Bolt in cage Idea
Thread Starter
Drifting
Joined: Oct 2003
Posts: 1,486
Likes: 10
From: Big Pine Key FL
Bolt in cage Idea
All this talk about roll cages has me thinking (I know it's a dangerous thing)!!
What about the aircraft style conical joint? It bolts together two sections of tube, or a tube and a flat. It could be replaced with a cap when the bar was not in use and if done correctly it might just be flush with the floor or the bulkhead when not in use. I'm sure the tech inspectors could be petitioned to accept it as a workable compromise if approached beforehand.
Just a thought...
What about the aircraft style conical joint? It bolts together two sections of tube, or a tube and a flat. It could be replaced with a cap when the bar was not in use and if done correctly it might just be flush with the floor or the bulkhead when not in use. I'm sure the tech inspectors could be petitioned to accept it as a workable compromise if approached beforehand.
Just a thought...
Thread Starter
Drifting
Joined: Oct 2003
Posts: 1,486
Likes: 10
From: Big Pine Key FL
Conical bolted joints
This style of bolted joint was used in offshore oil rig towers, motorcycle, car, and aircraft frames where a tubular member needed to be removable or assembled and loads carried in all directions.
A cone shaped "socket" is welded to the end of one tube or flat and a matching cone shaped "ball" is welded to the mating end. The joint is held together by bolting through the face of the ball and into the socket parallel to the tubing. Typically three bolts spaced at 120 degrees around the circumfrence would be sufficient to hold the joint together in tension, the geometry of the cone works in compression, the taper in and bolt sheer (like a drill chuck) in torsion, and so on. There are details to work out like the diameter of a bar vs the diameter and wall of the tube, angle of the cone and size and number of bolts to hold it together. I suspect an advanced engineering handbook would be of some help. It's a simple joint to make with a lathe and mill.
I haven't found any pictures yet but they do exist.
Mark
A cone shaped "socket" is welded to the end of one tube or flat and a matching cone shaped "ball" is welded to the mating end. The joint is held together by bolting through the face of the ball and into the socket parallel to the tubing. Typically three bolts spaced at 120 degrees around the circumfrence would be sufficient to hold the joint together in tension, the geometry of the cone works in compression, the taper in and bolt sheer (like a drill chuck) in torsion, and so on. There are details to work out like the diameter of a bar vs the diameter and wall of the tube, angle of the cone and size and number of bolts to hold it together. I suspect an advanced engineering handbook would be of some help. It's a simple joint to make with a lathe and mill.
I haven't found any pictures yet but they do exist.
Mark
Abby Normal
Joined: Dec 2001
Posts: 53,513
Likes: 92
From: Press "2" for English
might want to see if norval has any thoughts on the subject. he's pretty well versed in the engineering aspect and just posted about a bolt in cage. it didn't have this type of joint though so i'd be interested what he, and the rest of the better educated have to say about the idea.
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Race Director
Joined: Nov 2000
Posts: 16,416
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From: NC,USA
I was doing some pondering last night...
What would happen if we installed a beefed up transmission crossmember, and triangulated the frame under the cabin. Just like the Old C1's... BUT, using welded in plates, and heim joints. Put the frame in compression...
Dont know if it would work or not, but given its all tight, I dont see why 4 points mounted off the center of the transmission cross member, would not give SOME improvement.
Its a bigger headache in my opinion... for us vs the unibody cars. They have all the mounting points pre-defined. Want to stiffen it up? Put a bar between two mounts!
Is there an easy way to test the twist that our frames are subjected to? A picture, kind of like what solid works can create... to show where we need to concentrate our efforts?
I wonder if the GM book about C3 racing has anything on the topic.
What would happen if we installed a beefed up transmission crossmember, and triangulated the frame under the cabin. Just like the Old C1's... BUT, using welded in plates, and heim joints. Put the frame in compression...
Dont know if it would work or not, but given its all tight, I dont see why 4 points mounted off the center of the transmission cross member, would not give SOME improvement.
Its a bigger headache in my opinion... for us vs the unibody cars. They have all the mounting points pre-defined. Want to stiffen it up? Put a bar between two mounts!
Is there an easy way to test the twist that our frames are subjected to? A picture, kind of like what solid works can create... to show where we need to concentrate our efforts?
I wonder if the GM book about C3 racing has anything on the topic.
Team Owner
Joined: Sep 2003
Posts: 88,393
Likes: 2
From: eville in
Originally Posted by clutchdust
might want to see if norval has any thoughts on the subject. he's pretty well versed in the engineering aspect and just posted about a bolt in cage. it didn't have this type of joint though so i'd be interested what he, and the rest of the better educated have to say about the idea.
Melting Slicks
Joined: Jul 2002
Posts: 3,000
Likes: 22
From: Boulder Creek California
Originally Posted by ZD75blue
triangulate the frame under the cabin
Racer
Joined: Jun 2002
Posts: 254
Likes: 0
From: Lonoke Arkansas
I like the ball/socket idea. If the cage is welded together and each of the attachment points to the frame are the ball/socket type, is there any need to prevent the ***** from rotating in the sockets? The structure of the cage will try to keep the frame in it's original planes. The only way I see rotation is if a single frame member tries to twist/rotate about the center of a ball. What about heim joints at each frame/cage connection? Or just a clevis type joint? A shoulder bolt through reamed tight clearence holes that would pinch the clevis together taking out clearence. The heim joint would take out some alignment problems though.
Although, if the cage is fully welded, how you gonna get it out of a coupe any way?
Although, if the cage is fully welded, how you gonna get it out of a coupe any way?
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Originally Posted by clutchdust
might want to see if norval has any thoughts on the subject. he's pretty well versed in the engineering aspect and just posted about a bolt in cage. it didn't have this type of joint though so i'd be interested what he, and the rest of the better educated have to say about the idea.
I got this email last week from a guy, I will not mention his name but this is the email missing parts at the beginning.
We have used bolt together joints on helicopters that had tube frames. They ALWAYS held together, and that's saying a lot for anything attached to a vibrating whirlwind. The joints that we used were machined to slip over the tube and be welded on. the face of the joint was machined at about a 30 degree angle, I suspect more for a compact joint than for any other reason. Either 4 or 6 bolts were installed around the premiter of the tube to hold the joint together. No holes were through the tube only in the machined joints. The joints were then welded to the tubes. One joint was threaded for the bolts while the other was a close tolerance hole. The resulting joint was VERY strong.
If this has not been clear and if you'd like for me to make up a drawing I would be happy to.
Have a great day.