Has anybody built the flame eater “Nick”?

[Brian JohnParticipant @brianjohn93961]

Roy : yes, I will.

The soldering on my crank has not held and it all came apart. I am not sure what went wrong here. I can soft solder brass to brass or copper without any problem but brass to silver steel is not working for me. I will have to start again from scratch.

I attempted to make a new base plate and after VERY carefully measuring and marking it out, I proceeded to drill with a 1.6mm drill bit. The drill bit snapped off in one of the holes (top LH in photo). I then tried to dissolve the drill bit by placing the work piece in an Alum solution. I put it in a Pyrex bowl which I was heating on a portable gas stove when the Pyrex dish exploded ! I was lucky I was not injured as this thing went off with a bang.

I thought you could heat Pyrex directly with a naked flame but obviously I was wrong. Didn't we heat up chemical solutions at school in Pyrex beakers over a Bunsen burner ? Or was there an asbestos pad in there somewhere…I cannot remember ?

All in all, a very bad day. Next time I drill with a small drill bit I will use a drop of tap magic in each marked dimple. I just hope I can save this work piece somehow. I am not in the mood to make a third one.

UPDATE : I now know that there is Pyrex used in laboratories and there is Pyrex used in kitchenware. They are NOT the same product. Today was a lesson in what NOT to do !

Edited By Brian John on 02/06/2016 10:07:36

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[JasonBModerator @jasonb]

Brian have you seen this build of Nick?

German

Translated (hopefully)

[Brian JohnParticipant @brianjohn93961]

Thanks Jason, that will be useful. I notice that he machined the flywheels by holding them in the chuck by the inner rims. I might give that another go. I was getting nowhere with the face plate.

I have worked out how I will do the crankshaft : rather than cutting the short shank exactly 16mm and trying to solder that in position, I will cut it oversize (26mm) so that I can solder from the outside then cut of the excess later.

I will give the Alum another go on the aluminium base plate but I will let it soak at room temperature in a glass jar ; it will probably take a week or so to disolve the broken drill bit…maybe even longer.

Edited By Brian John on 02/06/2016 12:32:39

[Ian S CParticipant @iansc]

I would have though that by solder for the crankshaft, it would actually mean silver solder, ordinary low temperature solder/plumbers, electrical solder is not much use for any joint that has any stress. You would get a stronger joint using shaft lock adhesive. Ian S C

[Brian JohnParticipant @brianjohn93961]

In the instructions they actually warn against using silver solder : '' Do not hard-solder the crankshaft !!! Distortion !!! "

I was surprised as I did not think silver solder would be a problem.

I am going to use high temperature (243 degree) soft solder this time.

I am still toying with the idea of drilling right through the crank plates and the shafts by drilling and tapping for M3 grub screws and holding everything in position that way.

Edited By Brian John on 02/06/2016 13:19:24

Edited By Brian John on 02/06/2016 13:24:12

[Brian JohnParticipant @brianjohn93961]

I had another go at the crankshaft today using lots of 243 solder…probably too much. But everything held together this time. I think I let the flame linger a few seconds too long ; I should have removed the heat as soon as I had a nice fillet of solder around the joins. I am still getting used to my small burner which I use for soft soldering. It produces more heat than I expected.

I put some flux on the inside of the holes on the crank plates before sliding them onto the shanks hoping that some of the flux would stay inside and not get removed in the process. I put most of the flux on after everything was placed in position : lots of flux on the outside of the crank plates for the short shank and lots of flux on the inside of the crank plates for the long shank as these are the parts to be removed later.

I tested it in the lathe and it  runs true…all good.

NOTE : if anybody is looking for Alum powder for removing broken taps and drill bits then ask at your nearest Indian grocery store (fatakdi powder).

Edited By Brian John on 03/06/2016 09:54:55

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[Brian JohnParticipant @brianjohn93961]

Is this a safe way to grip the flywheel by the inside rims using the flat of the external jaws ? It seems to be the only way I can get the wheel to run true. I only want to drill the centre hole before putting it in the mandrel.

