3d Water Jet Information
 

Hi Everyone,

I am looking for a bit of advice. We have recently developed a partnership with a company that has a number of really cool machines - one of these being a 3d waterjet system. I do not have the specs on size but needless to say it was the largest in the world for a few years. The problem? We are so used to building with framing materials that I'm not sure where to begin or how to best make use of this resource. The owner of the business is excited to help us and is even sending a number of engineers to work with us through kickoff - I'd just like to have something in mind.


Best -
Daniel

Re: 3d Water Jet Information
 

We are fortunate enough to have a partnership with OMAX Waterjets, and have had access to several different models over the years, A-Jet included. However, most of what we cut for our robots are sheet metal plates for drive-base construction, brackets and other 2D Frame-work.

I did cut some prototype hooks for climbing the pyramid last year. I attached a crude paint drawing showing the idea. The tilt was on the inner part of the hook, which would allow us to drive at the pyramid's corner and have the hook geometry match the pyramid's. This turned out to be entirely unnesceary, but was kind of a neat waste of my time.

I have tons of 3D parts that I've designed and cut at work for fun. I attached some of my favorites designs. Nothing that I can really think of Robot-related though...

My 3D F-22 (Not true 3D Tilt-Cutting, but 3 Orientated cuts):



And my Batarang collection, before they were anodized Gold:

(Tilt in 3D used to create sharp edges)

Probably the coolest thing I made though was the Bevel Gear Assembly:
http://www.youtube.com/watch?v=mesdfQOEYek

*All parts were cut on an OMAX machine with an A-Jet :)

Re: 3d Water Jet Information
 

One of the concerns when designing for 3D waterjet is that everything has to be treated as a 2D plane of sorts, in that the jet will cut straight through anything in its path.

I think a helical gearset would be a useful and very awesome project. Another possibility could be a countersunk holes (cut through from the non-countersunk side).

Re: 3d Water Jet Information
 

Countersunk holes are easy if you need them. I've made Helical gears too, but its tough to hold great tolerances when it comes to 3D cutting gears. Even the slightest offsets can cause meshing problems. Bevel gears and the like are certainly possible. However I'd still recommend purchasing COTS gears, It's likely to be more cost, time, and labor efficient to do so.

Re: 3d Water Jet Information
 

Quite a few teams have has sucess with waterjetted/lasered gears. The only difference is that with laser you want to stack up multiple plates instead of having a one piece gear. For a few examples, 148 has run gears like this before and 973 has run many gears like this before, such as gears used on their swerve and 2013 arm.

Re: 3d Water Jet Information
 

Flat gears and sprockets are pretty easy for a waterjet or a laser cutter because the involute profile is relatively tolerant. Navid is talking specifically about cutting helical gears on the waterjet, where not only linear tolerances but also angular tolerances can cause meshing problems.

Re: 3d Water Jet Information
 

I can't see much of a use for 5 axis waterjet in FRC parts. Just have them do simple 2D work for you-still extremely valuable.

Re: 3d Water Jet Information
 

Seconded, normal waterjets are still crazy useful. We like to use the TS waterjet to fab our gussets really quickly, and also for large plates (bellpans, shooters, etc). The main FRC use of the multi-axis head in my mind is to eliminate kerf on stuff like gears and bearings.

Re: 3d Water Jet Information
 

"how to build your everything really really fast" by charles guan might be relevant. even if it isn't, its still a god read...

Re: 3d Water Jet Information
 

Do you guys still work with Red Jacket Firearms???

Re: 3d Water Jet Information
 

This is true, but we get along fine without that (for the sake of others reading this thread).

We have reamers for the size bearings we need, and for the few odd size we request they cut slow (this blows the hole out a bit more so account for that dimension ally, but it gets straighter edges). The reamer will make your waterjetter FAR happier. Ours cut 20 37mm holes for our swerve at .8 ipm in 2012 and was NOT happy with us after that (~2 hours runtime). For that run alone, the reamer was cheaper than half the holes cut.

For gears, there are two cases. First is you're running a waterjet gear on a waterjet gear. We run them with opposite tapers so it matches nicely. It feels junky at first, but quickly wears in pretty smooth.

For steel on aluminum, we just let it wear in an the steel wins pretty quick against the high spots in the aluminum and a happy medium is reached pretty quick.

I wouldn't recommend waterjetted gears going a few thousand rpm though.

EDIT: Keep in mind the above numbers, and the affect of taper will vary machine to machine and operator to operator.

Re: 3d Water Jet Information
 

Sending this from my Omax 55/100 controller. 5 axis waterjet cutting is quite specialized for certain applications. Most the time Milling operations are a much more accurate and efficient alternative. We have seen some instances where weld prep on production level jobs is a good fit. You should see very little taper in your cuts if the machine is properly set up. We cut .250, Al, Steel and Cu to within +- .003 regularly.We can cut 4.00 steel plate +-.030.