Camshaft design

[MrWild]

Re: grinding zirconia oxide - While I can not speak from experience with regard to grinding zirconia, I can speak with a degree of expertise with regard to grinding hard face materials (chromiun-nickle-boride aka "stellite") as well as some special high alloy tool steels that have nickel, cobalt and/or other very hard alloys.

Holy CRAP! You're making cams out of D2? The most miserable stuff I have ever worked with. I can see the material lasting through a lot of serious high rpm abuse. Just grinding it is a major PITA though. What do you use, borazon, or diamond wheels?

[NC Cams]

We've never made cams out of D2 but we have made them from M2, CPM42 (all at Hrc 60 to 64), the "cast carbide plus graphite laced" Proferal, chilled iron plus the major PITA H/F welded 8620 and 5160 and flame hardened 4150. There are were others but I can't recall them all or, perhaps can't adimit to anything specific. The H/F was welded with Wahl-Colemanoy 5, 6 or 56 "stellite" material - as difficult at this was, it was not our most challenging effort - we had some 8620 carb and hardened to 63+ that really gave us fits as strange as that may seem.

Essentially, each cam alloy needs/wants its own specifice abrasive to both cut/shape the part. Then, perhaps a different one is needed to finish grind the part. Due to the size of our machine, we are not blessed with the ability to grind with CBN. However, we've used ceramic, silicon carbide, aluminum oxide, plus various "blends" of abrasives not the least of which was a "plastic bond" on one particular situation.

Understandably, we don't/can't talk specifics, especially in the rare instance when we discuss grinding processes. I can say, however that we had the grinding engineer from one abrasive company for a problem - he walked in with this "I'll show them" attitude - he walked out with tail between legs. He admitted that he'd never, ever seen the problem we were having at the time and he'd been in the industry for quite some time. Although he didn't have a clue for a solution, we still had to complete the job.

Half dozen calls later and we had wheels offered by a COMPETITOR for trial - he bought wheels from a totally different abrasive company. They worked unbelieveably well. Imagine, a competitor helping out a competitor??? Needless to say, I still buy my wheels from him to this day and I always pay his bills the day they hit my desk.

Semi-related story: I went to have a root canal and the dentist started boring the tooth and was doing so as if he were trying to break concrete. I forced him to stop as it was EXTREMELY uncomfortable. WHen I gained some composure, I asked him "who the hell taught you how to drill tooth enamel?"

He arrogantlychallenged how/why I should know more about drilling teeth than he did (I suspect he was from U of M). To which I responded, "I grind harder, tougher materials than you do each and every day. Moreover, I KNOW that the procedure you're using for grinding tooth enamel must be bogus - anytime the bit chatters like yours is and then has to be jammed into the part in order to remove/cut material, you're doing it WRONG - try doing it like this..." and I then went on to explain him how we cut materials that are far more difficult to cut/grind than tooth enamel.

Imagine his surprise and my immense relief when the drill cut faster and with NO chatter almost immediately when using the suggested method. What had been a miserable, beyond white knucle experience became at least tolerable.

Life is full of shared experiences - some good and some bad. It seems like a waste to have to learn new ones from scratch - it is always good to use prior knowledge whenever one can.

Although I won't/can't share all of my "secrets" at this time due to the pressures of competition, I do plan on retiring one/some day. Perhaps someone will come along before then and want to buy/carry on the business that I/we do.

At that point, I'll make provisions for my successors to be left with all the knowledge that I can ever hope to share. Think how much more they'll be able to do and how much better they'll be if they don't have to rediscover all over what I already learned.

Besides, for some reason, I don't think there is going to be much need for racing cams in the hereafter. If there is, surely, there's enough technology available to assimilate better capabilities than I have now.

[LongRat]

I work in the dental industry myself at the moment. For a company making machines for grinding custom dental restorative parts out of hard ceramics. I know what you mean about the 'I know best' attitude in that industry. Unfortunately dentists are rarely if ever given any training into the mechanics of proper grinding. It is more a case of 'hit it as hard as you can so they are out of the chair sooner'. Unfortunately as you experienced this is often a slower and more painful method. The physical trauma often leads to complete death of that tooth too.

[NC Cams]

The machine tool industry has spent FORTUNES both in developing and/or creating new ways to remove metal.

They used to use grunt/hog metthods to bury tools running at slower speeds into metal. Then, they found that higher speed spindles, with proper cutting tools and plenty of coolant, cut better and faster. Amazingly, the reality of obvious "technology transfer" has not filtered down to medical schools, and especially the makers of the dental equipment.

