Quote:
|
Originally Posted by _GP_
Any tips for removing weight, we used mostly angle aluminum for our chassis and structure, where is it ok to take away metal without severely reducing the structural integrity?
|
The trick is to keep in mind where you expect loads. There's many engineerng courses on this topic... so I'll give easier methods and some general guidlines that I have used in years past. They're not perfect, but some ideas to look into.
In general, covering your robot with tiny holes won't reduce much weight.. especially in aluminum...
For example:
If you drill a 1/2 inch hole in 1/4" plate... it would take roughly 200 holes to get 1 pound of reduction. Try to get big bad square cut outs if you can, just be careful that you avoid removing too much material in areas where bearing and shafts run, and make sure that you think about worst-case sitautions. (What if my robot falls off the bar? If a robot on the bar falls off on me?! What if the corner of a robot drives into this particular point?)
Keep in mind that aluminum weighs about 35-40% the weight of steel... so you're better off looking where you can reduce weight in heavy steel components such as gears and sprockets. If you have access to a lathe, reduce the hub diamter and width. If you don't have a lathe, cheese-hole the steel where you can. Avoid getting too close to the teeth on sprockets and gears.
In general... if you really need to reduce signicant amounts of weight, reducing the thickness of parts by actually replacing them may be best. For many typical components (NOT ALL), 1/8" thick structural shapes are sufficient to function over typical light to moderate loads. 1/4" plate and other thick structural shapes should be reserved for where significant loads will occur.
Anywhere you see a square or rectangular plate, ask yourself if you could trim the corners off.
For light loads, do you REALLY need steel gears? Would brass, aluminum or nylon work? How about nylon chain in light applications?
If your frame has any box shapes that are greater than 1"... that might be over doing it a bit. If you're using that 4" x 2" rectangular stuff... there's PLEANTY that can be removed from that.
In general, assuming that you have a beam that's supporting a load (such as an arm) you want to make sure that you keep the cheese holes bigger and more frequent near the end where the load is. Putting big cheese holes near the base where the greatest stress concentrations exist could lead into trouble.
Have you considered aluminum fasteners for certain applications? How about aluminum sprockets?
Just a few thoughts, good luck everyone!
Matt