First 4 Stroke First V twin.

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minh-thanh

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c_mario !

I didn't know that plan was proven or ..!?
So I can't give any comments .
Just a suggestion , if you want to make new camshaft , make 2 cam lobes and shaft and assemble it into camshaft , and test it with 1 cylinder , It helps you check the opening and closing time of the valve... This saves time....
Anyway, good luck !
 
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Mechanicboy

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c_mario and all folks...

Here is the instruction from CAD + Modelltechnik-Jung ...😩

"Nockenwelle Die Nockenwelle wird aus einem Stück mit anschließender Härtung gefertigt. Dazu die Nockenwelle in einem Härteofen, bei 900 °C, ca. 10 min lang erhitzen und anschließend in Öl abschrecken. Auf ein Überschleifen der Nocken und Lagerstellen kann verzichtet. Die vorgenannten Stellen einfach mit feinem Schleifpapier auf der Drehmaschine abziehen. Für die Anfertigung der einzelnen Nocken der Nockenwelle ist eine Nockenwellen-Schleifmaschine vorteilhaft. Nähere Info hierüber über die u.g. Email-Adresse."

Translated to English..

"Camshaft The camshaft is made from one piece with subsequent hardening. To do this, heat the camshaft in a hardening furnace at 900 °C for approx. 10 minutes and then quench in oil. There is no need to grind the cams and bearing points. The aforementioned points simply scrape it off with fine sandpaper on the lathe. A camshaft grinding machine is advantageous for the production of the individual cams of the camshaft. More information about this via the email address below."

I have visited the website of CAD + Modelltechnik-Jung and searched for the job description how the camshaft is manufactured since the 35 ccm V2 engine comes from there. Inadequate explanation of how to manufacture without using a camshaft grinder as described in the job description. Not all model engine builders have a camshaft grinder that is needed in the workshop since special tools cost 💰to manufacture or obtain a camshaft grinder that one uses once or twice and then dust in the workshop for years🗓🗓🗓.

Not even valve timing of the engine or opening angles on the camshaft itself that we usually find in other drawings such as Edgar Westbury's, L. C. Mason's or other well known engine constructors provide detailed drawings of the cam profile and what tools we are going to make which are in these model engine drawings.

So in general, I personally think🤔 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💴💴💴.

CAD + Modelltechnik-Jung is adapted for model engine builders with all tools🔧🛠🔩⚙ and a bold and thick wallet💰💰.
 

Ghosty

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So in general, I personally think🤔 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💴💴💴.
I have also built the OHC 17cc single, the drawings had mistakes in them in relation to dimensions not matching up. Cam in that one is at the same info level as the "V" twin. And as has been found out, there is very little info on the web site on the cam cutting.
It took me cutting 3 cams to get the engine to run.
Also shown is the plans for the "V" 8(8 required), and 17cc single, cam, same info as all the other engines, very little.
Cheers
Andrew
 

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Mechanicboy

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I have also built the OHC 17cc single, the drawings had mistakes in them in relation to dimensions not matching up. Cam in that one is at the same info level as the "V" twin. And as has been found out, there is very little info on the web site on the cam cutting.
It took me cutting 3 cams to get the engine to run.
Cheers
Andrew

Andrew,..
But you already tried o_O all 6 cam shafts in same engine as in post #25 where you wrote here:

"Mechanicboy, they have very limited info on the cam angles, It has taken me 6 different cam grinds to get close to getting one to run correctly, and I am still working on it

Cheers
Andrew "
.

It's a waste of the material and time to get try and fail before your engine ran correctly...


Here is bad explained how to create the cam profile...😫 (FAQ from Cad+Modellthechnik-Jung)...

