Discussion in 'A Work In Progress' started by josodl1953, Dec 10, 2016.
Great Tip! Now where do I find used Submarine Diesel piston?
You can melt down the old piston and pour in the steel pipe who are larger than piston diameter. Let it cool down , then the cast aluminium bar will fall out of steel pipe. See what i converted the OS MAX 61 to a pure diesel engine in the picture series when i created the piston and cylinder.
It was a marine diesel piston, not a submarine diesel...I only used this material because I had it still laying around. Only if you are looking for material for a ringless piston in an chromium plated brass cilinder it is worth the effort. If you are using piston rings you might as well use any good quality aluminium,preferably the type specified on the drawing.
After drilling the inside of the piston I proceeded wit the the wrist pin holes. Now I don't drill them on the drill press because I don't trust the perpendicularity. I have been drilling wrist pin holes with a fixture on the lathe ever since I started making pistons. I leave the pistons a little bit longer so they fit snugly in the fixture. The top of the piston is turned to size later on. The advantage of this method is, apart from the perpendicularity, that a groove for a retainer clip can be made, not necessary in this case, but indispensable with, for instance , .90 CMB two-stroke engines.
Next step: milling out the inside, again with a fixture on the toolpost.
To finalize the piston, I turned the top, measuring the height with a template I made from an old speedboat rudder.
With most of the parts complete now, it is time to give the small bits some thought.
I have been thinking a lot about the fabrication of the cam followers. The cylindrical part, the stem, is the first to be machined but the part is to be clamped on this tiny bit in order to machine the hammer-shaped end. The stem is only 3 mm thick so I wondered if it would be strong enough to withstand the machining forces. As usual, the proof of the pudding is in the eating, so I started off with a number of hardened dowel pins I had so lang in my scrap box I forgot where the came from. First they had to be annealed to make them machineable ( red hot with a blow torch). After that, I milled a flat surface on the side to prevent is from moving while machining the hammer end . The stem is having a semi-hemispherical end contrary to the original design which shows a hollow end of the cam follower. I did this because is difficult to make a semi- hemispherical hole in a 3 mm shaft. After the stems were finished the hammer ends were machined in a fixture which went surprisingly well.
So, another step closer to the end of the project.
Some more tiny bits..15 intake and exhaust flanges have to be made. First drilling the holes for the tubing, then drilling the fastening holen with the same drill jig I used for the cylinder heads. After that, cutting them apart the old fashioned way: a saw and some elbow steam. The periphery was machined on the lathe and the finishing touch... Dremel work.
One of the last parts to be machined is the inlet manifold . After turning, planing and drilling of the inlet holes was done on the toolpost ( as usual). But I used the wrong end mill for the O-ring chamber ( 12 mm instead of 10 mm) so I had to make another one ....
To make the poppet I got a 1/8" x 1/4" piece of O1 steel. Held in the 4 jaws I turned the round tail.
Then made a fixture with a hole and a slot to accept the flat part protruding just enough to round it. A thin Slit is sank deeper in the slot to make the fixture flexible enough to clamp the head. A center mark was sunk where the center of the radius is to be located. Clamped the fixture and the part with the center mark coaxial with the rotary table. The flat head is clamped on all its extension, then head and fixture are rounded.
Sounds complicated...do you have pictures of this operation?
Jos I know you do not have a mill/rotary table so my method may not be usefulo to you.
Have no pictures. Perhaps is my explanation that makes it look complicated.
The basic idea when dealing with a part that is difficult to hold, orient or register is to make a cradle. A fixture nearly a matching cavity. Then add some method of clamping with set screws or allowing the fixture to collapse like a collet by slitting on a suitable plane.
Yes, I get your point. But is seems difficult to me to get the flat part perfectly in line with the stem , that is, with my humble machining faclities..
I was having some piping problems lately. First, after pain in my chhest, they found out at the hospital that my coronary arteries were a bit clogged up, not severely, just bit. This problem was solved by installing two stents, a job of three-quarters of an hour, amazing what they can do. Next day I went home and after a week's rest or so I went on with the intake tubes of the Edwards. I tried bending of brass tube (after heating up to make it soft) withe a home made tube bender but the first attempts were, well, less then satsifactory , to say the least. It was important to me to maintain the inner diameter of the tubing to get maximum power out of the engine, bearing in mind that , if all goes well, this engine will be used on a R/C plane. The brass being difficult to bend, I changed to aluminium tubing. This material being easier to bend, it also contributes to weight reduction togetyher with alu intake flanges ( with an extension, to be fitted with epoxy).
The first attempt withe alu tubing, filled with sand, gave a better result but still not good.
Some wrinkles on the inside of the 115 degree bend developed which is not good for optimal gas flow. Also I found it hard to get the tube bent in the right shape. So, I made dummy intake pipe frome 3 mm wire. With this dummy, I made a sturdy fitting jig so that I could bend the tube is shape avoiding putting stress on precious engine parts.
Filling the the tube with molten lead prior to bending gave, at last, the required result.
So, another job done. The to-do-list is getting shorter and shorter.....
I love it when a plan comes together.....John "Hannibal"Smith --- The A-Team
I haven't tried it yet, Cerrobend. It has a melting point of 158 degrees. You can melt it in boiling water in a container, get it into the tubing you want to bend, bend it and then put into boiling water again and I guess it flows out of the tubing.
Neat. Where do you get it?
Some places I've found:
IMS Supply: https://www.industrialmetalsupply.com/Products/specialty-metals/cerro-bend#1
I've used cerrobend at it works just as advertised. One tip is to coat the inside of the tubes with a little oil (I used vegetable oil) before you fill with cerrobend, so the tubing can 'slide' over the cerrobend as it is bent. Once the tube is bent I just flash the torch over the tube and the cerro falls out quickly.
Interesting stuff. However, I had the lead already available and it worked for me.
I did the exhaust tubes too, was a lot easier with only one bend.
Finishing and polishing them took most of the time...
Sorry to interrupt this thread, but I am unable to start a new conversation. Each time I try I get the message "Invalid recipient"
Can anyone help please?
O.K. I might as well post it here:
Several people on this site have been searching for plans, originally drawn by Strictly I.C.
I have every copy of this magazine and will probably not use most of the plans.
Is it breaking any laws/rules for me to sell these plans to others? I did buy them in the first instance.
Cerrobend works great have used it many times, don't forget to anneal the mettle to be bent first or it could split or wrinkle.
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