1 eight scale 3HP buffalo marine twin

[90LX_Notch]

Mike-

This is a very impressive build.  I love the gearbox; but, I love the engine even more.

-Bob

[Roger B]

Looking good    As the others have said having your hand in the picture shows just how small it all is    (Unless you're a giant  )

[mike mott]

Thank you all for the kind comments.

I have had a few moments of difficulty with the cams, I read through a lot of threads on this and other forums about how to make the cams.
My first attempt was to make a pair for each cylinder, I turned up a blank on the lathe bored and pinned it to a 1/8th shaft of drill rod then transferred the chuck to the rotary table. I had drawn up a chart with the rotary table and marked off the degrees the first cam went well I flipped over the pair to cut the second cam and realized the old mirror problem and cut the second cam the same as the first.
in order to confirm I went to rotate the cam and grabbed the wrong handle



and wound the work into the cutter chipping it and bending the shaft.



Costly  mistake, I usually remove the mill table wheels when doing rotary work, for just this very reason.

This episode caused me to reconsider the methods I was employing, I decided to make the cams using the lathe as a shaper. the first order was to add the indent device to lock the spindle using the 60 tooth main gear normally used for the back gearing on the Myford.



I did a drawing showing the progressive cuts of the shaping bit. and the tooth number to index to.
as I progressed with the ever deeper cuts a I also marked the gear with a blue marker progressing down to the half way round the diameter of the tooth to the 14th tooth either side of the lobe apex each cut was gust under .001" and cut very nicely.

After this cut I rounded the tip a little more, to about a .01 radius



the results are encouraging I only have about .008" to go before the final clean up and polishing





The long cam form will get bored  and reamed to 1/8th then drilled for taper pins and then parted off and hardened finally slid onto the shaft and pinned once the locations are set.

Mike


 
 

[Roger B]

I have milled my camshafts in the opposite plane using a simple jig with a 60 tooth change gear as the divider. Maybe this reduces the chance of a crash 

[mike mott]

Roger I might have to make myself a set up similar to that for future work, what I would really like is good indexing head.

today I finished shaping the cam form and polished it with 600 then 1200 wet and dry.

the lift ended up being .02" instead of .022" I can live with that.





next I turned down to the root diameter for the area that will take the pins. This diameter is .156" and the width of the cam is .108" after the roots were turned I bored and reamed the length of the form to .125" and then parted it of.





then slipped it onto a shaft of 1/8th drill rod the drill the pin holes, after the holes are drilled I will harden the cams before positioning them on the camshaft.



once the shaft is pinned to the sacrificial shaft I will use a fine parting tool to separate them keeping them on  a new piece of 1/8th drill rod for hardening.

Mike

[mike mott]

Whipped up a 75DP cutter for 30 tooth gear today







The quick and dirty test confirms that the method will work, when I cut the gear for the engine I will need to set the cutter properly to the tangent and control the depth accurately.

Mike 

[Dan Rowe]

Mike, Nice work on the cams. Did you use the gear cutter as a shaper in the lathe? It looks like the cutter is mounted in a quick change lathe tool holder.

Dan

[mike mott]

Hi Dan, yes I did and it worked very well I think, I ended up grinding the cutter face both left and right so that I can hold it top or bottom of the piece being cut. I am going to do some work on the thumb adjusting screw on the quick change so that I can accurately adjust the depth of cut.

mike

[mike mott]

I had to rethink the whole gear cutting sequence the headstock gear turned out to be 65 teeth, I am not sure why I came to think it was a 60 tooth gear, without actually counting the teeth.

I set up the rotary table vertically



and worked the degrees I made the small gear first for the crankshaft.



then worked on the 60 tooth, I worked the mill in the same way as the lathe and shaped the teeth rather than cutting them rotating the bit I locked the quill and unplugged the mill and I am glad that I unplugged it because 2 or 3 time I went to turn it on or off. The other reason for not rotating the bit is because I do not have a way of holding it in a mill collet , and I will not use the drill chuck to mill with, but holding it in a fixed position was acceptable for my purpose.



it was slow but the finish on the teeth turned out really well, I did 2 or 3 finish cut without adjusting anything on each tooth.



back to the lathe for final shaping.



well it is not finished yet I still need to turn the eccentric for the waterpump.



I am pleased with the 75DP gears and the mesh though.





Mike

[Dave Otto]

Beautiful work Mike!

You make it look so easy.

Dave

[90LX_Notch]

Mike-

I can't wait for this build to be completed.  It really is a cool build.

-Bob

[Don1966]

Those gears turned out great Mike. You do some awesome work.

Don

[fumopuc]

A really beautiful work Mike. Very impressive.

[Roger B]

Great work on the gears   

[mike mott]

Thank you all for your kind remarks, I have been busy with the engine but had a short interruption due to some family sickness which is all OK now.

I worked on the waterpump and associated piping, I made some special pipe benders out of some 1/4 inch diameter rod. the pipes were annealed then filled with some styrene bent then the styrene was burnt out, it worked like a charm.





the union required some tricky threading for which I made a 6x80 tap to do the internal threading the male threads were done on the Myford.









next task was the spark plugs these are quite small the corian core was sliced off the edge of a small cutting board.



Turned down to .078" and bored out to .028" for the music wire electrode.



The body was made from an annealed allen key and is threaded 6x40




The cover plate and circular top plates were fitted and the small 00x90 machine screws were completed next, the screws were remachined from some 00x90 hex head because the commercial round head ones were too large in diameter.







To bring it all up to date I am working on the waterpump excentric, I made some filing sleeves to shape the excentric body and next it will need the arm silver soldered to it.







That is where I am at to date.

Mike