-509