Cutting Aluminum Panels

[bikerglen]

I’m thinking about ordering a ShopBot Desktop to mill aluminum panels for electronics prototypes. I’m currently using an internet-based service bureau to cut the panels and they do a great job but take two weeks and are expensive.

The attached photo shows a panel I had them cut for me. I’m trying to figure out if I could get similar results and quality using a ShopBot Desktop with the HSD spindle option as I can get from the service bureau.

These are about 2" by 1". They are milled out of 1.5mm thick anodized 6061 aluminum. The cut outs are done using a 1mm bit giving a 0.5mm corner radius.

The 1mm tools I’ve found online have 6mm shanks. Can these be used with the collet on the Desktop spindle? The bits in the Desktop’s example bit kit all have 1/4" shanks. Is this like a chuck on a drill where it can hold different sized shanks or is the collet optimized for a single shank size?

Can anyone recommend some quality metric bits that can be used for cutting aluminum with the Desktop? Maybe 1mm, 2mm, 3mm, 4mm sizes.

Thanks,
Glen

[scottp55]

Glen, ER-20 collets that Desktop uses are available in many sizes. english go to 1/8" which we use most. Pretty much 1 collet for each shank size. Here's the Technics page for metric. You'll have to wait for aluminum guys to chime in for bits as we're mainly wood but have 2 Desktops. Top notch machine,company, and forum.
http://www.techniksusa.com/metal/cnaerpcm.htm

[Brady Watson]

Glen,
Yes. Those parts can certainly be cut on the SBDT. I would recommend the spindle. All tools 1/8" & smaller have an 1/8" shank, unless you pay a premium for 1/4" shank (for guys who have routers). So, if you wanted to use a 1/32" or 1/16" dia cutter, it would have an 1/8" shank. These are generally sold as end mills.

I wouldn't get caught up in the whole Standard/Metric thing when it comes to tooling. Either can be used (or both) - this is a matter of preference.

-B

[bikerglen]

Thanks, guys.

I think that answers my questions and I now understand a lot more about what happens and how things work from the spindle to the collet to the end mill to the material. I would definitely get the model with the spindle. Agreed on the metric vs standard systems too. I’m just used to the metric sizes since that is what the service bureau uses.

Probably will have to start a serious wood working hobby in addition to cutting aluminum panels!

[tlempicke]

On a piece that small wouldn't a punch press be more to the point?

[scottp55]

Glen, When you talk to Dianne at Shopbot about ordering get a current quote for factory installed additional proximity switches(Z-axis to prevent loosing position when "topping out", and X,24 and Y,18 limit switches do the same thing). Also if you are interested in safety they make a "spindle interlock" to prevent spindle turning on when changing bits. It will eventually be a standard feature they say, but if you specifically ask for it, I believe it's a no cost option. We have it on our 2 Desktops and much safer.

[BrandanS]

Hey Scott,

Do you know if this interlock is available for HSD spindle on the PRSalpha?

-Brandan

[bikerglen]

Where is the spindle interlock switch in the spindle circuit? Before the VFD, after the VFD, etc.? Is it a manual switch or something where like the Z axis clip has to be removed from the spindle and put back in a certain place on the machine for the spindle to start up?

[scottp55]

Brandan, NO idea on anything except Desktops. I THINK there already is one because when I made it a "buying point" for safety "Like the big boys have", Gordon at Shopbot fabbed me one that is elegant, so we had them do the second Desktop the same. Ted liked it so much they plan on making it a standard feature, but it hasn't happened yet. They thought it would make Desktop much safer in school settings and I agree.
Glen, To my knowledge they have only done our 2, as they were trying for the most rugged, simple prototype before starting production. Gordon was the only person that really knew the wiring and input/output in Jan.,it may have changed now. I would say it was located before the VFD as when key is turned off to change bits, VFD is DEAD. If you can, get the barrel key like mine(shown) as Kirks Desktop got a flat key that could get snapped off. Gordon said Barrel key was a PITA to fab because of tight spaces, but his key placement right next to E-stop is perfect and easy to use.
Talk to Dianne at sales and mention my Desktops and she'll know what you are talking about and forward your questions to Gordon.

[scottp55]

Oh. The cable is attached to the collet nut wrench. So unless you change bits at 24,0 or close, you HAVE to use it.

[bikerglen]

The spindle interlock looks like a great feature.

[JohnCoker]

Aluminum sheet cuts easily. I've cut 2024 in 1/16" and 0.100" thicknesses using a 1/8" 2-flute end mill.

http://jcrocket.com/images/aerobee/nozzleaftplate.jpg

[gene]

John,
What feed and speed did you used to cut the al,?

[JohnCoker]

What feed and speed did you used to cut the al?
I started with the sample provided by ShopBot: SB Desktop Starter Set / Aluminum / 1/8" Straight


Pass Depth: 0.01"
Stepover: 50%
Spindle Speed: 17000rpm
Feed Rate: 2.0 ips
Plunge Rate: 1.0 ips

These are conservative settings, but they seemed to work nicely to make smooth edges. Next time, I'll probably increase the pass depth or feed rate.

[bikerglen]

Thanks for the examples, John. I watched your CNC video on your jcrocket site. Very nice. Did you cut all the electronics package aluminum parts on the Alpha too? Any need for an oil mister or can of WD-40 while cutting the aluminum?

[JohnCoker]

Did you cut all the electronics package aluminum parts on the Alpha too?
I've used the Alpha at the TechShop for some parts, but the part in the picture I posted was cut on my Desktop. (Everything in that video (http://jcrocket.com/cnc-routing-intro.shtml) was made with the Alpha, but now I'm using my Desktop instead.)

Any need for an oil mister or can of WD-40 while cutting the aluminum?
I didn't use any lubricant; I've heard mixed things about lubricants for aluminum. (I always use carbide tools.)