Big drill vs rout/milling?

Questions about the BatchPCB service

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spamiam
Posts: 33
Joined: Wed Sep 14, 2005 6:40 pm

Big drill vs rout/milling?

Post by spamiam » Sun Feb 24, 2013 7:17 pm

I need to make an 11mm diameter hole is this something that I can define as a drill hole since it is so big?

Or is it better to define it as a circular rout/milling? Is it as simple as drawing the shape in the milling layer? Is there something else I need to do with the CAM when it comes time to make the gerbers so that the rout/milling gets treated properly?

I also am using the Allegro ACS756, which uses a footprint provided by EAGLE for a similar, older, part. It has an oval hole for wide PTH terminals which is defined in the milling layer. So, no matter what the best answer for the 11mm hole might be, I still need to know how to be sure the gerbers include milling information.

Thanks!

-Tony

MichaelN
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Re: Big drill vs rout/milling?

Post by MichaelN » Mon Feb 25, 2013 5:15 pm

You need to talk to your fab house or look at their FAQs. Typically this would be drawn in the same layer as your PCB outline (ie, milling layer), but might need a special note as well. 11mm is way too big to drill out.

spamiam
Posts: 33
Joined: Wed Sep 14, 2005 6:40 pm

Re: Big drill vs rout/milling?

Post by spamiam » Tue Feb 26, 2013 4:57 am

Thanks, I figured 11mm was too big to be a drill. I searched this forum and got conflicting reports on whether BatchPCB will support the milling. Their FAQ apparently says "no internal routs" but one person said slots are ok. So maybe the slots for the ACS756 will work and maybe the round holes will not?

-Tony

MichaelN
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Re: Big drill vs rout/milling?

Post by MichaelN » Tue Feb 26, 2013 6:31 am

spamiam wrote:So maybe the slots for the ACS756 will work and maybe the round holes will not?
If they can do slots, they should be able to do round holes - both would use the same router bit. The only difference is that an 11mm hole would leave a small cutout piece instead of just dust - I don't think that would cause issues though.

spamiam
Posts: 33
Joined: Wed Sep 14, 2005 6:40 pm

Re: Big drill vs rout/milling?

Post by spamiam » Tue Feb 26, 2013 7:36 am

I can make the slot for the ACS756 pretty easily. The slot is 2mm x 6mm. The ends are 1mm radius. I can create a similar cut-out using 2.2mm drills overlapped just enough to achieve high spots that leave a gap of 2mm.

I suppose that I COULD do something similar for the 11mm diameter holes. It would be a little tedious to lay it out in Eagle, but it is certainly possible.

-Tony

MichaelN
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Re: Big drill vs rout/milling?

Post by MichaelN » Wed Feb 27, 2013 5:26 am

spamiam wrote:I can create a similar cut-out using 2.2mm drills overlapped just enough to achieve high spots that leave a gap of 2mm
Many PCB places won't allow overlapping drill holes, as they can break drill bits.

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