My Flame Gulper

[NickG]

Here is tonight’s instalment. It’s quite hard to get motivated to get out there initially after being at work all day but once I get out there I don’t want to come back in! Came in at about 11:20 tonight, got a reasonable bit done.
First I thought I’d measure the 12mm end mill to see if it was actually a 12mm – it was! So I decided to put it in the vice and try opening the bearing housings by hand:

To my surprise it worked a treat – nice push fit:

I decided to put a dab of loctite on them; they will never be coming back out.
So with that bit quickly done, I was feeling quite good and made a start on the crankshaft. I decided I would do it my old way, but with more care and attention – threaded shaft, disc and pin.

Started by facing off the stock (think this is either 32mm stainless or some sort of chromium steel I was given at work) it seems to machine quite nicely whatever it is. I then drilled and tapped 3/16” x 40 tpi.

I didn’t fancy my chances of parting off – am a bit nervous about doing steel for some reason, it starts to make squeaking noises then I get the hacksaw out! Anyway, it was sticking way to far out of the chuck for parting off. Getting it closer to the chuck would have meant another saw cut since it didn't fit through the chuck body. So this time I just skipped a step and went for the hacksaw – which is now pretty blunt!

About 10 mins later I had this:

I was pretty happy with that straight cut and the finish was ok, so I thought I’d just leave it!

Lol, just checking you’re awake, of course it would be screwed to the shaft and faced off later!

Started machining down some 10mm stainless for the shaft.

It cuts really nicely, think it’s 303 or 304. The metal comes of in long spirals:

In fact on one of the cuts it was one continuous piece of swarf

Taking finishing cuts and lots of passes at the same setting. I had a bit of a flexing issue so the end furthest from the chuck was always larger – this makes it hard to test fit in the bearings. Consequently it is a marginally looser fit on the end near the chuck that I would have liked, no play but just a sliding fit rather than a push fit. I contemplated buying some 6mm bar but I think it would have needed reducing marginally to fit the bearings anyway.

I turned the shoulder for the thread and gave it an undercut with the hack saw – dodgy I know but a parting tool wouldn’t work that far out from the chuck.

Then I put the 3/16” x 40 Tpi thread on. This engine is a bit mix & match on the sizes. It was originally designed in metric so for the first time I am trying to stick to that, but all my taps and dies are imperial or BA and some of my metal was imperial! Oh, and my machines, so there’s been a bit of conversion going on! I used to always use imperial but I think I actually prefer metric now – if I had DRO’s I definitely would.

Crankdisc screwed on and loctited in place.

Facing disc down to thickness. This also gets it square to the shaft if there is any misalignment in the threads. The back face doesn’t matter as long as it doesn’t catch on anything but there doesn’t appear to be much misalignment anyway.

Bit of a polish with some wet & dry and here is the crankshaft / disc.

Next I turned the crankpin which is 3mm. I decided to use some 1/8” silver steel for this, it didn’t need to be silver steel, just about anything would do, it was just the nearest size I had.

Turned the slightly smaller shoulder and threaded 6ba, don’t think I took a photo of that.

I set the crankshaft / disc up in the milling machine to drill & tap the hole for the crank pin. To do this I just aligned the centre drill by eye to the centre pip then wound the table out 13.5mm which is the throw.

Centre drilled, then drilled and tapped 6ba. Screwed and loctited the pin in place:

Some of you will notice I’ve deviated from the drawings here. I’ve just got a pin sticking out rather than a special shoulder and screw that clamps together. The cylinder / bearing housings will be arranged on the baseplate such that the big end bearing is positioned in the centre of the crank pin (1.5mm space either side) but it is free to slide which should allow it to account for any out of squareness without binding. It would probably be better practice to do it the way Jan has in his drawings but this is the same method I used on my stirling engine and it seemed to work on that so I’ll give it a go here. If not, I can easily make up a spacer and a screw to make it rigid.

I'm also not bothering with any balancing. I think the pin / big end is light enough and the flywheel sufficiently heavy not to make a difference on this design.

