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Exporting From OrCad/Cadence/Allegro PCB
Setup
Setup Checklist
- Do you have at least an hour to kill?
- Is there a decently fresh aluminum sacrificial board in place
- Is your copper clad sufficiently large
- Does your copper clad have the alignment/holding holes drilled
- Do you have the required tools (drills, end mills, router bits)
- Is the drill usable
- Is the endmill usable
- Are the table vacuum holes drilled into the sacrificial board
- Are you feeling lucky enough to use windows XP?
Drill Depth
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Always drill FIRST then mill. Doing it the other way around may result in the drill pulling up an etched trace and destroying the work of the milling process (especially for thin traces) |
The easiest way to verify the correct drill depth is to insert the drill into the collet all the way up the collar (the little brightly colored plastic ring that should be on all the drills, should have the drill size marked on the same ring in white). Use the jog function of the mill to move the head so that the drill bit itself is just to the left of the copper clad board but the foot of the head is still squarely on the copper clad. Use your hand (NOT the head down command in the jog window) to gently lower the head until you either reach the bottom of the head stroke or the drill touches the material. If the drill touches the material before the head bottoms out you need to adjust the Up/Down adjustment ring on the head until the drill just barely grazes the aluminum sacrificial board. Now adjust the lower limit of the head so it will go down just a little a more into the sacrificial board. Ideally you want the conical section at the top of the drill head to be fully embedded into the sacrificial board so that only the uniform section of the drill goes through the copper clad.
Once you believe that you have set the drill depth correctly, jog the drill head to a spare spot on the copper clad, turn on the drill spindle to reasonable speed and then activate the "head down" command in the jog window. Inspect the hole to insure that it has fully and cleanly penetrated the entire copper clad, but has not gone too far (more than 1/4 of the way) into the sacrificial board.
Go ahead and run through all the drills that you need to do on the entire board. Since the drill bit collars are gaurenteed to all be at the same height, you do not need to readjust the drill depth for every new hole size you have to drill.
If your drill does not have a collar (AKA you got it from ELEC 342 or the likes...grrr....) then you will have to re-adjust the drill depth for every drill that you use or insert all the drills all the way to bottom of the drill collet (or get the bits from the OEDK).
Mill Depth
| Note |
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Always mill the traces AFTER you drill the holes, doing it the other way may result in the drill pulling up an etched trace and destroying the work of the milling process. |
The easiest way to set or verify the correct mill depth is to insert the mill all the way into the collet. Be careful with the end mill as jogging the head while the end mill is too low, will result in snapping the end mill on the edge of the copper clad. The end mills are extremely delicate.
- Jog the head to a spare area on the copper clad and gently lower the head with your hand onto the copper clad.
- Make sure both the tip of the end mill and the foot of the head are on the copper clad.
- If the end mill touches the top of the copper clad before the head bottoms out, adjust the limit screw so that the head bottoms out before the end mill touches the top of the copper clad.
- Spin up the drill head from the Jog window interface.
- Toggle the "head down" to engage the endmill. The end mill should not be touching the top of the copper clad after the head goes down!
- Once the foot has struck the top of the copper clad, begin lowering the limit screw until the end mill engages the copper layer. The pressure from the machine should keep the drill head at the lowest position allowed by the limit screw.
- Once the end mill engages the copper you can jog the end mill around in a single direction with the arrow keys on the keyboard. NEVER engage copper clad or jog the end mill across the copper clad without the head being spun up. This will immediately and permanently break the end mill. They are very expensive...don't break them...please!
- With the end mill engaged and a small jog in an arbitrary direction, you want to continue to lower the limit and jog the end mill a little until you can see the black/brown backing underneath the layer of copper.
- Adjust the limit screw 3-4 clicks down (that is to say lower the end mill just a smidge more). This is because the copper clad is not always perfectly flat and the section you chose to test may be just a bit lower than other sections, if that is the case and you do not lower it just a smidge more you may end up with sections where the copper is not completely milled away.
Speed and Feed Rates
In order for the end mill to properly cut through the copper layer of the board the machine needs to know how fast (think inches in a the X direction per second) to move the end mill.
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