Drilling the Connecting Rods

Centre drilling for the Big End Bolts

Using a Slocombe/Dormer centre drill to start the big end retaining bolt holes, in the big end.

Space was a bit tight, but all was well, this centre drill is held in an aluminum extension tube, to give a little bit more clearance.

Really the centre drill should be held in the chuck, for the most rigid and accurate centering.

In this instance, I cent red the work piece in the vice, relative to the drill chuck.

Then I used the mini-mill to measure the correct drill spacing.

The drill spacing does not have to be spot on, but it does look better if it is.

Drilling the bolt holes

Using a titanium coated drill, to drill the bolt holes in the big ends.

This brass forging drills freely, and doesn't tend to bind on the drill.

The Big Ends, Drilled

The big ends with holes, ready to be cut across the big end before drilling and milling the big end bearing.

Big Ends Split

The big ends have been cut in half, (well nearly in half) the bottom section has to be cut to the finished size, before proceeding.

Big end's Cut to Size and bolted

Here we can see the two parts of the big end having been machined to the right size, then bolted together.

They are starting to look like the real thing now.

Drilling the Big End Bearing

Centre drill first, having mounted the big end carefully in the vice, with a packing piece underneath, to keep things square.

This time I used a bit of square steel tube, as a packing piece, leaving it in place, and drilling through it as well as the big end.

Things are a bit more secure, and less likely to tip or move, when using this method.

Well That's That Drilled

Reaming the big end

Using a slow speed, the big end is carefully reamed.

At this stage, I only use the first part of the reamer, and as that is slightly tapered, it means the hole is slightly undersize.

I leave the hole undersize at this stage, as there are a few more operations required on the big end before finally cutting the bearing to the correct size.

Big Ends looking the part

The big end are now ready for the next stage.