This tri at my school I chose to take manufacturing with metals as my elective. We pretty much have free reign over what we get to build, so I decided to build a cam (won't actually use it of course). Yesterday I ordered the Aluminum (6061) and a took apart a gear4rocks cam (scarily easy) to salvage the axel and springs. When the aluminum arrives I will start building and keep this post updated with pics, etc. If all goes well, I hope to end up with a rigid stem cam with a range slightly smaller than a number 2 camalot.

Stay tuned
KBH

Do you have access to a Lathe and/or a 4-axis CNC machine? I am a BSME / MS Metallurgy, I don't see any reason you can't build a cam I would climb on. What type of mechanical test equipment do you have access to, an Instron or MTS?

I can see scavenging the springs, but why the axle?

Yup.
Rigid stem with no welds or swages to fail and you'll be good to go.
Pad the dimensions found on store-bought models and you can put a little faith in it.
I think it was Aric Datesman that gave me the idea of testing it using a 'circuit-breaker' technique where you could use accessory cord with a known strength and pull until that breaks. That way you can give it a limited stress test without destroying it. (1 strand of 5mm cord with clove hitches at each end will break somewhere around 4-5kN. Not precise at all, but it can give you a warm fuzzy feeling about your handiwork.)

Sounds fun... think big. Go for a 36 inch span if you can..protect those nasty chimney moves.

We climbed the wide pitch on Blocktop with home-made cams, thanks to Greg D. Greg is a master and machined two #8 cams in 1983. I stacked them with wood blocks on pitch four. The pitch goes free now but we never would have nailed the FA without Greg’s cams. To shape the cams (lobes) Greg simply drew rays from the axle and then extended the rays beyond the #4 Friend's lobes until he thought he had the dimension we needed. He did well.


www.mountainproject.com/v/block-top/106151030

A 16yr old kid building a cam.

There IS, hope!

LOL!



EDITED:

or 18yr now? Same deal though. Still COOL!

Hey everyone, thanks for the replies! Pretty psyched to get working on this.

Bill- as far as I know, i don't have any testing equipment at my disposal, to test it I will probably go with the circuit breaker method described by Gregger man.

Nathan- I was originally going to build an axel, but I used the gear4rocks lobes as a template for designing my lobes, so I figured having an axel already built for something like them would be easier.

Woodchuck- if only I had enough aluminum. I am considering making a set of novelty lobes maybe in the BD #6 range if I have enough time and metal left over.

Locker- thanks, still 16.

Good luck Kevin.

A bit late to suggest it, but Rock Empire cams come apart just as easily and are a bit nicer than Gear4Rocks. In either case be aware you're looking at metric holes for the axles (100% certain on RE, suspect it on the G4R), so pick your drill accordingly. A bit of clearance between the lobe and axle is needed, but not much (think 0.003" at most).

I should have a copy of the article I wrote ages ago on building a cam with nothing more than a hacksaw, drill and file, tucked away somewhere and if I can find it will post a link (was on RC but removed when I left the site). IIRC it was #3 size, cost ~$30 to build and the sample broke at 19 or 20kN. Took me a couple hours start to finish to build.

UPDATE:

Metal arrived yesterday, brought it to school today and began working on it. Got the stem cut out and a hole for a sling drilled. The other marks on the stem are where I plan for the trigger to go and the Axel. Haven't finalized the marks, just a rough guide right now.

Start of Cam Submitted By: Kevin Brooks Henry on Apr 3, 2012

looks big from that view...dimensions please?

sorry, forgot. dimensions right now are 5.5 inches long by 3/8 inches thick by 1/2 inches tall. Will probably change a bit though after sanding.

are you wearing climbing shoes in metal shop? haha

UPDATE:

Finally got back to work today after having to spend all of yesterday finding parts for the milling machine that hasn't been turned on in 2 years. Got the trigger hole machined out and also got a hole for the axel drilled. Also had enough time left to add the axel, which fits in the hole without sliding around. Machining the trigger hole took off a little more metal on either side than I would have liked, but since I don't really plan on using it and don't want to go to the trouble of machining another stem I think it is fine.

side view of stem with trigger hole cut out Submitted By: Kevin Brooks Henry on Apr 5, 2012

Top view of stem with axel Submitted By: Kevin Brooks Henry on Apr 5, 2012

Nice work bro! Keep the updates going! I'm excited to see how your cam turns out!

this is awesome!

how thick is the remaining aluminum around the trigger slot?

Cool project!

Came across this 2009 link to Trango's homemade cam comp. Maybe they should resurrect a 2012 version.

I bet if you wrote to BD QC Labs they'd test if for you.

Just FYI, Kevin- when slotting on the mill you're best off first using a smaller size endmill to get the bulk of the material out and then finishing with the final size endmill or (better yet) keep using the smaller endmill and offset the work to either side to achieve finish size. Less force on the cutter this way and you'll hold better tolerances. Oh, and there's no need to slot full depth in one pass...

Looks like you are making some good progress.

UPDATE

Cut part of the plate today and began milling it to the correct thickness. Was able to Finish that and cut the plate into three parts to begin making lobes. The fourth part was messed up a bit by a loose milling bit, so I experimented with it and the band saw to see how well cutting the lobes would work. It turned out fairly nice and I might finish it to make a keychain ring or something....

Messed up section that I practiced cutting lobes on. Submitted By: Kevin Brooks Henry on Apr 6, 2012

Finished milled plate with lobe for sizing Submitted By: Kevin Brooks Henry on Apr 6, 2012

Side view of milled plate Submitted By: Kevin Brooks Henry on Apr 6, 2012

Love the can of TapMagic in the background. That said, kerosene or WD40 works better as a cutting lubricant for 6061 aluminum unless you pony up for the special "aluminum" TapMagic.

I've gone through pretty much all of my archives and it looks like I no longer have a copy of the article I wrote for RC on making a cam with nothing more than a hacksaw, drill and a file (see post above). IIRC the drawings I provided was for a cam that was ~#3 C4 sized, cost $35 in materials and failed at 22kN, but damned if I can find a copy of it. The SolidWorks models I used for the graphics are likely still floating around somewhere, but probably wouldn't do you much good.

Very cool. I have zero metal working experience but am intrigued by your project. Cant wait to see how it come out. Looks like you have lots of sage advice around MP.

Keep up the good work it's looking good.

That Cam Building Comp was so much fun (I made the big WebCam), I was pissed when it didn't go the next year but what can you do.