Making the Crank Shaft - Part 1

Using A Dowel to Locate the Vice

Using a Mini Mill to drill the holes in the Crank Webs.

If you make sure the vice is accurately aligned to the mill it will make life much easier.

This gives an initial fairly accurate method of locating the Crank Webs as you can look at the side of the vice and check that the gap between the vice and the Dowel are the same.

The accuracy can be further checked by using feeler gauges to measure the differences each side.

The best method for aligning the vice to the chuck is explained below.

Using a Dial Gauge to Centre the Vice

Once you have located the vice using the dowel.

Mount the Dial Gauge in the chuck and tighten the chuck gently.

With the dial gauge facing you, adjust the ball so that the dial gauge shows about 15 thou of movement, then zero the dial.

Turn the chuck 180 degrees and check the measurement.

Move the cross slide until the dial gauge reads half of the amount on the dial gauge, zero the gauge.

Turn the chuck 180 degrees and check the measurement.

Repeat the above until the dial gauge shows less than 1 or 2 thou.

The vice should now be accurately aligned and centered to the chuck.

Drilling the Crank Web Holes

Start by using a centre drill, make sure that is accurately aligned with the centre punched marks.

Check, check and double check that the centre drill is aligned correctly.

Drill deep enough that the chamfer on the centre drill leaves a good size starting hole for the drill.

At this stage I always spray or brush some form of cutting oil onto the work in progress, as it makes for an easier and cleaner cut.

If you don't have cutting oil, pretty much any oil will help, WD40, Three in One, Engine oil, Sewing Machine oil, any of these will be better than dry drilling..

Drilling the Crank Web Holes

I'm using metric sizes (mostly) so I'm drilling 6mm and 7mm holes in the crank web.

Each time I drill I use a 4mm drill to drill the pilot hole, then follow up with the correct size drill.

There are some that find that drilling the correct size hole with one drill is the best for them, I have always found that I can get a better and more accurate hole using 2 or more drills working up to the final size, but you do have to be careful that the drill doesn't snatch.

So do your drilling gently.

Drilling the last hole

That's the last 7mm Hole drilled and the piece is ready for cutting into two separate sections.

I used a hacksaw to cut the piece in half, you could use a slitting saw, but it would probably take longer to set up than cutting with a hacksaw.

The sections will be turned to size later.

Drilling complete waiting for the hacksaw

Jig or Fixture for Turning the Crank Webs

The jig is made from a piece of steel bar and has a 7mm spigot with a threaded hole to take a retaining screw.

This fixture can be used for turning the Crank Webs and for turning the Con Rod flanges.

Turning the Radius on the Crank Webs

Care and small cuts are required for this function, but other than that it is fairly straight forward.

You probably noticed that I am turning the Crank Webs one at a time.

That is because I made the fixture, for turning the Con Rods, and didn't think ahead about turning the Crank Webs.

So I suggest that you make the fixture spigot longer, then you can turn the Crank Webs two at a time.

Turning the Radius utilizing the 6mm Hole

This fixture is even easier to construct, as it comprises a Bolt and a couple of nuts, as shown in the picture.

Use washers on each side to prevent damage to the Crank Webs when you tighten the fixture.

Crank Web Turning Complete

This picture shows the completed Crank Webs.

The nice thing about doing the Crank Webs this way is that it produces even sizes.