Milling Camshafts

[mikemill]

Reading through the many interesting exchanges on making camshafts, and wanting to get my new CNC mill to justify it's cost, I was convinced a CNC machine could generate a decent cam

Undoutably the best way to make a camshaft is with a cam grinder, but there is an old saying ' what's the point in owning a dog and barking yourself ' , so I set about writing some G code to generate a camshaft.

The princible as follows, useing a slot drill ( two fluted end mill) centre over shaft centre, that will give you a square profile, zero Z axis on OD of shaft, jog X to centre of cam and zero, also zero A axis (rotary table set verticle).

This process uses only two axis Z & A, start cutting by lowering Z onto shaft by 15 thou, and rotate A to desired degrees say 120 then -120, go back and forth to the depth that give you the base circle dia required.

Now with cutter running, A at 120 raise cutter by 10 thou and rotate A to 125
then A at 5 degree and Z at 10thou increments cut to 140 degrees, then go to 10 degee increments around to 180 degrees, and Z at 0, now rapid around to -120 and repeat.

This process gives you a series of very small flats , but all is requied is a wipe with some emery cloth and you have a very exeptible cam with slight curved flanks and nice rounded lobe. By altering Z and A increments you can get a wider or narrower lobe to give longer or shorter valve opening.

If you make the last line of code A90 and then zero A when you move along to next cam to cut, your cams will be perfectly indexed.

Try it out, now where's that dog!

Thanks

Mike

[stevehuckss396]

#1 I bevieve you have violated some rule of posting by not posting photos.

#2 That is how i made my cams only I cut everything by hand. Instead of Gcode I made a spreadsheet of the lift of lobe at what degree. Please post some photo's if possible.

[HuFlungDung]

Tighten your seatbelt for the appearance of NCcams in this thread!

You would not want to use a flat (square end) cutter, because the possibility of the cutter gouging the part where you are not paying attention, is almost a certainty. But, a ball nose tool should have adequate clearance to allow this. Depending on what cadcam you might use, it is possible to break the contour into very small fractions of a degree and take many many increments to end up with something that is decently smoothed. Its still not likely to be smooth enough to race with, I would not say that, but it might be a good exercise for you.

[mikemill]

Hi Steve
That was my point, to make full use of these wonderfull machines, will post pics soon

Your cylinder head looks interesting, also large, could you post more info on it, looks like an Offy.

Thanks

Mike

[John S.]

Mike,
You also need to make a move in X at each cut otherwise you will not get a flat cam due to the radius of the cutter unless you are using something very large diameter on a narrow cam.

Other than that it will work OK and clean up easily.

John S.

[NC Cams]

The advent of home affordable CNC's has made it a LOT easier to craft up previously "secretly" made parts - camshafts fall into that category.

Although 2, 3 and 4 axis machines have made the process easier, it has not eliminated nor prelaced the need for true expertise when it comes to creating and/or duplicatng profiles.

Yes, it is possible to create a cam "shape" but to literally create a cam tha will both move the valves or system and NOT wear and/or violate the laws of dynamics and physiscs is not easily done nor readily shared or conveyed.

Can a DIY cam be crafted? Yes, we did it but did so after spending a lot of time first learning how to design cams and then how to make them as iit would be done day in and day out "for real". We then essentially duplicated high volume production methods in low volume prototype tooling. We have since learned how to use unsophisticated "you can't do that" machines" to make high RPM professional quality race cams. And we do it on a onesy twosy bais LITERALLY on a custom basis for pro and /or DIY budgets - not via the "cookie cutter" off the shllf cam profiles that the name cam companies make but literally all new, custom, one off designs. This is not cheap but tailor made suits never are

This is tno to say that the cookine cutter profile is wrong or bugus - we just CUSTOM tailor easch cam profile to the specific blend of parts that the client wants/needs to use - not every guy needs or wants this but if you do, we offer the service. To do this, you can't simply "cut a cam" - you literally have to ENGINEER the whole system (cam/springs/parts/etc) from the get go. The fact that we helped a client win 12 of 16 "restrictor plate" race wins with the technique goes to show that there is a value to the process when you get to "That level" of competition.

The aftore mentioned techniques of hogging out metal will affect cam shapes. However, there is a bit more to the process and that could invllve weeks of time to develop the processs and untold experience and expertise associated with metallurgy and/or heat treating. I will not bad mouth well intended efforts spent to learn new processes or techniques. However, as this is my livelihood, you'll surely understand why we don't share EVERYTHING when it comes to 'splaining how do you do that????"

Why? Not? because we offer that servcie for a fair and reasonable price and stand behind the work we do perform. References and pricing provided via PM to serious inquiries ONLY. Training on the "how to's" offered only at a much higher price....

[John S.]

Nr NC Cams,

Wow, Sorry I didn't realise you spent that much time effort and expense on a $40 model IC engine which is what Mike and company was talking about.

[Mcgyver]

Mike, good stuff, I made cams before on a manual mill by raising and lowering the table while indexing the cam....did the math and made up a table. while technically a 'faceted' cam, the increments are so small you just about blow on it and it knocks the corners off.

NC, I wished you'd put as much effort into teaching us some the hows and whys instead of how tough it is to do and how well you can do it. us amateurs would love to get some help, insight, ideas, knowledge etc into this specialized area of which you have so much expertise, doesn't help much though just hearing about how inadequate it is what we're or how you have 1.5m cam grinder.

