Our team has been experimenting with arm designs and different ways to power them. Our current supplies, as far as a spocket set up goes, are completely iron. We’ve ordered aluminum sprockets, which cut the weight by50%, if not more. We’re were wondering if we could use aluminum for the shafts. We’ve looked around quite a bit but can only find keyed shafts made of steel or an alloy of steel. We were wondering if anyone had a supplier or maybe knew of a different material , similar weight-wise, to aluminum. Any help would be useful.
Here is what we’re looking for:
Keyed Aluminum Shaft
3/4" in diameter
3/16" key width
1/16" key depth
Without seeing your basic design it’s hard to know if this will help, but you migth be able to redesign it so that the sprocket attatches to the arm instead of the shaft (with a bearing between the two)…this might allow you to use a smaller shaft and not have to worry about keying it.
igus parts are really nice for arm pivots, although it takes some effort to figure out how make it all work. And possibly a lathe.
Misumi is a good place to find precision shafts and such. We use them a lot when we want to buy commercial off-the-shelf assemblies. You can get pretty much any type of shaft, bearing, or gear you could want.
Team #75 has been using Aluminum Sprockets and Shafts for many years. The type of Aluminum you specify is important. The application loads, forces and process will dictate the use of these materials. We have also used Titanium (6Al-4V (a/k/a Grade 5)) for shafting. The Aluminum we have used in the past has been 7075 for shafting and sprockets. The Aluminum has held up in most applications but a Slight press fit helps the application. We have also used Lock-tite to help in the assembly. If you are using a set screws or screws during assembly, with aluminum you should size the screws for Course thread pitches. I would also double up on the set screws, as then tend to loosen during use and eventually fall out. Getting back to your original question. These are specialized materials and you would probably have to get a machine shop to fabricate the keyways in the shafts. I’m sure any local shop would help out if you ask.