Quick test assembly:

I still need to machine the slot and hole in the piston, make the conrod, make the base plate, a base from brown stuff and now I think a burner. I was planning to use the glass burner from my chemistry set I had when I was about 10 but it’s a sort of bulb shape and interferes with the cylinder columns so I don’t think I will be able to manoeuvre the flame into the correct position with that one. Not sure whether to solder a burner or machine one from solid alloy as I did with my stirling. This will need a lot more fuel though so think I may solder it to save time boring stuff out!

Got one eye on the finishing line but am determined not to attempt any start up until it’s completely finished!

Nick

 

[Powder keg]

Looking good there Nick!!! I like how you built up your crank. I have a project coming up I'm going to do that on now. Thanks,

 

[Deanofid]

Hi Nick;
Glad to see you got the bearing mounts fixed up without too much fuss!
You seem to get right along with things. Even after a day of work.

Dean

 

[NickG]

Thanks Powder Keg,

I always used to use that method but a couple of years ago I realised it was a bit floored. the hard bit is getting the crank pin square - I'll be honest, I had to 'tweak' it afterwards! The problem I think is the thread size is too close to the OD of the pin, so when I screw the pin in, there is not a proper flat shoulder for it to screw up against. So a better method would be to have a crank pin with a shoulder turned from bigger stock so it has a datum to seat against. Please see sketch. Another better way is to use plain diameters, no threads and solder the bits together. I just couldn'tbe bothered messing around with solder and the cleaning up afterwards.

http://img.photobucket.com/albums/v287/NickG24/My%20Flame%20Gulper/untitled.jpg[/img]]

Dean,

Yeah I was glad about the mounts.

Not sure whether I mentioned it anywhere but originally I planned to make this in a week! Perhaps a bit ambitious but I took a week off work to do it but other things got in the way. Up to now it's taken a month and it's not finished :-[ If I get motivated and nothing else crops up, hopefully I should finish it this weekend. People will now be thinking I might be finished by christmas!

Nick

 

[NickG]

Hi all,

Made a small amount of progress tonight although it doesn’t feel like I’ve done much!

When I did that test run of the flywheel on the crank in its bearings I realised there were a few minor issues.
The first one was that I hadn’t yet carried out a method of attaching the flywheel to anything! I can’t remember why, I think I just got bored and decided to do something else! Anyway, it’s pretty essential so I decided just to use my usual method - drill an angled hole, tap and stick a bolt in it.
Here’s the set up on the drill (the first time I have used it during this project I think!

I started the taper tap off in the drill at the same setting before moving it to the vice to finish:

That was the flywheel done – ish! On carrying out another test run I realised something else- I the 4ba bolt to hold the flywheel on stuck out too far and fouled the bearing housing. So I just chopped it off and put a slot in it to make a grub screw.
Then there was a problem with the clearances between the bearing housings & flywheel which allowed it to move around and rub on the housing. This was because I got a bit carried away when doing the flywheel – I didn’t realise that the spokes actually have a slight curve from one side to the other, so because I was concentrating on getting the amount the boss sticks out on each side the same, the boss actually ended up narrower than the width of the flywheel!
Anyway, I decided to measure up and make some brass spacers to give necessary clearances and avoid rubbing.
I don’t have pics of the machining but I just turned some brass to a smaller OD than the boss, drilled a hole for the crankshaft and parted off. 2 x 0.5mm thick and 1 x 2.5mm thick.

That pic was straight from the lathe, surprisingly there are no burrs, which is why I picked brass. Just gave them a rub on some wet & dry after this.
I skimmed 10 thou of each side of the flywheel outer rim to avoid any rubbing with the housings. Another test build showed that when the grub screw was tightened, it made the flywheel slightly wonky – d’oh! Yes I have committed a cardinal sin! So I had to find a small piece of shim to pack under the side where the grub screw isn’t. That seems to have solved the problem. Being a cast flywheel the spokes aren’t very balanced or uniform anyway, there’s not a lot I can do about that but at least the outer runs true – ish!

