minh-thanh
I am sure of one thing: you cannot maintain the radius, cam time, cam parameters exactly as you describe this way.
It works well if you produce a camshaft as I described in a previous post instead of a camshaft grinder because it is easier to make a camshaft whether you use these methods:
Edgar Westbury's, method: Use the lathe to make curved side camlobe. As described in Edgar Westbury's article, plan and in older model engineer magazines.
Check this:
E. Westbury's jigg for cam shaft
Len C. Mason's method: Use the lathe to make curved side camlobe. Title book: Model 4 stroke petrol,
Building "Mastiff": A 4-cylinder Petrol Engine
Bob Shore's method: Use the milling machine to make flat side camlobe. As described in Bob Shore's plan. He used milling machine and his own designed fixture to hold the cam in same time rotate the cam with pointer to degree disc.
The curved nose top of cam and base circle must be done with needle file and hone stone. Base circle can be fixed on lathe to remove a sequence of tiny flats.
No need to have a rounded nose of cam if the model engine runs up to 5000 rpm, in fact the camshaft is 2 times slower than crankshaft.
The marks of tools must be removed carefully.
More informatin here:
How To make Cams for Four-stroke Engines
The grinding machine for cam is grinding in the whole way around the cam with the master cam to form the cam on the camshaft as you can read and see here:
Grinding machine for cam.
Movie of camshaft crinding machine.
Timing of the engine depends on whether you are building a slow or high speed engine. As I showed timing is calculated for high speed engine.
You can copy the timing from other model engines or from car engine if you want to design own engine or it's lack of timing or the complete plan of cam in the plan.
Here Ahmed Iqbal from Nagpur in India manufactures a camshaft for a Peugeot SRD diesel engine from scratch. The original camshaft had been lost, and none was available for comparison. So this one was built without specifications or dimensions, based simply on his calculations from the rest of the engine. The engine ran with excellent results. It’s rare for a machinist to take on such a challenge, and even rarer for one to successfully pull it off. Attentive: no curved camlobe and no indexing head!
Each cam design depends on one important thing: Rocker Arm !!
Rocker Arm will reflect the timing of the cam in a ratio : 1:1 , 1:1.2 or ,....
In case you want to have large open of valve than cam lift to example due design of engine where there is not room for a larger lift from cam or you need increase power out of engine then you need rocker arm with difference lift ratio.
The rocker arm ratio multiplies the lift on the cam lobe and applies it to the valve.
But it is determined by how far you can open the valve without hitting the piston.
It means timing is not affected by rocker arm.
To example in the car engine those results found the 1.6 rockers making
more than 20 hp over the stock 1.5 rockers.
to manufacture or obtain a camshaft grinder that one uses once or twice and then dust in the workshop for years🗓🗓🗓.
it's stupid to order drawings from CAD + Modelltechnik-Jung as not everything is included to get a complete and successful model engine without errors. Boring when you have to make several camshafts for trial and error since materials cost money
🛠
⚙ and a bold and thick wallet
all 6 cam shafts in same engine as in post #25 where you wrote here:
(FAQ from Cad+Modellthechnik-Jung)...
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