I’m looking for plastic billet (if that is the term. Looking for low quantities of about 15"x15"x1" of high flexural models plastics that are easiest to machine. I’ve not worked with plastic before so the cheaper the better as I learn. I’m making outrigger feet for my floor standing speakers as the first project (hence the need for strong/stiff. Thanks!
Patrick
Hi Patrick,
I’d check McMaster Carr. They sell all kinds of different materials.
As Enginerd indicated, McMaster Carr is a good source. Something like this perhaps?
https://www.mcmaster.com/vibration-damping-sheets/water-resistant-rigid-sound-absorbing-sheets/
No idea how it might machine but it does indicate it is rigid material.
Hey Patrick, I was going to make outriggers for my uber heavy towers too but opted instead to make plinths with thin sound isolation material like “Second Skin” between the tower and plinth. It provided a really clean look that accents the maple subs sitting next to them.
I can pm you a picture in the case your are interested about aesthetics like I tend to be. (I cut the plinths on my 1F)
Send the pic! I’m always interested in new solutions. I was going with outriggers since I have cats, but I’m not in love with the look.
Here is a pic of one of a speaker and it’s plinth. Between the two is a thin layer of sound absorbing material though it does not look like it in the picture. I recessed the plinth’s pocket for the material just a tiny bit so it the gap almost disappears. The speakers are bolted through the bottom of the plinth so I oversized the bolt holes then used large fender washers with the same sound absorbing material under them so the bolts were isolated as well. Note also, there is a small air gap between the side walls between the plinth to speakers as well so there is no contact between the two.
I have a friend who is a partner in a high end speaker company that gave me guidance on how to improve the sound performance of the speakers. After the modifications I was completely satisfied with the sound improvement.
The plinth design was done on Vcarve Pro and, luckily, the two sided carve worked perfectly the 1st time. (a triumph for me)
Patrick,
Go to Walmart and buy their cheap plastic cutting boards. These come in various sizes and are GREAT for learning how to cut plastic without breaking the bank.
Or save milk jugs, cut them into pieces. Shread them with a blender or tree branch shreader. Then put those pieces in a mold in the oven (at 200° IF I remember right) and you can make bricks of whatever size you want.
Pony
Hey Pony, hey all,
I would pay attention to what material they are made of. I got one made of HDPE which is an excellent material. Not as cutting board, because it started to smell bad after getting cutting grooves from the knives despite being cleaned in the dish washing machine (wooden boards did not), but the material is 100 % recyclable in that you can just melt it down.
Same for milk containers, look at the material icon, many are made of HDPE
Image from Wikipedia, the free encyclopedia
Thanks! Cutting boards are a great idea!
That looks really nice. I like that it adds weight down low. How thick is the plinth?
It does add a bunch of weight which makes the towers incredibly stable.
The plinths are made from 2" thick maple butcher block left over from the equipment rack I’d made for my system.
Here’s a decent source I found if you’re in the US and want specific sheet sizes.
https://www.tapplastics.com/product/plastics/cut_to_size_plastic/hdpe_sheets/529
Cutting boards are definitely cheaper!
Granger is a good supplier too.
Do they sell to individual consumers? I tried to place an order with them and it got cancelled along with an e-mail saying they only sell to businesses.
I’ve order stuff from them for work and order some HVAC duct at home once but it was deliverd on a semi 
Maybe call and talk to customer service about options. It seems like if you’re paying what they’re asking and the shipping and taxes there should be a way. Or maybe go to a local machine shop and see if they can order it for you.
That is strange, I have ordered a lot from McMaster, no issues, fast delivery, only thing it cost more than a lot of places.
That would leave a nasty taste in my mouth as well.
Pat
Are you Canadian? 
(As a fellow Canadian I sympathize!)
Many, many moons ago, I used to do a lot of plastic machining (CNC) before I got into designing and building injection molds, thermoform molds, vacuum form molds.
Delrin, Nylon, acrylic, polycarb, ABS, even some PVC (must have great ventilation), etc.
For this application, I would probably start with ABS or Delrin, depending on the geometry.
