Shark Capabilities for smooth aluminum cutting?

[raiderwiz]

Hi Everyone-

I've been watching here for a while, thinking about getting a CNC Shark. I had planned on going to the Rockler Shark demo today, but it got cancelled at the location nearest to me (about 40 minutes away) because they had a part that was broken and didn't get replaced in time. Luckily I had been in contact with the store, and they confirmed by email last night that the demo was cancelled so I didn't show up for nothing.

The main reason that I'm looking to get a cnc router is to make templates out of .063" thick aluminum. These templates will have a series of circles cut out. Sizing must be very precise, which doesn't seem to be a problem from what I have read. My question is, how smooth can the circles be? I have had these made with a laser cutter, but the actual cuts of the circle aren't smooth, and I have to use a dremel with a sander flapper wheel to smooth out the cuts. I also saw another cnc router demo, and had them cut circles in aluminum with the same results. Does anyone know if the shark might be the solution that I'm looking for?

Hopefully I have explained well...the part that I need to be smooth is the inside of the circle that has been cut out. So if you rubbed your fingernail around the inside of that circle, it would be very smooth, not with a bumpy or grooved edge.

Thanks,
Gene

[Consultingwoodworker]

Gene,

You will need to get the proper bits for cutting aluminum. While regular carbide bits will work, a bit designed for aluminum is ground to minimize the clogging that tends to happen when cutting aluminum.

For the best results, I would recommend programming the circle cut in two operations. Rough mill the circle leaving 0.010" or so, and a cleanup pass to recut to final size. the Shark is a bit more flexible than a steel framed system, and you will notice a bit of distortion under heavy cutting loads.

The two step approach negates this issue quite well.

Ralph

[raiderwiz]

Hi Ralph-

Thank you for the response. I was thinking that maybe I could do a second cut using more of a "sander" type bit rather than a cutting bit. I'll have to look into that and see if it's something that is available.

I do have to say that I'm a bit concerned regarding the local shop's problem that cancelled the demo though. I'm not sure what part broke, but the demo was scheduled for a Saturday, and on Tuesday I contacted them to make sure it was still scheduled as I had seen it online. On Tuesday they already knew that there was something wrong with their shark, and by Friday they still hadn't been able to either get the part or fix the machine, so the demo was cancelled. That's not a good sign when a Rockler store's machine is down for at least 4 days!

Thanks,
Gene

[RhB_HJ]

Gene,

My suggestion: Arrange with the store to cut you a sample part, be prepared to bring your own cutter and the file on a memory stick. BTW how smooth is smooth, how precise is precise? Any old time I wanted to test a milling/copying machine I used a block of alu. It will show every little glitch, starting with vibrations in the cutting spindle, reversing errors in the different axis and drag in the interpolation of the axis when cutting circles. Hope that helps.

[Wolf]

Gene,
I know of a shop in sunnyvale called The saw dust shop www.sawdustshop.com I know that you have to schedule your appointment time for there shop bot that they have, and I think you have to bring your toolpath file with you too.
I have been using my shark pro for about a year, although no aluminum, just solid wood and HDU sign foam.
Joe

[raiderwiz]

Thank you for the replies RhB_HJ and Wolf. I'm starting to debate whether I should be looking to purchase a machine or just have someone do these for me. I figure I'll get a good amount of use out of it over time, but for now I'm getting antsy about getting my project done. I've been to a machine shop to get these done, but I guess it wasn't a big enough project for them to do. Wolf...how about getting into aluminum cutting?!

[Wolf]

Raiderwiz, No aluminum cutting here, atleast not intentional, I ran the cutter right across my clamps when I first got the machine, and it wasn't pretty, and gummed up the bit permenately too.
Joe

[btray]

newbie to this forum...need to know if the shark can handle drilling 3/16 thick alum. plate 600 holes a day? Perhaps twice a week for small production project.

thanks bill

[kghinsr]

the shark can handle the drilling but i'm not sure the router can
the bit would burn very quickly at the lowest speed setting
if you could get the bit to turn at normal speed and not 10,000 that would be fantastic

Ken

[btray]

thanks Ken for your response, these are the things I need to know going into this purchase. I wounder if I can vary the voltage to the router and slow down the speed to metal bit speeds or maybe there is another drill motor I can use to handle the drilling?

thanks again