Starting a new engine

[cfellows]

John,

Do you just leave the one side on the crankweb free? Do you use a pin or setscrew to secure it?

If you have any other questions, don't hesitate to ask. Can't think of anything else you should know about the poppet valve.

Chuck

 

[Bogstandard]

Chuck,
To see if the crank needs to be pinned for that one free hole, you need to have the side support plates and bearings in position. I use a lot of ball races and so after fitting two races each side of the crank I don't envisage it to flex, but if it is going thru one bearing or plain bushes I would definitely drill and tap thru the crankweb to hold everything rigid, but still be able to be dismantled to replace the ballrace if necessary.
Basically it is exactly the same as the setup on your engine, but putting a takeoff drive to the other flywheel from the crankpin sticking out from the side of the big end bearings.
What this method does is allow you to have a raced or plain bearing big end without having all the hassle of making split bearings.

'Clear as mud' he replies.

John

 

[Bogstandard]

Not much to show for a couple of days work, but I have managed to get the basic platework made and the engine bits bolted to it.
It turns over nice and easily, so I don't envisage any problems getting it to turn over with air input.

This platework is not finished yet. What took the time was matching the fluting on the straight sides of the baseplate using the miller, to the fluting that was put on the curved ends on the lathe.
Just a bit of holographic engine turning on the top of the baseplate plus some profiling to the uprights should see them finished.
So that is the basic engine completed, now to get onto the bits that will make it come to life.
This is where the thinking bit comes in, and the data supplied by Chuck.

John

 

[cfellows]

John,

How did you fasten the cylinder to the pedestal and base, long screws from the bottom?

Chuck

 

[Bogstandard]

Chuck,
Single recessed screw in the column into the meaty part of the cylinder, then two short screws from underneath to hold it to the baseplate. Doing it that way when lining everything up the cylinder and columns are one unit, and only the short screws are used to align everything.

John

 

[Bogstandard]

I was hoping to have this engine finished to a running stage this week, but my body has said otherwise, I can hardly walk to the workshop never mind use the machinery. So this has been put on hold for a bit.
What I am going to try and do is sort out a few easy hints and tips while I'm chairbound, just to keep me active.

John

 

[Bogstandard]

Right, slightly mobile again, and managed to get a few hours in today.
Over the years I have amassed large quantities of allsorts, including gears, never throw them away, have you seen the price for them nowadays.
Anyway, back onto the subject in question. I am going to try to get this engine to 'fire' every fourth full stroke, and if I am very lucky and careful with my timing, and by using a remote poppet valve that hopefully will give a slight delay before the air hits the cylinder, it just might run in reverse as well.

So here is the first pic.

The same thing as the hunks of junk on the left, with a couple of other bits of metal were turned into the gear setup on the right for my 4 to 1 gearbox. You will notice on one a bit sticking up. Instead of making a proper cam, in this situation I only need a striker to give a little nudge, so a bit of silver steel soldered in will do the job.

This is how my gearbox assembles. There are no holdown nuts, just pins stuck into the ali backplate, with spacers underneath the gears to put them at the correct height to each other. The gears are prevented from falling off their spindle by the flange on the little input gear and there will be a striker plate over the bottom gear.
No fancy footwork on this gearbox, just put the first little gear on, push the second one up to it with the spacer underneath, and using a transfer punch, dot thru for the pin location, then the same for the bottom gear. Ended up with a free running gearbox with negligible backlash.

A little bit of progress at last.

John

 

[cfellows]

Lookin' good, John. Have you decided where you are going to put the valve assembly?

Chuck

 

[Bogstandard]

Hi Chuck,

I want to make the engine look 'busy' so I am going for a more complicated setup than is really necessary. The striker plate assembly is going to be mounted on the square face to the left of the cam gear.
To make it totally simple I could have used a very small pneumatic microswitch operated directly from the cam pin instead of a striker mechanism and poppet valve.


John

 

[wareagle]

Bog, I have been watching this build and am very intrigued with the timing mechanism and valving. I am eagerly awaiting seeing the final product!

I also like the shape of the base and the way you have mounted the cylinder. It isn't anything complicated, but it is different from the usual square base that is typically used. Very nice!

Thanks for taking the time to share your ideas and progress. Your works are an inspiration!

