brison ???
11-15-2017, 01:20 PM
#6
They are probably heading towards extinction one way or another. They have a 3/8 inch diameter crankshaft, Top Flight and Master Airscrew are the only props around with a 1/4 inch diameter hole. It can be opened with a 3/8 counter bore with a 1/4 pilot. Other than that all the 10mm holed props are oversized.Dan
11-16-2017, 05:42 AM
#7
Man, I would never retire a good engine for that. It's too easy to machine up a bushing to center the props!! I have even filled wooden prop holes with epoxy and re-center drilled them with great success. The clamping loads hold the prop; all you need do is center them.
Electric props even come with a bushing set, and at start up an electric motor has more violent torque than a comparable engine.
AV8TOR
Electric props even come with a bushing set, and at start up an electric motor has more violent torque than a comparable engine.
AV8TOR
Last edited by av8tor1977; 11-16-2017 at 05:45 AM.
11-16-2017, 08:35 AM
#8
My Feedback: (19)
Man, I would never retire a good engine for that. It's too easy to machine up a bushing to center the props!! I have even filled wooden prop holes with epoxy and re-center drilled them with great success. The clamping loads hold the prop; all you need do is center them.
Electric props even come with a bushing set, and at start up an electric motor has more violent torque than a comparable engine.
AV8TOR
Electric props even come with a bushing set, and at start up an electric motor has more violent torque than a comparable engine.
AV8TOR
11-16-2017, 01:55 PM
#10
My Feedback: (19)
Hi Dan,
I no longer have access to a lathe so I do a bit of backyard (basement in my case) machining to make my bushings. I make these thin wall bushings from sections of K&S brass tubing. In this case I use a piece of 3/8" ID tubing and chuck it in a drill. The OD of this tubing is about .407" so you only have to remove about .017" of material from the OD to get to the desired 10 MM to fit the props. I simply turn the drill on and use a sanding block to remove a bit of material from the tubing to get down to the desired OD. You can also use a smooth file and finish the work with fine sandpaper to polish the surface. I then use a Dremel cutoff wheel to cut off the desired length of tubing with the tubing turning in the drill. The results are quite satisfactory and look professional.
Certainly a lathe would work better but many of us use what we have to get by when we need a special part.
Don't sell the paper bushings I mentioned earlier short. They only have to hold parts in alignment until the prop nut is tightened and there is no wear on them in any way. I've had them last for years usually getting lost before they show any signs of failure. I use this technique all the time to shim wing dowel holes, wing or canopy locator pin holes, prop shafts, etc. CA hardened paper pretty much acts like bakelite or G-10 as far as wear goes. Acts much the same as phenolic board.
I no longer have access to a lathe so I do a bit of backyard (basement in my case) machining to make my bushings. I make these thin wall bushings from sections of K&S brass tubing. In this case I use a piece of 3/8" ID tubing and chuck it in a drill. The OD of this tubing is about .407" so you only have to remove about .017" of material from the OD to get to the desired 10 MM to fit the props. I simply turn the drill on and use a sanding block to remove a bit of material from the tubing to get down to the desired OD. You can also use a smooth file and finish the work with fine sandpaper to polish the surface. I then use a Dremel cutoff wheel to cut off the desired length of tubing with the tubing turning in the drill. The results are quite satisfactory and look professional.
Certainly a lathe would work better but many of us use what we have to get by when we need a special part.
Don't sell the paper bushings I mentioned earlier short. They only have to hold parts in alignment until the prop nut is tightened and there is no wear on them in any way. I've had them last for years usually getting lost before they show any signs of failure. I use this technique all the time to shim wing dowel holes, wing or canopy locator pin holes, prop shafts, etc. CA hardened paper pretty much acts like bakelite or G-10 as far as wear goes. Acts much the same as phenolic board.
11-17-2017, 09:50 AM
#12
I would recommend aluminum, though there is nothing wrong with the other methods mentioned. If/when you have a bushing made, have them size the length of the bushing to be around .030" more or less shorter than the thickness of your favorite props. That way, the bushing centers the prop, but does not interfere with the clamping force/compression of the prop hub.
If your needed dimensions are going to result in a very thin walled bushing, the brass tubing method might be best. Or, to be able to use a thicker walled aluminum or brass bushing, you could use a prop reamer to enlarge your prop center hole.
There's nearly always "more than one way to skin a cat" if you are willing to "think outside the box."
By the way, the better equipped Ace Hardware stores have bushings and spacers made of plastic and aluminum that are often handy, and can be modified if/as necessary for the intended task.
AV8TOR
If your needed dimensions are going to result in a very thin walled bushing, the brass tubing method might be best. Or, to be able to use a thicker walled aluminum or brass bushing, you could use a prop reamer to enlarge your prop center hole.
There's nearly always "more than one way to skin a cat" if you are willing to "think outside the box."
By the way, the better equipped Ace Hardware stores have bushings and spacers made of plastic and aluminum that are often handy, and can be modified if/as necessary for the intended task.
AV8TOR
Last edited by av8tor1977; 11-17-2017 at 09:54 AM.
12-28-2017, 03:01 PM
#13
WhiteRook , Did you ever find what you needed . I've had many Brisons for many years and the only parts that cant be sourced or fabricated are the crankshaft, rod , case . The crank can be straightened if bent .The bearings can be replace easily with exception to the lower conrod bearings on the twins . The pistons/cylinders are either Sachs or Mahle . Let me know what you need I may have it .
