johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment. I read every comment and respond to most.

Pistons for triple expansion steam engine.

Yesterday I turned the pistons for the steam engine.

The plans called for the pistons to be made in 2 halves, and the rings to be cast iron.

But the plans also showed the cylinders were cast iron, and my castings were all gunmetal.

So with gunmetal cylinders, I decided that iron rings were not appropriate.

I have used graphite impregnated packing for other steam engines, but after investigating the use of Viton O rings, I have decided to use them.

Viton rings are easy to install, cheap, easy to replace, and apparently work well.  They would not be used in an engine doing serious work, but my steam engines are more for display and interest and education, and will do few hours under steam.

Also Viton rings are quite small.  So if I decide later on that I want to change the Viton to packing or something else, I will simply turn larger grooves in the pistons to accept the alternative.

The pistons with Viton rings .

The pistons with Viton rings .

24000 RPM spindle for CNC Mill 2

Yesterday the spindle was wired to the Variable Speed Drive – single to 3 phase converter, and to power. It span smoothly and quietly, and very fast.  Much quieter than a woodworking router of similar power and RPM.

Today I hooked up the coolant, after testing the pump.  But when I ran the coolant through the spindle, there was no movement of the coolant.  So I reversed the fluid connections in case it was direction specific, but still no action.

The pump and lines were OK, so there was a blockage in the spindle.

I removed the coolant connectors on the spindle, and I could see something white and foreign deep in the works.  A bit of poking around revealed that it was probably a bit of packaging foam.  I dug out some, then blasted the rest out with compressed air.  Testing with the compressed air showed that the way was now clear, so I reinserted the supplied fittings.

And one of them snapped level with the surface of the spindle cover.  Bugger bugger.

I managed to get the broken buried thread out of the spindle using an “Easy Out”.

The broken fitting looked complex.  I certainly did not want to wait for one from China, and I was very doubtful that it would be available locally.  I could have made one, but it looked like a half day job.

So I silver soldered it!

The top of the spindle.  The fittings, with the broken one on the left.

The top of the spindle. The fittings, with the broken one on the left.

The coolant fitting and its broken thread, fluxed and ready for silver soldering.

The fitting in position for silver soldering. Resting on a nail held in a vice.

IMG_2723

The fitting after silver soldering. The threads needed to be cleaned up by running a die down them

This is the setup during the first engraving job.

This is the setup during the first engraving job. The green fluid is the coolant.

Engraving a small brass plate, at 20000 rpm.

Engraving a small brass plate, at 20000 rpm.