 

[Bogstandard]

Wareagle,
I try to do nothing that the average engine builder can't do with the equipment they already have.
Maybe where I am different is that I will sit in my workshop for hours just doing nothing other than looking for easy ways to produce something that looks different, and planning a procedure for making it, then just noting it down on a scrap of paper.
The base was made like this - cut a disc, using friction turning and cutting from the chuck side (to hide the centre drilling under the plate). Just using a profile tool and a standard turning tool. Then wacking off (with bandsaw)the two sides after previously marking the plate to width from a centre line.
Then into the miller to clean up the edges. Then mounting the plate horizontally and using a round nose cutter, mill out to match the curved groove from turning, and then with a standard end mill match up the square cuts. Simple but effective, BUT if done in the wrong sequence could be rather difficult. Only four basic cutting tools used.
Why make life difficult when there is usually an easier way.

John

 

[wareagle]

Bog, I am with you on the "keep it simple" concept. This is where "vision" pays off! You have it, and it inspires me (and a lot of the others) in the things I (we) do!

Thanks for sharing!

 

[Bogstandard]

What a crappy day today.
Thought I would start on the poppet valve, so opened up the shop and saw the engine sitting there with the extra bits of the crankshaft sticking out of the sides. Will trim them to length, thinks I, disassembled the engine, stuck one bit in the chuck to part it off and 'bang'. I had forgotten about the crankweb and it hit my toolpost, effectively turning the crankshaft into a banana, but not tasting as nice. Spent today making another straight banana and a vid.
So here goes. Sorry about the quality of the vid.

[ame]http://uk.youtube.com/watch?v=mMWYomG6UG8[/ame]


John

 

[cfellows]

That's going to be a great running (and great looking) engine. Can't wait to see it finished!

Chuck

 

[Bogstandard]

Finally got around to the bit that this engine is all about. It brought back memories of my foray into ic engines, the valve for it was just like the ones I used to make.
Here is a pic of the bits that go into a poppet valve, nothing special at all. Just a bit of carefull drilling and using a good quality 90 deg countersink bit to make the valve seating face in the block. The pic behind is my rough working sketch to make the drillings and as you can notice the block isn't machined all over, just enough to hold it in the correct position in the miller, why waste energy. Also notice that I have blued the block and rough marked what parts of the block I want to machine away to make it lighter and better looking. The outside machining is all done by eye.

About an hour later, the block has been tidied up and profiled. Just the end cap to make, two mounting holes to drill and a bit facing off the bottom to get it to the right height to the centre line of the cam follower.

I hope that this post and the previous one about the cam and gear setup has gone a long way to explaining how the air is fed to the top of the cylinder.

Once I have the cylinder head done (next job), I can lash up the air delivery to see if I need to make any changes before proceeding any further.

John

 

[rake60]

John I have several sketches of engine idea laying around in the piles
of papers in my shop.

I've never once tried to turn any of those sketches into an engine.
Watching yours come together is giving me the idea that I should at least
give it shot...

Very interesting thread!
I'm always looking forward to the next progress post.

Rick

 

[Bogstandard]

Rick,
It isn't rocket science. If I can do it, I am sure you can.
You have the basic understanding of engines, just take it from there.
This one is only coming about because of that one I saw of Chucks.
Mine will operate in exactly the same sort of way, just a few things in different positions. So basically I have stolen his design, and modified it to suit my way of making things. I am even using his method of making a poppet valve, if I was going to design my own I would most probably used a striker pin lifting a ball bearing off its seat, but why not use a proven design.
Just start with cylinder, piston, rod and crank and go from there.
If it doesn't quite work as expected you can always recycle it.

John

 

[Bogstandard]

I moved this across from the old site so that there was a bit of continuity to the post.

After beating my head against a wall, I actually cured a problem I thought wasn't there. Not having any specific dimensions to work to I just made the head with its sliding piston to what I thought it should be. But the engine wasn't as free as it was before I put the head on. To cut a long story short, I was preventing the cylinder from breathing correctly to atmosphere on the unpowered strokes by having the holes too small, 4mm diameter. I opened it up to 5mm and put a secondary exhaust port in and this is what I got.

[ame]http://www.youtube.com/watch?v=30tFCnAuBnc[/ame]

Grinning John

 

[tattoomike68]

I will update the how to post a video thread.

we have a youtube button in the post window now.

[youtube=425,350]30tFCnAuBnc[/youtube]

[youtube=425,350]30tFCnAuBnc[/youtube]

 

[Bogstandard]

Great Mike,
Starting to make myself at home, just need to get the bed in.
Are there any limitations on pic size and quantity, just in case I have to resize before posting. I have been setting my pics to 8" by 6", don't understand them pixelly doodahs yet, will that still be ok.

John