Molding a spinner

[Dave Osborne]

Hi.
I am about to attempt moulding my first spinner. My first attempt will only be a static example and I am reasonably comfortable with the theory of the process except for one step, finishing the base of the spinner and truing up.

Even though my first example will be static I think it would be good practice to get it to the same standard as a flying item. Once the laminate has been laid up in the mold and cured there will be some waste material and stray strands protruding out of the mould around the base of the spinner. These clearly need to be removed in a way that results in the spinner having a smooth, flat and true base. One possible approach that occurred to me would be to file and sand the waste material to the same level as the mold (Of course if I have the wrong approach please let me know) but I am cautious about using a permagrit file / sanding to remove material down to the mold itself in case i damage it, as I want to reuse it. the spinner also has to sit true on its base with the apex central etc. What is your advice / best approach?

I have small a lathe if that helps!!

Cheers Dave.

[Peter Smedley]

You place the spinner on a true flat base then run a laser level around it, marking off where the laser pointer hits the base.

[Dave Osborne]

Sorry but I do not see how this works unless you have some more detail. If the spinner base is not true then it will not sit on the flat surface plate correctly and all that happens is the laser scribes a line around the base that is also out of true by the same amount? In effect the laser is scribing a line at a set distance from the surface plate?

thanks Dave.

[Steve Morris]

Once you have laid the spinner up and it has started to go off but is still not fully hard, you can trim the surplus off with a sharp knife. Provided your mould edge is true then the spinner once it is fully hard will be too.

Steve

[Phil Clark]

I always make the 'pattern' longer than the finished spinner, then when it's still in the lather, scribe a 'cut line' into the surface to leave an overhang of anything up to an inch on big spinners (I've moulded spinners over 8" diameter using this method). Once moulded, this will show as a ridge on the inside of the mould which in turn will leave a shallow groove in the final moulded part. Once removed from the mould, run a diamond wheel (in a Dremel) around the groove to trim off the excess, then finish off with a light rub on a sheet of 120 paper taped onto a flat surface. This prevents any damage to the mould and leaves a perfectly flat rear edge.

These photos of a 1/6 Ta152H spinner I did for a customer last year show the basic idea.

Phil

[Dave Osborne]

Thanks for th advice. Nice spinner Phil.