An experimental, gearless, horizontal 4-stroke

[geoff_p]

For a couple of years, on and off, I've been playing/struggling/getting-frustrated with this engine.  It's gone through many-and-varied attempts to make it a 'runner'. (01_overall_view.jpg)  It's 25mm bore x 30mm stroke, with a 28mm O-ring cut-down to 25mm, a very experimental carbon big-end (made from electric-motor brushes) and ball-race main bearings. 

It's near-enough all castings - even the crankshaft at one time - cast in my back-yard, and I'll bore you with that in another thread, another time. (02_failed_casting.jpg)

Since I don't have a 'proper' milling-machine (see later), I couldn't attempt to cut timing gears.  I came across this idea on You Tube and made my own version (03_close-up01.jpg)

I used "Sprocketeer" to make G-code for two sprockets: one at 13-tooth, to form the outer, stationary ring, and one at 12-tooth with every-other tooth omitted, which appears as the inner 6-tooth 'gear'.

A brass eccentric on the crankshaft 'wobbles' the 6-tooth around so every 2nd revolution of the crank, another tooth lines-up with (say) the exhaust-plunger.  By a bit of sneaky, the in-between-revolution operates the ignition-cam - hence the odd angles between the two brass plungers.

When I can get the blighter to run, I'll try to beg/steal/borrow a movie-camera, but meantime this sequence of pictures must suffice.

BTW, when it does fire, the 'kick' is enough to shear M3 cap-head screws between the flywheel and the crankshaft.  But I can't/haven't yet got it to fire regularly!

Geoff,
Thailand

My 'mill' is a CNC-ed X-Y table (with built-in vice) and much backlash - see the varying shapes of the 'teeth' in the pictures.

[Roger B]

That's an interesting concept  . I have seen several versions of this idea in books on old engine designs when they were trying to avoid the "half time" shaft.

Good luck with getting it (her?) running. It can be very frustrating but feels good when you finally get there 

[geoff_p]

Blooming 'eck!  It runs (sort-of) but not for long-enough to rush out and buy a movie camera.

I had to make another crankshaft because the screws 'securing' the flywheels were just shearing-off.  They were let in to fairly deep indents in the shaft so before shearing, they chewed-up the shaft, which made removal of the flywheels Very difficult.

The new crankshaft has steel 'ends' - the bits that go through the bearings and out to the flywheels - but retains my experimental cast-aluminium crank-webs+big-end .  I'll take some photos at the next strip-down/rebuild.  Outboard of the bearings I milled 3mm keyways ready for the next spot of madness.

Of course I can't get keyway broaches over here so it might be a long time before I save enough to get from UK or Canada - forget duMONT (USA) at their prices!

Meantime I drilled along the keyway to form a half-hole in the flywheels, gingerly tapped M3, and put a cap-head screw in to form a primitive key.

A few pops and bangs later it seemed to me I was getting more like 'explosions' rather than combustion and advancing or retarding the ignition was having little effect.  Could it be compression?

Playing with a spreadsheet suggested I was getting almost exactly 6:1, less than most of you talk about.  I could remove metal from the head to increase the ratio but what about lowering the ratio instead?

I made a spacer 5mm thick with recesses for 'O'-rings each side, which Lowers the compression to about 4:1 and Eureka! the beast popped-and-farted for much longer than ever before - about TWO-seconds!

Interestingly, though the valves seat directly into the aluminium of the head, they seem to be sealing better now than when first made.  Perhaps not for long ....

For now she'll start-and-run very easily.  All I have to do is prolong the run a bit more.

Oh, and fix the timing-eccentric, which keeps slipping.  I've put some Loctite in it for now and will try again tomorrow.

Then, maybe, I'll try to get a camera.

Geoff
Thailand
 P.S.  This my 'electric start'.  These polyurethane belts get a good grip as they warm-up.  And the motor gets really HOT after a short while.

[Roger B]

Good stuff!    The move to continuous pops and bangs is always good. Is your electric starter an 'outrunner' model aircraft motor?

[geoff_p]

Well spotted Roger, it is indeed an 'outrunner', of completely unknown brand.

It has a matching, unknown driver, a Turnigy 'servo tester' as a speed controller and a 12V lead-acid battery.

