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BobH

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  1. BobH

    Buma Boring Bar

    Hello, Thanks for your reply. The number on mine is 5080, and it's an A.P.M. model like yours, so one of the later ones I think. There's one on Ebay at the moment in Northern Ireland, and that's blue like mine. However, there's also another one advertised on Ebay that doesn't look to be in very good condition. It's green and has a plate on it saying it's the AU model and the number 631. It's also got a very odd looking cutter mic, so I guess different models had slightly different cutting methods, and different colour schemes to help identify them. I must say I prefer the bright red of yours to the rather washed out blue of mine, but I wonder if they changed the colour scheme to prevent confusion between their tool and the American Van Norman boring bars which are also bright red. Regarding the Rotax barrels. They are off a converted snowmobile or hovercraft engine that was used to power one of my microlight aircraft. The particular pair of barrels I've been playing with both had broken exhaust manifolds, so I decided to use them as practice bores as I don't have any aluminium welding kit to try and weld the manifold castings back on. Even if I did get them welded the face of each manifold would then have to be machined back exactly square to the original angle so that the exhaust header could bolt to it successfully. As it is I now have something to practice on with my boring and honing equipment, and I've got another spare engine sitting in the garage should I need it, so no great loss to the microlighting world. I've attached some photos of the engine before the manifold castings broke away, so that you'll see where the barrels came from. The first photo shows the other side of the engine, but gives you a better overview of what the engine looks like in situ. Lastly, I've put two photos of the plane after it's had a clean. The last of those two shows the plane ready for me to go off on a flight, with a jerry can full of petrol strapped to the back seat as a backrest, and as a 20ltr supplementary tank to the 47ltr plastic tank that's fitted under the engine. This means the plane could theoretically fly with just me in it for just under 8 hours, at around 50 - 55mph, although I'd have to land after a while to top up the main tank from the jerry can. Also, my bladder wouldn't last that long, so I'd have to land anyway at regular intervals. :-)
  2. BobH

    Buma Boring Bar

    Mister Mad Mower 2, Thank you very much for your reply to my questions. Since posting them up I managed to find someone who had an imprint of the Buma Operator's Manual, so I bought a copy and have it sitting in my garage, alongside the boring bar. Having figured out how to make it all work I was then able to sharpen one of the tools, and adjust the micrometer to get within a couple of tenths of a thou accuracy when setting the tool to cut a particular size. I practiced my reboring skills by boring out two barrels I had sitting around, and have practiced honing them as well with the two kits I bought (one from India and the other from America). I've attached some pictures to show you that underneath all the grime the old girl wasn't so bad after all, and there are a couple of photos of one of the bores after I'd bored and honed it to a nice criss cross finish. The only thing is that the new stones chattered a bit, so I'll have to dress them back a bit to stop that from happening in future. By the way, your restoration of your boring bar is stunningly good. I'll never manage to emulate that, but after a good oiling and some slight adjustment of the Allen bolts on the main bar clamp I've managed to set the bar to move smoothly up and down almost to the very limit of it's downward movement. I've put a new drive belt on it as well, and I also found that the metal springs that are supposed to hold the centring fingers were like worn out knicker elastic, so I've used a narrow gauge elastic cord instead. It does the job, and doesn't present any problems. It's also easy and cheap to replace if it breaks, as I have a long roll of it in my garage. So I've now started advertising my services on various forums for others who share my hobby of flying around in microlights. I've also advertised on a classic car site, but I need to start advertising on classic motorcycle and scooter sites, and I also need to make up a clamp for attaching the boring bar to car engine blocks. The clamping mechanism I used to use on the Van Norman boring bars I used when I was a full time engine reborer aren't the same as the design for the Buma, so I'll have to see if I can get one or two made up so that I can bore out anything from a Series A engine to a V8. I'll have plenty of time for this though after the end of April when I retire from my current job. So I'm looking forward to spending more time in my garage this coming summer, and fully re-acquainting myself with the finer points of boring and honing various sized cylinders, both 4 stroke and 2 stroke. While I'm at it I also hope to recondition some cylinder heads as well. I've got hold of a valve seat grinding kit almost identical to the one I used to use in the motor trade, and I've also got a valve cutter that can recut the seat on the valves. All I need for that is a new pair of drive belts, as it uses two of them to gear the speed of the valve spinning motor down. The trouble is they aren't like V belts, but instead are flat, like a piece of inner tube, and I don't know if I'll be able to get them, as the apparatus is quite old now. I'll have to Google around to see what I can find. Once more, thank you for taking the time to reply to my questions, and I hope your boring bar will prove to be as useful to you as I'm hoping mine will be to me. Best regards, Bob
  3. BobH

    Buma Boring Bar

    Mister Mad Mower, Hello, I've just joined this group so that I could contact you. I've recently bought a Buma boring bar like yours and I'd like some advice/information if that's OK?. It came with all the tools, etc, but when I was in the motor trade 50 years ago I used to use a Van Norman boring bar and many, if not all, of the controls are quite different. I managed to figure out that the left hand thread screw item on the left of the bar (as you face it) is the lock for the screw drive to make the bar descend through the cylinder. However, there's also a similar arrangement at the top of the bar, and I haven't yet figured out what that one does. I also have no idea why there's a spindle sticking out of the left hand side of the unit that looks very like the one that the bar winding handle uses on the right of the unit. Furthermore, you mentioned a quick release for the motor. I haven't yet spotted that, so would be grateful for any photos of that item as well. I've attached some photos of the unit I've purchased, and included a photo of the jig it came with, that's used for holding the cylinder that's being bored. Best regards,
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