Elmers Standby #19 Model Steam Engine

[Mr Bowcat]

Thanks Jim.

Most of this weekends parts were made on the lathe, with a few features then added on the mill.

in terms of accuracy, yes a lot of the parts need to have close tolerances. The crank for example has to be able to hold steam/air, yet still be able to turn smoothly in the bearing.

I have DRO's (digital readouts) on both my mill and lathe which have a resolution of 5 microns (5 one thousandths of a mm) which helps a lot in holding tolerances. I would hate to do it the old fashioned way of counting revolutions of the hand wheels and dealing with backlash.

[Jim R]

a resolution of 5 microns (5 one thousandths of a mm)

I find it almost impossible to visualise something that small!

[Mr Bowcat]

Yep, its pretty diddy. My micrometers and dial indicators go down to 1 micron (0.0001mm).

An average human hair will be around 50-100 microns, to give you some idea of scale.

[HAWKERHUNTER]

This is so above my skill level Bob. Fascinating build though.

[scottie3158]

Great skills. I have often thought about getting a small lathe.

[Mr Bowcat]

Cheers guys.

[Richard48]

Wow thats some lovely work.Swarf!!,Thats a word i havent heard since metalwork lessons in 1980s in my teens st secondary school.
Richard

[Mr Bowcat]

Cheers Richard.

[Mr Bowcat]

Morning all.

Small update, I braved the cold yesterday and finished the connecting rod. This just involved sawing off the ends and filing a small radius.



As I had already made the wrist pin (and was already cold) I decided to finish the sub assembly by making the piston. This was a simple turning operation, the outside was turned to a sliding fit with the cylinder, some oil grooves added, then the inside bored out to two diameters and a cross hole drilled. This is the completed assembly and a rough idea of how it will look when installed.




There's only a couple more parts to make, I think I will machine the crank next which will complete this side of the engine.

[Steven000]

That's looking very good Bob, lovely work ?

[Airborne01]

Absolutely impressed!
Steve

[Mr Bowcat]

Cheers guys.

[Mr Bowcat]

Morning all.

Despite storm Bert I managed to spend most of the weekend in the workshop. There were two main components left to make, the crank and flywheel. These were made from the same piece of 50mm brass round bar.

I started on the crank first. This was an interesting piece as it started on the lathe, went to the mill, back to the lathe and a final trip on the mill.

This is it after the first turning operation, which involved bringing the overall diameter to 28mm, stepped down for the boss to 10mm and the 5mm drilled and reamed central hole added. Then it was over to the mill.



The piece was located off the central hole, the second M3 tapped hole added for the crank pin, and the scallops cut, then back to the lathe to be parted off.





While the stock was set up in the lathe I switched to machining the flywheel. This was reduced in diameter slightly just to clean up the edge, a 6mm central hole drilled and reamed, and dished out. This appears to be more cosmetic than necessary and went OK. I used a form tool I had made a while back and had quite a lot of chatter, I really need to grind a proper trepanning tool.



Brass is lovely to machine, cuts really easily and leaves a nice finish, but the mess!



With one face of the flywheel completed it was necessary to part off and turn the other side. My parting blade isn't deep enough to reach the middle of such a large part, so I went as far as I could and hacksawed the rest. With the flywheel flipped over it needed mounting back on the lathe concentrically, so a piece of aluminium bar was chuckled up and a 6mm spigot turned. The central hole wasn't visible yet (brass is expensive so I had only drilled just deep enough) so it was initially held on with CA glue until the waste material was faced off, then once the hole was fully visible the arbor was drilled and tapped for a retain screw, and the remaining features machined.







Back to the crank, this needed a radius added so I made up a couple of filing buttons and removed the excess material by hand.



Both the crank and flywheel needed a means of securing to the crankshaft, so each was cross drilled and tapped M3 for a grub screw. And that was the crank and flywheel completed.





Now, remember that long hole in the frame right back at the beginning of the project? Well that needed to extend into the bearing so that the steam/air could get too and from where it needed to go. The bearing, inlet pipe and inlet pipe bracket were fitted to the frame. The bracket and pipe determine the fixed position of the bearing, so the assembly was placed upright in the mill and a 3mm drill passed down the long hole and drilled through the bearing.



There were two last small parts to make, the plug for the end of the long hole, and a pin for the cross hole on the flywheel for the grub screw to bear against.



These are all the competed parts.



And the assembled engine.

[Steven000]

Well, that left me speechless...
Amazing work Bob, you made your own metal modeling kit and it spins like a dream, respect ? looking forward to your next projects, cheers

[Tim Marlow]

Lovely stuff Bob. All you need to do now is build the stationary engine to drive it ?

[minitnkr]

Beautiful precision work. Amazing what can be done with proper tools & skill to utilize them.