Another little niggly job that I had put off was milling the slot in the piston and drilling the hole for the gudgeon pin. So thought I might as well get that out of the way too.

Set up in the milling vice. First I centre drilled and drilled 3 holes, 1 in centre then the 2 extremes of the slot. I should maybe have used a slightly smaller drill than the cutter but I used a slightly larger one.

Joining the holes up with the 3mm milling cutter:

At first I started taking tiny cuts, but then thought I’d try half depth – that worked so it only took a couple of cuts. Think I could have done it full depth to be honest but I am still finding the limitations of the milling machine. I’ve given it a bit of a slagging off recently, but it actually works pretty well, it’s just not the highest quality but I guess you can’t expect that anyway. Would love a Harrison one to match the lathe!

Here is a pic of the finished slot. It worked reasonably well. If I wanted a really accurate thing I would have had to use a smaller cutter then take extra cuts to come up to size. But I knew this 3mm would give a little more than 3mm, which is what I needed on this occasion. I don’t want any friction between the piston and con-rod.

Now all that was left on the piston was to drill the hole for the gudgeon pin. For this I just clamped in the mill, lining the slot up parallel to the top of the vice jaw by eye. I also just aligned the point of the centre drill to centre and edge by eye - good enough for this since there is still scope for adjustment with this engine.

Drilling the hole gently. This cast iron cuts like butter anyway though, a joy to machine.

Test fit of the gudgeon pin material. 3/32” stainless. It is a lovely free fit but no play. The steel measured 2.36mm I used a number drill that measured 2.38 on the shank.

Cut the gudgeon pin to length and faced the ends. 1mm shorter than the dia of the piston.

The bearing surfaces will be those in the cast iron piston, it will be a tight fit through the rod so maintaining its position in the centre of the piston.

Here’s a bit of a mock up on the aluminium that will be the base plate:

Unfortunately the glass burner I was planning on using won’t fit to give me the right flame position so I will need to make one.
I even remembered something for scale- the coin is a 2 pence piece. (Just over an inch dia)
It will certainly be the largest engine I have ever built. Can I still call it an engine if it doesn’t work?!

I’m not sure what to do with the edge of the aluminium plate. For the wooden base I will chamfer with a countersink as I liked the look of that on my rocking engine but not sure how well that will work on alloy.

Maybe I could do a stepped edge? Any ideas? Don’t think it’ll look great just square.

The finishing line is definitely in sight now:
Con rod
Base Plate
Wooden Base
Burner

Nick

 

[Deanofid]

It looks great as an assembled unit, Nick.
Regarding cast iron, I like machining it too, except for the mess. Sure does cut nice, though.

For the edge of the base plate, try running a ball end mill around the perimeter, about halfway through the thickness of the plate. Pick a diameter of mill that makes a radius that looks good to you and have at it. Use a regular end mill to remove the majority of material first, then the ball.
Or, maybe just give it the same treatment as for the bearing uprights, to echo that appearance and maintain a theme. You may want to taper off the sharp edges if you go that route.

You'll think of something you like, I'm sure.

The end is in sight!

Dean

 

[cobra428]

Nick G,
If you have a 45 deg chamfer end mill I'd put a 45 about half or 1/3 the thickness of the base. I've seen cove (or what ever the wood guy's call it and I have the router bits for wood) kind thing done in metal. Kind of like I have on this wood base

Dean,
Cast Iron is great to cut but very abrasive to the ways and you (least I know me) come out of the shop looking like a coal miner :big:
Nick
I noticed that you where using that foreign language.....gudgeon pin and centre. Maybe you can translate....what's a spigot plate looks like a head gasket on the plans.

Tony

 

[Deanofid]

Dean,
Cast Iron is great to cut but very abrasive to the ways and you (least I know me) come out of the shop looking like a coal miner :big:

Tony

Yer darn tootin' it's abrasive. I cover my ways just as if I were using sand paper or grinding gear cutter teeth. It gets everywhere, too. Yeah, my hands look like I've been playing in the coal bin.

