Dinkus - A Side-Crank Rotary Valve Engine

Time for the next bar stock monstrosity!

This will be a simple single-acting engine, with a rotary valve at the outboard end of the cylinder. The valve will be turned by offset cranks at each end with matching disks/pins on the end of the crankshaft. The mass of the four crank disks will hopefully be enough to do the job of a flywheel.

This afternoon I got the cylinder and valve blocks to size, and made the bores for the piston and the valve. Also made the air inlet because I found a piece of scrap brass the right size while looking for something else I made a separate threaded tube to connect it, so it'll fit flat to the surface without any leaks.

Here are the bits with some piston and valve placeholders. Pretty boring to look at but there we go. 

Drilled and threaded the holes for the air inlet passages - really need to shorten that plug a bit though (the long brass rod) Also faced the valve to length and drilled the longitudinal passage. Next will be the passage that transfers air to/from the cylinder, the flats on the valve and the holes for some long screws to hold the valve block to the cylinder. Oh yeah, need to turn a spigot on the valve block as well.

Turned the spigot on the valve block (need to sharpen that tool!), drilled the second passage and plugged the first one. Despite putting some thin shims between the jaws and the part I found that they'd marked the edge of the valve hole so I'll need to tidy that up 

In case anyone is interested in how the air gets in and out... first photo view of the two passages in the valve bore. Second photo, the open and plugged passages into the cylinder.

Made the holes and threaded those in the cylinder block ready to attach the valve block, here held by two temporary screws. One of the holes is a bit out of position; I'm pretty sure I marked it up and punched it accurately but the old pillar drill has a mind of its own  -  this strike rate of 1 in 4 having an issue is typical. Thanks to the orange man-baby my chances of affording a new one are receding further, I'll probably end up with a brace and bit by candlelight at this rate. 

Made a bit of progress. Looks more like an early 20th century ice cream cart than an engine.

Minature traction engine, with the front wheels missing? 

Looks great, coming along nicely 

Quote from: Sanjay FMinature traction engine, with the front wheels missing? 

Looks great, coming along nicely 

Cheers Sanjay.

Made the first of the two side rods this afternoon....

Made the fiddly end bits for the second rod as well.

A little more done today. One day I'll make some of those nice piston rod/con rod joints that mesh together...

Quote from: PaulRA little more done today. One day I'll make some of those nice piston rod/con rod joints that mesh together...

In a 100 years time when your engines are on the Antiques Roadshow, collectors and the experts alike need to be able to recognise them as a 'One of Paul's engines' - I wouldn't go changing anything, they are unique and great the way they are 

Quote from: Sanjay FIn a 100 years time when your engines are on the Antiques Roadshow, collectors and the experts alike need to be able to recognise them as a 'One of Paul's engines' - I wouldn't go changing anything, they are unique and great the way they are

Thanks for this 

Just a short session today but enough to complete the simplistic big end. Not much room for error but as ever one of the holes went a little adrift. It's only cosmetic and nothing a one-eyed man on a galloping horse would notice 

Made the parts for the simple crankshaft. The drill press managed to keep its **** together for a change so all the holes were in the right place! Fixed the 3mm journal in place with Loctite,  once that's set I'll get the main shaft to length and fix that in the same way. Hopefully Loctite will prove strong enough but if not I guess I could make some tiny pins or silver solder it.

Chopped out the middle bit, seems to fit ok, next up, bearings of some sort.

Are you building a miniature steam powered drag racer? This I gotta see! 

Haha, it does look a bit like that at present but it'll look much less exciting in a bit 

Due to lack of forethought and materials on hand I'm going to fit sealed ball races as I've got some left over from the Stirling engine. The ones I'll be using have an 8mm OD and are 3mm thick so I need to make a flat bottomed hole to accommodate them. To do that I need a small boring bar so I just winged it and ground one from HSS and have to say it works rather well. Here's the hole it made in on some scrap steel that I bored out to fit a 12mm dia race as a test.