Mills 1.3

[Ghosty]

Hi All,

I looked into making a Mills 1.3 engine as they are getting very hard to get.

Found a web site with plans https://outerzone.co.uk/plan_details.asp?ID=13735

Printed the plans out and studied for a few hours. Have found many mistakes in downloaded plans in the past.

Found a mistake, width of the starter block for the crankcase was marked at 1-9/16" wide. on plans the width of the crankcase is total of 1.654" a difference of 0.0915".

After double checking dimensions, I checked on what I had at hand. I had enough to get started with.

First got the material cut, then squared up and sized the block for crankcase.

Then marked out and drilled 4 holes for the mounting lugs, then drilled and tapped the 4 holes for the cylinder mounting.

Will move on to crankcase machining tomorrow.

Cheers

Andrew

 

[Ghosty]

Hi All,

Started the machining of the crankcase, setup, trued and centered, machined crankshaft pocket and bore, and threaded for backplate, thread is listed at 26TPI, as I can't cut imperial threads on my lathe, I used a 1mm pitch and the dia listed on the plans.

Then rotated the case, trued and centered then machined the cylinder bore.

Then moved to the mill, machined conrod relief, exhaust ports, and transfer port.

Will now move on to machining the outside or the case.

Cheers

Andrew

 

[Ghosty]

Hi All,

Got on with the outside of the crankcase/body.

Started with the base/engine mount lugs, then the top sides, then cut the sides to the angle.

Then machined up two jigs to hold the case to machine on the lathe.

Machined the nose of the case and then on to the mill again to machine the base of the case.

Then glass bead blasting to get the finish on the case, then back on the lathe to do the final machining(sorry no pics of machining) of case.

Great care is needed when you do this step so you don'y drive the tool into the case.

Cheers

Andrew

 

[Ghosty]

Hi All,

P.S. Remounted crankcase to show final cutting of case. tool post compound set at 7deg for cutting.

Access for grub screw is through the crankshaft pocket.



Cheers

Andrew

 

[Ghosty]

Hi All,

Worked on the cylinder today.

Machined the first end out of square bar, thread should have been 0.540" x 26TPI, I used M14x1(0.551") as I cant cut imperial threads on my lathe.

Then, with a bit of 19mm hex bar, I drilled and tapped M14x1 to use as a jig to hold the cylinder , so I can machine the other end.

I machined down the other end to fit the case body, then drilled and reamed to 0.406".

Then I started on the cooling cap. Drilled and tapped M14x1, and checked fit of cylinder.

Machined the cooling fins, parted off, tapped for compression screw, then machined compression screw and assembled.

Cheers

Andrew

 

[Ghosty]

Hi All,

Started on the crankshaft today, machined the crankshaft bearings from bronze and installed in cases, then reamed to size.

Machined and tapped the nut from 7/16" hex bar.

Centre drilled the crank blank, and then machined the end down for the threaded end as per plans.

Then machined crank down to suite the bearings, then machined taper on shaft.

Machined the prop drive hub, cut slots to drive hub instead of using drive pins as plans.

Cut groves with tool on side, 15thou deep.

Cheers

Andrew

 

[Ghosty]

Hi All,

Started on the fuel tank/venturi today.

Machined the tank body from Perspex and alloy.

Machined needle valve from 1214, machined venturi/needle/jet in two pieces. Machined nut(5/16) from 10mm round bar.

Assembled needle/jet/ fuel tank top/venturi with loctite, when set drilled through and then cleaned out jet and needle threads.

Cut fuel tube piece and assembled fuel tank.

Cheers

Andrew

 

[Ghosty]

Hi All,

Started with conrod machining today.

Used a piece of 7075 10mm alloy plate, cut a 10mm slice off and squared up.

Marked out and drilled and reamed big and little ends to size.

Then machined to thickness, then machined centre section to thickness.

With the use of a 1mm(big end) and a 1.5mm(little end) drill bits I machined the outer sides to size.

Then machined the outer big, and little ends.

Still have the final finishing to do.

Cheers

Andrew

 

[Ghosty]

And some More

 

[Just for fun]

Thanks for sharing, very nice work! I'm enjoying your build thread.

Tim