Geoff

[cfellows]

So, I guess that outrunner motor has quite a bit of torque?

Chuck

[geoff_p]

Surprisingly, Yes.

I'm old-fashioned and don't (didn't) believe in these new-fangled motors-without-brushes, so I was amazed that it can spin my engine, not merely turn-it-over.

Perhaps I'll try a Spragg-type clutch and make a proper electric-starter for my "Ultimate Weapon Mk X1V"

Geoff

[geoff_p]

Well, I did say it's experimental, so I can't blame anyone but me.

The original crankshaft was machined from an aluminium casting, but the main shafts were too soft and grubscrews just chewed grooves in it when the crank turned and the flywheels were "slow to follow."  So I replaced the main-shafts with steel, loctited and cross-pinned into the remains of the cast-aluminium gubbins.

Sorry, that's a poor description!  Pictures to follow will show it more clearly.

Anyways, when the blighter began to make "pops and bangs" (it actually ran for about 20 seconds at one try  ) it stressed this assembly both in torsion and in flexing, with this result, which I thought was just bent:

[geoff_p]

The main-shafts were also twisted (that torsion element) See next pic.

OK, perhaps I need a less-unconventional crankshaft.  So I very carefully turned a bit of steel to 6mm shafts (had to fit the existing ball-races) and 8mm where it would go through the webs.

3mm keyways were machined at both ends, right up to the bearings.

[geoff_p]

I might as well try to improve the flywheels while I'm at it, so a trip to a local machine shop got me two "rims", about 88mm O/D and 65mm I/D by 20mm wide.

These could fit on the lathe only by wedging the motor away a tad, and then the rim was just one paper-thickness clear.

Lots of "chatter" later, the outside was sort-of-smooth, and the bore opened to 72mm.  The original aluminium flywheels were turned to just fit inside, with the help of a hammer!

The end-results each weigh 350 g whereas the original (ali) ones were just 50 g.

[geoff_p]

Meanwhile, back in the jungle ...

The only "stuff" to hand for crank-webs was my precious lump of 1"sq. brass bar.  I drilled (and pseudo-reamed) right through for the main shaft and the new, all-singing, all-dancing STEEL big-end pin.  Then sawed the piece in two and cleaned up. 

Another trip, this time to York Air Conditioning, got me some Flux and a piece of "Silver brazing" rod (marked "Harris USA") with which I assembled the bits.  The (kitchen) gas cooker provided background heat and a hand-held, canister-type gas torch got the lumps to suitably hot.  I let it all cool down naturally.

On close inspection, there were a couple of places on one web where the solder (braze?) hadn't fully penetrated, so I cooked it all again and concentrated heat-and-solder on those places.  Let it cool a little then plunged the whole crankshaft into my "pickling bath" - a basin of water+lemon-juice.  (This had zero effect on the flux but dire consequences - see later.)

[geoff_p]

Those crank-webs are downright UGLY but hey, they should be strong in both torsion and flexing.  Quoth he!

With growing impatience, I re-assembled the engine, connected the fuel tube (vapour carb.), and electrics.

And she fired first turn!  Then clattered loudly.

One side of the main-shaft had twisted, not just a little but near-enough 180 degrees.

Observation: this side of the crankshaft had been allowed to cool naturally, so softening the steel, while the other side had been plunged into the pickle-bath, chilling it.  Perhaps?

Mai pen rai - Thai for never mind - let's tighten the flywheel and try again.  After a few short "pops and bags" she ran, like Billy-O, shaking all the junk off my desk (where else do you run an engine but on the computer desk?) for some minutes.  Speed control ranged from Fast to Faster.  Eventually I pulled the fuel-pipe off to stop her.

One happy fool in Aranya!

All I need now is to build (yet) another crankshaft, Oh, and to buy some broaches for keyways in the flywheels - for those of you that noticed the partial screw threads in the current shaft.  Oh, and work out how to throttle the blighter.

[Roger B]

Good stuff    I think that your crankshaft may be a little bit too small. My 25mm bore engine has a 12mm diameter crankshaft and big end.

[geoff_p]

Well, I did say the engine is experimental: it sort of evolved from some steam-engines, which were quite happy with the cast-ali, 6mm crankshaft.  That was before I joined this forum and found much more sensible 'designs'.

