Actually that part IS plastic.

It's the Delrin shoulder washers used for isolating the connectors and their diameter is virtually the same as the diameter of the through holes that the connectors are protruding through.

I could have just mounted the RCAs without them but the diameter of the shoulder on the shoulder washer was 3/8" and the diameter of the threads on the RCA were some metric dimension so I just made it simple and drilled 3/8" holes.

se

Anyway-- it looks like a great product so far.

I'm making one more headphone amp that runs at about 70V (little steps for me), then it's time to move up to the real stuff so I can see what all the chatter about MQ iron is all about.

Basically like a hot glue gun except you use hot plastic, yes?

SE --- Copper would be cool!

*grumble* *grumble* *grumble*

se

Oh! Hehehe. Ok. I thought you might have been talking about a different photo that was of a walnut case without any top or bottom and you could see the edge of the maple piece.

Anyway-- it looks like a great product so far.

Thanks! Now just have to work on something to put INSIDE it.

I'm making one more headphone amp that runs at about 70V (little steps for me), then it's time to move up to the real stuff so I can see what all the chatter about MQ iron is all about.

You're a braver man than I. I'm a big pussy when it comes to high voltages. However now that Mike's starting to develop some line level trannies I'll be able to use some MQ iron in spite of that.

se

As someone had noted, Teflon is very easy to machine when using a razor sharp end mill. Delrin is even easier to machine, and machines more accurately, but requires a bit more deburring in most cases. But unlike some plastics, both these plastics can be very easily deburred by lightly scraping the edge of a stainless steel 6" scale over the burr. PVC is brittle, and more difficult to deburr. There are many different Nylons available, but the common type 66 is easiest to work with.

The feasibility/possibility of laser cutting plastics was mentioned. What you'd want to use is abrasive water jet cutting, where a fine garnet oxide abrasive is fed through stream of water under tremendous pressure. It cuts plastic like a hot knife through butter, and leaves a very clean edge except for the entry/exit point.

For scratch resistant clear plastics, nothing beats Lexan polycarbonate. But unlike acrylic monomers (Plexiglas, Perspex, Acrylite, Lucite), any scratches cannot be polished out very easily at all. Scratches will come right out of Plexiglas with ease using Novus plastic polish, which is hands-down the best polish available.

I used to machine 12" long bevels on these 18" wide, 2" thick Plexiglas plates, that had to be scratch-free, crystal transparent across the entire 12" x 18" area when done. I used some progressively fine sanding discs on a hand sander to work out the flycutter marks and then the coarse sanding marks, then I went to some jeweler's rouge on a cotton buffing pad to get a dull shine. Finally, I went down to the coarse and fine Novus polish on cotton pads. It looked absolutely perfect when I was finished. They had used jeweler's rouge in progressively finer grades on the original prototype part, but it proved less than satisfactory. I recommended the Novus polishing system, and that made all the difference.

I'm also a welder, with 2 years of welding school, and some 24 welding certifications, but quit work as a welder years ago. Plastic welding was a subject in welding school. I was even offered a job welding plastic once at a company that made machines to deflux PC boards after soldering. Very few thermosetting plastics can even be welded successfully, and polypropylene and polyethylene are definitely the easiest, best candidates. The weld is performed using a heat gun and a filler rod, just like oxyacetylene or TIG welding, except there is no actual molten puddle. The plastic is just heated to a semifluid state a little below it's scorch point, and the rod laid in in a continuous bead.

Thermionic

The huge gear with the four holes cut in it (on the waterjet cutting page) was done for the tool and die shop I used to work for. The gear was actually a scrap piece that we had; the four round plates were our actual parts to do the job. The gear just happened to be the right thickness of material.

Thermionic

• http://acccutting.com/

msl

Here ya go.

se