Quote:
Originally Posted by Joseph Smith
I've been investigating some new design and construction methods that my team hasn't explored in the past, and I really want to try assembling the frame and important structures with machined gussets and bolts. I have a few questions for teams who have used this construction method. In this scenario, I'd be using two gussets, top and bottom, to create a 90 degree joint between two lengths of rectangular aluminum tubing, all 1/8" wall thickness.
1. Is it better to put a long bolt all the way through and use a nut on the other side, or to tap the gusset and tubing and use shorter bolts?
2. If a bolt all the way through is used, are large washers needed to spread the load to prevent the tube from being crushed?
3. If the parts are tapped and a short bolt is used, would it be preferable to tap both the gusset and the tubing or to drill clearance on the gusset and only tap the tubing?
4. Is locktite a necessity with the tapping method?
5. What has been your overall experience with this method of construction? Pros/Cons?
Thanks!
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1. Whenever we have bolted a gusset/tube we have gone all the way through with a bolt. We try to keep tapped parts to standoffs and to a minimum. If its a part you may have to remove and install several times you start increasing the risk someone who is rushing won't make sure the threads are lined up and damage the threads. Our first year using tapped parts was in 2013 and by mid season a few standoffs were replaced because the threads were gone.
2. To prevent the tubing from being crushed you need to work on training teammates (and sometimes adults too) how to properly use tools. There is a difference between making sure you have a snug fit and turning the wrench to extremes to get a tight fit which typically ends in bending the tube.
A downside to using bolts extensively is they are much heavier than other alternatives such as aluminum rivets. The more parts you have in your assemblies the more weight you need to consider that is getting used holding it together.
This past build season we relied mostly on gussets from Vexpro or homemade versions held together with 3/16 aluminum rivets. We did use bolted connections in a few key areas we knew could be removed frequently and didn't want to rely on drilling out rivets over and over.