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javaguy
Oct 3, 2003, 5:43 PM
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I'am studying machine engineering I'am playing with the idea to make my own cam. I guess a forged steam like WC forged friends would be the easiest way to do it.
Have anyone here tried to make their own cams?
Have they worked?
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lifeguard4
Oct 3, 2003, 5:46 PM
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Sound like a good idea if you have the right equipment to make them strong enough.
Sorry no experinece in making my own cams. I have to shell out the big bucks for them.
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thinksinpictures
Oct 3, 2003, 5:49 PM
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In reply to: Have anyone here tried to make their own cams? Have they worked?
Presumably if someone tried to make their own and was still able to respond to your post, their homemade version worked :wink:
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petzl510
Oct 3, 2003, 5:50 PM
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That doesn't sound like it is to safe :shock:
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vegastradguy
Oct 3, 2003, 5:51 PM
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talk to Tom (apollodorus)...he makes the Valley Giants (9" & 12" cams made specially for the giant offwidths in the valley)
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stick233
Oct 3, 2003, 5:54 PM
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yeah, those babies are huge... and handmade!
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redpoint73
Oct 3, 2003, 6:00 PM
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In reply to: That doesn't sound like it is to safe
Didn't Ray Jardine machine his own Friends when he first invented them?
If he has the right equipment to machine them, and the right knowledge to engineer them, I don't see why it would be inherently unsafe. Of course, a way to strength test them would be good.
Its not rocket science. Hell, rocket science isn't even as complex as most people think.
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javaguy
Oct 3, 2003, 6:02 PM
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wow...huge monster cams :D
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noshoesnoshirt
Oct 3, 2003, 6:46 PM
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super easy to make your own. do you have access to a CNC machine?
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just_me
Oct 3, 2003, 7:39 PM
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The guys who started Splitter Cam were engineering students at the University of Colorado. I believe that their idea to make cams came from a senior design project.
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traddad
Oct 3, 2003, 7:39 PM
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Back in the early eighties I owned a couple of machine shop made friends I got fron a guy in Ft. Collins. Bombproof and every bit as nice as Jardine's. If you've got the experience, mills, materials and intuitive ability, I don't see the problem.
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euroford
Oct 3, 2003, 7:59 PM
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i think aliens also started out as handmade/homebrews.
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the_pirate
Oct 3, 2003, 8:25 PM
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In reply to: i think aliens also started out as handmade/homebrews.
Back before they were sold in REI and were called Alien Sex Toys.
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rockvoyager
Oct 6, 2003, 4:18 AM
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In reply to: i think aliens also started out as handmade/homebrews.
They still look home-made to me, like some kid making them in their high school metal class.....which was OK when they were cheap.
Brad
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apollodorus
Oct 6, 2003, 7:13 AM
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Making your own cams isn't rocket science. It's more like materials science. If you essentially copy the forged Friends, in terms of thickness of the cams and the stem, you'll be fine. Commercially available, and very common, 6061-T6 aluminum is the most widely used material for cams. The more exotic, and slightly stronger, 7071 isn't going to make much difference unless you're trying to optimize the cam to get the highest strength to weight ratio.
The axle is the weak point for most cams. Almost all the companies out there use a cro-moly axle, either 5/16" for single axles, or 1/4" for the BDs. I use 3/8" stainless steel for the Valley Giant axles, which is a bit heavy. The cold-worked stainless bolts I use have a yield strength of about 80 kpsi; I'm guessing that the cro-moly stuff that WC and BD use is more like 120 kpsi. You can use grade 8 bolts, which are at least that strong. Tighten the nut down fairly tight on the bolt, and cut the rest of the threads off with a thin grinding wheel or cut-off wheel. Back the nut off, and carefully clean the burrs off the end. After finally assembling the cam and tightening the nut, you can peen/mushroom the end to lock the nut in place.
The shape of the cams is critical. You MUST use an exponential spiral, and not some other shape. I posted a short article here on RC about cams that describes the mathematical shape, and how it's derived. Basically, the angle between the tangent at any point on the curve and the radius from the axle is a constant, about 76 degrees (14 degree "camming angle"). WC makes a big deal about using 13.75, but I think that's because it winds up being a round number in radians, like 0.2 radians.
CNC is definitely going to be the most accurate way to cut the cam curves. It's also going to be the most time-consuming. If you're going to make a whole rack, that might be the way to do it. If you don't have access to a CNC mill, it will cost you $$$ for someone to turn an AutoCAD drawing into the pieces.