 

[Twmaster]

That is coming along very nicely Nick. The finish line is in sight!

 

[NickG]

Dean, I didn't think of echoing the bearing uprights. Might try that. Then I could give the base a stepped treatment like this:

Another thing is, how am I going to fasten it down. I could screw up into blind tapped holes from underneath so you can't see any fastners, or I quite like Hex bolts. Not sure if I have any the right size but have a small amount of hex bar I could make some from - that's more work though!

Tony, beautiful hot air engine, is it Ryder ericsson or something? When I was much younger I remember my dad helping me rout and edge the same as that on the base of my GCSE technology project! It looks good, may have to pop round and get him to dig the router out.

Nick

 

[NickG]

I noticed that you where using that foreign language.....gudgeon pin and centre. Maybe you can translate....what's a spigot plate looks like a head gasket on the plans.

Tony

Tony, the gudgeon pin is the pin that holds the small end of the conrod into the piston. I think I've also heard them called wrist pin?

Where did I say spigot plate? Don't know what that is! ???

 

[Twmaster]

Working with my father in his truck repair shop we always called that a Wrist Pin.

 

[NickG]

Both right it seems! http://en.wikipedia.org/wiki/Gudgeon_pin

 

[cobra428]

Where did I say spigot plate? Don't know what that is! ???

You didn't, it's on the plans of my Whittle V8 build it looks like it goes where a head gasket
would go.
I was lookig for a translation or ....
Tony

 

[NickG]

Ah right! Sorry!

Spigot plate, hmmm ??? Can't think what it would be but I know some cylider heads would have location dowels etc - anything to do with that?

Nick

 

[cobra428]

Yeah Nick,
The head hold down bolts go true it then up thru the heads....... :noidea:...I need to check the material. If it's copper then it's a head gasket

I'll get back to you after I get home from work tonight

Tony

It's a headgasket

 

[NickG]

Tony, glad you worked that one out. Never heard it called a spigot plate before!

 

[NickG]

Made a little more progress tonight. I thought I’d better turn that awful looking bit of brass plate I’ve been staring at for the last month into something – the connecting rod.

Started by finding a drill that would suit the 7mm bearing. Found one just under and did a test drill. It was ok, a sliding fit but I would loctite it. The brass was bloody hard stuff though.

Milled it square, to width and to length:

Then marked it out a bit – well I knew what it meant! Incidentally this rod is 20mm longer than the drawings to account for my larger flywheel, slightly different design too.

Back into the mill to drill the holes while it’s a uniform shape and more rigid.

Wasting away the sides to give the narrow section:

I then flipped it flat in the vice and milled the radii making sure I wasn’t climb milling. Stupidly, I decided I’d take a lick off the end but because it was only gripped by the narrow centre section the mill tried to pull it upwards. I really do some silly things sometimes! Luckily I backed off straight away and was able to clamp it back straight in the vice. There is a tiny machine mark on the end now but nothing to worry about really.

Fitted to the piston and the bearing loctited in:

Another trial mockup, nothing is bolted down here but it seems pretty good and if I bolt the bits in the right place it will be very free running so that’s the first tick in the box.

It was really the first time I got to try the ‘pop’ test with the piston on the rod and something to pull on. The vacuum was more than I thought with the valve covering the port it took quite a bit of force to pull the piston out which resulted in quite a tuneful pop! So that made me a bit happier – ½ a tick in the box I reckon – don’t want to count my chickens!

Base, burner and brown stuff left to do!

Nick

 

[Twmaster]

Sweet. This is getting better every day Nick.

Oh.. Darn. I knew I forgot to do something today... I need Dykem....

 

[cobra428]

NickG
VERY NICE BABY she's almost there :bow:

Twmaster
If you lived closer, you could come over and borrow a cup of Dykem :big:

Tony