Making a spinner by "spinning"

[JulianJ]

Thanks Dave, that's really useful to know, looking forward to trying it out!

Posted by dave windymiller on 22/05/2018 17:33:24:

The cyno is enough as long as there is enough area. My 3" spinner was held perfectly well by a 2" dia face taking a maximum of 20 thou (0.5mm) off each cut. Dont let the parts get too hot.

I used a very thin cyno and made sure the parts were well forced together as it set.

Cheers

Dave

[dave windymiller]

Final push

I attach the prop to the back plate so i can mark off the blade positions. An old crankshaft is useful here.

Mill out slots to miss the blades (not too wide, enough to clear the blades with say 1-2mm gap.  This can be done on a lathe quite easily!

Once the prop fits the back plate, cut out the spinner to miss the blades with a small gap. I find an old prop with one blade handy here. Once the cutout shape is good trace it and use the shape for the other cutout(s).

Note the cut out has to be big enough (underneath the blade) to allow the spinner to fit without angling it.

Once the backplate, prop & spinner all fit together, i make a reference mark on both backplate and spinner so these always align.

To fit the screws I drill through both components with the tapping size. Im using m2x5mm CS screws four of between each blade. Drill at the right angle so the screw head is flush to the spinner. I have used an m4 rod to hold the parts tightly together, we dont want them moving.

Open up the holes in the spinner to clearance holes and countersink to suit the screws.

The end result! If made accurately, it shouldnt need balancing!

Im sure there are other more scales ways of attaching the spinner rather than screws but this works well and can withstand a starter motor no problems.

I have never found a need to add grips/nurling to stop the prop rotating on the back plate on a 2 stroke. A 4 stroke may be different.  Just keep an eye to make sure things stay aligned and check the screws stay tight. A mild thread lock may be necessary on the screws if they undo although i have never found this.

 

I wouldnt bother with all this for a sports plane, its so much easier buying a spinner. For non-available spinner shapes for scale planes it certainly works if you have the patience and is rewarding to do.

Fee free to post any pics of spinners you make on here!

Now back to finishing off the ME109

Dave (Windy) Miller

 

Edited By dave windymiller on 26/05/2018 21:03:32

[onetenor]

Windy what about closing the hole in the middle?

[dave windymiller]

ME109 had a cannon in the centre. I discuss this earlier in the thread.