I can still recall the days of the belt drive dental drills - my childhood dentist had that type. ANd it was no wonder people did NOT get their teeth worked on with those "weapons". When I moved to Cleveland, the dentists there had the new "high speed" pneumatics and when I moved again, the ones in Ann Arbor had the newest ones with thru the drill fed coolant.

Frankly the ones in Ann Arbor also had the latest, high speed, high stock removal drills but they were using the old, bury the bit and grind/hog it out and WRONG drilling methods.

The sad and amazing part about the fiasco was this: when the "doctor" (pound and grind hack was a more appropriate description) used a more appropriate procedure (light, steady infeed with resultant smooth, cool cutting), the drill actually cut faster and cleaner and with less discomfort than his brute force method. Not only did he take less time but he also didn't fry/clog the bit which he did right away with his "old" method.

Sadly, it must be true what they say about some doctors - they PRACTICE medicine as opposed to performing and/or perfecting it.....

[LongRat]

Absolutely.
There are now 450,000 RPM dental drills on the market and many are plowing them into material slowing them right down to sub 50k. They are designed to operate at high speed for a reason - it cuts right that way.

[M-man]

Nc-cam - What is the max velocity per degree that would work on an average engine with 4 valves/cyl Max engine rmp approx 5700.. I ve got 0.18mm at some points on the profile, is this high or low would you say?

[skippy]

Hey Justlesh, when you said "Don't count me in on poking at NC Cams. I totally respect his accomplishments and believe he has every right to boast". Hopefully that wasn't intended for me because if you re-read what I posted you'll see that I didn't "poke at him" as you called it.
Hey Fred, speaking of dentists, I was getting my front teeth crowned some years back and first they grind the tooth base down so that it resembles a post to attach the crown to. They then trial fit the crown using two steps. First is to fit the crown using a filler to take up the gap between the post and the crown then the crown gets removed, cleaned and primed and finally a permenant glue is applied to hold the crown in place. Well that's all very well but at the filler stage the dentist got a phone call and the filler glued itself to the post (my tooth) so when she came back she had to remove it with the dental equivalent of a slide hammer. Now you and I both know that if you have a slide hammer with only one finger on the end you have to hammer one side then the other or else all the tension goes to one side. Unlike you, I didn't stop her and sure enough she snapped off the post part of my tooth.....

[NC Cams]

First a minor correction - my name isn't Fred.... On this M/B, NC Cams works as an adequate monicker.

Regarding peak velocity: Peak velocity it NOT a absolutely MAGNITUDE limited. The peak velocity is determined by:

1. Tappet diameter (flat follower)
2. Base circle radius (small BCR's allow LOWER peak velocities before the profile goes inverse - the larger the BCR makes for larger velocity before the profile goes inverse)
3. Follower type, IE Flat or bucket tappets (even with a spherical radius'd foot) MUST NOT GO INVERSE and with a radius'd roller follower, you also have manufacturing issues which limit any allowabe inverstity than can be tolerated and/or made by a grinding wheel.

The value cited of 0.18mm/deg (0.00708"/deg) is somewhat low for a large OD follower and too large for a small diameter follower. As stated earlier, I do NOT do other people's homework problems but do show them where they can find the answers.

EDIT:

Come to think of it, I actually DID already provide a solution to this velocity problem, albeit NOT in a/the way it was desired (served up as an "answer" as opposed to a place where the knowledge/method on how to figure out the answer can be learned/derived) back as far as post #17.

END EDIT

To that end, one or more of the articles I listed in post 17 outlines how to measure/calculate the instantaneous eccentricity point for your lift or any curve. MOreover and specificaly, you'll surely find the Stoddard article from Machine Design to be MOST beneficial in this regard - some of the SAE articles are also good primers on/for the development of an understanding on this topic.

Skippy: at the point in time when the tooth broke due to the misapplication of a slide hammer , I'd have told the technician who slide hammered my mouth that the their ignorance and stupidity just cost the office a free crown job - either than or their job, take your pick....

I dare say the the or any doctor would NOT want to go to court to try to justify why you should ever have to pay a bill when someoned does something that f/ing stupid. Righteos indignation is but a prelude to what would have happened if that had been done to me.

