My prototype whistle heads had cast resin fipple plugs and sounded very sweet and pure.
I tried switching to Delrin plugs for the finished heads, but the tone most definitely loses something… hard to describe really.
It seems very strange to me that exactly the same design would sound so different with just a change in fipple plug material.
I’m going to switch back to cast resin plugs even though they are more fragile than Delrin, but I’m still baffled by the significant tonal difference.
Perhaps it’s because the resin plugs have more density than the Delrin… I really don’t know what else it could be.
Venturing :
- Resin is cast, thus smooth as pure malt…
- Delrin is machined, thus harsh as sour-mash…
?
Gary,
I have a few thoughts. Do the Delrin heads have a similar sound to other heads that use Delrin, such as Burkes? Also, I wonder if the sound has a lit to do with the smoothness (would that be porosity?) of the material. It seems that if you had a very smooth (i.e. Teflon-coated) surface, that the air would flow over the fipple without any disturbance. I would guess that this would lead to a purer and cleaner sound. If the material was very rough/porous, it would disrupt the flow of the air, which would lead to breathiness/chiff.
Just some random, untested thoughts. Don’t get discouraged.
John Mac
Epoxy resin or polyester resin?
One thought:
The loudest, purest-sounding whistle I own is a Copeland D. Delrin block.
I’d rate alo quite high a Parkhurst “quiet” D I recently offred. Delrin block…
My Sindt A/Bb is a lovely whistle; Delrin block and mouthpiece…
How smooth is the surface of your Delrin block ? There must be ways of polishing it, or machining it in a way that if you do get ridges, they go lenghtwise, not transversely.
On 2003-01-17 11:29, Tony wrote:
Epoxy resin or polyester resin?
Polyester casting resin.
I trust it not to be toxic after curing because the packaging showed a fake ice cube with a fly inside as one of the possible uses for it. 
The resin is easier to work with than Delrin too, so it’s not discouraging to have to use it… just puzzling.
Maybe the surface of my Delrin plugs was not perfectly smooth… cast resin is as smooth as glass.
MEK resin hardner is toxic. Since it is a catlyst, it doesn’t change in composition. I would believe trace amounts on the surface can be washed away, not sure on this.
Polyester is brittle and shatters on impact, the acetal (Delrin) is resilient.
Do you think the polyester resonates or transmits sound and the delrin insulates it?
Raindog,
If you can get an acceptable result without using polyester casting resin, I would encourage you to avoid it. Although it may be non-toxic after it’s completely gassed off, the fumes from the fresh resin are toxic while you’re working around it. This may not be at a level that OSHA would recognize as a health hazard, but I’m a firm believer (after having developed health problems from exposure to “safe” levels of industrial chemicals) in keeping exposures to the absolute minimum possible.
Best wishes,
Jerry