WTB shaft spacer for props with larger hole

**RknRusty** Wed Apr 11, 2012 2:26 am

My new APC props have a larger hole. Rather than stuff it with fuel tube I would like spacers/adapters.

Would a Medallion .15 or TD .15 drive plate fit a standard Bee crank? If so, that would work, as they appear to have a built in adapter. http://coxengines.ca/cox-.15-tee-dee-medallion-drive-plate.html

WTB shaft spacer for props with larger hole Cox%20015%20medallion%20drive%20plate%201

WTB shaft spacer for props with larger hole Cox%20015%20medallion%20drive%20plate%201

Kim Wed Apr 11, 2012 3:33 am

You might try telescoped sections of brass tubing to take up the slack. They'll align the prop better since they don't flex.

andrew Wed Apr 11, 2012 7:55 am

Rusty --
The holes in the APC prop hubs are not always accurately centered -- they are drilled after molding. However, the recess in the hub is molded and centered. Your spacers should have a shoulder that fits the recess. Some of the APC props shipped with fittings and some do not. Your ideal situation would be to make friends with someone who has a small lathe and turn your bushings from aluminum. You may be able to cobble up a few by chucking some drilled aluminum rod in your drill and working it down with a file.

PV Pilot Wed Apr 11, 2012 8:07 am

Usually the APC's come with plastic spacers in the package. I usually will find the next size down, regardless if one of them goes over the shaft, then I will CA glue the smaller size into the hub, then slowly ream to fit the shaft (I Just want it to slide over the shaft after reaming), and then balance the APC.

I know, alot of extra work, but they spin really nice when they are done that way.

Mark Boesen Wed Apr 11, 2012 8:09 am

Brass tubing

PV Pilot Wed Apr 11, 2012 8:16 am

Tried the fuel tubing spacer trick and if you get some fuel or exhaust residue on that tubing, it can slip on the shaft and in the hub. Makes a horrible racket and not condusive to long crankshaft life.

**Cribbs74** Wed Apr 11, 2012 8:23 am

RknRusty wrote:My new APC props have a larger hole. Rather than stuff it with fuel tube I would like spacers/adapters.

Would a Medallion .15 or TD .15 drive plate fit a standard Bee crank? If so, that would work, as they appear to have a built in adapter. http://coxengines.ca/cox-.15-tee-dee-medallion-drive-plate.html

Rusty,

A .15 or .09 is way to large for a bee crank. APC holes are huge and I am not even sure they would fit on a .15 plate though I could be wrong.

If you can get a hold of some dowel rod of the correct diameter you could just re-drill the center. I think you can even find plexiglass rod. Take a trip over to hobbly lobby. I find lot's of supplies there in the crafty girly aisles.

**RknRusty** Wed Apr 11, 2012 10:35 am

I think I'll try to fit some brass tubing in it. I know I have the right OD. I will have to see if I can step it down with smaller tubes to fit the 5-40 screw snugly. I have some aluminum that might fit over the screw. Or it means another run to the hobby shop. That should get me in the air this Saturday. If the smaller holes are drilled after molding, and possibly off center, then my balanced props are actually not balanced. What a pain in the axe.
Thanks for the replies.

**RknRusty** Wed Apr 11, 2012 11:02 am

I just found balancing and shaft alignment info on the APC site. They say to ream the front(drilled) hole and use metal or fuel tube to align the prop on the engine shaft with the molded hole.

http://www.apcprop.com/v/html/balancing.html

dankar04 Wed Apr 11, 2012 12:07 pm

Mark hit it on the head and keep it simple use brass tubing. I don't know why APC wise up and make props for Cox. Not many small engines on market and new ones are Cox. Millions and millions of Cox engines out there. I think APC's bite and hate them. Ugly / off centered holes.
I know some use them and good luck. Only planes I have are some APC 8/7 for my B-Team racers. Hubs are right size for my Froom 1 1/2" spinners. Flying

Mark Boesen Wed Apr 11, 2012 2:22 pm

looking back I think kim actually mentioned it, APC sells the same thing: 'pre cut' brass sleaves and I think KK sold them as well.

I think most of the 'modern' 1/2a engines use the larger diameter shaft and they probably sell more props for those.

**RknRusty** Wed Apr 11, 2012 2:36 pm

Mark Boesen wrote:looking back I think kim actually mentioned it, APC sells the same thing: 'pre cut' brass sleaves and I think KK sold them as well.

I think most of the 'modern' 1/2a engines use the larger diameter shaft and they probably sell more props for those.

The APC site says they only sell them for the electrics.

**Admin** Wed Apr 11, 2012 3:15 pm

Didn't you get any spacers with your APC? Up at hub hobby, they have a little container hanging by the APCs filled with spacer trees with several different sizes of spacers made by APC. I'll try to run up there later.

**RknRusty** Wed Apr 11, 2012 3:59 pm

Admin wrote:Didn't you get any spacers with your APC? Up at hub hobby, they have a little container hanging by the APCs filled with spacer trees with several different sizes of spacers made by APC. I'll try to run up there later.

That would be great. I was just in the shop trying to cut perfect donuts of 1/4" fuel tube. It seems to fit snug and hold the screw tightly, but it's such a shallow hole, I don't have much faith in it. It did need re-balancing. I wanted to put one on the RR1 but I'm not trusting it that much. I'll try it on an old clunker first.
Thanks Jacob.

stevej Thu Apr 12, 2012 8:14 pm

Mark Boesen wrote:looking back I think kim actually mentioned it, APC sells the same thing: 'pre cut' brass sleaves and I think KK sold them as well.

I think most of the 'modern' 1/2a engines use the larger diameter shaft and they probably sell more props for those.

Those brass ones are no longer available from anyone, as far as I can determine. I'd like to find some. I only have one left.

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WTB shaft spacer for props with larger hole

WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole

Re: WTB shaft spacer for props with larger hole