Thanks Roger, you are absolutely right so I'm presently making an 8mm shaft - the biggest 'bit of bar' I happen to have - and right at the limit of bearings, which-just-might-work in the original casting.  I have Loctited the lumps together (as well as cross-pins) and will give it plenty of time to cure (patience not being on my attributes-list) before doing any more to it.

The flywheel-bosses have been bored to suit, brass (Thai response: "Bronze?  Isn't that the same as copper ton deng /red metal ") bushes/bearings made, and the eccentric has been bored.  All I need now ...

Hopefully I will have some keyway broaches winging their way here "shortly" - I want to give the new shaft every chance of success.

I just never thought this engine would run, let alone have any power;  learning to the contrary is great fun.

Geoff

[geoff_p]

P.S.  Fired with the prospects of success, today I lashed out a whole 5quid on a USB Web Cam so as to provide you lot with some laughs.

Well it seemed like a good (read Cheap) idea but how do you use it to record a movie? 

It's fine on Skype, and shows a moving-image in Windows but I can only see how to save a single frame e.g.  picture001.jpg

Help, please.

Geoff

[SHOPGUY]

Neat little engine Geoff
Thanks for posting your continuing saga.
Must generate some power to twist up a crank like that.  Yes, you might want to consider a bit heavier version of the crank . Lots of inertia in the crank and flywheels.
Experimental is always good and certainly a multifaceted learning experience.
Ernie J
Olds, Alberta

[Ian S C]

Geoff, I find that 1/4" steel is even too light for most of my hot air engines.
     You could have made a little tool to fit on your lathe so that you can cut an internal keyway.  It looks something like a boring bar, and you lock the chuck, and crank the saddle back and forward.  Easy to grind up the cutter in HSS, a bit of old centre drill/ broken tap,  Or you can make it from silver steel/drill rod and harden and temper.     Ian S C

[geoff_p]

Thanks for your comments, Ian and I did think of that but I doubt my little 'ole MJ189 would stand for it;  the saddle wobbles about enough in ordinary use so I think it would allow the tool to spring rather a lot. 

Besides, I fancy getting some 'right' tools for a change and 'proper' broaches be a useful start.

Now for the big question - which orientation should the keyways be in my attached sketch?

Assuming, that is, that twisting the crankshaft through 180 degrees again is not an option.

[Jo]

It is normal to fit the keyway in position C as there is often an oil way that goes from the crank bearings to the big end bearing.

Jo

[geoff_p]

Thanks, Jo.

In the past I've only used ball-races on mains so haven't needed to 'do' any lubrication for them - the big-end just got a slastering/squirt-from-the-oil-can when I remembered.

And this engine has a carbon big-end, which seems to get impregnated and hold oil for quite a while.  Part of my experimenting is to find how well it will hold-up/wear in practice.

I'm not sure how to drill the passageways - the main-shaft is still solid, as I want to mill the keyways before chopping-out the centre part.  And even after that's gone ?  please.

Geoff

[collbee]

 Hi Geoff,
 Try this ..........

Windows computers come with the "Windows Movie Maker" program already installed on the operating system so you can start recording the scenes for your movie right away. The free program lets you record from any connected video device, in this case your webcam. You can also import video clips you have already recorded from the same webcam or a different source. Once you are finished recording the end result is a movie.

In my bigger engines ..... if it starts to run away on us and is uncontrollable ...... one of the first things I do is to start retarding the spark.

Cheers....
collbee

[Jo]

Oil ways: I have attached a picture of my R&B crank.

You can see that the crank has been drilled from one end. On this engine there are counter weights bolted on so the oil way going up the web has been drilled under the web to save having a plug showing.

The crank pin has again been drilled from one side half way across the crank pin. Both the crank pin and the crank are cross drilled to let the oil flow from the mains into the big end. All the unnecessary holes are then plugged to keep the oil in.

I have seen one R&B with an oiler on the big end  one can only speculate what happens to the oil in the oiler as it runs 

Jo

[geoff_p]

Cheers, Collbee.  That works.  Now when I've taken Jo's advice I should be able to record oil flying everywhere (Sorry, Jo.)

Thanks for your sketch, Jo, I'll give that a try.  Though I'm a bit concerned about weakening the shaft with a hole right along its length.

