Philip Duclos Fire Eater

[fcheslop]

Hi Bob, the cam can only go on one way as you correctly say. The engine will run or at least my engine will run at any position on the adjustment slot it just goes faster oneway and a wee bit slower the other
One problem I remember was that I adjusted the valve to come to far forward it only needs to fully cover the port by about 1/64 thats the leading edge of the valve I set it wrong and it wouldnt run or ran erratically. I think I had a problem with the shim bit that holds the valve I bent it up slightly wrong but maybe Im wrong as its 20 years ago
It must be lubricated with graphite anything else kills it .I just use a 4B pencil and scribble around the piston again to much graphite chokes it up hence just using a pencil. I also lubricate the valve face the same way
It needs to spin freely any binds will stop it running even the slightest
If you need a pic I can to one or two Sunday
cheers
frazer

 

[CFLBob]

Hi Bob, the cam can only go on one way as you correctly say. The engine will run or at least my engine will run at any position on the adjustment slot it just goes faster oneway and a wee bit slower the other
One problem I remember was that I adjusted the valve to come to far forward it only needs to fully cover the port by about 1/64 thats the leading edge of the valve I set it wrong and it wouldnt run or ran erratically. I think I had a problem with the shim bit that holds the valve I bent it up slightly wrong but maybe Im wrong as its 20 years ago
It must be lubricated with graphite anything else kills it .I just use a 4B pencil and scribble around the piston again to much graphite chokes it up hence just using a pencil. I also lubricate the valve face the same way
It needs to spin freely any binds will stop it running even the slightest
If you need a pic I can to one or two Sunday
cheers
frazer

Thanks, frazer. I ordered a liter of 90% ethyl alcohol from Amazon, so I won't be able to do anything until Sunday. I'm not sure what picture would help me, but your description of the cam adjustment helps tremendously.

My piston is graphite, and when I turned it to its final size, I collected the dust to sprinkle or rub on things as the lubricant. There's no oil in the cylinder at all, but I have put some light machine oil on the moving pieces on the flywheel, and on the cam roller. The original Duclos engine had the steel flywheel shaft running on the aluminum bracket and had little oil ports bored into the tops of the brackets to lubricate the flywheel shaft. I used ball bearings for those.

I really like the idea of a soft lead pencil to scribble on the sides, though!

 

[fcheslop]

Hi Bob, my bad for not reading the thread fully although I struggle due to dyslexia so tend to miss things
My engine is as per the original design and the crank shaft runs direct in the alloy and is still good although Little Blazer has a lot of wear no idea why as its half the age and made from the same grade of alloy.If I was building another I would also use ball bearings
I did have a few problems getting it to run due to my errors mainly piston fit and the valve adjustment and its seating but once these things were sorted its ran for 20 years plus with no new parts what ever . Be sparing with the oil as it gets thrown about a bit a gets into the cylinder then you end up with black crud
On later engines I used graphite but have gone back to bronze or leaded mild steel as I just didnt get on with the stuff for some reason
Im a fan of this engine as its just so reliable and not to fussy about flame position although you need to make sure the flame covers the port but does not touch the valve
One other area for leaks is the small end fitting that screw into the piston I sealed it with a bit of gasket glue
cheers
frazer

 

[CFLBob]

No sweat on not reading everything. Heck, I wrote a lot of it and I'm not sure I remember everything.

One of the reasons I picked this one to build is reading (here, I think) that it was a reliable runner. I'm hoping the hotter burning fuel will help, but either way I'm kinda dead in the water until the alcohol gets here.


Bob

 

[Cogsy]

If you're using ball bearings, have you removed the grease from them? The drag on a shielded ball bearing with grease lubrication is quite large, and with full contact rubber seals it's even worse. Ball bearings in an engine like this will work fine with a tiny bit of graphite in them and no other lube.

