Online Source for Plastics (e.g. HDPE, Delrin/Acetyl, PVC, etc.)

(William Adams) #5

Another source for HDPE is cutting boards — restaurant supply stores usually carry largish ones in various thicknesses which are pretty affordable.

It’s also available as 4’x8’ sheets at some building supply stores.

http://www.shapeoko.com/wiki/index.php/Vendors#U.S.

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(Kevin) #6

Very true, could go that route. Any opinion on working with HDPE and results?

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(William Adams) #7

HDPE mills quite nicely. I use it for test cuts, and mounts / dust shoes, as well as fixtures.

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(Kevin) #8

Ok so it’s great for testing. How about a finished product though, any other materials that mills and looks great?

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(Mark Bellon) #9

Ok so it’s great for testing. How about a finished product though, any other materials that mills and looks great?

Delrin (Acetyl) is one of the finest plastics for machining and can have a FINE finish. It’s also LOVELY when toughness and low wear characteristics are necessary. That said, it’s a bit pricey for some applications.

Another excellent choice is a variant of HDPE - Starboard. It’s HDPE reformulated to be slightly tougher and UV resistant. It’s often used for marine applications. I use it preferentially over HDPE.

Both HDPE and Starboard machine quite nicely with a nice finish.

PVC is another plastic that is nice to machine and takes a nice finish. It’s harder than HDPE/Starboard. I use it for my Tesla coils due to it high dielectric strength and breakdown voltage.

Here are the parameters I’m using for a Starboard project I’m doing right now (all at 10K RPM using 2 flute AlTiN coated end mills):

marks

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(Mark Bellon) #10

I use TAP Plastics for my source of plastics. @patofoto does too.

They have an online presence… but I just drive over to one of the stores (sort of a candy store for plastics users) and buy what I need.

They have a cut to size service so if it’s difficult to cut down from a large piece yourself (which is more cost efficient), take them up on it.

mark

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(Kevin) #11

I will try Acetyl then! Could you share the settings you use for Acetyl?

Thanks,
Kevin

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(Mark Bellon) #12

I would use the same F&S as Starboard. There is a screen shot in my earlier posting.

mark

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(William Adams) #13

http://www.shapeoko.com/wiki/index.php/Materials#Delrin

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(Kevin) #14

Great stuff guys. I went ahead and ordered a sheet from amazon. Delrin acetal does look great but it is expensive as mentioned.

Thanks,
Kevin

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(Hank O'Donnell) #15

I just picked up 3 nice blocks of Onyx Delrin from eBay. $47 total. :slight_smile:

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(Warren Bailey) #16

Tap plastics and also Inventables has nice selection of various stuff. Some pricey but you can get smaller pieces if you just want to try something before committing to another supplier selling you a larger order.

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(Leith) #17

Acetyl is great plastic and probably it’s best feature is that it chips well for machining, that said, it can be brittle which makes it unsuitable for quite a few applications. If you want acetyl in sizes that will fit on a nomad your best to find an industrial engineering plastics supplier near by and go through their off cuts bin - I live in New Zealand (a small island nation on the bottom of the world) and even here these off cuts are cheap as chips.
Nylon is also machinable (not to say it can be done on a Nomad or SO but maybe it could be - would have to check on G-Wizard for feed and speed) although it’s really a molding plastic however the PA6 grade is incredibly tough! On a ISO 179 impact test it doesn’t even break! That said I’ve heard it’s a bugger to machine - although big industrial CNC’s definitely can do it and produce a near mirror finish.

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(Mark Bellon) #18

Delrin/Acetyl isn’t THAT brittle and it takes a LOVELY finish. One must keep in mind what their project is. Treated properly, Delrin/Acetyl is extremely tough.

There are multiple grades available. The most common Delrin is “100” and it serves for many purposes. I’ve seen it used for gears under quite a bit of stress.

Nylon is an excellent plastic to machine but it is often more difficult to find than other plastics (which can result in some priceiness to it). I would only touch it with Onsrud plastic handling end mills. It is a bit twitchy, especially for finishing. A single flute Onsrud does wonders.

…however the PA6 grade is incredibly tough…

You got that right! :+1:

There is a gotcha - Nylon melts a bit too easy for my taste; it gets “stringy” when machined improperly. Coolant - with no water in it (Nylon is seriously hygroscopic (it attracts water)) - is appropriate. A micro drop dispenser would be perfect for this job.

Use G-Wizard and I cannot see why the Nomad cannot machine Nylon just fine.

mark

P.S.

My “go to” plastic WAS HDPE (for many prototyping jobs). I’ve been spending a lot of time with Starboard and I have to say I’ve been won over. It machines just like HDPE… well it is a modified HDPE… but is a bit tougher and it’s UV resistant (good for outdoor uses).

When I need something a bit tougher, I use PVC. PVC is a bit brittle but it is also a bit forgiving. It take a nice finish.

When I want toughness, durability and awesome finish, it’s Delrin/Acetyl all the way.

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(Kevin) #19

Back again, could anyone provide a picture of there settings for HDPE. Nomad should be arriving Tuesday next week. :slight_smile:

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(Mark Bellon) #20

These are the settings I use for HDPE and Starboard on the Nomad:

All at 10K RPM using 2 flute end mills.

mark

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(John) #23

I buy 1.25" thick by 12x12" cast acrylic. TAP is around $85, PP is $45.

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(Mark Bellon) #25

I verified that price difference. eplastics has the same for ~$53.

I’m researching the actual materials. Acrylics can range in price quite a bit. Perhaps they are different materials. Sometimes differences matter… so I’m investigating.

I verified that Professional Plastics is often cheaper than TAP plastics and in some cases, considerably cheaper.

mark

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(John) #26

If it’s clear and cuts sharp, that’s fine by me!

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(Mark Bellon) #27

If it’s clear and cuts sharp, that’s fine by me!

I understand. Often slight differences in materials do not matter. In other places that differences are critical. Price differences that large make me curious that it’s not just a price difference, hence my researching.

mark

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