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| building a Duclos "flame sucker" |
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| madjackghengis:
This is an odd log, I built this engine when it was published in Projects in Metal in 92, spent a few months building it in between jobs, and being totally frustrated when it would not even attempt to run, when I "finished" it. Much of the original design was customised, I used a miniature ball bearing instead of a cut wheel for a cam follower, I put an identical bearing in the big end of the rod, rather than a sleeve and aluminum bearing on the steel sleeve, and I only noticed I had cut off the cylinder too short for head fins after it was cut off, but decided to go with it anyway. For almost twenty years, I've fooled around with it on occasion, lost it, found it, played with it, yet never accomplished anything of note. When I started my build log on the radial engine I am building, I saw a number of "flame suckers" of varying design, built and running on this forum, and you have to go to Jim's build log to see my initial reaction and my determination to make this seemingly simple engine run. Then someone posted a very similar version to mine running on that log and further motivated me. I opened this log in order to stop stealing space on Jim's, because it ended up entailing a bit more work than I first supposed. I started with a complete dissassembly, and laying all the parts on the magazine, comparing outlines and profiles with the pictures, and noticed my cam profile was substantially different. I did not use a rotary table, as I didn't have one, to generate the cam, and in translating the work to a four jaw chuck, failed to properly assess the issue of radius versus diameter, and this was the reason for the vastly different cam shape you can see the difference in the cam profiles here this is the old crank/cam set next to the blank new cam with the crank not yet cut and finished. After finishing the crank/cam, and replacing the old one, I noted a distinct difference in tone and the feel of the engine, but it still would not even attempt to run, so I turned a new piston, better fit, better compression/vacuum, but still no life. I decided the cylinder should be right, head fins might well be "that little bit" which makes or breaks. going back to the plans, the new cylinder was made and turned out a much better fit, tighter clearances, but still fully free movement with the new piston. I deliberately made the head fins longer than called for, figuring it couldn't hurt. cutting the fins with a .062 slitting saw, 3/16ths deep, the fins about .055 thick with an 1/8th in end mill, cutting the valve port in the side face of the cylinder, I didn't get it perfectly at the top of the bore, and used a second cutter, a ball mill same diameter, to provide a full opening which worked like a charm. I made a burner pretty much exactly as shown in the original, and got the flame where it needed to be without blocking it up or holding it, neither of which were much fun. the old parts laid out, the new parts installed, this does not show milling off about fifty thousandths from the face of the brass valve plate, lightening the load considerably, unfortunately, that was about five thousands too much, as I slit from the opposite side for the valve spring to seat in, and milled into the cut. I fluxed and soldered the face of the valve, and then filed and sanded off all the solder except that which was in the tiny slit, and got a good sounding compression and firm "pop" from the suction, which had disappeared as the slit appeared. This only lasted for a short time, and I wore through the solder with the end of the spring, and suddenly lost compression and pop. I almost made a new valve, but ran across a piece of .012 brass sheet, a piece about ten percent bigger than the valve its self, and decided that was a sign, so I filed it flat on both sides, tinned one side, put flux on the valve, and laid it in the center of the piece of sheet with a tiny bit of tinning showing on all sides, and put the torch flame to it for just a few seconds, getting a visible drop in the valve as it cleaved right up to the sheet. The edges were filed to match the original valve, the face was filed almost flat, and then it was sanded on a piece of 600 grit wet or dry, on a surface plate until flat. The compression and resounding pop were back, and spring pressure was just right. Putting the burner in front of the port, and spinning the engine over got the first visible response I ever had, and by moving the flame around, got the engine running fifty or sixty cycles instead of just five or so. Some adjusting of the valve, some tightening of all the grub screws and a few pulls on the flywheel and the engine was actually running, immediately showing interesting aspects of where the flame should be to start it cold, warming it up, and finally moving it to a point which brought the engine up to an estimated two or three thousand rpm, which will be determined today, when I put my digital tachometer aimed at it. This is a very short video, I have a longer one which must be chopped if I am going to fit it in this build log in a reasonable amount of time. The first engine I ever built in my life which did not run when I was "finished" with it, now is a runner, and I can hold my head up again, without self-doubt and wondering what went wrong. To say I am stoked, would be a vast understatement. I hope all of you get as much satisfaction from your builds as I received last night. I will have a good solid video of this engine running posted tonight, after I tighten up everything and get it as it deserves to be, on a walnut board with the burner secured in place and everything properly polished and clean. :nrocks: :beer: :lol: mad jack |
| sbwhart:
Well done Jack persistence always pays off you should be very pleased with your success . :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: Stew |
| cidrontmg:
Congrats Jack, :clap: :clap: :clap: flame lickers, as well as some Stirlings, can be a real PITA to get running. Itīs astonishing how sensitive they are to the flame position. But once you get it right, they run at marvelous speeds. Do you now have a 100% record of engines that you made, running? I canīt say the same, Iīve done 2 non-runners :bang: :bang: I guess the cooling fins in the cylinder head area are really vital for the function. That area has the greatest effect in the formation of the vacuum inside the cylinder. The fins close to the base contribute next to nothing in that respect. The base itself is also a big factor, there should be no obstructions to heat transfer between the cylinder and the base. Iīm not trying to learn you to suck eggs, just that some potential builder might read this, in the future :) Well done! :thumbup: :wave: |
| jim:
:clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: i'm chuffed to hear that you got it going. well done :thumbup: |
| madjackghengis:
Thanks for the note cidrontmg and Stew, I am exceedingly pleased with my success, I do want to clarify something. I'm new in the model engine building since I was a child, I've been building and rebuilding engines for money on the side since I was about ten, still building antique Harleys and other interesting engines, so it's not like I've built a bunch of these smaller versions so successfully. A full sized engine is generally a good bit easier to keep running, even if you can't afford parts and have to patch and make-shift as you go. I had attached the flamesucker to about a four by five inch quarter inch thick plate of 6061 with two #4 flat head phillips screws, expecting vibration, that crank web does not come close to balancing out the rod and piston, but I found what you said, cidron, it is a vital heat sink. I had a nine minute none stop run last night, and at the end, I was moving the flame all over trying to keep it running. I don't know if the head fins are so vital, its hard to judge without gauges and the like. I'm thinking of an aluminum cylinder with a "squirrel cage" form of sheet around it, as in a lawn mower engine, fan blades in the flywheel, a stainless steel head, with a good thick gasket to insulate, and a good polished concave reflector at the head end, set up with a valve like the "poppin". By the way, I've learned a lot from people who've been doing other things longer than me, and some who've been doing them shorter, as well. My friend in town, George, he tells me about a full sized flame sucker he saw a few years ago, had about an eight foot flywheel, and about an eight or nine inch bore. He says the man running it, set up the burner just right, got the water cooling going, had already set the flywheel where it needed to be, went around the engine with an oil can and a wipe cloth, got it all set in about five minutes or so, walked past the flywheel grabbing it about eleven o'clock with his left hand, carried it over center, and walked to the back as the engine started up and just set to running about a hundred and fifty rpm or so. I'd like to see that flame sucker more than a bit myself. As soon as I can edit down the long run, I'll get bits and pieces of it on the post. Cheers from a happy camper, mad jack an addendum for jim, thanks much for the motivation and inspiration to get it done, it was worth stopping work on the radial just to hear it :nrocks: :lol:making the world a better place! |
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