Disk brake hub

[savarin]

I think I have come up with a method of making a disk brake hub.
At the moment this is only a concept so discussions welcomed.
Find 2 angular contact bearings. I can only find ones to fit a 12 or 15 mm shaft with an outer dia of 35mm or 42 mm so find some tubing that they will fit in.
Tack a couple of spacers inside to prevent the bearings from being pushed through. Make a spacer for the axle to prevent clamping the bearings too tightly and binding them.
Use Brads delta wolf method of making wheel hubs but weld the washers to this tube instead of the shaft.
Make the washer/disks large enough to bolt the adapter to.
Bolt the disk rotor to the adapter.
I believe the adapter could be made from 4 or 5, 4mm disks of aluminium or steel, depending upon what clearances are required.
http://i154.photobucket.com/albums/s258/savarin48/recumbent/adapter1.jpg
Some drilling and filing to fit and hopefully it should work.
http://i154.photobucket.com/albums/s258/savarin48/recumbent/adapter3.jpg
http://i154.photobucket.com/albums/s258/savarin48/recumbent/adapter4.jpg
I've gone down this route because I want disks on the tadpole and I cant find 14mm bmx hubs for love nor money (well, ok, plenty of money)
Obviously machining it out of one piece would be better but I still hope this would work. I will get started once I get the bearings.
I should have explained that the disk the rotor bolts to has a smaller dia centre hole so some meat for the bolts is left. the other 3 disks have a much larger dia centre hole to clear the axle/bearing combo
I hope this makes sense to someone.

[TheKid]

You could use 13mm (or 1/2") thick aluminum or steel for the rotor mounts, rather than four 4mm thick pieces. They have to be a minimum of 2 1/4" in diameter, (57.15mm), and there's no need to shape the inside diameter. The ID simply has to be large enough to allow the axle to pass through. To change the bearings on the disc side, just remove the disk and unbolt the adapter from the hub. Or you could make the retainers and compression tube as one unit removable from the non disc side.
I came up with a similar design using 1 1/4" EMT and flange bearings. It didn't work because the rotor mount is too small. However, I've revamped the design to take 5/8" ID x 1 3/8" OD bearings, and the retainer/compression tube insert. (It's easier to find sources of tubing in inch sizes rather than metric here in the States, So I assume for almost anywhere else in the world, metric would be the way to go.)
I came up with a similar design using 1 1/4" EMT and flange bearings, but it won't work because the rotor mount has to be too small. I revamped the design using non flanged bearings. The spoke flanges are 2 7/8" in diameter, with the center hole bored out to 1 1/2" to fit over the EMT. The rotor mount is 1/2" thick and has the center hole drilled out to 3/4" to accept a spacer which is 3/4" OD, 5/8" ID and 13/16" long. The spacer is welded to the rotor mount so it protrudes 1/4" beyond the outside of the hub. It's then welded to the spoke flange. You insert a bearing from the plain side, then the retainer/compression tube unit, then the other bearing. Slide a 3/4" OD x 5/8" ID x 1/4" wide spacer over a 5/8" bolt, (the axle) from the plain side, and insert it into the kingpin unit, which by now you have drilled out from 9/16" to 5/8", and tighten with a nylock washer. I'm only using these sizes because that's what I have on hand. This method can easily be modified to accept smaller tubing for the hub, and smaller bearings and axles.

[savarin]

So in general what you are saying is that it works fine?:D
I thought of thick aluminium but because I haven't started yet I was unsure how thick it would have to be.
I also felt that trying to get the bearing inserted through the hub from the plain side to the rotor may be too difficult which is why I chose to bolt the adapter to the spoke flange. How easy was it in reality?
I would guess that the most difficult part is getting the spoke flange welded exactly at 90' to the axle tube so the disk rotor tracks square with no runout

[TheKid]

I think you're right about getting the spoke flanges square on the hub, but if you make it nice and tight on the tube, it's easier. Just do like Brad says and tack weld, check alignment, tack weld, etc. Bolting the rotor flange to the spoke flange is probably easier than welding it, especially if you use aluminum. I would put some good strong epoxy between the steel spoke flange and the aluminum rotor flange to prevent electrolysis and to add strength. You could use 3/8" thick aluminum for the rotor flange, as that's the thickness of the aluminum disc adapters I bought for my Streetfox. Aluminum is a good choice, because it's easy to work with. Rotor bolts are 5mm, so if you go to a hardware store, you'll need a 5mm tap and whatever size drill bit is required. They should know that at the store. Taps that small are very inexpensive, and last a long time, especially if you only use them on aluminum. I haven't made my hubs yet, but I just figured out I was right the first time. I could fit the rotor mounts on the 1 1/2" OD tube I'll be using for the hub. When I was figuring things out the other day, I was working with no sleep for two days and got a bit confused. I posted plans for those hubs somewhere in the old forum, but I don't remember where. At any rate, I may use your idea of bolting the rotor mounts to the spoke flangeinstead, just because it's easier to tap aluminum.

[savarin]

I would put some good strong epoxy between the steel spoke flange and the aluminum rotor flange to prevent electrolysis and to add strength.

Ha Ha, not much chance of that here. Wet? what wet?

[TheKid]

What I mean is the electrolytic action between two dissimilar metals. They don't have to be wet for it to take place. It doesn't often happen between aluminum and steel, but I saw the beginnings of it on my quad when I disassembled it. I had some aluminum flat bar bolted on with steel bolts. I was told I should have used stainless steel bolts to prvent this from happening.

[savarin]

What I mean is the electrolytic action between two dissimilar metals. They don't have to be wet for it to take place. It doesn't often happen between aluminum and steel, but I saw the beginnings of it on my quad when I disassembled it. I had some aluminum flat bar bolted on with steel bolts. I was told I should have used stainless steel bolts to prvent this from happening.

Actually it does require an amount of moisture to produce the reaction between dissimilar metals as without it there is no electro chemical process to take place.
Aluminium is coated in an incredibly tough inert layer of aluminium oxide.
This starts forming very rapidly once the aluminium is exposed to the air.
This same oxide layer is an electrical insulator which is what helps prevent the reaction from taking place.
However,aluminium oxide is a brilliant abrasive so when torquing up ally onto other metals its possible to scratch the oxide layer off in particles which abrade the surface of the ally allowing any moisture present to start the reaction.
I must say I've owned many motorcycles where steel bolts were used in the alluminium crankcases and else where with no signs of electrolytic corrosion at all but get a bit of salt in with the moisture and watch out. That makes the water electrically conductive and it corrodes like wildfire.

[TheKid]

Thanks for the info. There's plenty of moisture around here, and I'm near salt water quite often. I live only a half mile away from the closest source.