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3 cyl Pip engine

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David Kenyon 222/12/2018 14:47:14
193 forum posts
144 photos


I also need two centres through the crank pin axes for machining the big end.
To do this the bar is fitted to two 'V' blocks and clamped in my mill vice on the mill.
I centred the mill spindle over the first centre drill and then moved the mill table
over to the crank pin axes and put a second centre drill. The bar was flipped 180 degrees
while still clamped to the 'V' blocks and the process was repeated.

David Kenyon 222/12/2018 14:48:13
193 forum posts
144 photos


Now I have the centres I mounted the bar first between the mains and then the crankpin to remove
the bulk material. p1030687 (medium).jpg

David Kenyon 222/12/2018 14:51:28
193 forum posts
144 photos


Then more material is removed to form the basic shape



As I get down to the final sizes lighter and lighter cuts are used to try and get a nice finish.p1030689 (medium).jpg

David Kenyon 222/12/2018 14:52:44
193 forum posts
144 photos


Back on the mill table I need to cut a 20t 48dp gear on the crank to drive the planet gears
I made earlier. I could not use the gear cutter I used on the planet gears as the gear is cut
close to the crank web and needed to be a smaller diameter cutter. So I made cutter from
silver steel , there is plenty of info about making gear cutters on the internet so I won't describe
it here.p1030695 (medium).jpg

David Kenyon 222/12/2018 14:53:45
193 forum posts
144 photos


With the gear cut I used a milling cutter to form the crank web p1030696 (medium).jpg

David Kenyon 228/12/2018 20:37:35
193 forum posts
144 photos

The crank needs extra weight to balance the engine so I turned and milled a counterweight
out of mild steel.p1030751 (medium).jpg

David Kenyon 228/12/2018 20:38:23
193 forum posts
144 photos


Then it is pinned in placep1030752 (medium).jpg

David Kenyon 228/12/2018 20:39:34
193 forum posts
144 photos


Once pinned I silver soldered it in placep1030826 (medium).jpg

David Kenyon 228/12/2018 20:42:31
193 forum posts
144 photos

Camshaft, the camshaft is made from 1.25'' silver steel round bar.
First I turned a piece down to size and then turned a small shoulder on the front.

David Kenyon 228/12/2018 20:43:22
193 forum posts
144 photos


The centre is then drilled and reamed ready to accept a bronze bush. Using a
parting blade I made a thin groove which is used to separate the inlet lobe
from the exhaust lobe then parted the piece off.p1030816 (medium).jpg

David Kenyon 228/12/2018 20:43:58
193 forum posts
144 photos


With the piece mounted on the mill I drilled and reamed the two holes which the planet gears
will run in. These holes were drilled through into the mounting block so I could fit two
pegs in to help locate the piece.

David Kenyon 228/12/2018 20:49:13
193 forum posts
144 photos


Next job was to mill the sides away to form the inlet lobes , only milling down to the grove used to
separate the lobes. Then the piece was flipped over and the exhaust lobes were milled in the same way. p1030822 (medium).jpg

David Kenyon 228/12/2018 20:50:05
193 forum posts
144 photos


The piece is then heat treated to harden the silver steel p1030832 (medium).jpg

David Kenyon 228/12/2018 20:51:19
193 forum posts
144 photos


Made some bronze bushes and pressed them into the Cam p1030852 (medium).jpg

David Kenyon 228/12/2018 20:53:21
193 forum posts
144 photos


All the items for the cam drivep1030930 (medium).jpg

David Kenyon 228/12/2018 20:53:53
193 forum posts
144 photos

p1030931 (medium).jpg

David Kenyon 228/12/2018 20:54:55
193 forum posts
144 photos


I made the big end bearing from phosphor bronze, the bearing is threaded into
the master con rod to help with assemblyp1030933 (medium).jpg

David Kenyon 228/12/2018 20:56:01
193 forum posts
144 photos

Then I started the con rod, this is made from 6061t alloy which has a greater mechanical strength than
the 6080 I have used for the crankcase.

David Kenyon 228/12/2018 20:56:51
193 forum posts
144 photos


p1030935 (medium).jpg
So I mounted a piece of alloy on the mill centred over the big end , I used a scrap piece of alloy underneath
to save damaging my rotary table.
I centre drilled ,drilled and tapped m10 fine through for the big end bearing then moved the table and
drilled , tapped m4 the holes for the slave rod pins.

David Kenyon 228/12/2018 20:57:57
193 forum posts
144 photos


The slave rod holes were then opened out to 6mm for half the depth of the rod. The big end bearing is screwed
into the rod by hand, I machined a slot and tightened with a screw driver then using an m6 end mill I relived the
bearing were it covered the slave rod holesp1030937 (medium).jpg

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