 

[fcheslop]

Another thought that Cogsys post brought to mind. For these and Stirling engine dont make the bearings a press fit bore/ream to size and use a wee dab of loctite or super glue to hold them in place. Probably telling my granny how to suck eggs
Good luck they are frustrating little beggars to build but great fun when they run

 

[CFLBob]

If you're using ball bearings, have you removed the grease from them? The drag on a shielded ball bearing with grease lubrication is quite large, and with full contact rubber seals it's even worse. Ball bearings in an engine like this will work fine with a tiny bit of graphite in them and no other lube.

No, I haven't. This is one of those subjects that didn't seem clear to me while reading about things. I've read both ways on it, and it seemed just as many guys were saying it never bothered them as saying flush them. That makes me guess it depends on who manufactured the ball bearings you bought and exactly what they used in them.

These are not rubber sealed, they have metal seals, and I'm honestly amazed they can make ball bearings that have a 1/4" shaft and fit in a 3/8" hole. (These bearings) Boca Bearings has a whole page on how to remove the lube and they basically say to soak them overnight in mineral spirits. I can do that, I just never made it a priority. As I run out of options, I probably will.

 

[CFLBob]

...Probably telling my granny how to suck eggs...

Nope. In my case, I'm a retired engineer, but an electrical engineer. That means I'm more like the students than the teacher in this far side cartoon:

I need, will take, and am grateful for all the help I can get.

 

[Cogsy]

Those are indeed very low profile bearings and because of that, they will have many very small balls in them, rather than a few larger ones (like you'd see in a 'normal' profile bearing), so there is the potential for a lot of grease 'pumping' inside the bearing and drag. It's an interesting thing to do, just for your own curiosity, to grab a couple of brand new ball bearings and test for yourself the difference with and without grease. For ease and cost, a couple of 608 skate bearings would be perfect. At a guess, with the inner race pinched between your finger and thumb and spinning the outer race by whacking it with your hand, the shielded 608 full of grease will spin for only a second or two at the most after you stop hitting it. The washed out one, without any lube at all, will likely spin for 60+ seconds. Even saying that though, just turning them slowly by hand will demonstrate the amount of drag the grease is causing.
I'm not sure the bearings are causing all the running problems, but the extra drag is certainly not helping you.

 

[CFLBob]

Just an update.

The alcohol arrived as scheduled, but it isn't enough to get the engine to run. It's still binding and not moving smoothly. I need to go after that first. BTW, the new stuff, which says 90.5% ethyl, also has yellow in the flame.

 

[Cogsy]

Here is a video of my Jan Ridders design running so you can see the flame colour. It still has yellow/orange but the 'heart' of the flame is blue and that's the bit you want to draw in to the engine. The fuel I use is sold as 'methylated spirits' here in Australia and is about 95% alcohol, mostly ethanol with a dash of methanol to make it undrinkable.

 

[minh-thanh]

CFLBob !
--- Mechanical friction: It is an extremely important issue
unfix it and check each section
Flywheel + crankshaft + bearings + bore of bearings: You rotate strong the flywheel it should rotate for about 60 seconds - or more, it rotates as long as possible ! With the friction of the bearing, bore of bearings : You should follow the way Cogsy and fcheslop said
Friction between piston and cylinder: The piston must be virtually airtight fit in its cylinder but also with the lowest possible friction. This can be as follows with a completely dry and clean piston and cylinder:
- With the cylinder in the vertical position and closed on top with your thumb the piston must stuck in the cylinder; airtight
- When the thumbs off the piston should spontaneously fall out of the cylinder; friction is low enough.
The friction between the valve and the cylinder surface: The valve just needs to be kept in place,it should not create pressure on the cylinder surface, because the vacuum part in the cylinder will pull the valve into the cylinder surface , it will create airtight.

 

[goldstar31]

Don't have any with 2.5in inside jaws. A search for calipers with long jaws only showed long outside jaws.

I've got a micrometer with adjustable jaws going up to more than 6". So I can measure a Myford lathe on a good day!
However, if the barrel of a 0-1" mike is put in a 6" or whatever metal clamp, it should be possible.