 

Edited By Brian John on 03/06/2016 12:47:11

[JasonBModerator @jasonb]

It's probably as good as you are going to get. Watch out when with drawing the drill as that is when it may try to pull the flywheel out of the chuck, the rest of teh time the forces will be pushing it into place

[Brian JohnParticipant @brianjohn93961]

Is it more important to get the out rim running true than the hub ? Ideally, both should be running true but if not…?

 

Edited By Brian John on 03/06/2016 13:30:50

[Andy HoldawayParticipant @andyholdaway]

Brian, bearing in mind that I'm a rank beginner at this, I would have thought that with your flywheel mounted as you have it you could drill the centre hole and machine the outside rim and face of the flywheel at the same time, then turn it round to do the other face. That way the centre hole and outer rim would be concentric.

Andy

[JasonBModerator @jasonb]

Inner Rim as true as possible

As Andrew says if there is room bring up the tailstock ctr for support once teh hole is done then turn the outside or at the very least rough it out.

[Brian JohnParticipant @brianjohn93961]

Well it was all going well and I was getting down to the polishing stage of the first flywheel when I noticed a crack. (photo 1). So I put that to one side and moved on to the other flywheel. I held it in the jaws as previously discussed to take a facing cut on the hub then drill and ream the centre hole. Even this caused problems because the lathe jaws are almost completely closed hence stopping the reamer from passing all the way through. I ended up finishing the reaming on the drill press later. I then turned the wheel over to take a facing cut on the other side of the hub. But for this second wheel I decided to use a mandrel from here on to machine the rims and outer surface (photo 2).

I do not think it is safe to do any more machining on that cracked flywheel. I really hate machining cast iron flywheels : they always seem to give problems that I never have with brass flywheels. On my lathe I can only take 0.1mm cuts at a time on cast iron so it takes forever. I can never get a decent finish like I can with brass so I have a big polishing job ahead of me tomorrow on that second flywheel.

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[Ian S CParticipant @iansc]

Brian, I don't think I wouldn't worry too much about the crack in the hub, some filler, and a coat of paint should fix it.  Its not highly stressed on a motor like this.   Ian S C     

Edited By Ian S C on 04/06/2016 10:52:45  I,m having problems getting this post to post up!

Edited By Ian S C on 04/06/2016 10:55:47

[Brian JohnParticipant @brianjohn93961]

Ian : I was not quite finished machining it and I am not keen on doing that now. I might try polishing it up in its present state and see how it goes after I finish polishing the other flywheel.

I made a start on polishing the good flywheel today but after a few hours I decided to do something else : soldering up part 19 (cylinder bracket).

I made a up a spring as per Jason's link to hold it all together but it just would not sit right. A closer inspection revealed that the left hand side recesses were not machined as deeply as the right hand side. I did what I could by rubbing it along the edge of a large file but decided to hold everything together during soldering by using pieces of brass. The brass cylinders were all oiled to stop any excess solder adhering to their surfaces.

I used 243 degree solder (photo 1) along the bottom surfaces before cleaning in the pickle. Then I cleaned up the brass again to solder the rest of it using 188 degree solder (photo 2). I had to use a 3mm drill bit to remove a bit of solder so that the M2 socket head screws would sit flat (photo 3). The finished product is in photo 4. I did think about using small pieces of brass angle to reinforce it all but there is nowhere to put it. On the inside it would block the insertion of the M2 screws and on the outside it would block the screws for the bearing cases (part 13) so in the end I had to let that idea go.

Edited By Brian John on 05/06/2016 10:09:34

Edited By Brian John on 05/06/2016 10:11:09

[Ian S CParticipant @iansc]

Make sure that the solder flows through between the bits of metal, and you don't rely on the fillets of solder, these have little strength. If I was building this motor myself, I'd probably make the frame from steel, and either drill and tap, and screw it together, or weld it, but that's just me, I'm a bit worried that the solder will let go after a while with the vibration of the motor running, and depending on the heat of the motor it might not be too long, it didn't take long for the steel fins on my motor to go blue with the heat, far above melting solder. Ian S C

[Brian JohnParticipant @brianjohn93961]

I agree, that is why I tried to get some brass angle in there so I could screw it together but wherever you put the brass angle then it will block something else so I had to give up on that idea. These parts which are 2mm thick should have been made much thicker for the reason you have given : 4mm would have been good.