I had a dental technician dig too hard and deep when cleaning the teeth. I told her to either be more gentle, IMMEDIATELY, or else get some one else to finish. She was MUCH more gentle then and every time thereafter when she worked on me. You are the patient and you are paying the bill. Unless you ENJOY the abuse, you DON"T have to take it!!!!

[justlesh]

I wasn't trying to say anyone was, I was just saying I wasn't, It was mentioned that they were coming at him from all sides or something like that, I'm not going to read back thru these threads to find exactly how it was referred to but felt like I was being added to the "playing a part in it". I just guess the hard core math and science and the thought of spending my life savings on equipment just to make one cam for a model engine doesn't hold my interest anymore than some would find hard core math, science and their life savings spent on equipment to make a single deep drawn part for their hobbies to hold their interest. Just hammer it out on a rock, file the edges, throw some paint on it and smile when someone comments on it. I'll keep my progressing education aimed towards my job.
To be honest I took offence to some of the comments by NC Cams if you hadn't noticed. I for one felt belittled and no man deserves that. I believe from the statements he and others have made in the past that he is very educated and knowledgeable. But I have worked with people with like traits in the past that possibly unknowingly give people the impression that they are either to lazy or just incapable of accomplishing a task with relative success. I pride myself with diligence and perfection, I'm one to set back, view the whole picture and devise a plan of attack on a project and welcome imput from people above and below me in both education and experience. I can tell you first hand how it feels to have a Toyota or Ford engineer come into my workplace, look at the process and tooling and compliment my work and designs and wasn't a bit shy of giving credit where credit is due. To be honest, I respect the man that chooses to educate him or herself for the betterment of them selfs, but also respect the man on the floor using the tools we design to build the product that came off tooling we design and maintain. Some days I go home wishing I were that person, A lot less headaches but just as rewarding in its own respect. I have a lot of accomplishments in my job past that I'm very proud of and I'm sure there is much in the future for me. I just like being told to go figure it out for yourself when there is much to be gained sharing knowledge.
To stop the rambling, and to also apoligize for any statement that might have offended anyone especially NC Cams. We come here looking for suggestions as how not to screw up too bad. I for one am not trying to reinvent the wheel let alone improve upon it. Just to duplicate it on a scale. Sure, what were asking isn't as simple as what mat'l should I make my crankshaft out of or what size bearing for this or that but it is none the less equally important. I've been to the machinerys handbook for materials to suit my needs. But would love to here it from someone who has more experience and knowledge than me that , X mat'l works with Y mat'l and you might have luck with Z mat'l, maybe to use a lifter diameter of 2X cam lift or 3X cam lift. With a ratio of lift to total lift in X amount of degrees of cam rotation. I'm sure there is some simple and effective ways of doing this knowing were not going to break records and our engines aren't going to last forever. We just don't want it to wear out or fail within minutes of its first breath of life.

[NC Cams]

I, likewise am offended by attitudes that are/were displayed against me and my skills and as I go thru life and, perhaps, I give it back when I shouldn't. How so?

To some people, a lot of skills come naturally. SOme guys play ball, run, catch and are very well coordinated - I wasn't. Did the kids who could play sports take the time to show/coach me on "how to"? No.

Did the teachers make an effort to do anything to alleviate this "unfairness"? NO. I was the nerdy/geeky/last kid chosen, if I did get to play - WHY? because I sucked at sports. So I retreated to my own devices of which mechanical things took my fancy. I was able to "see" and understand mechancal things and that directed my efforts toward a professional choice, namely engineering as a result. So, my involvement with cams sort of was predictable/inevitable.

In school, I was called "gifted". Yet, I was still picked on, made fun of and NOT supported. I had to sit, bored to tears finding ways to look/stay busy while less gifted kids got attention and a disproportinaly amount of effort and educational $$$'s spent on them. After all, I was gifted and would do OK on my own.

And when I did get into trouble ("he's always done with his work early and then is disruptive"), I was effectively punished for being "gifted". So I did things to adapt. I learned on my own, found the answers on my own, I worked for each and every technical skill that I acquired, ON MY OWN. BLAH BLAH, many years later, I eventually came to being able to design and grind cams, again, on my own.

Am I supposed to take the skills, secrets and techniques of my PROFESSION, not hobby, not past time, not toys, MY PROFESSION and lay then out on a message board? The day Bill Gates makes his source codes public I'll do just that but that is not not going to happen any time soon, and hence neither will I.

The point is/was always this: anyone can (and I quote to get it perfectly right):

"...Just hammer it out on a rock, file the edges, throw some paint on it and smile when someone comments on it ..."

