Has anybody built the flame eater “Nick”?

[Brian JohnParticipant @brianjohn93961]

I had no luck turning the flywheels. I just could not get them to run true on the face plate. I spent an hour mucking around but in the end I gave up. I then tried to grip it by the hub in the lathe chuck as I have done many times before but I just could not get it running right : either the hub was out or the outer rim was wobbly. I have never had so much trouble getting flywheels set up for turning. I did manage to grip it on the inner rim using the external jaws (photo 1) but this was not secure and it came loose as soon as I tried to centre drill it. Can I turn the internal jaws around and grip the  inner rim of the flywheel this way ? I only thought of this now.

I made a start on the smaller parts : more problems here too (photo 2). The bearing mounts are the same as the Stirling engines I have built. They are always a bit small and in the past I have spent ages filing them down so that the 10mm OD bearings fit snugly. This time I drilled and tapped the bearing supports then placed them in the vice to ream them out with a 10H7 reamer…bad mistake. I forgot that reamers are always a bit large so now the bearings pass right through. I may be able to salvage the situation by filing a bit off the flat mating surfaces.

What should I have done to get a good fit for the bearings ?

The parts of the crank have been cut, reamed and filed ready for assembly by soft soldering as per the instructions. I am thinking of drilling and tapping for grub screws so that nothing moves while soldering. They warn that this part should not be hard soldered due to the likelihood of distortion.

 

Edited By Brian John on 20/05/2016 13:58:21

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[Brian JohnParticipant @brianjohn93961]

I will leave the flywheels until later. At this stage I am not sure what to do but a solution will always present itself eventually.

The bearings supports which were reamed out to 6H7 were sanded down a bit on the flats using a sheet of glass and 600 grit sandpaper until I could pick up the bearings by squeezing the two halves of the supports together with my fingers. The fit is now perfect : this will be my standard method of machining the bearing supports.

I have encountered a problem with parts 8 and 9 : the eccentric and its bushing. The hole in the eccentric is marked as 9H7 on the plans ; it is already drill out to 7.6mm (very strange dimensions…where did they get this from ?) I was worried that drilling and reaming out to 9mm as per the plans would bring the hole too close to the edge. Anyway, I do not have an 8.8mm drill bit or a 9H7 reamer so I left the hole as it was and made the bush to fit the hole, Nothing has been soft soldered yet as it is raining here and I do all my soldering outside in the courtyard.

I am thinking of making this bushing again but a bit larger ( OD 12mm) as there is not much for the M3 X 2mm grub screw to engage with here. Is 2mm of thread enough do you think ?

Edited By Brian John on 22/05/2016 08:08:55

[steamdaveParticipant @steamdave]

Posted by Brian John on 20/05/2016 13:52:02:

I made a start on the smaller parts : more problems here too (photo 2). The bearing mounts are the same as the Stirling engines I have built. They are always a bit small and in the past I have spent ages filing them down so that the 10mm OD bearings fit snugly. This time I drilled and tapped the bearing supports then placed them in the vice to ream them out with a 10H7 reamer…bad mistake. I forgot that reamers are always a bit large so now the bearings pass right through. I may be able to salvage the situation by filing a bit off the flat mating surfaces.

What should I have done to get a good fit for the bearings ?

You could have put a piece of shim brass (say 2 thou) between the faces of the bearing mounts, ream as you did and find the bearing is loose. Depending on how loose the bearing was, you might have been able to put the shim under just one side of the bolting flanges. Now, remove the shims and the bearings will be gripped. In effect what you did by sanding off the faces after reaming. Better than reaming would be to bore the hole; that way you could get the hole 'just right'.

Dave
The Emerald Isle

[Brian JohnParticipant @brianjohn93961]

Does anybody have any idea what this part does ? At this stage I am not actually sure where it goes or what function it performs but I am hoping things become clearer as I make up the other parts. I assumed that ''teil'' indicates that a shallow groove should be cut into the brass part to hold the O ring in place. How would you a drill a hole in the centre of this rubber ''ball bearing'' as per the instructions ?

 

Edited By Brian John on 23/05/2016 10:06:59

Edited By Brian John on 23/05/2016 10:07:40

[JasonBModerator @jasonb]

Part 11 may look a bit lost in your second photo but I think you will find that it follows the profile of the cam as it rotates thus moving the rocker arm up and down

As for the hole, pop the o ring off the outside and push out the ball which will leave you with a ring that can be opened upto 6mm.

This thread may be of use

[Andy HoldawayParticipant @andyholdaway]

Brian, 'Teil' is German for 'Part', so the plan says 'O-ring part 44'.

