Hoglet build

[Trialnterror]

Looks like I found it but it's in metric (scratching head) will it be precise enough if I convert it to inches? http://www.homemodelenginemachinist.com/showthread.php?t=23303
???

 

[Trialnterror]

Does this look right?

 

[Jasonb]

Flank radius less the base radius will give you how far to offset the work from the spindle.

0.400 - 0.168 = 0.232"

You only really need to move one axis rather than the two in your drawing but it will give the same result as 0.232" is the diagonal distance you get by moving 0.202 and 0.112.

Those metric sizes in the other thread are for a different engine!

 

[Trialnterror]

So if I move the cutter .232 and the swing on the boring head is 0.8"

Has anyone wrote down start and stop angles for each of the 3 lobes? If not I'm sure I can figure it out..... Hopefully....:/

 

[Jasonb]

I think each cam needs 248.4 degrees of cut so you should be able to work it out from that. teh 0.4 is not worth worrying about so 62 cuts of 4degrees each.

 

[Trialnterror]

Awesome thanks, I should be able to get it, thank you so much for your help and knowledge!

 

[Trialnterror]

Cam built (i cut onto the flat piece of metal to get my swing cutting.8) this is the 3 lobe I plan to build a for lobe.

 

[Trialnterror]

This is how I measure the .8 boring bar swing! You could also use a piece round rod (aluminum)

 

[Trialnterror]

Just curious, the cam came out with lines where each cut was made, does anyone have a idea of what the boring head tool should look like? (The shape of the cutting tool, rounded tip maybe) And maybe what speed to run it at? (For the stress proof metal) if not I'll do more research and see if I can't find it. The surface was not very smooth per say.....

 

[Cogsy]

Just curious, the cam came out with lines where each cut was made, does anyone have a idea of what the boring head tool should look like? (The shape of the cutting tool, rounded tip maybe) And maybe what speed to run it at? (For the stress proof metal) if not I'll do more research and see if I can't find it. The surface was not very smooth per say.....

This is the cam I just made for the Rupnow Vertical using my boring head. I used 12L14 but I've cut 1144 as well and achieved a similar result. The tool was a standard boring bar (as can be seen in the picture) and I would have been turning it somewhere around 500+ RPM. Finish was very good and literally 2 minutes work with a small file to blend the facets and round the transitions. The boring head was set to something like 1-1/2" swing and running backwards - although this is not best practice from what I hear as it can unscrew.

 

[Trialnterror]

I guess the thing I worry about with that type of cutter is when I do my cam it has three lobes and I had to grind part of it off so it wouldn't cut into the lobes above the lobe I'm currently cutting. When I did that it left cut lines. Although I was running the machine at 1000 rpm. I'll do a test tonight on one and slow the speed to 500rpm. I have a different style cutter, like one I believe JasonB posted before. I'll try both and see what kind of finish I get.

 

[gg89220]

hello
Yes, 3 lobes cut in the mass

 

[Trialnterror]

You saw my question on the youtube! Excellent build sir! I really like your idea of cutting with a keyway cutter.

 

[Trialnterror]

Is it just me or does this drawing try and defy logic? I didn't know you could fit a 2.5" circle in a 2x2" square?

 

[Trialnterror]

Finished the head fixture just need to install pins, pretend the extra hole isn't there! Whoops!!

 

[Trialnterror]

Ordered .342 reamer

The spark plug is M10x1.0 is this a common spark plug thread size? Before I tap it I'd like to be sure.....

 

[Trialnterror]

.342 reamer came Today

 

[oneKone]

Ordered .342 reamer

The spark plug is M10x1.0 is this a common spark plug thread size? Before I tap it I'd like to be sure.....

Yep M10x1 is a common size. I've used them in rc plane engines

 

[Ghosty]

Ordered .342 reamer

The spark plug is M10x1.0 is this a common spark plug thread size? Before I tap it I'd like to be sure.....

Yes the M10 X 1 is the size for the NGK CM6 most gas RC aircraft engines or the NGK CMR7H plugs, the later one is for most Zenoah engines in the 26 and 30cc range.

Cheers
Andrew

 

[Trialnterror]

Started machining da head! Next step install in head fixture then do angles!
I've started on the left side, I took a picture of the drawing and used a app to mirror the image. That way I don't get confused when machining da left side!!