Winfield, Isky, Engle and many other cam "pioneers" did just that - like 50 years ago. Does that mean we should still do it that way today? Probably, not. I chose to try to stimulate the assimilation and use of the scientific methods by showing folks where to find PROPER SCIENTIFIC cam design info - you don't need an education to show/tell anyone how to "pound and grind".

I, on the other hand, offered links to sound technical articles that could and would allow those interested in futhering their EDUCATION. Once one got the articles, ways to learn more about the SCIENCE and MATH associated with cam design could be explained and understood - more so and better than I could.

Get off your a$$es, get the articles, read them ONLY IF YOU ARE INTERESTED. Pound and grind away if you're not. Caveat emptor.

I do NOT feel that I can contribute and would contribute anything of value by giving a "feel good" "atta boy" "give it the shot" encouragement that, perhaps, the original inquirer was looking for. Sorry, that's not my style. Then again, folks either love or hate my style which is their perogative as well.

There are various ways that people can learn and/or develop bad techniques toward doing things - cam design is NO different. When it comes to cams, there simply IS NO go to "handbook" - the only ones are in the form of the articles previously mentioned. OR the websites of guys who sell software.

The guys who wrote the seminal articles were geeks, who fortunately, documented the fundamentals. Guess where the software guys who sell their wares got the formulae to write their software from????? After all, there are only so many ways to boil a 3 minute egg.

Those of us who are crazy enough to delve into cams and figure out how to do them found our niche. We're just like the sports hero's who didn't help/show their schoolyard pals how to hit the ball and run. Or the kids who kicked our ass at marbles or other competitive endeavors that teach kids how to win, and just perhaps, play fair.

Thankfully, the pioneers, did write SAE and Machine Design papers. Their legacy lives on forever as a result. The sports heros of today and our past, well, we all know how altruistic they are/can be.

I shared more in my posts about where to find cam design info than ANY of the people in my industtry (outside of one guy in particular but he sold me software). And, had any member chosen to get/read the articles, ACCEPTABLY COMPATIBLE MATERIALS are outlined in SEVERAL of the referenced articles and/or the bibliographies of same. To save the trouble of looking, go back to post #17.

I owe NOBODY anymore than that. The options at this point are simple:, read/learn or pound, grind and smile. With luck, perhaps, the "teasers" of knowledge I provided earlier may help M-man realize that he may be on to something - like on the verge of LEARNING something new that he didn't know before. And, more importantly, WHERE AND HOW TO START LOOKING TO FIND IT (hint: post 17).

The recognition I got for that morsel of enlightenment, "Thanks for the information you DIDN'T provide". Sorry, dude, but in my estimation, my failure to satisfy any members quest for instant gratification does not constitute disrespect. I simply DO find it to be a case of lazinness when people only want answers and not KNOWLEDGE. One result you get, the other you work to EARN/LEARN. Which to you prefer to do????

Or he or those so inclined can, "....Just hammer it out on a rock, file the edges, throw some paint on it and smile when someone comments on it..." M-man nor anyone will ever need my input or that of any other engineer to do a "pound and grind" cam.


If M-man (or anyone else for that matter) is/was merely looking/hoping for free cam design engineering on my part, sadly, they will be woefully disappointed - that ain't gonna happen.

Like I said, we offer the service - and they are affordably priced to anyones budget - from that of a go-cart racer to a NASCAR superstar. If you can do better elsewhere, go there. I'm sure Professor Blair will gladly give out free cam design info - yeah, right....

Just like EMI does for Bridgeport service and Fanuc for the service they provide for their fields of expertise - I charge for my expertise and sevices. As hard as that may be for some folks to comprehend, it is not anyone's rssponsibility to answer each and every one of life's questions for free on a message board.

Call and try to get free service and/or design info from Fanuc or EMI or Professor Blair. Been there, done that and have your credit card handy. They are/were MUCH less polite in their replies/sharing of info that I was or wasn't.....

At this point, I'm sorry I ever even got invovled with this thread....

