Elmer Engine Number 14 - Wobble Plate

[propforward]

Thanks Bill, as always it was great fun to make chips again.

It's very pleasing to see a couple of other people have posted their wobble plate engines above - some really nice work there, more inspiration. Very interesting soldering jig by Geoff - simple and effective, and I really like his boiler and engine set up.

sshires engine is a lovely runner, I hope mine runs like that. I must finish it so that I can find out. 

I did test fit the piston in the bore yesterday, and that feels pretty good, so I have high hopes.

More in due course!

[ths]

Good to see you back, Prop. Good to see the progress. Cheers, Hugh.

[propforward]

A bit of progress. My good buddy Oskar:



and I went over to the shop yesterday, and continued work on this little beastie.

First off, I re made the lever guide. The one I made two weeks ago probably would have "worked", but it wasn't very good. The slot wasn't properly centered, and holes weren't quite aligned....and various things. Anyway, it simply didn't represent what I can really do, so I made it again, and I have to say I feel really good about that.

I used my lathe to turn the little block to the correct length. Last time I used my mill, and I didn't get it square. This time I got it nice and square.



I used a slitting saw to make the slot:



I am getting in the habit of using edge finders and machine dials to locate holes and features, but I still blue the parts and mark them out sometimes, as a visual aid.

It's not exactly an impressive part, but nevertheless an important part of the engine.



Turns out I broke the tapping drill I need to finish this part two weeks ago, so I can't finish it just yet. Still, with all holes either drilled or spot faced, I moved on.

I drilled the center hole on the crank disc (I also did some clean up on a couple of edges of the crank, which were not great, and I'm happy with how that turned out).



I have now run into a bit of difficulty. I broke the drill off in the top hole (not the center hole). 

 I am pretty sure I can save it though. I have started parting off the crank disc, and have stopped at the top hole (the broken drill is too hard to cut through). I'm going to carefully grind through the broken drill bit, then finish parting off the disc. I am pretty sure I will be able to get the drill bit out then, as I will have access to it from both sides. Also, I have plenty of material on the crank disc, so that I can finish it to thickness afterwards and will be able to remove any grinding damage. Nasty, but that's where we're at. More on that after Christmas when I get back to it.

Other work performed - I started making the crank screw:



Turns out I don't have the threading die I need, so that part is also on hold now until I get the die.

I also made the crank shaft, but didn't take a picture. Once I get the crank disc parted off, I will press it onto the shaft, and finish machining the disc to thickness.

Here is my collection of parts for the engine - slowly taking shape.



I bought a cast flywheel for it, mainly for fun, and also to have a "first pass" at machining a casting. After this engine I intend to take a leap and take on a casting kit.

[b.lindsey]

Nice collection of parts so far. That flywheel is pretty big for this engine though it should work ok. Still following along.

Bill

[propforward]

That wheel is a bit of a big lump. Bit like me, really.

[sshire]

Prop
Looks like you're getting near the end. It will run. Mine started up first time (amazement). 

[propforward]

Thanks Bill and Stan, I appreciate your encouragement. Next time I go to the shop I hope to make up a soldering jog and solder the wobble plate and also the cylinder and head assembly. Then I'll be pretty close. Hoping to finish this by new years, but won't be too put off if I don't. (I've let it sit this long, after all )

[propforward]

Well, I had intended to go to my shop and do some machining today. However, we are under threat of a foot of snow, and since I now have to drive an hour to get to my shop, decided to do other things and wait until the storm passes.

That said, the storm has yet to actually arrive, so I could have gone anyway.

Be that as it may, I did take a moment or two to take a dremel to the crank, and grind through the troublesome drill bit that I broke off. Happily, everything went well and I ground through the bit, and was also able to poke the remnants out of the crank disc.





It's ugly, but there is more than enough material to be able to clean the disc up to the correct thickness once parted off, so I think I've managed to save this.

The chatter marks are a bit ugly though. Must improve on that.

Next opportunity to do more will be this coming thursday, friday and saturday. Hopefully 3 solid days of fun in the shop - a new years treat!

Happy New Year everyone.

[propforward]

Quick update. I managed to get a couple of hours in the shop yesterday. I had hoped to get more time over the holidays but that didn't happen. But yesterday was fun and productive.

I finished up the crank disc. Parted it off and pressed it onto the shaft, and then machined it to thickness and finished it. I also finished off the crank screw and did a test assembly.



It was actually very much a day of finishing up partially made components. There were several parts that were awaiting holes and slots, so I wrapped those up.

The lever guide - here shown being test fitted to the rest of the frame:



That all looks a bit rough at the moment, but I think once I've cleaned it up it will look reasonable. There are some chuck marks on the head that I'm not happy about, but I have to solder it all up yet, so we'll see how it looks after that.

Valve - which needed slot and hole for link pin:



And I also added the pin hole to the piston:





The reason these aspects had been waiting, is because I had to do some more basic test machining using the edge finder. I did my practice runs on the frame, using the edge finder to locate a zero reference, and then use dials to position the cutting tool / drill correctly. Anyway, that all seemed to go well, so I'm a step further along now.

Next, I'll polish up the frame assembly, press in the bearings and test the crank shaft fit. Then I'll make a solder jig for the wobble plate, and solder that, and also the cylinder to the head. Then all I have left is the lever pisvot, lever and flywheel. So - coming along!

[zeeprogrammer]

The crank disk came out swell.

You mention pressing it onto the shaft. I can't tell from the picture...is the shaft pressed into a thru hole or a blind hole?

The piston looks good too. How did you cut the grooves?

[propforward]

Thanks!

It's a through hole in the crank disc. I made the shaft end slightly longer than the thickness of the disc, so that I could skim them back together. I made myself sharpen the cutting tool, and mixed a fresh batch of coolant before starting yesterday, so I got a finish I am happy with on both.

The grooves in the piston were made with a thread cutting tool (for the V point) and just cut using the lathe. But I made a mistake, because I cut them AFTER finish machining the diameter of the piston, so that threw up a burr. It was easily polished off, but in future I'll get the piston near size, machine the grooves, then finish the diameter.

[sshire]

Everything looks great. Should be running before you know it.
About the Chuck marks. Make some copper or brass jaw covers. Thin copper sheet like heavy roof flashing is easily formed around each jaw and elimates the jaw marking.

[propforward]

Thanks Stan! I shall do that - one of those tips that really can make a massive difference to the finished article. 

[b.lindsey]

More nice progress! Not too many bits left now until this one will be a runner. Still one of my favorites of Elmer's engines and you are doing it proud!!

Bill

[mklotz]

Chuck marks. Make some copper or brass jaw covers. Thin copper sheet like heavy roof flashing is easily formed around each jaw and elimates the jaw marking.

Once you've made a sort of U-shaped piece to fit on the jaw, cut two slits into the verticals of the 'U' so you can bend the resulting tabs so-formed around the first step in the chuck jaw.  This will keep them in place while inserting/removing the workpiece.