Constructing a Variable width Crack

Hey everyone,

So I think I’m ready to pull the trigger on my longtime goal of building a crack machine to make up for the fact that I live in flatlandia and can’t make regular enough trips to the nearest solid cracks to progress as I’d like.  After doing some research, I’m thinking a vertical, fixed, variable width machine would be the best for my needs.  As cool as adjustable cracks look in theory, I’m not terribly handy, and have enough space to eventually put up a few different cracks to hit the different sizes.  I’m looking to follow something like this:
https://rockandice.com/climbing-news/crack-fix-how-to-build-a-home-crack-training-system/

My first project will most likely be a hand crack, as this seems the obvious first choice for training purposes.  I’m thinking of starting wide to be able to get situated and then narrowing to sustained #1 to 0.75 thin hands, which is a weakness I’d like to work.  

Am I right to assume that once I narrow the crack I shouldn’t worry about trying to widen it again?  It seems like this would be complicated, and I’ll only have about 10-12’ to work with.  However, it also means I have to be intentional about providing enough space to get adequate practice in different sizes.  
Also, do you cut the main boards into smaller pieces to adjust the width, or do the spacers accomplish this alone by bending the wood?  I was a bit confused by this in the directions.  
Finally, I’m on the fence about adding texture.  Is it worth it, in your opinion?  Would appreciate anyone’s thoughts who have been through this.

Hi Ted, Before there were gyms, a couple of my friends had wooden crack machines in their backyards.  All I can say is these wood plank machines with no texture were extremely painful to climb.  Now I climb at a gym with parallel sided cracks and artificial texture and even these are pretty painful to climb, but they are much better.  Both of these were a great workout, because you are working crack muscles, but with the plain wood ones, I actually felt like I was getting some tissure/nerve damage when I used them too much.  The best artificial cracks I've climbed were at the Planet Granite gyms, where there was texture and variation in the width.
Good luck with your project.

Hmm good to know.  I was thinking texture would add to the pain/damage, but I guess there’s a trade off between friction and...whatever it would take to stay inside a wooden crack.

all-thread rod with wing nuts and sufficient washer stacks.....along with wood spacers to size your crack

i have a 16ft tall vertical hand crack its 2x6's 1.5" apart nailed to a plywood wall in my shop the top 6ft has about a 10deg angle out and is secured to the ceiling, but i used that gritty deck paint sold at lowes or HD, the 1st few climbs where painfull but it took the profile off the grit and it was nice.  i didnt go elaborate with it since i didnt know what i wanted but it was quick and easy to put up a couple 2x6's to atleast get some hand action. 

Do you mean the top 6’ overhangs?  How did you make that section different from the rest if it’s just two long boards?

Has anybody tried mixing sand with paint and slapping that on the wood crack? Don’t mean to get sidetracked but I feel like the texture may help with the pain aspect of the wood

Ted Pinson wrote: Do you mean the top 6’ overhangs?  How did you make that section different from the rest if it’s just two long boards?

I am also curious about the joint. Seems like keeping the inside of the crack flush where the two cuts meet could be a bit tricky

Ted Pinson wrote: Do you mean the top 6’ overhangs?  How did you make that section different from the rest if it’s just two long boards?

i used 10ft  boards for the lower part these are vertical and screwed directly into a plywood wall, then from the top of those boards i angled out to secure them to the ceiling, if that makes sense. i wasn't focused on doing over hanging cracks when i put it together i wanted to get the basics 

Ted, have you considered going a little simpler and just ganging together a bunch of cracks instead of making one vary? A la https://i2.wp.com/www.aspiringalpinist.com/wp-content/uploads/2016/05/All-the-Cracks-1.jpg , but vertical for your uses.

Jeff Luton wrote: Has anybody tried mixing sand with paint and slapping that on the wood crack? Don’t mean to get sidetracked but I feel like the texture may help with the pain aspect of the wood

This is not a good idea. It tends to make your crack absolutely miserable. Bare wood is actually nicer, or just a coating of paint.

Tim Stich wrote:

This is not a good idea. It tends to make your crack absolutely miserable. Bare wood is actually nicer, or just a coating of paint.

Thanks Tim 

Have you seen this thing?
https://www.climbing.com/videos/the-crack-generator-3000/
Not sure my skills are up to that, but it makes me think if I attempt this (not adjustable) for myself I'll use plywood for stiffness like these guys do. I've had trouble with boards flexing, makes you have to jam extra hard to hold it. 

true psychonaut wrote: I'm going to epoxy peices of flagstone to the inside of mine. The machine will be 16' tall with fully adjustable pitch, width, and angle of crack. Will have pics beginning of next year.

This sounds awesome, and heavy.  Looking fwd to some pics!!

I've built two crack machines and both kind of sucked. Here are some of my findings:

-You need to either brace your beams or put spacers every few feet. I built one out of 2x12s that had spacers every 6 feet and the wood was too flexable so it was hard to jam.
-2x6s are a little narrow for hand jams. I would go for 2x10s so that you have a good amount of depth in the crack.
-If you go to home depot and get the shittiest wood in the pile you can ask the cashier for a discount. They are authorized to give you up to 70% off (usually they give you like 30-50% though).
-Use torx head screws. They are way easier than phillips

I've built a shorter variable width crack in my garage.  One half of the crack (2x12) was "fixed" as in it was screwed to the frame of my climbing wall.  The other half was the variable side. I used ~12" long fully threaded rods w/ washers and nuts to "bolt" the variable side to the fixed side.  To change the width of the crack I have to adjust all of the nuts so that the variable side is a bit closer.  It doesn't bend the wood so I can adjust it just about the full length of the rods.  I had to use a decent amount of rods, maybe one every 12" of crack length.  With a 2x12 you can put the rods in the back so it doesn't bother you much but every 3' one needs to be near the lip of the crack to prevent the crack from flaring when jamming.

Texturing seems to be pick your poison.  You either have to over texture it (sand in the paint, skate board tape, etc.) or under texture it (bare wood).  Over texturing can be really abrasive and can create painful pressure points.  Bare wood is IMO a lot less painful but its slicker requiring you to jam much harder to gain similar purchase to an outside crack.

+1 to Andrew Child's best practices.

Jeff Luton wrote: Has anybody tried mixing sand with paint and slapping that on the wood crack? Don’t mean to get sidetracked but I feel like the texture may help with the pain aspect of the wood

I read that mixing "play sand" with elmer's glue makes for good texturing, but have not tried it personally

I used play sand with latex paint and it worked very well.  Reminds me of gym walls...a little painful for the feet but hands are fine with tape.  I ended up using 3 boards to make two cracks, one as described in the OP and the other an offwidth monster.  Putting headboards on each end helped a lot and made it easy to mount...just drilled a few screws into the floor through the bottom board and one at the top through a joist.  Hasn’t fallen yet!