Has anybody built the flame eater "Nick"?

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Almost certainly not, Brian

... This an ideal job for a boring bar.

MichaelG.

What Michael says, the 7.8mm will just follow the 6mm hole.

Okay, I thought by using a stub drill it might not follow the hole.

But my boring bar requires a minimum 7mm hole.

Poke a 7mm drill through and then use the boring bar, I can't imagine the hole will be so far off that the hole won't be concentric by the time you get to 8mm.

Confession time, the flywheel in the photo that I posted has just a drilled hole. Brian you don't need a split bush in your FW, the reason I use them is that as they are temporary they would require otherwise require a hole to line up for the grub screw to go through. Put in a normal bush with some Loctite (not essential the grub screw will hold it in place). Just as an aside, a bush split as my ones are can be used in a pulley to save cutting a keyway, just make the slit the right width for the key, I have actually used this in full size to mount a sprocket on a 35 mm shaft on one of our Bale Feed Machines with hydraulic drive, it worked almost too well, the machine got a jamb up, and burst the right angle gear box. The bush was mounted with shaft lock, one 3/8" grub screw on top of the key, and another at 90*, through the bush and onto the shaft, a 3/8" square key was used. Ian S C

If I ever get that far, I might drill and tap another hole for an M3 grub screw to go right through the FW and the bush all the way to the crank. The original grub screw will hold the bush in place while this is done.

Edited By Brian John on 11/06/2016 14:19:09

I had go at fixing the wonky those flywheels. One of them I fixed by putting three grub screws at 120 degrees as per Jason's suggestion. That worked well with that wheel and it runs quite nicely now. The other one will require more than that as the hole was not drilled on centre.

This second wheel has the crack in it so no great loss if I stuff it up. I got it running true using the external jaws as before. Then I drilled with a 7.5mm stub drill followed by an 8mm jobber drill. The correct stub drills and reamers are still on their way from China and I am not going to wait another three weeks to try this. I then made a brass bush to fit this hole in the wheel and drilled the bush out to 6mm......no reamer this time. The crank fits nicely in the bush and the bush is a tight fit in the flywheel.

Can somebody explain to me why I now need to split this bush ? I still do not understand that. What would be wrong in using this bush just like it is ?

Edited By Brian John on 13/06/2016 08:38:18

Absolutely nothing Depends how tight it is in flywheel  if any play at all use Locktite ( or similar )

Roy

Edited By roy entwistle on 13/06/2016 08:42:53

There is no play ; as a matter of fact I may have to knock it all the way in with a piece of wood. I Intend to use the three grub screws I have already drilled to press on the bush. I will drill another hole on the other side of the hub to go right through the bush to the crank. I do not think I can redrill through the already tapped holes.

Brian either split the bush so the grub screws will close it up tighter OR leave solid but drill and tap right through flywheel and bush so the screws bear on the shaft.

Do you think I could redrill through the already tapped holes or is that a dumb idea trying to do that ?

Probably safer for you to drill and tap new holes on the other side of the hub, if the drill wanders you could easily wipe out the existing M3 threads

In the worst FW I was going to suggest that you plug the hole after making it well over size, then reboring it to size. You could always go up in size for the grub screw. My grub screws start off as off cuts from the end of over length screws, and most of my FWs and pulleys have 3/16"/ 10 32 UNF screws. The very small ones have 1/8" Whitworth on to as small as 1/8" shaft. Ian S C

I had intended to drill out the holes for M4 grub screws and use a solid bush then I remembered that in order to tap the holes on flywheels I need a special tool. My usual tap wrench will not let me get in close enough. A few months ago I made a brass tool to take M3 taps which can be seen in photo #1 below but I did not make one for M4 taps. (The taps are held in place with M2 grub screws.)  I decided it would be easier to split the bush then to make another tool and I did that using the Dremel tool.

The bush was a tight fit in the FW hole so I knocked it in with a piece of wood remembering to insert the split between the grub screws.

It all looks good but it is a bit tight for the crank ; I can only just get it on but not all the way. I might have to polish (800 grit) or drill (6mm) the inside of the bush to get a better fit. The problem is that using the external jaws as I did to hold the inside of the FW rim, then the jaws are almost fully closed up. The drills cannot be inserted all the way through the FW or they will hit the almost closed chuck jaws ; they only come out the other side about 10mm. A 6mm stub drill would have been better but I did not have one at hand. I have ordered one for future jobs.

I have now started polishing this FW starting off with 120 grit as per Jason's suggestion. It certainly gets the job done a lot quicker !

Edited By Brian John on 14/06/2016 10:28:12

Edited By Brian John on 14/06/2016 10:29:48

Edited By Brian John on 14/06/2016 10:31:42

Both flywheels have now been bushed and polished. It is much quicker when you start with 120 grit ! I am not entirely happy with the FW that has the crack in it. If it did not have a crack then I would give it another light machining but I am worried about the structural integrity of it. Depending on how deep it is, that crack could be why I have had so much trouble dealing with this FW compared to the other one. Anyway, I have a replacement FW on the way and I now know how to machine it. I might even give the face plate another go.

Tomorrow I will hone the cylinder then make a piston to fit.

Good to know the 120g worked for you

It is possible that the flaw extended into where you were drilling the hole and that would have thrown the drill/reamer off line.

Edited By JasonB on 15/06/2016 10:09:40

Brian it's probably better to hold the bush in the vice at 90* to what you have, ie by the ends, then it won't tend to close up as you make the final bit of the cut which if you are using the Dremel would mean a broken disc. My special tap wrench for getting in difficult places is a 4" Crescent spanner. Ian S C

I see your point about how the gap will close up as I get to the end of the cut.

Do you mean just to hold it by the ends but only 1/3 of it in the vice ?

Much like this Brian but with the slot facing upwards

Of course, thank you....I just couldn't see it before. I will do it like that next time.