Who needs large Aluminum Sprockets?

[Joe Johnson]

We all do!

What better to drive a big arm or turret or whatever?

We all like the large ratios for our last stage, but steel is SO heavy (.3 lbs / in^3 doesn't seem like much but an 11 inch disk, .160" thick is 15 in^3 -- that's 5 lbs -- even with webbing it is going to be heavy -- and then there is that problem of how do you attach it you your Aluminum arm -- welding isn't an option... ...and so it goes).

The problem is that large aluminum sprockts are not so easy to find "off the shelf."

Sprockets unlike gears are only arc so, in theory, they are fairly easy to make on a mill, though without CNC mill it is a bit of a challenge.

So... ...in the off season I did some hunting around the internet and found a supplier that makes off the shelf aluminum sprockets in largish sizes. I have purchased a bunch of sprockets from them and I can vouch for their ability to deliver a good product (with some limits that I will discuss later).

The company is Azusz Engineering (http://www.azusaeng.com).

They have an online catalog at http://www.azusaeng.com/catalog/dwnld/azctlg03.pdf (2.3Meg).

They do not sell direct, but use distributors. One I have used is Recreational Leisure ( http://www.recleisure.com/ ) in Michigan. I have spoken to them and they can process orders to be shipped anywhere in the country. Call Ray at (800) 521-6848. Mention FIRST so they will know of your urgency (FYI, I in no way get $ for this plug, in case you are wondering).

You can look through then entire Azusa catalog, but the aluminum sprockets are on page 29. The smallest chain they sell for is #35. The sell sprockets from 19-94 teeth.

In the catalog, they SAY they will put whatever size hole you want in the part and will put any bolt pattern in, but I recommend against this option. I spoke to them and I got a bad feeling about their ability to deliver a custom product that would be to print and made fast (the guy I spoke to at Azusa wanted a template shipped to him for him to use when he put in the holes -- scary business ;-). The guy from Recreational Leisure confirmed my wariness to use them for anything but their standard products (they took over a month to put in a custom bolt pattern he wanted -- UGH!).

So, I recommend buying there standard products which come with a 1" hole. You will have to enlarge it, put in your bolt pattern, machine in spokes (if you want to save more weight), etc. but the base sprocket will be in your hands in essentially the time it takes to ship them from California.

For #35 chain, the part number is T5201-NUMBER_OF_TEETH (e.g. a 60 tooth #35 sprocket would be T5201-60).

As to prices below are some examples of the prices from Recreational Leisure:

• T5201-60 $21
• T5201-70 $25
• T5201-90 $34

Not cheap but not too expensive either.

I hope this helps folks.

Joe J.