FAQ.jpg
 

c_mario

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Well,
Apparently it was stupid of me to order plans from Modelltechnik-Jung.
Funny thing is Its the first engine I have made that started rather easily.
I expected a big struggle to even start it. It took me 4 Two stroke engines before I got one to run and this was my first 4 stroke and it started within a few minutes of my attempts.
Hobbies always consume money, no matter what you do.
Since as I mentioned , I am a novice, so I guess I missed any mistakes that were in the plan.
None the less I was pretty pleased with myself when it started.
If I can refine its running then well and good , if not no matter Its just a hobby.
Thanks for you comments.
 

Mechanicboy

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Well,
Apparently it was stupid of me to order plans from Modelltechnik-Jung.
Funny thing is Its the first engine I have made that started rather easily.
I expected a big struggle to even start it. It took me 4 Two stroke engines before I got one to run and this was my first 4 stroke and it started within a few minutes of my attempts.
Hobbies always consume money, no matter what you do.
Since as I mentioned , I am a novice, so I guess I missed any mistakes that were in the plan.
None the less I was pretty pleased with myself when it started.
If I can refine its running then well and good , if not no matter Its just a hobby.
Thanks for you comments.

C_Mario

Same here I did not know about this company CAD-Modellthechnik-Jung until I came across what you wrote about the V2 engine, so I discovered everything was not complete in the drawing and description. For beginners, it is best to ask the experienced what is easiest to make a 4 stroke engine with simple tools instead of sophisticated tools that cost too much for a beginner.

We in this forum have gained a precious experience.

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 Edgar Westbury's, Len C. Mason's or Bob Shore's method.

Valve timing and angles of camlobe can be used from other model engine brand which works well if it is deficient or poorly described how one manufactures cam.
 

minh-thanh

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c_mario !

I didn't know that plan was proven or ..!?
So I can't give any comments .
Just a suggestion , if you want to make new camshaft , make 2 cam lobes and shaft and assemble it into camshaft , and test it with 1 cylinder , It helps you check the opening and closing time of the valve... This saves time....
Anyway, good luck !

For clarity,
If the plan has been proven : I cannot give any opinion that it would change the plan ., and back .

Mechanicboy

You give a lot of information: cam timing, radius..... as well as cam making, and especially timing diagram.
But there is a contradiction :

You can use Bob Shore's method of milling the camshaft: Mill the first flank and then turn slow the indexing head 240 degrees while continuing to mill the base circle until you stop 240 degrees and mill the last flank. To turn 240 degrees using the indexing head you need 18 holes disc. 26 turns and 18 holes in the 27 hole disc provide a 240 degree angle. Carefully remove the milling marks with a needle file and honing stone. Round a little at the top of the cam.
I am sure of one thing: you cannot maintain the radius, cam time, cam parameters exactly as you describe this way.

More :

C_Mario


Valve timing and angles of camlobe can be used from other model engine brand which works well if it is deficient or poorly described how one manufactures cam.

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 ,....

c_mario

If you want, I'll give you my cam lobe specs, , Let's make it similar ,but you have to rework the rocker arm with 1:1 scale.
 

Mechanicboy

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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 diagram.

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!

Iqbal4.jpg




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.
 

minh-thanh

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Do this cam or whatever camshaft you want , and let me know the results of the parameters , how you measured ....
27a.jpg
 
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Having worked on 4 or 5 sets of cams on a Triumph 500cc twin (back in the 1970s) I learned also that the cam follower curve is critical to suit the cam lobe. I also learned that many designs of high-speed cams in high performance engines effectively "launch" the valve on the opening stroke, so the inertia of the moving valve completes the last part of spring compression, then the cam profile is tuned to just follow the return of the valve under spring pressure, then "Catch" the valve and decelerate it before it hammers the valve seat. (to avoid valve bounce and valve seat fatigue fracturing from the hammering). Many race-tuners who make their own cams and followers develop a "skill" from trial and error, but engine makers use computer simulations to adjust the cam load. A curiosity: the routine audit durability test for cams, followers, and valve seat wear in a car company was an engine that idled for 1000hours, as that was the mode that developed most wear. A combination of a lot of factors, but including the lack of dynamic un-loading from "valve inertia" and "Spring" energy exchange.
K2
 

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