Spinners Aluminium & Plastic

[Stuart Z]

Hi

Just installing a Saito 82b in a model, my first 4 stroke.  Normally I would use a plastic spinner on a 2 stroke, but somewhere read that’s not good on a 4 stroke.  I bought an aluminium one but the spinner back plate insert needs to be made larger.  Can I used a reamer on it? Not a lot to get hold of to ream it out.

On the spinner itself the prop blade slots need opening up, is that best with a dremel sanding drum or a routing tip?

 

All new to me and can’t find a simple answer- can someone help please.  Is the plastic spinner safe for the job or do I need to somehow modify an aluminium spinner.

 

S

[Trevor]

I’m no metalwork expert, but you can certainly open up the hole in the spinner backplate with a reamer - I use a stepped hand reamer. For the blade apertures, I find a fine fretsaw easier to manage than a Dremel, but others will have different preferences. 

[Glenn Philbrick]

Most of my fourstrokes  have plastic spinners and so far none have been a problem apart from the odd vertical landing. You can ream out the aluminium backplate but I suggest opening up the prop slots with a conventional file as a sanding drum may pick up the soft aluminium.

[Stuart Z]

Thanks Trevor & Glenn, I welcome the input.  

 

No matter how much I build there is always something new to learn. 

 

S

[GrumpyGnome]

Never had a problem with plastic spinners on four strokes......... were you advised by the 'club expert'?

[Nigel R]

Some plastic spinners are too weak to take a starter. Avoid them and you'll be fine. 

[Robin Colbourne]

If you have access to a pillar drill, find a drill the size of the existing hole in the backplate and a drill of the size to which you want to enlarge it.
Use the smaller drill to align the backplate, then clamp the backplate down.  Remove the drill and then drill through with the larger drill.  Better still, enlarge the hole with incrementally with all the intermediate drill sizes you have between the initial and final drills.

With regard to the shaping the spinner itself, either a coarse sanding drum in the Dremel, a rotary burr or a round and half round file will work.  My preferred method is to remove metal from where the prop leading edge goes, so the prop is winding into the spinner as you remove material.  As you are probably aware, you must have clearance (about 0.5mm) between the spinner and prop, otherwise you will get fretting on the prop and the risk of a blade coming off.

If your spinner backplate is lightened with cutouts and has spokes, be careful when applying an electric starter to the spinner, as it is possible to push to hard and distort the backplate.

Edited December 31, 2022 by Robin Colbourne

[Paul De Tourtoulon]

As Robin says, Pillar drill bit by bit, I have gone back too plastic cones after this happened on my ME 109

[Ace]

Paul, that spinner looks as though it's had a hard life and owes you nothing 🤔

[Engine Doctor]

Most plastic spinners seem OK however there are some about that become extremely brittle. They are usually flurescent coloured ones  . Beware. I had one completely disintegrate in flight with only a thin piece left behind the prop washer ! 

The only other problem when using plastic spinners on fourstrokes is the backplate part where it fixes to the shaft. The plastic spinners with an alloy backplate seem fine. It's the other type that are completely plastic that can cause problems with four strokes. Problems arise as four strokes run a lot hotter than a two stroke so plastic backplates can be affected by the heat and props become loose. Horses for courses and all that .

[Paul De Tourtoulon]

No this was it's first plane, and it lasted around a dozen flight days now with a good old plastic one.

 

The problem is with the cones backplate, it is too thin and bends even when you screw the cone onto the centre nut

 it bends.

[Keith Billinge]

Since being put on to them by a clubmate I use Irvine spinners.
They are an aluminium back plate with a nylon-plastic cone.
You can pass a reamer through the aluminium or drill it if needed and they always seem to remain well balanced. I've had bad times trying to balance the cheap plastic spinners and these are a nice product.

You can get all sorts of different sizes and colours too.

 

 

[Paul De Tourtoulon]

I don't like the shapes, no good for my scale stuff,,,

[Ron Gray]

Personally I don’t like using plastic spinners on any of my Laser engines!

[Andy Stephenson]

+1 for Irvine metal backplate spinners but I wish there was a variety of shapes.

[Stuart Z]

Thanks for the continuing input.  Current plan is a 63mm Irvine spinner, found one in the box of "not sure when or why I bought it but glad I did.!"  Probably cruising a model air show dealer tent and putting it in the basket in hope I'd find a use for it.  I have quite a bit of "might need one of them".  

 

S

[Martin McIntosh]

P De T, that spinner looks like a pressed out Traplet one similar to one I fitted to a Laser 180 powered Spit. On an early attempt at a flight the starter broke it up. Luckily I was not standing in front at the time it flew off in jagged pieces.