MY CORLISS

ENGINE BUILD

Part eight by Vince Cutajar

The plan to do the front cover first had to be put on hold as I realized that to make a nice fit of the front cover I had to first hone the cylinder bore down to size and I did not want to hone the bore before drilling the 20 port holes.  So I drilled the port holes.

Took out the angle block and set it to 15 deg. and put the lot in the milling vice.

-

First thing I did was to make a flat surface with a 2mm slot drill.

-

First set of holes drilled with a 1.6mm drill.  Second hole from the left is where I broke the tip of the 1mm centre drill.  That will be OK as I still have to mill the pocket.  Some more photos of the finished port holes.

-

Bringing the cylinder bore to size was mostly done by honing. 

-

For the front cover I used a 45mm round section BMS and machined it to a diameter of 42mm and then machined the boss that goes into the cylinder to a slip fit.

-

It was then parted off. Changed my attention to the cylinder so that I could drill and tap 3mm the bolt holes for the front cover. Decided to use the DRO bolt hole function. Problem was that I had never used it so it took some time to figure out how to use it.  To make sure I spotted the position of the holes with a marker just to make sure that they came out where I wanted them.  I then drilled and tapped each hole one after the other. I hate tapping shallow blind holes. I had an ‘oops’ when using the first taper tap I stripped the thread but managed to save it with the second and final tap. I also ground off the point of each tap to go a little deeper with each tap.

-

I then wedged the front cover boss into the cylinder by using a piece of paper between the boss and the cylinder bore to make sure it did not move. Using the same bolt hole function I spotted the eight holes on the front cover.

-

The 3mm holes in the front cover were then drilled and a trial fit was attempted.  Would you believe it, they actually fitted. WOW!

The hole where I had a problem with the first tap is a little skewed but still works.  That was a relief.

-

I continued machining the front cover and left a 2mm boss on the outside.

-

I then continued machining the front cover and left a 2mm boss on the outside.

-

I assumed that the front cover needed a gasket. So I made a couple of gaskets from the thinnest gasket material I could find.

Not bad considering this was the first time that I made gaskets.


DRAWINGS HERE

PART SEVEN HERE  PART NINE HERE

 
https://www.sarikhobbies.com/model-engineer-builder/

Modelengineeringwebsite.com

the only free and the only weekly magazine for model engineers. 

Editor: David Carpenter