[Jo]

Hi Geoff,

The R&B  is a big engine (175cc) so has larger diameter oil ways. The Double Tangye has a similair oil holes drilled through the crank but these are only 1/16" diameter which is enough to feed a 1/4" diameter crank pin.

Jo

[geoff_p]

Thanks again, Jo.
I wonder if I can drill through at an angle from the bearing-location, as per this sketch.

Because of the twin flywheels, the crankshaft extends some 52mm beyond each web: I just don't have any small drills capable of going that deep.  Come to that, I don't have many large drills either 

Geoff

[Ian S C]

Our HR 6 Ruston Hornsby diesel engine, 28 hp single cylinder horizontal engine has an oiler on the big end, it also has a ring on the outside of the crank that  (sometimes) directs oil into the crank pin.  Crank pin about 4" diameter, big end white metal.   Ian S C

[geoff_p]

Sorry, Folks, more questions:

With luck my broaches should be here tomorrow, Monday - they've been in Bangkok for a few days, in the postal system, according to Royal Mail Tracking Service.

So, what poundage or tonnage is needed to push these blighters through mild steel?  I'm hoping to use 3mm keys and the bore length is about 12mm.
I've seen videos of rack-and-pinion bench-presses used, so would the force available at the quill of my bench-drill be enough? (I assume I would have to do it in stages because of limited quill-travel.)

Also ...
What/which domestic cleaning agents would/might work for a silver-solder pickle-bath?

Cheers,
Geoff,
Thailand

[Brian Rupnow]

Geoff--I don't think you will get happy results from your bench drill . I frequently broach 1/8" keyways into steel pulley hubs, and I find that it takes a fair bit of grunt on my 2 ton arbor press with an 18" handle.---Brian

[geoff_p]

Blimey Brian, that's put a stopper on that "great idea".

I guess I'll have to build an hydraulic press - 'tis a good job I live near the famous Rong Kluer Market where I can buy a car jack.

Cheers,

Geoff,
Thailand

[Ian S C]

For a pickle, you could use citric acid, comes as crystals similar to white sugar,  should find it at a supermarket among the cookery bits, or a home brew shop.  Another thing is white vinegar.  Or drain cleaner, or any thing for defurring/descaling kettles/pots.    Ian S C

[geoff_p]

Thanks, Ian.  I did try lemon juice but there are plenty of 5% hydrochloric acid-based "household cleaners" available in our shops.  I'll give them a try.

Geoff

[geoff_p]

Sorry for the long break, I've been busy stepping One-forward, Two-back.  And without music!

The broaches from ArcEuro arrived and set me the next task - where can I borrow/get the use of an arbour press?  I asked around town, of course, but then decided I can make that (or a sort-of approach to it.)

A few pieces of substantial bar, and a 3-ton hydraulic jack from the market, a couple of G-cramps and we're away.

Result was rather-nice keyways in two flywheels and the eccentric.  Pity the boss in one flywheel looked more-than-a-bit twisted (must have had my backing off-centre) but I can easily twist it back to sort-of true.
Famous last words!  The aluminium casting didn't like it.  Next time I fire-up the furnace, there will be a new flywheel-centre coming along.  But not tonight!

Lots of fiddlin' an' farting later, I got the wee sod to at least fire again.

And even more of the same F-and-F got a sustained run.  It didn't shake as much off my computer-desk as before, 'cos there isn't as much junk on it .

This "movie" (my first ever, by the way, and ain't it obvious) comprises several bits of runs.  Sorry it's all out of focus, and blurry.  It's also my first use of photobucket.

http://s1244.photobucket.com/user/geoff_p1/media/Engine_movie02_zps16f4c588.mp4.html?sort=3&o=0

[geoff_p]

Sorry, folks, I didn't realise Photobucket was so slow.  I'll attempt to create an account with YouTube.

[Myrickman]

Geoff- very neat you are making this gearless design. I saw this several years ago in Hiscox book and made one a bit larger from an old steam frame. Getting the teeth right was a real bugger using a mill and a rotary table. It will be worth it when you get it done...fascinating to watch. I prefer keys on all my flywheels and thing they're worth the extra trouble for the holding power even on the models. Here is a link to the larger gearless   <a href="https://www.youtube.com/watch?v=VPTtiTCesQY" target="_blank">http://www.youtube.com/watch?v=VPTtiTCesQY</a>   I tried the bucket link but it would not load...keen to see it go.