Í will have another look it and see if I can come up with an idea. I did briefly think of using silver solder but I thought the extra heat may distort the plates.

Edited By Brian John on 05/06/2016 11:54:44

Edited By Brian John on 05/06/2016 11:57:57

[roy entwistleParticipant @royentwistle24699]

Brian Did you tin the parts to be soldered together before joining them ? There is usually very little fillet with soft soldering

Roy

[Brian JohnParticipant @brianjohn93961]

No Roy, I did not tin the parts but I did use plenty of flux. Had I tinned the parts then they would not have fitted together properly. Do you think I should I do this again ?

The guy in Jason's link used solder paste for this. Would that be better ? The paste looks very useful as there is a huge difference between the initial melt temperature (221 degrees C) and the remelt temperature (343 degrees C). Had I know that then I would have used it.

http://www.ebay.com.au/itm/Silver-Bearing-Solder-Paste-7-1-Grams-/361522693893?hash=item542c6e8705:g:wTcAAOSwvg9XUUfH

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[Ian S CParticipant @iansc]

A good joint even if not tinned should when the solder is feed in one side should flow through the joint and be seen on the other side. Heat one side of the joint, feed the solder in the other side, it should flow to the heat. I do most of my soldering on this sort of stuff with a large (I think about 2lb) soldering iron heated with the gas torch, if you don't have one(or two) of these irons, use the torch. Ian S C

[Brian JohnParticipant @brianjohn93961]

I use a small torch for soft soldering.

If I were doing this again I would dispense with the supplied base and sides : I would attach a piece of my own 19mm brass angle to the main bracket using two M2 socket head screws and four M2's down into the aluminium base. No solder required and no risk of movement or failure. I will think about this overnight.

Edited By Brian John on 05/06/2016 14:44:09

[Neil WyattModerator @neilwyatt]

I think you've done a nice job of that bracket, myself.

Neil

[roy entwistleParticipant @royentwistle24699]

Neil All due respects but does Brian know that the solder has penetrated the joint ? If there wasn't a fillet he should be able to see it

Roy

[JasonBModerator @jasonb]

Brian, I use the soft solder paste for certain jobs and it works quite well (no tinning required) but do watch out as the fuux can be quite corrosive if left on the work particularly on steel.

[Brian JohnParticipant @brianjohn93961]

1. I re-read the instructions today and they do not specify soft or hard solder for part 19. For all other parts they are quite specific eg. crank shaft must be soft soldered and exhaust system must be hard soldered. I wonder if the cylinder bracket should be hard soldered ? I would have thought 2mm thick brass would warp with the extra heat. Anyway, now I have bigger problems…

2. I spent all day polishing up the good flywheel without the crack in it then I remembered that I had not drilled and tapped for the M3 grub screw. So I carefully placed it in the machine vice, protecting the polished surfaces with strips of thin copper sheet. The drilling and tapping went well so I checked put the flywheel on the crankshaft by placing it in the lathe…it wobbles ! It runs perfectly well on the mandrel but it wobbles when I put it on a 6mm axle. I really do not understand what is going on here. I have used these steel mandrels to machine about 15 aluminium and brass flywheels with no problems so the mandrel cannot be at fault.

What went wrong to avoid such problems in the future and what to do about it now ? I drilled the holes to 5.8mm and used 6mm reamer as per usual.

[JasonBModerator @jasonb]

Brian could be a number of things

Hole in the flywheel a bit oversize, different material can give different results when reamed

Mandrel not set true when you put it in the lathe, its usual to true up a mandel each time it is fitted into a chuck as they are not accurate enough to hold the mandrel true each time.

Grub screw tilting the flywheel

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