MY CORLISS

ENGINE BUILD

Part 10 by Vince Cutajar

I found a piece of 16mm square section brass which could be used for the valve covers, although the plans call for mild steel. Clamped it up in the 4 jaw chuck which in turn was clamped to the mill table.  Checked that it was straight.

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Indicated it to the X and Y axis of the mill table.

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I then drilled the four 2mm holes deep enough, hopefully, to get four covers.

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Using a 1mm slitting saw I cut the first cover.

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Managed to cut another 4 covers in about 15 minutes.

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I made some gaskets for the covers. There is an extra cover and gasket. An offering to the shop gnome.

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I decided to make the valve disk next, from 3mm 304 stainless flat bar. I did some calculations to extract some dimensions I required and did a sketch (understatement) with the dimensions I will be using.

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Marked up all the holes and noticed that the 3mm hole was too close to the edge. Took me about 15 minutes to realize that the datum (centre of square hole) is not in the centre of the part. 

Decided to do the four 2mm tapped holes first. Started with a 1mm centre drill and it snapped off as soon as it touched the plate. Decided to leave this hole for last and did the other two holes. On the fourth hole I broke the second 2mm tap. I had a sudden urge to grab the plate and fling it far away. Thankfully, I did not do that but instead went home to cool off. Next day I managed to remove the broken tap and finished it off with the third tap.

Back to the first hole.  Instead of using the drill to redo this hole I used a 1.5mm slot drill and then opened it up to 1.6mm. I managed to tap it with just the two remaining taps.

The 3mm hole was drilled and reamed and next started work on the square hole and drilled the four corner holes. I then noticed that I could add one more hole on each side (a total of six 1mm holes). On the last hole I broke a drill.

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I pushed out the scrap material from the hole and this is how it looks after a light touch with a file.

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The edges of the plate were milled.

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I still needed to round off the corners but at least the worst was behind me.


PART NINE HERE   PART 11 HERE

 
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