Author Topic: Going over to the dark (CNC) side!  (Read 10751 times)

Offline Jasonb

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Re: Going over to the dark (CNC) side!
« Reply #135 on: August 28, 2019, 06:55:09 PM »
Nothing too exciting on the machine this week so I did not take a video. Firstly did the eliptical flange on the end of the stock that will form the carb body.



Then used that to hold a bit of 1.5mm stainless steel that will be the exhaust flange



Rest of the carb was done with conventional tools and has a throttle barrel rather than the straight through venturi type.


Offline Jasonb

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Re: Going over to the dark (CNC) side!
« Reply #136 on: September 05, 2019, 05:20:25 PM »
Today we have a Conrod which may be of interest to Rod (Tangler)

2014 (HE15) aluminium, I made up the two parts on the manual mill, screwed them together with sacrificial brass screws and then popped in the two holes and while I was at it made a plate to hold it on for machining.

3D profile done with a 4 flute 6mm dia cutter with 1mm corner radius so no stress risers at 5000rpm, modest feed of 300mm/min. Then change to a 4mm cutter again with the 1mm radius to do the recess in the middle. Runtime was 12mins for the two ops plus 2 x 1mins for the other side.

Quite pleased with how it came out.



Offline tangler

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Re: Going over to the dark (CNC) side!
« Reply #137 on: September 06, 2019, 01:52:27 PM »
That's what I was trying to.  Sadly my mill won't  communicate with a PC at the moment and I've  already wasted too much time on it.  I need to get on with the Farm Boy.
Cheers,
Rod

Offline Jasonb

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Re: Going over to the dark (CNC) side!
« Reply #138 on: September 25, 2019, 08:20:12 PM »
Time to make a bit more swarf or more precisely 86.5% swarf and 13.5% left in the part which is the ignition bracket for the Midget engine.

6082 Aluminium, 3-flute carbide 6mm dia, 55deg helix, uncoated

Facing 5000rpm, 330mm/min feed, 0.5mm DOC, 5.0mm WOC to remove the saw marks and level the top

Adaptive 5000rpm, 330mm/min feed, 5.0mm height of cut, 1.0mm stepover. The cutter was not so happy with conventional cutting causing a bit of vibration in the chip tray but OK climb cutting.

Contour 5000rpm, 330mm/min feed, 3mm height of cut, 0.5mm depth

Helical bore 5000rpm 330mm/min, 0.5mm pitch. First time I had done this and very happy how it turned out. The hole was rough bored with a 0.5mm pitch followed by a 0.25mm full depth finishing cut and then a spring pass at the same diameter.

Finished off with conventional machine and hand tools.


Offline Jasonb

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Re: Going over to the dark (CNC) side!
« Reply #139 on: October 13, 2019, 12:31:34 PM »
When I first entered the dark side I was hoping that there would be some light on the other side. Well today the light shone brightly.

With all the Midget parts finished, 57 individual items plus a further 30 custom made nuts, screws etc.



It was time to see if I remembered how it all went back together. Valve timing was set by eye while turning the engine over slowly watching when the valves opened and closed. A little more oil than the normal running level put into the crankcase, some Colemans with a drip of 2-stroke oil into the fuel jar and give it a go. I got some pops straight away and with a bit more retardation of the timing it fired into life with a couple more pulls of the cord.

Throttle is by rotating the jam jar fuel tank but quite slow to react due to sizeable flywheel, advance & retard are a better way to set the speed which I had always intended was going to be for looks and noise rather than outright speed and performance.

Had to turn it off as I need to get that curtain cord back before anyone notices it is missing. Just needs a bit of colour to finish it  :pinkelephant:


Offline vcutajar

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Re: Going over to the dark (CNC) side!
« Reply #140 on: October 13, 2019, 01:17:09 PM »
Great runner Jason.

Looking forward to your next project and more CNC machining videos.

Vince

Online Dave Otto

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Re: Going over to the dark (CNC) side!
« Reply #141 on: October 13, 2019, 05:01:11 PM »
Nicely done Jason, she runs great!

Dave

Offline Admiral_dk

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Re: Going over to the dark (CNC) side!
« Reply #142 on: October 13, 2019, 07:30:29 PM »
Nice Jason and a good runner and starter too  :ThumbsUp:

There is one part that stick out in the family picture for me - the upper leftmost next to the O-ring ....
To me it looks like it has something to do with oil .... a breather perhaps ?

Offline Jasonb

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Re: Going over to the dark (CNC) side!
« Reply #143 on: October 13, 2019, 07:46:33 PM »
Thanks for all the comments

Yes it is a breather, the one in Popular mechanics had a big ugly thing off to one side but I went for something smaller and centrally placed. Also doubles as the oil filler and I added the brass screw lower down as level/drain


Online Kim

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Re: Going over to the dark (CNC) side!
« Reply #144 on: October 13, 2019, 10:24:32 PM »
Very nice little engine, Jason!
Kim

Offline Art K

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Re: Going over to the dark (CNC) side!
« Reply #145 on: October 15, 2019, 05:04:58 PM »
Jason,
Great build on that Popular Mechanics engine. They are right, I missed the build article. Is it a Midget because its smaller scale than original? :lolb: Great job on the cnc it was nice to see it in action.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King