[geoff_p]

Brilliant!  Is that your one?

How have you arranged the ignition "points"/Hall effect/whatever?
How do you control/set the exhaust-timing?
How much lift do you get on the exhaust-valve?

Since my last post, I have been messing/playing/cussing carburation problems: early runs used a vapour method, A-la Jan Ridders, but until I can get the beast back to stable I just don't have enough fingers to A/ Pull the starter-belt tight;  B/ Adjust the starter-speed;  C/ Adjust the air-bleed; D/ bung-up the air-intake to the fuel tank, all at the same time.

So I've made a more conventional "carb", using a hypodermic-syringe for a jet and the "standard" sewing needle for the jet-bunger-upper, arranged to dimensions not too unlike Chuck Fellows' design.

Although everyone predicts that compression should improve after a few "bangs and pops" mine has gone from moderate to "Holy Cow, I can't turn the blighter over."  And No! it's not something jamming, if I hold the exhaust open it will spin.  Drop the exhaust and the compression is there again.

And my little brushless motor can no longer turn her over.

Today I've revived/rebuilt a crankshaft-and-starter dog so I can use the electric-drill for starting, hopefully leaving some fingers free for fiddling with the things mentioned above.

We'll see.

P.S.  The Photobucket link seems to work, but there is an awfully long wait before anything actually shows.

[Myrickman]

Yes, it is mine. I also like oilfield engines so I patterned it after an ad hoc design in my head. It is 4" bore at about 3.5:1 CR. Fuel is propane, ignition is hot tube, exhaust valve clearance is just a bit to make the rocker clatter and close positively. I used a rocker arm to get about a quarter inch of lift and amazingly, the valve opens for darn near 90 degrees. All the cylinder bits were water jet cut from mild steel pipe and plate. The cylinder is an old sleeve from a McCormick Deering tractor. I have the luxury of living about an hour from an Amish foundry and I've become a good customer...they still do one off green sand casting of cast iron.
If it were mine, I'd put a spacer ring in her to lower the compression to something like 3:1 and give it a go. Of course you'll have to modify the valve train bits... No sense struggling with broken cranks and continual profanity. Your carb should work fine, others use them all the time...same for the ignition. For a free-running model, a lower CR should run fine. I like how you cut your gearless mechanism. Mine clatters in a rude manner due to the teeth being not quite uniform.

[geoff_p]

My word, there are some similarities here - ignoring the massive difference in size.

Exhaust timing:
By playing experimenting with the exhaust "cam follower" length I can vary the duration of valve-opening. 
In earlier, successful runs the exhaust started to open nearly 90 degrees AFTER BDC, using a fairly short cam follower.  So there was only 90-degrees to clear the exhaust gasses.  This was fine when she was running but before she started the first 90-degrees of what should be exhaust (Stroke 4 in the Otto-cycle) was actually another compression-stroke in effect.

I've just made another "follower" that sticks into the "cam" about an extra 1mm and the valve looks to start lifting somewhere around BDC, eliminating that unwanted compression in Stroke 4.

Rocker-to-exhaust-valve clearance is, quite like yours, slight.  I've got a Cap-head screw in the rocker, that accepts the end of the push-rod and allows some adjustment of what more conventionally would be called "tappet clearance".  Mine is set to about a boar's hair.  You can just feel it.

Compression-ratio:
According to my spreadsheet, the original CR was a tad over 6.  I made a spacer about 2mm thick, with O-ring seals, which should have brought the CR down to 4.5 or so.  It still displayed more of an explosion than a gasoline-engine's "burn".

Inserting these spacers only really affects the length of the push-rod, but mine are merely a bit of 2.5mm welding-rod (still with flux on it) cut to length and the ends ground (freehand) to look smooth-ish.

When I made the new, stronger, 8mm crankshaft, I also made a fatter spacer, some 5.5mm thick.  This should have the CR at about 3.5-ish and that seemed to work fine .... for a while.  After a few good runs on that, suddenly I have enormous "compression resistance" to turning-over, as I mentioned in my last post.