It's not new merely re-hashing what Professor Dennis Chaddock used as an addition on his Quorn tool and cutter grinder. Reminds me to add this to my machine, too

Norm

 

[fcheslop]

Hi Bob, cannot add to the advice already given.
You probably have already seen this
http://ridders.nu/Webpaginas/pagina_ervaringen_tips_happers/ervaringenhappers_frameset.htm

 

[Gedeon Spilett]

a very interesting thread ! very nice build.
Well, you almost got it, a little too much drag maybe, and some leaks in the valve
you have to feel the vacuum or compression easily for an immediate start of the engine.


this is the link for one of my album on googlephoto, where you can see some of my flame gulper engines...with some comments that may help you...
https://goo.gl/photos/zpJYqxgR4XHuv6hv5

 

[CFLBob]

Thank you so much to: Gedeon Spilett, fcheslop, minh-thanh, Cogsy and Goldstar31. There's much to go over here.

I sort of said last night that I think my issue is the engine doesn't spin smoothly enough on its own. When the crank arm is vertical (push rod at the top OR bottom), I can feel a little extra drag on the piston, a little catch. That's with both the piston going in and out. I've known about this since I made the piston, and I know I've said I ran the engine using my battery powered drill for a couple of minutes to smooth it out. I told myself "graphite on aluminum, graphite is softer and will grind away first". It seems it didn't smooth out.

I think I need to put some 400 grit sandpaper on a wooden mandrel and try to smooth that out until there's no drag. Of course, I'm afraid of taking away too much material and making it too loose. I do have some CRS bar to make a replacement piston, but would rather not (of course). I've never done the test Minh Thanh describes and Gedeon Spilett shows, where you hold a finger over the flame port and can't pull the piston out. Perhaps I should do that first and see if my piston is worth saving.

I noticed for the first time yesterday that the cylinder has a little wobble in the pedestal it mounts in. I can pull the pedestal and add a couple of setscrews to immobilize it.

Another thing is that I changed Duclos' flywheel support bracket, as I showed in post #42. I see wobble in the flywheel and that's the only place I can think to look that's different. I can always go back to the original design and make another bracket (able to accept my ball bearings, of course).

All I can think to do is make each part smoother, one at a time. Start with the cylinder and work backwards. Remove every little loss and inefficiency I can find.

 

[CFLBob]

I'd really appreciate comments on this video. It's hard to convey just how much force was involved, but it was hard to pull it or push it in with the port sealed.

 

[CFLBob]

Video #2. This is spinning the flywheel with nothing attached.



As always, comments, suggestions or old jokes appreciated.

 

[fcheslop]

Looks good to me apart from the flywheel wobble but thats more cosmetic
I would try it bolted together no valve fitted and see how it spins as the cylinder assy might not be square to the crank or the crank pin not square to the crank both these will give tight spots at top and bottom centre
Fit the valve in the closed position and you should get nearly the same amount of suction you show in the video
Just my two bobs worth from another retired member of the magic smoke club

 

[CFLBob]

I would try it bolted together no valve fitted and see how it spins as the cylinder assy might not be square to the crank or the crank pin not square to the crank both these will give tight spots at top and bottom centre
Fit the valve in the closed position and you should get nearly the same amount of suction you show in the video

In this case, we're trying to put the magic smoke in, not keep it from getting out.

I was surprised how tightly the suction pulled the valve closed and wouldn't let the flywheel do a rotation.

The part that gives me the most stickiness seems to be the valve push rod and cam roller fork on it. That hole in the pedestal says "Drill or Ream 1/8", and the rod is 1/8" dowel rod, but it seems tight. I'm all but sure I used a .001 over sized reamer (.126). I might enlarge that a little just so it doesn't bind in there. If the threads (#5-40) on the valve push rod get to that hole, they won't go through it. I didn't think a tap would raise the threads so much.