Making my own Light Weight Crank Pulley
your right its CAD Autodesk Inventor same as what i use at my school, ive tried solidworks and didnt realy like it but thats just cause i was brought up on inventor in school im sure if it was the other way around id be saying the same thing in solidworks
So i went and talked to my old boss about getting theses CNC machined which is do-able. He thinks my design is strong enough and wont have any problems supporting the belt load as there are 9 spokes around 1/4 inch think.
The cost to do the damper pulley is alot more expensive then doing the undampened pulley and thats without even getting an idea on the price to fill them with a rubber or material of that sorts.
Rough estimate in cost would be about 160$ for an undampened, with possibilities for powder coat or painting for an extra 5-10$ plating i think will be to expensive, and probably a little over 200 for a dampened pulley.
In order for me to break even i would need to sell about 15 parts and if i make them it will probably be un dampened.
90% of the cost is the programming and the 3-4 different steps involved with machining, and live tooling the parts. it would take about a full day for programming, and then another full day for each step so about 5 days total. Material being T-6061 Aluminum is fairly inexpensive and the difference to run 3 or 20 parts is very minimal.
From formulas that i have seen online it seems like every 1 lb removed from the crank shaft will increase about 2.5 HP. Using that figure and knowing that my undampened pulley has removed about 3lbs of mass then i estimate an increase in Hp of about 7-8 HP which is what RRM quotes for the underdrive pulley so in a real world application maybe closer to around 5HP while keeping the same belt length and not loosing the effectivenees of you alternator/PS pump/or AC compressor. This seems like a fairly reasonable figure to go by, but would be unknown untill i could test a part.
The way i see it know i have 3 options
1) u give me your OEM pulley and for a small fee i cn machine holes into it to save weight but keep the damper.
2) I can make 4 of the undampened on a manual mill by hand hopefully not screwing any up and have a spare or 2 to run tests on and give u guys a better idea before placing a cnc order for people would buy, but he may up the price from his very cheap quote if he knows im selling a whole bunch.
3) To go the ideal CNC route i would start right off with an order of about 20 parts but that means i would need 10 ppl committed and maybe someone money upfront as i can not afford the cost with being in school and am not prepared to purchase 20 parts and sit on them to sell.
I am still a few months away from production of either me doing it or having them CNC'd so ppl that are interested please PM me and ill answer any questions i can.
I hope this thread doesnt anger the evolutionm.net forum supervisors and get me removed cause i know im not really suppose to sell here but technically im not so.
The cost to do the damper pulley is alot more expensive then doing the undampened pulley and thats without even getting an idea on the price to fill them with a rubber or material of that sorts.
Rough estimate in cost would be about 160$ for an undampened, with possibilities for powder coat or painting for an extra 5-10$ plating i think will be to expensive, and probably a little over 200 for a dampened pulley.
In order for me to break even i would need to sell about 15 parts and if i make them it will probably be un dampened.
90% of the cost is the programming and the 3-4 different steps involved with machining, and live tooling the parts. it would take about a full day for programming, and then another full day for each step so about 5 days total. Material being T-6061 Aluminum is fairly inexpensive and the difference to run 3 or 20 parts is very minimal.
From formulas that i have seen online it seems like every 1 lb removed from the crank shaft will increase about 2.5 HP. Using that figure and knowing that my undampened pulley has removed about 3lbs of mass then i estimate an increase in Hp of about 7-8 HP which is what RRM quotes for the underdrive pulley so in a real world application maybe closer to around 5HP while keeping the same belt length and not loosing the effectivenees of you alternator/PS pump/or AC compressor. This seems like a fairly reasonable figure to go by, but would be unknown untill i could test a part.
The way i see it know i have 3 options
1) u give me your OEM pulley and for a small fee i cn machine holes into it to save weight but keep the damper.
2) I can make 4 of the undampened on a manual mill by hand hopefully not screwing any up and have a spare or 2 to run tests on and give u guys a better idea before placing a cnc order for people would buy, but he may up the price from his very cheap quote if he knows im selling a whole bunch.
3) To go the ideal CNC route i would start right off with an order of about 20 parts but that means i would need 10 ppl committed and maybe someone money upfront as i can not afford the cost with being in school and am not prepared to purchase 20 parts and sit on them to sell.
I am still a few months away from production of either me doing it or having them CNC'd so ppl that are interested please PM me and ill answer any questions i can.
I hope this thread doesnt anger the evolutionm.net forum supervisors and get me removed cause i know im not really suppose to sell here but technically im not so.
so is anyone actually interested in the CNC route? cause i may just get a chunk of aluminum to make 3-4 pulleys and my new maf flange this week and do them manually, keep 2 for me and hopefully not **** up the other two and maybe sell them
If i get all 4 no problems, i want to keep 2 one for the car and one for project/ cause itd look sick on my resume, and id sell the other ones for 100ish maybe cheaper 75$ to help cover material cost at least
i know the non damper shouldn't be a really big deal since there are many companies that sell these without dampers so, i know its not great cause the damper is important but, im not in this as a bushiness so im not prepared to spend thousands of dollars for a school project that probably wont sell really anything or change my marks at all. If i do the original 4 and results look good then maybe id look into CNC machining some for people but doesn't look like people are that interested so probably stick to my initial limited run and end it there.
if u guys really want a light weight damper pulley i think your real only option would be to have someone machine some holes into the stock aluminum pulley that we have.
edit 1: i just read a long spiel about hot crankshaft pulley dampers absorb the twisting from the crank caused by the combustion so that the crank wont break... from what i remember working at a company whose crank and alternator pulleys are used in 95% of vehicles on the road, the damper is there to absorb this twist/frequency so that it is not transmitted into the other parts altenator, power steering, ac etc if it wasn't, there would be massive failure in these components and belt slippage would be more prominent and tensions would need to be increased in the belt which lowers your power output and over all fuel economy. I dont think breaking the crank would be top on my list of problems from the undampened
Last edited by RallyartRob; Dec 7, 2012 at 06:41 PM.
Shouldn't break, but I haven't done stress testing on cad or vehicle test cause no part yet, my old boss whose been in aerospace machineing for 40+ years and has made parts for the canada space arm and Airbus A380 landing gear component's said it'll be fine so I trust his judgment but will do some testing aswell cause it'll make mh report better and give you guys some prices of mind
Rrm does not
Mine will not cause itll cost to much for a fun of 5 parts
The damper absorbs the very slight twist developed between combustion in each cylinder and stops it from going through the alternator drive belt parts ac, alternator, power steering, oem is rubber, if i did put one in my part would probably be urethane but theres alot more hows? That arise in doing so which is why 99% of aftermarket wont have a damper.
You might find one for an evo or sti or civic with a damper because they have the market
That should answer most you guys
Last edited by RallyartRob; Jan 6, 2013 at 02:50 PM.