Quote:
Originally Posted by Tom Bishop
A bit off topic, but does anybody know a good supplier for aluminum bolts? Mcmaster is the only place that sells them that I can find, but they are almost 50cents a bolt and only offer a few sizes. Just by using them on our wheels this year, they save more weight than you might think. Thanks!
Mcmaster has a good supply of 1/4" 20 hex bolts that are not unreasonable. Lengths range from 1/2" to at least 4" and you can get longer but they won't be fully threaded. Once you go over that size they get a bit pricey, but 1/4" is plenty big for most fastening applications. That's our standard size bolt.
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i don't mean to sound critical but why would you want to use an aluminum bolt?
Aluminum isn't terribly good in shear....
Why not just drop down to a smaller size bolt if you want to reduce weight? #10 bolts are just a little over 1/2 the weight of 1/4 bolt... aluminum bolts in the same sizes would be about 33% of the weight of steel....but would have substantially less strength than the #10 steel bolts
We rarely use an 1/4 X 20 bolts on our robot... the biggest size we use is 10-24..
compare the weight of a 1/4 -20 bolt and a 10-24 bolt... you might find that that the 10-24 is a better alternative.
Compare the Clamp load of a 1/4# grade 8 bolt to a #10 grade 8 bolt and you will find that the #10 has about the 1550 lbs of clamp load and and a dry assembly torque of nearly 60 in lbs...
!/4" grade 8 bolts have the same clamp load and a dry assembly torque of a little over twice that..(140 in lbs)... if you go to #10 - 32 bolts you go up to 1800 lbs in clamp load and go to nearly 70 in lbs in dry torque...
Our team uses a number of different types of fasteners... we are gradually changing over to more blind rivet applications as we transition away from weldments to sheet metal construction.
The key to the use of fasteners, in my opinion, is two fold.
One ... use the right one for the job....
Two ... try to limit the types of bolted fasteners (IE try to standardize on your robot...)
To those that are concerned with speed of removal and replacement... either powered or unpowered...
Most of the time...you only have to have access to ONE side of a connection to place or remove a blind (pop) rivet.... any bolt will require access to the other side...to remove the nut...
Of course the easier method would be to install a screw...but this requires an initial drilling and tapping operation...screws are always the easiest fasteners to remove and replace ....
I will happily race anyone to remove and replace 10 bolts vs 10 rivets...
Rivets will win hands down...and always leave a consistent torque application...
There are MANY different types of blind rivets... look into the types... review your options...
do the homework...
i have mentioned this before but it bears repeating...
Do you know what they call 1.5 million rivets flying in formation?
A Boeing 747