[Brian JohnParticipant @brianjohn93961]

Andrew : it means '' part, separated into parts, to split or divide ''. Part 44 is the rubber ball bearing on the parts list. I do not know if it is clear on the drawing but it looks like a groove should be cut into the brass ring otherwise the O ring will keep sliding off. I may have got that wrong which is why I made two brass rings, one with a groove and one without. The instructions in this kit are not as clear as the Stirling engine kit.

Jason : The ring of brass is already 6mm… I had to make that part then I cut the groove on the outside with a parting tool so the O ring could be located on it. What I want to know is how to drill a hole in the centre of the rubber ball ? I am not sure how to hold it ; I cannot put it in the vice because it will squash.

Sorry for the confusion.

 

Edited By Brian John on 23/05/2016 12:48:25

Edited By Brian John on 23/05/2016 12:48:40

[JasonBModerator @jasonb]

So thats a 6mm dia rubber ball you have pushed into your brass sleeve with teh o ring on the outside? What size hole do you need to put in the ball, drawing of that part would help.

[Brian JohnParticipant @brianjohn93961]

''The ball bearing (43) is carefully pressed or glued into the bearing ring and screwed onto the slide-valve rod (11)using a model building screw.'' But I know that part 43  is the two roller bearings for the crank supports so there could be a misprint there.

I have drilled and tapped the slide valve rod for an M2 screw as per the instructions but it does not give any further drawings on this. I think I will just have to keep on going and as the rest of the parts are made it may become clearer how this bit works. At the moment I have no idea and drilling a hole in the middle of a soft rubber ball will be a challenge !

MY MISTAKE : I think part 44 is a small roller bearing 7X3X2 (marked as ''ball bearing'' on the parts list : it is actually 6mm OD) and part 41 is grafi-sil ball valve. I think 41 is the rubber ball. I am still confused. Please note that there are no actual ball bearings as we know them in the kit.

I will just keep on going……

 

Edited By Brian John on 23/05/2016 14:03:20

Edited By Brian John on 23/05/2016 14:06:22

[Andy HoldawayParticipant @andyholdaway]

Brian, I haven't seen the plans for this engine, but I read on another forum that the rubber ball sits in the exhaust stack base and acts as a one-way exhaust / pressure relief valve.

Andy

[Brian JohnParticipant @brianjohn93961]

Okay, thanks for the information. There is nothing in the drawings to indicate that but it does mention in passing a ball valve in the exhaust system. However they advise in the plans that the exhaust system should be hard soldered as the heat would melt soft solder and that makes me wonder how this ball will tolerate the heat.

And I am even further confused now about part 11 above if that is not for the rubber ball ?

Anyway, I will just keep moving on. Once I get all the parts made it might be a bit clearer how things work.

[JasonBModerator @jasonb]

Brian

Part 11 is a brass ring with an groove for the O ring to fit around the outside which you have done. Into this ring you press the 6mm OD bearing and then a screw through the bearing attaches it all to the end of the rocker arm (slide valve rod). As the crank rotates the O ring runs against the cam and rotates on its bearing to reduce friction, the cam causes the rocker arm to move up and down and this in turn moves the valve up and down.

[Brian JohnParticipant @brianjohn93961]

Aha, thank you Jason. That does make sense.

But of course the bearing will not fit in the brass ring I have made ! I will try to polish the inside of the brass ring with some 1500 grit while spinning it in a drill chuck. The bearing is exactly 6.00mm OD so it must be very close to going in. I thought reaming it out would have produced a hole slightly over 6.00mm.

[Brian JohnParticipant @brianjohn93961]

Okay, that part is now complete and it can be seen in the photo beside the 29.

I have made a start on the chimney (parts 25 and 26) and I have encountered a few problems. The 6mm copper pipe came already bent but it has not been done well : there is a kink in it. I cannot find a supplier of 6mm copper pipe/tubing to replace this but I already have some 1/4'' brass tubing in my box of bits. My first attempts at bending this were not successful so I dug out all the threaded pipe fittings  I previously purchased from PM Research.

The threaded pipe fittings hold everything in place while it is hard soldered although it does not look as neat. It may look better once it is soldered. I still wonder about the need for hard soldering the chimney as there is a rubber ball inside part 26. One would think anything above soft solder temperature would melt this ball ?

What about that cone shaped part 29 ? Is that strange shape purely cosmetic as the hole goes straight through ?

I also had a problem when making part 26. My boring bar will not go in a 7mm hole so how would you get a flat surface at the bottom of a blind hole ? I ended up filing off the tip of a spare 7mm drill bit and did it that way.

