sprockets

[sahil]

Can I use aluminium sprockets for my car ?
We are using a 600cc Honda engine which produces around 80bhp and if aluminium is not possible then what should I use ,light weight being our only priority.

[Scalesy]

We had issues with an aluminum sprocket in the past...and our engine is a YFZ 450, I'd say it would fair even worse with a 600cc. Issues were galling and warping...I'd imagine with careful design, material selection and possibly coatings it might work but simply laser cutting a piece of aluminum won't work...just from what I've seen with our car.

[Drew Price]

Did you re-heat treat the sprocket after you laser cut it? If not, that's the problem.

Best,
Drew

[PatClarke]

Sahil,
I posted this reply to your query over at formulastudent.de

Sahil,

Firstly, you do not state whether you are talking about drive sprockets or driven sprockets.

I would not ever consider using an aluminium drive sprocket and I would not ever consider using anything else but an aluminium driven sprocket!

I would not even think about making sprockets. There are better things to do with your time! I would calculate what size sprockets you require and order two sets from one of the many mail order motorcycle businesses. Then order one each rear sprocket with one tooth more and one tooth less than your design aim (for fine tuning)

A vague description like 'The sprocket will be about 6mm thick' tells me you have not considered what size chain you will use.

Most teams use 520 chain, that is 5/16" pitch and 1/4" width. 525 or 530 chains are just too heavy. These are also 5/8 pitch but wider in width.

Some teams have used 428 chain. This is a lighter duty 1/2" pitch chain and is commonly seen on 125cc motocross bikes. 428 chain offers weight gains in both chain and sprockets, and the smaller diameter sprockets (for the same gearing) especially at the rear, reduces rotational inertia.

I would not recommend this size chain until you absolutely understand all the stresses and how to deal with them and until you are ready to accept the possibility of DNF due to chain failure.

Cheers

Pat

[exFSAE]

light weight being our only priority.

http://fsae.com/groupee_common/emoticons/icon_frown.gif

How about strength? Stiffness? Endurance?

I will disagree with Pat on one point here. Making spockets is pretty easy, rear ones anyway. Perfect part for a quick CNC job, lasercut, or waterjet. Then toss it on a lathe and hit the teeth with a file to chamfer em.

[PatClarke]

But my point wasn't whether the sprockets are easy or hard to make. The point I was making is there are better ways to spend your time =]
Pat

[The AFX Master]

Or do what some teams do, give a call to sprocket specialists and ask them to make a custom aluminum rear sprocket for you.

www.sprocketspecialists.com (http://www.sprocketspecialists.com)

[drywater]

@Sahil
we at delhi college of engineering were using alloy steel as a material for sprocket,its quite reliable but too heavy.so this year we are thinking on the same guidelines as you and we will be using a aluminium 7075-T6 rear sprocket.

@The FX Master
do they(sprocket specialist) really make custom rear sprocket ?or they provide you with the blanks and you have to reduce weight as per your design.Or you give them your own design??

[The AFX Master]

Totally custom, Give them a call, then you send the drawings, size and pitch by email (they only do round holes to enlighten parts), And they ship you a well done and finished part.

[exFSAE]

Originally posted by drywater:
@Sahil
we at delhi college of engineering were using alloy steel as a material for sprocket,its quite reliable but too heavy.so this year we are thinking on the same guidelines as you and we will be using a aluminium 7075-T6 rear sprocket.

@The FX Master
do they(sprocket specialist) really make custom rear sprocket ?or they provide you with the blanks and you have to reduce weight as per your design.Or you give them your own design??

Too heavy? Based on what?

[drywater]

@EX FSAE
compared to aluminium sprocket,steel sprockets are heavy.

[exFSAE]

You haven't convinced me.

[drywater]

why so,i think one of our goals is to save weight and reduce rotational mass,we are doing that by using alumunium sprockets.

[Chris_S]

Originally posted by drywater:
@The FX Master
do they(sprocket specialist) really make custom rear sprocket ?or they provide you with the blanks and you have to reduce weight as per your design.Or you give them your own design??

http://www.sprocketsunlimited.com/

[drywater]

which material is better for sprockets..dural(duralumin) or aluminum 7075-T6 .the composition i s a little bit different and the former has a less tensile strength.

[sahil]

@pat clarke
Thank you SIR for your reply
I would like both my sprockets to be of aluminium (7075) .Is it possible?
We are planning to use a 520 chain.

[The AFX Master]

@ exfsae

theorethically we can make rear sprockets from steel or aluminum of the same weight and size... but with steel you'll need to rip off far more material than you'll need with Al, for those who pay for machining hours that doesn't look nice, isn't it?

[Pico]

I wouldnt put anything less than an alloy steel on our output shaft. With a 600cc there shouldnt be any discussion there. As for the driven sprocket we have used blanks from sprocket specialists and milled them to our liking. What output torque are you looking at?

[exFSAE]

Originally posted by The AFX Master:
@ exfsae

theorethically we can make rear sprockets from steel or aluminum of the same weight and size... but with steel you'll need to rip off far more material than you'll need with Al, for those who pay for machining hours that doesn't look nice, isn't it?

Laser cut, waterjet, or even just have the right tools on your CNC and difference should be small and/or negligible.

[VFR750R]

i have a few suggestions.
Calculate at the accel rate in which you are power limited, what is the power loss of accelerating a steel sprocket.
IF, you still feel you need aluminum, 7075-T6 is the only choice, but hard anodizing is a good idea.
Also, aluminum is not the only option, can you design a new steel sprocket that's as light as the aluminum one while still surpassing the wear and strength? i bet you can, then decide if it's worth the time and money for a part that is readily available for realitively cheap. Also, you may want a few sizes so you can fine tune your gearing, that'll have an effect on cost to benefit ratio.

Don't even think about making the front sprocket from aluminum

[Scalesy]

I agree, the drive sprocket can not be anything but alloy steel, however if you do it right, you can pull off an aluminum driven sprocket. Our issues in the past I believe to be poor material selection and poor design. 7075 al t6, hard anodized is what we're going for this year

[drywater]

guys i have a query...what do you prefer machining a aluminium (7075-T6 hard anodised) blank sprocket shipped from sprocket specialists(about $55 +shipping to India) ,or, a alloy steel sprocket bought from local market(blank costs about $10 ) +machining the teeth and the webs.There would be a small difference in the weight though.

[sahil]

@ drywater

It would be better to import the sprockets. I am planning to import them soon ,if u are interested them let me know .

[drywater]

@sahil.will you be importing them from sprocket specialist..email me your contact number
blackbrains7@gmail.com

[Hector]

Sprocket are not hard to make at all. Our team has been running a 600 cc engine for the past decade and have manufactured our own driven sprockets every year.

Drawing them up is not difficult at all. I used notes from Gizmology (http://www.gizmology.net/sprockets.htm) to aid me and it worked great. Hint: draw a single tooth first and save it as a template. Now you can use just change angle size depending on which size sprocket you want, and do a circular pattern to create each new sprocket.

As for galling, we have typically experienced few-to-no problems. We can usually run sprockets for 2-3 years before they break due to overeager freshmen downshifting too early during summer jolly driving.

Just make sure to pick a good alloy of aluminum that you think will work. Which one is up to you, you're the engineer after all.

[rahul patil]

Originally posted by sahil:
Can I use aluminium sprockets for my car ?
We are using a 600cc Honda engine which produces around 80bhp and if aluminium is not possible then what should I use ,light weight being our only priority.