Same question for my WM180 – I'm sure I read aluminium change wheels are fine – cany anyone confirm please?

Pretty much anything will be probably outlast us but I chose FC steel for these " Myford" gears ( actually for the GHT bending rolls). They cut pretty easily with 2 passes of an RGD cutter.

Rod

Lovely job Rod – only 2 passes?

I wonder how my chinesium cutters will do…

Steel gears may “ring” and run a bit noisier than cast iron, as can be heard on some Chinese lathes with steel gears.

Alu. wheels will also make noise. But of course nobody will run gear wheels fast enough to make them noisy ?

Clive.

PS. I had an Opel Kapitan one time and the large timing gear was made of fibre which disintigrated. The replacement gear was aluminium and I could hear it when the engine was running.

An uncle of mine had one of these some many years ago, two features of which I remember: the speedo was a horizontal ribbon which changed colour to reflect the speed limits and when you opened the driver's door a small spotlight illuminated the ignition, both useful in their own way.

Today's cars are keyless and tomorrow, no doubt, compliance with speed limits will be automatic.

Just read this in Gears and Gear Cutting – Ivan Law, p66

"Always try to cut to the correct depth with one cut; nibbling away with a succession of small cuts is not recommended."

I guess that answers the question for me, but I will not be attempting steel or iron with my first attempt – confidence is key!

Chaps,

I accept the collective wisdom of the desirability of cutting the teeth in one pass but can somebody please explain to me the mechanism of more than one pass blunting the cutter?

In my case a combination of the power of my mill motor and the slowest speed of my auto table traverse, not to mention the noise from the back gear, led me to be more comfortable with 2 passes and the cutter (which I assume is Chinesium) still seems to be sharp.

Cheers,

Rod

If the tool is applied to cut in one pass, the whole cutting edge is applied to the work once only. Conversely, when the tool is applied in steps, the wear concentrates on the sharp end of the cutter. It's because, when nibbling, the sharp end does most of the work and goes blunt while the other end of the tool's edge is barely used at all.

Provided the machine has enough grunt and the tool can take the strain, using the maximum amount of edge possible per cut will extend the life of the tool. This is important in industry, but even something the size of Bridgeport has limits, which is why hefty horizontal mills are popular.

In practice, because my hobby mill flexes and the motor complains when pushed hard, I usually take more passes to remove metal than is ideal. Compared with the risk of damaging the machine or getting a poor finish the extra wear on the end of the cutters doesn't worry me much.

Rubbing tools with very light cuts is to be avoided at all costs. As well as concentrating the wear, rubbing rather than cutting damages the edge rather quickly. Being over gentle with cutting tools is a good way of reducing their useful lives.

Dave

Rod

Thanks for the pic, Rod.

I would have probably fitted 4 blanks on an arbor, to cut them.