 

 

Edited By Brian John on 24/05/2016 10:21:32

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Edited By Brian John on 24/05/2016 10:23:40

[JasonBModerator @jasonb]

It's a typical exhaust silencer design found on a lot of German engines, in full size it would have been made in two halves from thin sheet so is more just a cosmetic thing in this scale.

Grinding down the end of a drill is one option, 7mm milling cutter another or making a "D Bit" from silver steel is a third option. The main thing is that the ball seals the hole, try sucking air through part 26 with teh ball in place and it should act like a one way valve.

6mm brake pipe from a car shop or 6mm copper from refridgeration supplies should do but not easy to get a tight bend, annealing will help a swill filling with water and then freezing.

[Brian JohnParticipant @brianjohn93961]

Further progress on the chimney has been stopped by an unexpected problem : how do you make the 15 degree angle part (LH side part #29) ? I think some sort of mandrel is required but I really have no idea at this point. I have drilled and tapped all the exhaust parts for 1/4-40 so that everything will screw together prior to hard soldering it.

What about the tank ? I cleaned up the cylinder and the end parts but I had to use a boring bar to trim a bit off the inside rims of the cylinder so that the round ends would fit snugly prior to soft soldering it. Is this how you would have done it ?

[Brian JohnParticipant @brianjohn93961]

Can anybody tell me what parts 14 and 16 are on the burner and where they go ?

[JasonBModerator @jasonb]

Try looking at a few photos on the net it on;y takes a second

[Brian JohnParticipant @brianjohn93961]

Thank you.

I spent this afternoon silver soldering the chimney and the meths tank. The chimney has turned out okay : it is perfectly straight and is perpendicular when placed on a flat sheet of glass. There is nothing worse than a wonky chimney…well, maybe a wonky flywheel ! I  used a mandrel to complete part 29 of the chimney.

I will silver solder the wick socket to the tank tomorrow. Then I will soft solder (243 degrees) the meths plug/bushing and the holding brackets that fix to the bottom of the tank.

I also made the piston rod and the connecting joints as in the photo. I am a bit puzzled about the lubricator (part 24) as the instructions say NOT to use oil on the piston, only a little graphite. Could graphite be put inside this lubricator…I would not have thought so ?

I will be buying an 18mm flex hone (240 grit) to finish the cylinder for this engine. The 18mm flex hone can also be used on 16mm bores so this one 18mm flex hone can do three of the Bengs kits (John, Nick and Sophie).

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[Brian JohnParticipant @brianjohn93961]

I was going to start on the cylinder today but I am a bit confused about something : the holes in photo 1 seem to be at the wrong ends. The six holes should be on the left at the lubricator end because the cylinder bracket (19) goes at that end. The four holes should be on the right at the cylinder head (21) end. Am I missing something here ?

I

 

 

Edited By Brian John on 28/05/2016 10:31:46

Edited By Brian John on 28/05/2016 10:33:01

[JasonBModerator @jasonb]

It is just what is known as "drawing projection" depending on whether the drawing is in first angle or third angle will determine where the end views are placed.

J

[Brian JohnParticipant @brianjohn93961]

Thank you, hopefully I will drill the holes in the right ends

What about that ''shoulder'' on the LH end of the cylinder (20) : it does not look like there are any dimensions for that. I assume that this is not critical or perhaps not even necessary ?

NOTE : This is the largest and most important part of the engine so I have to get this right.

Edited By Brian John on 28/05/2016 14:52:01

[roy entwistleParticipant @royentwistle24699]

All dimensions appear to be there to me

[JasonBModerator @jasonb]

Do you mean Chamfer? if so then its not critical. The 20mm dia by 4mm long spigot is important.

[Brian JohnParticipant @brianjohn93961]

Jason : yes, I need to be careful of that spigot. I might just leave the chamfer for now. It's going to be covered by the cylinder bracket (19) so I am really not sure why it is even there.

Roy : no, you probably cannot see it on the photo but the ''inside'' of the chamfer lines up with the 20mm line but the ''outside'' of the chamfer does NOT line up with the 19mm line.

I still have to work out how I am going to make the cylinder head (21). Ideally this would be made in a milling machine but my options here are a hacksaw or angle grinder/cutting wheel to remove that top section and then tidy it up by polishing on a sheet of glass. The chimney is fitted to the top of this so it needs to be flat and accurate.

 

Edited By Brian John on 28/05/2016 17:37:37

Edited By Brian John on 28/05/2016 17:39:23

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