My cylinder is exactly 25mm.  Off-the-shelf O-rings are 25mm ID so I carefully snipped a few mm out of one and wrapped it around the piston's ring-groove.  The thinking being: if a cast-iron piston-ring is split and designed so the ends nearly touch when installed, why can't an O-ring do the same, nearly-touch, that is.

Geoff

[geoff_p]

"I ain't dead yet" as Granny Weatherwax would say.

Well I am, in the brain department.  I have been working away on this engine and doing the three-step dance (two forward, one back) and have replaced lots, usually with crazier ideas than before.  However, I have a runner - occasionally!

I promise I will write a log, with (still) pictures of some of the trials, which have dragged improvements out of their hiding places.  But not tonight.

Back in June, in Post #19, I showed the crankshaft, loctited and pinned.  And today it failed!  Sheared the crosspin AND the Loctite 680 on one half, the one where I apply the Black-and-Decker to the  starting-dog. 

In hindsight I see that the "kick" at ignition and occasional backfire have put the very devil of a load on it, and it twisted about 90-degrees relative to the crank-web.  And totally changed the ignition and exhaust timings.

Luckily the 8mm shaft hasn't twisted in itself, and the keyway is still quite straight.

With a wooden wedge under the flywheel and a shifting-spanner on the crank-web, I was able to "wring" the shaft back to somewhere near its original alignment.  So I want to pin it with something "stronger" than the previous 2.5mm welding-rod.

Materials I have are: M3 high tensile (I think) socket-head cap screws, M4 ditto, and 4mm welding-rod.  Bearing in mind the shaft is only 8mm dia, which of these would you use?

Geoff

[geoff_p]

Phew!  The blighter runs;  not as powerful as I would like but much better than I had any right to expect.

I've bought a phone-with-camera (new-fangled stuff - more to learn ....) and will attach a link to Photobucket.

Later I might bore you with some of the many re-cludged experimental aspects of this engine but for now:  some pictures.

(If, as is likely, Photobucket seems to be taking a million years to "stream" the movie, you can use Downthemall/Flashgot to download-and-save it.  What I Uploaded was 62,752 Kb but what downloads is a "mere" 25,771 Kb.)
(The streaming version has a severe mismatch between the sound and the image, and makes a total mockery of the movie.)

http://vid1244.photobucket.com/albums/gg572/geoff_p1/VID_20141030_175105_zps65ild6vf.mp4

[geoff_p]

Ahhhhhhh.  That Photobucket is even worse than I thought.  Sorry chaps.

Can anyone suggest a better place to store movies - NOT youtube -they don't love me since I signed-off from Google+.

Meantime, a few more pictures.

The fuel-tank filler "cap" has a 2mm breather-hole.  The delivery elbow, which is 6mm bore, has a 4mm hole on top for by-pass air.

Observation:  my earlier runs had a vapour-delivery tube the same size as aquarium air-line, about 4mm.  The engine ran, just!  With this new 6mm-BORE tube, it goes like billy-oh.

(I did measure 2600 (and a bit) RPM.   The governor holds it down to about 1550 RPM.)

Observation:  if the gasohol/petrol is VERY fresh, as in I just nicked it from my motorbike, the engine runs best with the fuel-tank filler capped and LOTS of by-pass air.  In other words, the fresh fuel makes a very rich mixture.

But if it's stale - a few hours standing in the fuel-tank - the by-pass air must be blocked  (my digit does this in the movie) so as to make the mixture richer.  Presumably most of the "goodies" in the fuel have evaporated.

[Roger B]

Glad you got there in the end      It's a lively little beast 

[geoff_p]

Roger, thanks for that comment.  Did you get the video to play in Photobucket?

I must admit my ears are still ringing - I recorded the vid., and I've played it umpteen times trying to figure-out getting it from the 'phone to the PC, then change the format, and from the PC to PBucket.

Currently it's running Open-exhaust, so the next "improvement" must be an exhaust/silencer system but without throttling it too badly.

The exhaust valve is 10mm dia and the port starts at 8mm then down to 6mm - a hole through M8 into the Silencer Mk1 - failed.   Obviously the next attempt must have an 8mm passageway at least.

[Roger B]

I just clicked on the link and it opened and played in window media player. I was at work so the sound was turned right down 

[geoff_p]

That's a relief.  I hope others can see it also.