Disc Brake Rotor Specs

[patches]

I'm thinking of getting some 160mm rotors CNC laser cut and see how they perform.

 

This is a design (based on the IS 6 bolt spec) that I put together in Inventor, and according to it's calcs they should weigh approx. 100g each. I'm still going to do a full stress analysis on them, to find the weak spots and tweak the design.

 

My questions to you tech guys and weight watchers are:

 

1. What does an average 160mm rotor weigh?

2. What is the thickness of an average rotor?

3. Is the IS 6-bolt spec a PCD of 44mm with M5 lock bolts, or am I wrong?

[patches]

Anyone?!

[AndreZA]

 

 

I do not know all of that stuff you are asking but I replaced my Shimano XT 6 bolts front last week with an Alligator Windcutter and I saved 30gr just on the front. The Alligator is 92gr. The Alligator 140mm is just 61gr.

 

 

 

Can you please let me have the number of who can do this. I want to have some of my own design cut.

 

 

 

 

 

 

[patches]

92g Alligators... So weighing in at 100g for a 160mm, I'm not far off for my 1st  draft design!

As for who can do it... Do you  have access to CAD software to draw it up? (and stress test it, if you want to be safe)

 

If not, I'd be happy to do that free of charge. Work is boring at the moment, haha!

 

If you do... there's a place our engineering firm uses called:

 

Plasma Cut (Germiston)

 

Their number is 011 902 5550

 

I'm not sure of cost, and obviously the more you do the cheaper they are, but when my design is finalized, I'll have all that info. Cost for 304L St/Steel sheeting, etc.

patches2010-01-14 08:15:44

[Procrates]

 

Would you be able to do something like this?

 

 

 

http://www.dirtydogmtb.com/2006preview.htm

http://www.dirtydogmtb.com/rotors.htm

[patches]

 

Would you be able to do something like this?

 

http://www.dirtydogmtb.com/2006preview.htm

http://www.dirtydogmtb.com/rotors.htm

Totally possible. It's all in the CAD work. The CNC rigs interpret from the CAD design, and cut where you tell them.

 

I guess the only 2 big factors are:

 

1. Strength

2. Time needed to cut. (I think the laser cutting guys probably charge per hour).

 

But yes! crazy intricate designs are totally possible

patches2010-01-14 12:48:49

[parabola]

In my experience laser cutting is generally charged by the weight of material of the final product. The actual cutting is very quick, but leaves a rough edge and might need some post machining to clean it up.

[patches]

In my experience laser cutting is generally charged by the weight of material of the final product. The actual cutting is very quick' date=' but leaves a rough edge and might need some post machining to clean it up. [/quote']

Cool! That's great then, cos I'm aiming at a sub 100g 160mm rotor

 

I must actually phone our laser cutting guys and find out exactly how they charge?! (when it's work stuff one doesn't pay that much attention, but when it's outta my own pocket, different story, haha!)

 

And yup, you're totally right, one needs to do some post machining work on the surface, especially where the laser leaves the start/finish etches. 

patches2010-01-14 12:57:20

[Procrates]

 

 

 

 

MMM, I sense a project coming up.

[parabola]

Even the Avid rotors I recently bought from the LBS had quite rough edges, but they dont really affect rotors performance in any way.

[patches]

 

 

MMM' date=' I sense a project coming up.[/quote']

haha! yup!

 

Here's another idea I had... (this 160mm one weighs in at 111g. Heavier than Windcutters, but about 35g lighter than all the Mad Dog designs (granted it's not at intricate)

 

 

...but like all progects of an engineering nature, there's still a lot of research i have to do.

 

Like what percentage of the braking surface area has to be solid, and what has to be air? (in order to maximize stopping power, and minimize heat build up)

 

So yes, Proctates... it's a project, but a long way from producing a prototype

[patches]

I've just spoken to the laser cutting guys we deal with. They said they charge based on the complexity of the design. I then emailed them CAD drawings of the two concepts shown in this thread, so that they can give me an estimate price.

 

I'll keep eveyone posted as to how much it's gonna cost. Then maybe us South Africans can have locally produced custom made rotors too

[AndreZA]

I would love to get involved in this. This is what I have in mine in both 160 and 140mm. This was done in Coreldraw so it it not 100% CAD quality.

 

 

 

http://www.vukileprops.co.za/pics/xt.jpg

[patches]

Awesome! Yeah! I'm surprised no one has decided to produce rotors locally. It's probably one of the easiest components to manufacture!

[patches]

So I messed around on Inventor and came up with this as a first draft of your concept, Mampara

 

 

 

(according to the software this 160mm rotor should weigh 104g)

 

What you think?!

[AndreZA]

If you make the XT logo a little bolder and bigger you can lose a few more grams. But I will take a set please.