HDPE

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Re: Laser-Guided Water Jet

Postby macona » Sat Jan 22, 2011 9:55 am

r691175002 wrote:
trwalters001 wrote:That's really cool!

I wonder what wavelength laser they're using? It couldn't be CO2 because water absorbs 10.6 microns.


Their technical specs say 532nm and/or 1064 nm.

I know that 1064 is a commonly available diode wavelength as well as the lasing wavelength from nd-yag (which is almost certainly what they use as it is pulsed). I can't imagine that they would intentionally use 532nm although I have read that at high enough power densities laser wavelength can double as many materials are optically non-linear. According to sams faq, people blinded by infrared often see a flash of green because the fluid in ones eye doubles the frequency into the visible range.

They list laser diode pumps as a future improvement so they are probably running flash lamps into a rod of nd-yag. They also claim 200W of cutting power; however they also list a typical co2 system as requiring 1500W so one might be able to use less.

This looks a lot more plausible as a diy project than a true water jet because the pressure is much lower and you don't have to deal with abrasives. I'm not sure what the technical difficulties are in machining a nozzle that can produce a narrow stream of water though (they claim 0.005mm). I'm guessing it would have to be a laminar flow nozzle which would probably require EDM or some other expensive process.


The 1064 is YAG, 532 is doubled YAG. The beam out of a fiber coupled laser diode is pretty awful, various modes. Bleah. They are most likely running krypton arc lamp driven Nd:YAG. I am surprised they are not already using DPSS YAG, they are so much more efficient than arc lamp based units and they are virtually maintenance free.

Its hard to compare power between the two kinds of lasers. It all has to do with the material you are working with and the process.

I got a couple more 32W 810NM Coherent FAP modules the other week. Eventually hope to build a DPSS system with it.
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Starboard

Postby bdring » Sun Jan 23, 2011 11:58 pm

I bought some of the eBay HDPE "Starboard" mentioned earlier in this thread. I bought a piece of 1/4" black material. It measures dead on 0.250" which is nice. It has a slight pebble texture.

It arrived quickly via free FEDEX shipping. I made some parts for the 2.x laser. The material did not appear to cut quite as well as the cutting board I used earlier. It is better than some of the Walmart cutting boards I have used. Some of the material did start to coil around the bit. This means I need to babysit the router to make sure too much material does not collect on the bit. The material kills the vibration of the motors a little and it is more compliant for a press fit bearings.

I used a 1/16" bit for the test. I need to try it with the 1/8" bit to see if it chips more.

starboard_part.JPG
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Re: HDPE

Postby tylerv » Sun Mar 13, 2011 3:20 pm

This is kinda late, but another decent source for HDPE is Industrial Plastic Supply. They've got tons of other plastic and a good range of thicknesses in sheet and rod stock. They only have white and black HDPE though.

I bought some 1/2" thick 12"X12" sheet to make circles for a cider press I made a while ago and the router cut through them like butter.

Their website has changed since I was last there and they now have the HDPE and the LDPE on the same page. If you're looking for prices, just verify which type the price is for.
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Re: HDPE

Postby mike » Sat Mar 19, 2011 7:10 pm

Just wanted to make a second comment about Industrial Plastic Supply -- If you're lucky enough to live close by (Anaheim, CA), it's worth checking out. Last time I was there they had a bunch of odd sized sheets of scrap acrylic sold by the pound -- great for lazering.
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Re: HDPE

Postby tylerv » Sat Mar 19, 2011 7:34 pm

That's pretty cool. I'm going there (Disneyland) in October, so I'll have to stop by and see what they've got.
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Re: HDPE

Postby LaughingLarry » Mon Jul 25, 2011 11:57 pm

I must have done something really good in a previous life. I live in San Diego, and was up in Orange County visiting my brother, when I remembered reading your post. Soooo, I went to theIndustrial Plastic Supply place. You are right. They have this little area where you go to pick stuff up, and they have hundreds of little hunks and chunks of all kinds of plastic. Like 40 different materials I would guess, and from tiny to pretty good sized pieces. They sell most of the little stuff by the pound, and I came home with a bunch of machinable pieces. Thanks for the heads up.
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Re: HDPE

Postby naPS » Tue Jul 26, 2011 12:40 am

If you live in San Diego, Ridout Plastics on Ruffin Rd. also has the same setup. I bought a ton of scrap pieces there the other day - they have just about every type of plastic or acrylic scrap you could want.
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Repro HDPE

Postby bdring » Tue Jul 26, 2011 2:00 am

I just finished test cutting some reprocessed HDPE. It is a cheaper version. Most HDPE requires FDA approval because it gets used in the food industry. Reprocessed doesn't come with that approval.

I get mixed results from various suppliers on the cutting. Some is so gummy I have to clean the bit all the time. I usually just rub it with the scrap while the job is still running, but I would rather be doing something else than baby sitting the job. The worst for me tends to be the starboard brand. The repro version is as good as I have seen and appears to be stiffer. It is about 25% cheaper.
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Re: HDPE

Postby onlyjus » Wed Jul 27, 2011 6:23 pm

I have been scoring some HDPE and UHMW off of thewayoflife on ebay. I think I have been getting decent prices...

HDPE: 10.625" x 7" x 1" (4 pieces); $11.99 (shipping: $4.05)
UHMW: 6" x 11" x .375" (12 pieces); $13.76 (shipping: $10.90)

I haven't found a nice place to get scraps in Morgantown, WV yet....
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Re: HDPE

Postby vincenttor » Thu Jan 19, 2012 9:17 pm

Well i live in the Netherlands so i gues shipping costs will be pretty high,
but i work with HDPE allmost everyday and we have allot of garbage material from different sizes
most of it is black material 10mm 15mm 20mm 25 mm thickness.

If you like i can ship some scrap pieces like 100 x 300 mm 300x300 mm etc to you.
Only have to find out how much the shipping costs will be, maybe its not to expensive for 10 Kg

This is what i make with my company
Image

Image
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