Cam Grinder

[dynosor]

Originally Posted by bluejets The proof is in the pudding as they say and with my engine running to 10,000 in the wink of an eye I'd say the cam design is quiet sufficient thankyou. If you want to run around with calculators and the like, all the best to you. Just one request, show us some of your achievements in 3D.

No arguments here - it is what works that counts, not theory. However, if I dream up a profile that causes a calculated 10,000 G acceleration it is probably not going to work for very long, if at all.

How did you determine your cam profile?

I have not made any cams yet - still trying to figure out how I could do it.

The only thing I can show is a practise straight 6 cylinder crank machined from solid - I figured that is the most difficult significant component to make, with the cam shaft at a similar degree of difficulty.


http://www.bimmerfest.com/forums/att...1&d=1194461147

I am busy setting up to make a second crank with larger journals to be closer to scale.

[NC Cams]

The requirements needed to go from a turning to a finished cam, especially a full sized automotive cam are NOT inconsequential.

As mass goes up, forces and dynamics become MUCH more substantial. Basically, what you can get away with on a model engine can/will result in havoc and broken parts when one attempts to "scale things up" from model to "real car" levels.

Another real tough thing to deal with in "real" engines is material compatibilities. Cams and lifters are NOT no brainer parts - simply making them "hard" doesn't alays work due to the wear and load phenomenon that they encounter. There is a lot of science involved in selecting and prepping the parts properly.

As far as grinding, spec'ing mat'ls and/or heat treating, we do offer that service on a boutique basis to/for our clients. These are NOT necessarily a DIY viable process - especially, the H/T and material spec'ing part of the process..

[dynosor]

Originally Posted by NC Cams The requirements needed to go from a turning to a finished cam, especially a full sized automotive cam are NOT inconsequential....

Thanks NC, I have gained significant insight by reading all your informative posts on the subject. Each one of us wants to produce the best cam/engine we can with the tools and expertise at hand. Most of us have a lot to learn and will probably never produce a commercial quality valve train. Fortunately, this lack of ability is of lesser consequence than for someone who wants to set themselves up producing cams for sale to others.

This is a hobby forum and while I appreciate being told what are the correct methods, designs and materials, I think protecting others from trying anything that would not be commercially viable on a hobby engine is not your responsibility.

That said; I recognize that I seem unable to follow my own advice – most of my post to CNC Zone involve trying to persuade others to see things “correctly” with regard to global warming. In the GW context I mostly just want everyone to think for themselves so that they actively develop their own opinion based on facts and logic and don’t just adopt that of anyone who speaks charismatically or with authority.

For instance:

http://www.cnczone.com/forums/showthread.php?t=45545


http://www.cnczone.com/forums/showthread.php?t=42162

[NC Cams]

The charming thing about designing cams is that they are locically responding devices that pretty much DO follow the F=MA axioms. It is not a question if you can/will follow the "rules" but whether or not you don't violate or sodomize them entirely.

Regardless of the engine, smooth valve operation is the goal. Yes, you can pound things open and close but that breaks parts, wastes power and ultimately time and effort. So, why bother???

Learning how to do/make things traditional and technically PROPER ways is akin to crawling before, walking and walking before running. I didn't even think of doing a race cam until I found that I could duplicate a known production cam from scratch. When I know how to duplicate it, I knew the vagaries and WHY the design programs did what they did and how you could bend/mold the cam curves into the shapes you ultimately wanted/needed.

The "beauty" of a well designed cam is in the smoothness of motion. The lack of jerk. I show guys cams running on the cam grinder. Essentially, you can literally feel the motion that the cam will apply to the valvetrain when it moves the rocking table on our Berco. As well it should as the same force signature is being generated by the cam in/to the engine.

For grins, I show guys two cams - a stocker and a "violent" race cam. Amazingly, engineers who should know better typically guess them WRONG. In my example, the race cam is actually LESS violent than the stocker. Part of it is due to design philosophy, some due to simple duration and lift.

Yet, the guys often wonder, "How the hell does he get such violent valve action to be so smooth????" Lots of time and effort spent studying the math and practice in designing things via the computer. WHen you figure it out and understand the mess, you can literally LOOK at the graph of the profile'd dynamics and tell if it will work or not.

But when you know WHY this is the case, you can do a better job of designing and making either hard core race or banal stock stuff. Spend the time to learn the basics and how to do things as properly as you can and with as much verve and character as you can muster. Learning the basics enables you to find even more exotic solutions because you know more about where and HOW to look.

OVerlook the details and you're missing out on some really neat stuff - trust me, its there if you take the time to look and find it....

[bluejets]

Thanks mcgyver.. V8 is still in construction ..... it is the 4 cylinder that cranks out the tune.... sweet as .....

NC ..... try it with 25cc's ........

[bluejets]

Mcgyver ..... 4 pot is over here ......
http://www.cnczone.com/forums/showthread.php?t=35241 ...... take a peek...... presently being shown at engineering conv. in Capital ...... also fitting it to a Rivierra 1020mm timber hull (home grown)

[NC Cams]

Re: 25cc vs 2500 cc

It really doesn't matter - ALL engines have to follow the same laws of physics and thermodynamics.

We went thru the same sort of "hobby vs real car" arguement with R/C cars. The R/C guys contended that my "big car" ideas wouldn't work with the hobby cars. They continued to do that as I was trouncing them with under powered/superiour handling cars.

The point is, the engineering works - regardless of the scale. It is purely up to the user to develop and recognize the proper corelation coefficients however.

[bluejets]

NC ..... I say again ...... try it with 25cc's ... and then show us your 3D.

[NC Cams]

I"ve already done everything from a 5hp B&S cam to a Cosworth DFX to priceless 20XX advanced model year prototypes - all day, for a living, not merely a hobby.

We even do injector cams for 6000 rpm 3000hp diesel pulling tractors - try generating .472" of lift in only 70 deg followed by a 90 deg turn and NOT tearing the hell out of follower and/or cam lobe. Compared to the dynamics of this bruiser, the challenge of a 10K 25cc engine should NOT prove that substantial. After all, we already did 10K rpm cams with PUSHROD 5700cc V-8's.

As a result, I don't see a need to "practice" doing 3D on toys. Give me a break.....

[Kevin Taylor]

NC as a realworld shop owner and having twentyfive plus years of nearly 24/7 trying to make happen what the customer think's is possible with there engine it's all in what you have to work with and it's all castiron or aluminum ect. the differance is the size of the debris field when it fail's You have a great understanding of the way it realy need's to happen because you have to make it happen to make payrol payment's and deadlines ect somthing our customers and the average hobbiest don't have to contend with on a daily bassis Well enough I always enjoy your post's even on unrelated sub. I have a crankshaft to atend to in my 270 Berco so I can eat this weekend Thank's Kevin