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-   -   Polycarbonate/Plexiglass Ruling (http://www.chiefdelphi.com/forums/showthread.php?t=153939)

Bob Steele 20-01-2017 14:48

Re: Polycarbonate/Plexiglass Ruling
 
Waterjets cut all of these materials pretty well with no fumes.

Oblarg 20-01-2017 14:54

Re: Polycarbonate/Plexiglass Ruling
 
Quote:

Originally Posted by Bob Steele (Post 1634057)
Waterjets cut all of these materials pretty well with no fumes.

When convenient, affordable desktop waterjets exist, I'll look into them for sure.

engunneer 20-01-2017 16:45

Re: Polycarbonate/Plexiglass Ruling
 
Quote:

Originally Posted by Oblarg (Post 1634063)
When convenient, affordable desktop waterjets exist, I'll look into them for sure.

they are now in the $5000 range. https://www.wazer.com/

It was really nice to work for a waterjet maker back when I was on 1318. our 2009 robot was made all of waterjet polycarbonate sheet (which was recylced from a building demolition!)

Our 2008 robot had a waterjet 1/4" titanium sheet as the only frame element. everything just bolted right to it. it also has infinite rotation swerve drives using waterjet copper sheet for custom slop rings.

frcguy 20-01-2017 18:33

Polycarbonate/Plexiglass Ruling
 
Quote:

Originally Posted by engunneer (Post 1634125)
they are now in the $5000 range. https://www.wazer.com/

Quote:

Originally Posted by Cory (Post 1606692)
My opinion is that the Wazer is absolutely useless for FRC purposes (but cool as a technology demonstration).

It cuts REALLY slowly, the cutting area isn't large enough for more than a few small parts, the cost to run it is high, and accuracy will be questionable compared to an industrial water jet. Maintenance will likely add up to more than the cost of the machine within a few years depending on how much its used.

You'd get a lot more mileage out of paying for $5000 (plus cost of consumables) of waterjetting from a legit vendor.

A legitimate water jet cutter is going to be $100-200k depending on how it's optioned out, plus a minimum of $45/hr (up to $60+/hr) to run in power/abrasive/water/amortized maintenance. They are very finnicky and constantly have little problems that pop up that require you to stop and clean things out or perform minor fixes. When the pumps reach their service intervals you're looking at a multi-thousand dollar rebuild. The mixing tubes/orifices are not cheap either and need somewhat frequent replacement. These are also enormously loud and messy machines. Glenn can speak more to his experience with ownership of one, but it would take a unique set of circumstances for a team to have a shop that is suited to owning one.

Legitimate metal cutting lasers for FRC use (1/4" aluminum) are so expensive they're not even worth discussing. $200k-400k. Huge power requirements, though much cheaper to run than water jet due to fewer consumables and lower maintenance costs. These are machines designed to cut 4'x12' sheets all day long as fast as possible and people who own them have to run the machine virtually nonstop, often for multiple shifts a day to make any money off them. Just totally in a whole other world than FRC usage,


Not sure about the Wazer.

JohnFogarty 20-01-2017 18:58

Re: Polycarbonate/Plexiglass Ruling
 
Quote:

Originally Posted by frcguy (Post 1634185)
Not sure about the Wazer.

From the short amount of research I did. It takes about $5000 to get 1 ipm of cutting speed for waterjet machines using 1/4" aluminum as a baseline material.

engunneer 21-01-2017 22:54

Re: Polycarbonate/Plexiglass Ruling
 
Quote:

Originally Posted by JohnFogarty (Post 1634191)
From the short amount of research I did. It takes about $5000 to get 1 ipm of cutting speed for waterjet machines using 1/4" aluminum as a baseline material.

and to compare to industrial level waterjets, a 60ksi jet can cut 1/4" Aluminum at 22 inches per minute with a nice cut, and ~55 ipm if you tear through it at max speed and don't care about the cut.

dmaggio744 21-01-2017 23:25

Re: Polycarbonate/Plexiglass Ruling
 
As exciting as waterjets are, my team has found huge success with desktop CNC routers. They are relatively cheap, relatively intuitive to use, and cut softer materials like wood and polycarb very easily, and are advertised to cut aluminum if you know what your doing.

We use a Shapeoko 3 XL with DeWalt Router and it's become our new favorite tool. It has a build volume of 33" by 17", and comes with very easy to use software. Our XL version is about $1,600, abut you can scale up(XXL 33" by 33") or down(Standard 16" by 16"). Feel free to pm me if your skeptical, on the fence about buying one, or just want to know more! :D

GreyingJay 24-01-2017 11:27

Re: Polycarbonate/Plexiglass Ruling
 
Quote:

Originally Posted by FrankJ (Post 1633850)
One easy test to tell acrylic from poly. Hit a piece hard against a table top. If it cracks or shatters it is probably acrylic. Wear your safety glasses. So in the robot world. Lexan=polycarbonate=good. Plexiglass=acrylic=bad.

The test I was taught (not sure how accurate) is to look into the cross section. If it's clear, it's acrylic. If it's dark, it's polycarbonate.

I have also done an experiment for a non-FRC related group of kids. I took two identically sized pieces of polycarbonate and acrylic plastic (about 2" by 12"). (Fun note: polycarbonate is easy to cut with woodworking power tools like miter saws. Acrylic, I scored with a knife and snapped.)

To the eye, other than the cross section, both pieces look very similar. Then I folded the polycarbonate in half like a sheet of paper. You end up with a nice 90-degree bend. Then I tried the same with the acrylic, and it shatters into pieces (wear gloves). Insert your favourite object lesson here about things looking the same but being very different inside, don't judge inward strength by outward appearances, looking OK on the outside but handling stress and pressure very differently on the inside, etc.

FrankJ 24-01-2017 12:04

Re: Polycarbonate/Plexiglass Ruling
 
Quote:

Originally Posted by GreyingJay (Post 1635570)
The test I was taught (not sure how accurate) is to look into the cross section. If it's clear, it's acrylic. If it's dark, it's polycarbonate.

I have not heard that. It might be possible. They have different optical properties. Acrylic is "brighter". It might be something that a person regularly working with both can judge. I would be hesitant using that criteria as a relatively non expert.


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