[skippy]

Justlesh,
I wholeheartedly agree with everything you said and likewise, sorry if I came on too strong.
NC Cams: I will stick to your monicker now that you don't use F... here anymore. Sorry about that! Regarding your comment: "At this point, I'm sorry I ever even got invovled with this thread" that might be how you feel at the moment but I don't think that is what anyone wants as I and I'm sure others feel that you make a valuable contribution to this site.
Regarding cam design, I have a question for you if you feel like answering it and it only comes from my curiousity. Is there any merit in taking a cylinder head (just one, even if it did come from a V8) from a race engine, bench mounting it with an electric motor to operate it within the usual rpm range (oil supply connected of course) in order to see what's going on at the valve prior to fitting it to the engine. I'd imagine high speed cameras to record the motion. Do people do that kind of thing in the racing world to determine valve behaviour or is it a useless exercise due to not having the other real-world conditions in place such as compression, ignition, airflow, heat, etc. As I say, I'm just curious that's all and answer only if you feel like it.

[NC Cams]

Re: the "Fred thing" - if there is someone who's also using NC Cams and is going AKA "Fred", it isn't me.....

Re: single cylinder spin fixture - Isky did this in the 60's and they, perhaps, did some of the first bench testing of a psuedo-valvtrain - there were pictures of the system posted in their catalog at one time.

I've also seen it used on a flow bench wherein a dynamically flowing valve was evaluated. Hint: it did/does prove to be an enlightening experience as dynamic flow is not the same as simple single point static flow characteristics.

For that matter, wet flow tells you even more than dry flow but it is messy as hell to do.

As far as a single cylinder spin fixture, it will tell you MUCH more than looking at catalog figures about a cam ANY day. However, when you're working in/with an engine, there is interaction that takes place between cylinders (IE: 6, 5 and 7 in a V-8 Chevy firing order). Moreover, the inertia forces in a valvetrain dwarf those generated by the spring(s).

These forces, as they interact on/at the cam can cause the cam to deflect and/or twist. Not only do they play havoc with cam timing but they do horrible things to the ramping strategy. A cam that is smooth running on a single cylinder basis can be a herky jerky mess when all the cylinders are looked at in a real time/real mode fashion. You'd be amazed at the deflection differences that occur at 7000+ rpm that do NOT occur at the 3 to 7K rpm ranges. I've seen as much as 0.030" dynamic deflection occur in a pushrod valvetrain at 8500+ that can NOT be fixed by "doing something to/with the cam". A valvetrain that moves that much needs to be fixed/stiffened, PERIOD and heavier parts and/or more spring won't necessarily fix it = actually, it can make it worse.

The OEM's did and still do single cylinder testing and some feel this was adequate. A number of years ago, a guy in Detroit developed the Spintron. This device literally lets you bolt up/on a full engine block and valvetrain where you can run 1 or all the cylinders at the same time.

The device is fitted with laser poximity probes and computer data acquisition equipment that records real time valve motion for any/all cylinders that are instrumented - most teams who have this find the worst responding cylinder and tune to it.

High speed cameras have been used and the conditions that they show in a high speed valvetrain are downright frightening. Optrons were the first such devices but these didn't always work or provided poor data.

The problem with cameras is that at typical race engine speeds, you burn up film so fast that you don't necessarilly catch what's going on - especially, as you sweep thru the whole RPM range and the system goes into and out of control due to harmonic excitition(s). Yes, you can trap the funky motion but you have to first have to find and recognize that it occurs and that takes time - time (film) that you don't always have available. For this reason, digital data acquisition methods works better and faster.

If you have NO information or way to get it, a single cyl spin fixture is better than nothing. However, it is always more enlightening to use as close to real, live operation when you try to do data acquisition for ANY IC engine function.

Regarding the use of the Spintron (or any bench test) for valvetrains = any development one does with a spin fixture of any type does need to be taken with a grain of salt. As a noted racer we work with said recently about the Spintron data he spent weeks obtaining, "it is really good but we learned recently that the only things it lacks are spark and fuel...."

The Spintron, like the dyno, are tools. We all know that tools can be used properly and/or improperly. These are high dollar tools that, too, can be used properly and/or improperly. Guys who use them properly can get phenomenal results. Guys who don't, will waste time and money but they'll feel good in that they did so via the use of professional looking/acting data acquisition equipment - and sadly, they'll never be any wiser if they don't know or learn what they're doing wrong....

Hint: i saw traces from a spintron that clearly indicated that the system was bouncing all over hell and essentially out of control. Yet the team felt the system was "raceable". I wouldn't let them start an engine with that lame a system but they judged it "raceable". It is truly sad when a team has high dollar equipment and it is clearly showing them that there ARE MAJOR problems and they don't even recognize that a problem even exists.

Go figure.