Patrick Donnelly

01-20-2008, 06:42 PM

I posted this on the CrossFit boards, and all I got was chirping crickets. I'm hoping someone here has experience with this sort of stuff. I'm just brainstorming at the moment, and could use some commentary from anyone with the know-how.

Requirements:

- must be able to support 4 people, kipping

- must be able to be disassembled (for storage when I go to college)

- must remain firm on the ground while in use, without being bolted down or buried in

- must be suitable for outdoor use

Plan A:

A square apparatus, built using 1" pipe. Each corner will have a 60# concrete base, in the shape of a tapering cylinder (approx. 11" diameter base, 9" diameter top, 11" tall). Each concrete base will have a flange screwed in it, with an 8' length of pipe coming up. All four pipe lengths would be connected with T's (or Y's if I can find them) and 5' lengths.

Issues:

- Would 4 people be able to kip without kicking each other on a 5x5' square? What if they faced outward instead of in?

- Would the bases shift around? I have a feeling they would without any additional cross supports near the ground. All they have connecting them are the pull-up bars themselves. How could the concrete bases be connected without putting something that would either get in the way of kipping, or get in the way of landing on the ground?

Plan B:

A rectangle apparatus, 4' wide by 7' long. Two people would be on each 7' long part. Once again, it would have 4 concrete bases, though there would be an additional pipe spanning the 4' sides (for a total of 2 on each side), which would provide a bit more structure. Possibly, additional pipe could be set in the concrete bases to make each of the 4' sides into a squat rack too, of a set height.

Issues:

- Is 4' a big enough space for people to not kick each other? What if they face outward?

- Is a 7' bar strong enough to support the weight of two people, with the midline of each person located ~2' away from the end of the pipe? (Remember, there will be ~5" of pipe that is directly over the concrete base, assuming the flange goes in the middle of the top of the concrete.) If the bar is not strong enough, what if it were filled with sand, and had the insides sealed off? A non-compressible fluid would disperse the pressure throughout the whole bar.

Plan C:

Same as B, but add two additional concrete bases at the midpoint of the pipe (for a total of 6 bases), which would form two 4x3.5' rectangles, joined along a 4' edge, with people kipping on the 3.5' parts.

Issues:

Price and construction time. Hahah.

General Issues:

- I was looking at pipe at Home Depot today, and the costs didn't seem too bad. However, I noticed the gray pipe (galvanized) was 50% more expensive than the black pipe. I know the galvanized is used for water utilities (whereas black is gas) because the zinc coating waterproofs it, but is there any difference in the strength? Assuming the strength is the same, or at least sufficient in both cases, how would one go about rust-proofing black pipe?

- What would be the best way to secure a flange? I know there are concrete screws, but concrete itself has a tendency to deteriorate (or have small cracks, haha) when roughly shaken by something like kipping. Could a 4x4x11" of lumber be put in the concrete while it is poured, allowing for a wooden place to screw in the flange? Another option is to use pipe. Either a 1" piece of pipe could be left protruding, and left to be attached to an upright by using a union, or a 1.25" each piece could be used, which would actually allow the 1" pipe to fit inside, sliding all the way down concrete base, and be secured there through some other means which I have not yet devised.

- The pipe diameter used for the bar will definitely be 1". A quarter inch in either direction made it feel very awkward for gripping. However, there is the possibility of using 1.5" for upright and horizontal supports, assuming there is some way to taper them to 1" for the bars, and that they don't cost way too much. With lumber, ever extra inch gets exponentially more expensive; I don't know if it's the same way with pipe. (Probably not, since lumber costs more since a larger tree must be found and cut down and found to have good wood... Pipe doesn't grow on trees.)

I think things through too much...

Requirements:

- must be able to support 4 people, kipping

- must be able to be disassembled (for storage when I go to college)

- must remain firm on the ground while in use, without being bolted down or buried in

- must be suitable for outdoor use

Plan A:

A square apparatus, built using 1" pipe. Each corner will have a 60# concrete base, in the shape of a tapering cylinder (approx. 11" diameter base, 9" diameter top, 11" tall). Each concrete base will have a flange screwed in it, with an 8' length of pipe coming up. All four pipe lengths would be connected with T's (or Y's if I can find them) and 5' lengths.

Issues:

- Would 4 people be able to kip without kicking each other on a 5x5' square? What if they faced outward instead of in?

- Would the bases shift around? I have a feeling they would without any additional cross supports near the ground. All they have connecting them are the pull-up bars themselves. How could the concrete bases be connected without putting something that would either get in the way of kipping, or get in the way of landing on the ground?

Plan B:

A rectangle apparatus, 4' wide by 7' long. Two people would be on each 7' long part. Once again, it would have 4 concrete bases, though there would be an additional pipe spanning the 4' sides (for a total of 2 on each side), which would provide a bit more structure. Possibly, additional pipe could be set in the concrete bases to make each of the 4' sides into a squat rack too, of a set height.

Issues:

- Is 4' a big enough space for people to not kick each other? What if they face outward?

- Is a 7' bar strong enough to support the weight of two people, with the midline of each person located ~2' away from the end of the pipe? (Remember, there will be ~5" of pipe that is directly over the concrete base, assuming the flange goes in the middle of the top of the concrete.) If the bar is not strong enough, what if it were filled with sand, and had the insides sealed off? A non-compressible fluid would disperse the pressure throughout the whole bar.

Plan C:

Same as B, but add two additional concrete bases at the midpoint of the pipe (for a total of 6 bases), which would form two 4x3.5' rectangles, joined along a 4' edge, with people kipping on the 3.5' parts.

Issues:

Price and construction time. Hahah.

General Issues:

- I was looking at pipe at Home Depot today, and the costs didn't seem too bad. However, I noticed the gray pipe (galvanized) was 50% more expensive than the black pipe. I know the galvanized is used for water utilities (whereas black is gas) because the zinc coating waterproofs it, but is there any difference in the strength? Assuming the strength is the same, or at least sufficient in both cases, how would one go about rust-proofing black pipe?

- What would be the best way to secure a flange? I know there are concrete screws, but concrete itself has a tendency to deteriorate (or have small cracks, haha) when roughly shaken by something like kipping. Could a 4x4x11" of lumber be put in the concrete while it is poured, allowing for a wooden place to screw in the flange? Another option is to use pipe. Either a 1" piece of pipe could be left protruding, and left to be attached to an upright by using a union, or a 1.25" each piece could be used, which would actually allow the 1" pipe to fit inside, sliding all the way down concrete base, and be secured there through some other means which I have not yet devised.

- The pipe diameter used for the bar will definitely be 1". A quarter inch in either direction made it feel very awkward for gripping. However, there is the possibility of using 1.5" for upright and horizontal supports, assuming there is some way to taper them to 1" for the bars, and that they don't cost way too much. With lumber, ever extra inch gets exponentially more expensive; I don't know if it's the same way with pipe. (Probably not, since lumber costs more since a larger tree must be found and cut down and found to have good wood... Pipe doesn't grow on trees.)

I think things through too much...