Unless you are going to make really small cams, the accuracy of the shape is not going to be a big factor. For example, if you make a #4 Friend, and the curves are only accurate to within 1/32", you won't lose much strength. More important is that there be no flat spots. I bandsaw my cams to rough them out, then grind them to final shape with a disk sander. I use a special jig for consistency (to within about 0.005-0.008 inch), but you can get them to within 1/64 inch or better by hand. You can draw up the shape on a CAD system, and print out a full-size template; glue it to the material with something like urethane varnish, and then grind down to the line. Do a good job on that first cam, and then use it as a template to scribe lines for the other three.
You'll probably have to wind your own springs. You'll need both a right and a left-handed spring. You can find 3-foot pieces of piano wire at most hobby stores; 0.039"-0.045" is about right. www.mcmaster.com sells spring wire, including stainless, in various sizes if you want a whole coil of the stuff. Watch out for the spring snapping back as you wind it; you won't be able to move your hand out of the way fast enough.
Except for the novelty and fun of making your own cams, you can probably get the worst-paying job in the world and make enough money to just buy them. The first one or few that you make are going to take you a LONG time. The only reason I did it was because I wanted huge pieces so that nobody would have to do the Hollow Flake without pro. As a bonus, it got me off the couch and back up onto the walls.
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javaguy
Oct 6, 2003, 7:51 AM
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Thanks for all the replays :)
I am pretty sure I want to try this out. But maybe I'll wait until I have completed a few more courses like the advanced DAK course and the course about materials :) I'll post some pictures and tell you how it went when I have made one
PS: DAK is norwegian for CAD
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norushnomore
Oct 6, 2003, 8:28 AM
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How about making your Valley Giants out of titanium?
That would make them way lighter (stronger too?).
Somebody mentioned titanium friends but I could not find anybody selling them
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apollodorus
Oct 6, 2003, 9:28 AM
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Yeah, I remember when Steve had a titanium #5 cam, way back when the only cams were Friends, and the largest cam was a #4.
Yep, that titanium #5 was his secret weapon. I was lucky just to touch it.
He let me take it with me for a whole night, so I could study it. Back then, I always had the HP-15c with me, so's I'd be smart. I also had a calculus book in the back of the Squareback, and found the page that figured out how to dee-fine a curve with a constant tangent angle, and then solve for the ee-to-the-theta 'quation. Polar equation. Not that x-y stuff.
Foun' out later that titanium alloy is not something you'd want to machine. Or buy. And the weight savings would be near to nothing. Sure, you could optimize and 'speriment and get rid of a few grams, but it'd cost so much money, only Bridwell goin' Karakoram could afford it.
To get the weight down, the secret is to get rid of the steel. Aluminum has a specific gravity weight factor of about 2.5. Titanium is heavier, and to a higher degree as its stiffness, when sideways-a collapsing of the big cams is a factor. Steel is about 7.5 times as heavy as water, or about 6 times heavier than kevlar rope. So, the key is to get rid of the steel and use kevlar. Once you get rid of the steel, then you start thinkin' 'bout using titanium instead of aluminum.
Hopefully by then, some dumb folks be funding you right up, and you can afford the material and the tungsten carbide tools to cut it. Otherwise, you just use dumb ol' aluminum for the parts that need thickness to avoid lateral buckling, and try to save the weight where you can.
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wlderdude
Oct 7, 2003, 12:36 AM
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Yeah,
Unless you have some crazzy new idea that is not yet avalible in commercial cammong units, you will not come out ahead making your own cams.
-Stong
-Light
-Cheap
You will not likely be able to do more than one of these, two if you are lucky. If you can do all three, let me know what you did!
I have made a bunch of my own gear and almost all of it sits in the closet. I wish I had not wasted my money on it, but invested in the welld esigned gear from reputable companies.
The two things taht are really good I have made are a custom rope bag/back pack and a retrofit with an incredibly cool Luxeon Star LED in a BD headlamp.
So, if you want to make your own cams, make them somehow better in design than what you can buy. Otherwise, make a really cool headlamp that runs a Luseon Star LED.
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wishiwasamonkey
Oct 28, 2008, 1:55 AM
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I just finished making my own 11" cam and am fine tuning the spring action. I was wondering if anyone has experimented with different spring configurations (anything other than torsional) for bigger cams? such as extension springs or compression springs like in the c3s
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carbonrx8
Oct 28, 2008, 2:59 AM
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EDITED TO ADD: IF this is sincere, post up some pics. Also some diagrams would be nice as well. Just curious.,
(This post was edited by carbonrx8 on Oct 28, 2008, 3:00 AM)
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patto
Oct 28, 2008, 12:18 PM
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These guys made a kinda large forge friend for chimney cracks. It works really well but it is a little on the heavy side.
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adatesman
Oct 28, 2008, 1:41 PM
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