Spinner Problem

I know this is a rather mundane issue for most of you, but I have no idea on how to cut out the grooves for this spinner I have. I thought it was pre cut, but unless you have the worlds skinnest props...

Anyway, the back plate is aluminum, and the cone is a hard plastic. How am I supposed to cut/shape this stuff? Seems like a tough (and dangerous) job for an exacto knife.

I have most hand tools and a dremel but that is about it.

Be careful whilst shaping it with your exacto. Yes, that's what you do. A file also might work. You want the plastic spinner not to be in contact with the prop, but to have a minimum of clearance.

DREMEL TOOL with a rasp on low setting and TAKE YOUR TIME!.

Scott(do two)Riese

LAST EDITED ON Jun-06-04 AT 12:36 PM (CDT)
 
I would never use a knife- you can slip and cut the BLEEP out of yourself- the spinner cones are hard to hold. Use the Dremel and appropriate cutting/sanding bits until you get close (try/fit constantly and take off a LITTLE at a time), finish with jewelers hand files and fine grit sandpaper if and as needed. That is why they make them power tools for to begin with!

Jake

And, of course, once you have it shaped, re-balance it.

I have to agree with Jim T.--- sharp Exacto knife, carefully of course.

>I have to agree with Jim T.--- sharp Exacto knife, carefully
>of course.

No thanks, been there, done that. Power tools is the only way to go.

Jake

Care to guess how big of a gash an Xacto #26 blade can make? (ask me how I know)

>Care to guess how big of a gash an Xacto #26 blade can make?
>(ask me how I know)

In metric or English, Steve?

I didn't know there was a metric measurement for the gnashing of teeth and blue clouds of smoke which followed my "slip".

Strangely though, I've suffered far more greivous injuries from screwdrivers (make dandy puncture inflicting devices), hammers (obvious) and my favorite weapon - pliers. I can't count the number of blood blisters I've encountered from the nasty bite of a cheap set of pliers. Needle nose seem to be the worst offenders.

I do believe that in this thread is the very first mention I have seen on this site of balancing spinners. Strange.

And I note this caution applied to spinner cones which have been relieved for a specific prop, hand-jive methods assumed whether with a knife or a hand-held grinder.

I submit that all spinner cones and back plates need to be at least checked for balance. And that in many cases those turned-from-bar spinners and related parts are the worst offenders.

You might mount the spinner to a wood block and put the block in the vise or clamp to your bench. That gives you two hands to manipulate the Dremel, file, or knife. This is easy if your part has a spinner nut, not as easy if it has two small screws, and a pain if it is a Goldberg snap-on type. I recently cut a GZ .049 aluminum spinner. These are small, and come with NO cutouts....

This is all well and good, and I agree that Xacto knives coming out of an almost inpenatrable material tend to go deep into penetrable material, like thumbs.

Doesn't matter, the question wasn't what with, but HOW. Other than just gouging and grinding away till it fits. It's an art, don't look at mine for proof, but lets get a methodology going here on how to do it well. APC can cut you a hole to fit your prop, what do we have to do?

Now other than marking a blank spinner at 180 degrees apart or 120 for a 3 blade, then how do you mark the blade location. I've thought about stretching a pop bottle over the in question spinner, than mounting that in place with a prop cut to fit inside the dummy. Mark an 1/8 of an inch around the blades, then re-attach the clear dummy to the real deal. Then start grinding. Balance and it should fit.

But that pop bottle cowling trick is recent, so how did they used to do it? I have an old spinner that simply has square cutouts up to the prop, looks pretty cheesy but it answers how one person did it at least, and it did balance, weird but true. Heck, I always put the heavy side with the heavy blade and mount it away from the piston on my Foxes. With luck, you can get a pretty smooth running Fox.

So, TECHNIQUES fellas, whatcha technique?

Technique?

1. Wrap spinner with white electricians tape to protect "new" look.
2. Collect all props you plan on flying.
3. Measure hub thicknesses of all props in (2) above.
4. Mark depth of cut on spinner of thickest prop plus .03." Remember to account for the backplate if the spinner overlaps it. A Sharpie fine point pen works well for marking.
5. Look at blade root shapes of all props in (2) above.
6. Either eyeball or make template of the "fattest" root profile. I used card stock. Bill's clear plastic seems like a much better idea.
7. Transfer profile to spinner on one side. Use divider head to transfer leading edge of first cutout to opposite side and mark leading edge.
8. Determine if the spinner should extend behind the propeller or if the cutout at the leading edge should simply extend straight back. Repeat 5, 6, and 7 for the aft face of prop if you want the spinner to conform exactly to the prop shape.
9. Cut using methods that are appropriate for you. (Tools you have; acceptable safety margins.) Remove material until you are fairly close to layout line and then fitcheck and continue trimming. Trim until you have a uniform clearance. Suggest .03" minimum.
10. Break sharp edges and deburr.
11. Fitcheck all props listed in (2) above. No rubbing allowed on any surface of any prop. Rework as required.
12. Check balance of spinner and backplate. If backplate is not uniquely indexed, check backplate separately. Rework as required. Deburr.
13. Polish and/or wax.
14. Install.
15. Test at maximum rpm.
16. Declare victory. Put away unused bandages. Build new plane to match spinner.

LAST EDITED ON Jun-09-04 AT 02:08 AM (CDT)
 
(snip) Heck, I always put the heavy side with the heavy
>blade and mount it away from the piston on my Foxes. With
>luck, you can get a pretty smooth running Fox.(snip)

Ron B.
F4Fguy

Yeah,it'll run pretty smooth,for a while,if you don't care how long the main bearing lasts.Counter balancing opposite ends of a shaft gives a rocking couple which loads the already marginal Fox front bearing front and rear.Far better is to properly balance the spinner and prop and statically balance the shaft + about 1/2 the weight of the conrod.
Very aproximate,but about as good as needed.

As to the spinner cutouts,make a template by cut and try or,better yet with a transfer guage.Apply masking tape to the outside of the base of the spinner.Use the front edge of the existing cutout as a reference mark,and trace the template outline onto the masking with a sharpie extra fine pen.Whack out the offending material with your weapon of choice.BALANCE the backplate and spinner,backplate first,then the spinner cone assembled to it.

I seem to have inflicted the worst damage whilst building planes too - I have renovated houses and come out less broken.

Second worst was putting a screwdriver right through the webbing of my thumb and pointer finger while opening a can of paint for a plane (my mother was a nurse and even she flinched when she saw that one).

The worst was as I was packing up my heavy soldering iron after soldering up a fuel tank. I was holding the metal part of the iron winding the cord round it when I smelt this plastic burning smell and realised that the cord was melting - and that it was still plugged in and turned on. Luckily the burns pretty much completely healed with no loss of finger movement, but I was a mess for a while.

What is a "GZ" spinner? Where does one get one? THANKS!

<I recently cut a GZ .049 aluminum spinner. These are small, and come with NO cutouts....
Dave
LA_Flyer>

injunnut,

You can get a GZ spinner here..
http://home.earthlink.net/~whizzz/

They carry the CS line of engines. The spinners they have for 1/2a's are really nice. Only bad part is they have no cut outs and you have to make your own hardware to mount them.