[mikemill]

As a relitive newcomer to the CNC world I find these forums very usefull for the exchange of ideas and help when you get stuck. But please guys lets keep it in context.

Pro engineers are one group and model engineers are another, whilst the latter can learn a lot from the the former, there is no need for the former to look down on the latter, and with a bit of inlightenment we can all learn from one another. I have been model engineering for 30+ years and have had a lot of enjoyment solveing the challenges varios projects thro up, hence attempts to make camshafts.

I have some pics of cams but can't seem to load ,when I press insert images, promp asks for a URL rather than browse. anyone know how?

Thanks

Mike

[NC Cams]

"Teaching" how to make cams is not something I do - afterall, I MAKE them for a living and rely on the proceeds to survive.

GUys like MACHINETEK (a tech by trade) frequent the board to HELP guys with this hobby - yet yet the guys who run EMI (bridgeport techn's and engineers) do NOT frequent the Zone because they actaully design and engineer the stuff as OEM's. Hence, EMI does NOT "give" away their secrets in trade EVER. I offer no more nor less with regard to my camshaft expertise..

If folks REALLY want to learn how to make cams, there are books written on the subject. Ditto that for desinging. How did I learN? Bought ALL the manuals and ALL the books and then set about LEARNING how to make cams - sometiems by hooh and sometimes by crook. And not the least of all by making some and making them WRONG and still having to make good on the parts that I was on the hook to provide in the first place.

M/S doesn't "give away" their O/S. THe guys at Mach don't do so either. Are we, as profewssional cam makers supposed to "give away" our trade secrets??? If so, tell me where as I've spent WAY too much hard work and money learning when I could have got it for free on the internet. Get real guys - doing it for a hobby is one thing, for a livelihood is a whole different level of involvement. Better yet, call Harvey Crane (creator of Crane Cams) and ask him to "show you how" to design a cam. IT simply won't happen.....

Want to learn how to make cams? Look for a manual written by Don Hubbard. It is THE BEST primer on how to make cams. Probably athe best $100 or so you'll ever spend to get started. Then go looking for some articles from the early 1950's in Machine Design that deal with "polydyne cam designs'. The article was written by Stoddard or Stoddart - can't recall. Regardless, pretty much ALL the computer based cam design programs are/were developed from this seimnal article. Once you find that areticle, start doing bibliography searches thru SAE and other references. Over time, you'll find enough to get by on and you'll have enough foundation to know what NOT to do - the rest wil come with time and effort.

ONce you understand the math concepts conveyed in the articles, cam design and manufacturing become easy. Lacking that knowledge and background, yes, it is NOT easy nor simple to convey until/unless you do know the math - at least the way we and other pros do it.

Essentially, what guys seem to want is an "easy" way to craft up a camshaft. Frankly, the OEM's have tried to do just that and haven't been able to do so. They've tried fine blankkng, casting, billeets and P?m and god knows what else. to this dday, there are still only so many ways to grind/make cams that WORK and work reliably. Even today, the Berco and other "rocking table" cam grinders (condieved in the 1950's) are "stare of the art" when it comes to grinding cams. Yes, even Norton and Landis grinders of the 56's and 6o's still make cams today. Some technologies simply DON"t change.

Want to really "learn' now to grind and make cams? take some money, buy a grinder and LEARN. That's how I did it. I literally bought a company too and LEARNED. Paid DEARLy for the learning process. Am I supposed to share all my hard learned/earned experiences on a message board??? Good opportunitity if you can find it. 10 plus years and nearly 1/4 million dollars later and I "know how".want to learn how? care to venture a gues what the coast would be???

We offer custom cam services to pro's and DIY'ers alike and offer the services in the form of finished cams. We do not offer OJT on how to cmmpete in an already competitive market. And to an earlier comment, yes we do NOT spend that much time and money crafting cams for $40 model engines - we do so for REAL engines and it costs a LOT more than the cost of the model.

[NC Cams]

Another good book is "Cams, Design, Dynamics and Accuracy" by Harold Rothbart. This book and the bibliography containted therein, should provide ANY camshaft devotee with enough seminal infomration on "how to" make and design cams.

After buying and studying these and other books, I thought I knew enough to take the plunge into camshaft making. So I bought into a company. Piece of cake. Yeah, right. Hundreds of hours later and thousands of dollars later, I know enough to get by on. We can make cams that work and live. We do so with pride and verve.

Clients want miracles. Racers want the stfuff for free. The employees think that money grows on trees. IC engine enthusiasts hope that we'll explain how to make these not so easty to make jewels "for free". If the business were more altruistic in nature, perhaps but not in this life time....Besides, if it were easy to do, there would be far more people than there are making cams and people are NOT really llning up to carry on what some consider to be a diminisihing need for the process.

[stevehuckss396]

Originally Posted by mikemill Hi Steve That was my point, to make full use of these wonderfull machines, will post pics soon Your cylinder head looks interesting, also large, could you post more info on it, looks like an Offy. Thanks Mike

Close, It's a Bugatti. 1933 vintage. It's 90% done with only 25% to go!

It is 1/4 scale so that makes the head 8.25 inches long. Came out to 5 cubic inch. The cam lobes were scaled down from a 330 Oldsmobile cam. .075 lift.