[jdawg]

I just finished soldering all the parts to the PCB and the next step for me is to drill out all the holes in the Hammond enclosure.  I have no problems with drilling the smaller holes but what's the best way to drill the big holes on top for the tubes? 

[hagtech]

Best way is with a punch (Greenlee type).  Otherwise, a step-drill can do it.

jh

[jdawg]

Thanks. I know it says in the instructions to use a punch or step drill but I thought I would ask anyways because maybe others might have found a better or easier way to do it using different bits.  Anyways I bought a step drill bit and the holes turned out a little rough but after a bit of sanding it looks pretty good.   

[srb]

Anyways I bought a step drill bit and the holes turned out a little rough but after a bit of sanding it looks pretty good.

Which step drill bit did you use?  I had much cleaner holes with a Unibit® compared to a Harbor Freight el-cheapo.
 
Steve

[jdawg]

I bought a 1/4" to 1-3/8" step bit.  Its a Samona brand bit I bought for $35 at a local hardware store.  I used a drill press to make the holes.  I'm satisfied with the way it turned out but it just needed a bit more work than I expected.  I thought the holes would would turned out really nice and smooth without any extra work needed.  I'll post some pictures later once I've finished everything.   

[bregez]

I used a 2 flute endmill on the back panel for the RCA holes.  The larger holes (for the tubes) I used a step drill.  Make sure your mount the panel rigidly before drilling.   Try to use a drill press or milling machine.  I had my top panel in a machine vise with some 2"x4" wood pieces underneath.  The step drill will go through the under laying wood without a problem.  Makes for a perfect circle.  You may need to do some deburring,  I would get a deburring tool for this as it will make for a real nice edge compared to sandpaper.

[jdawg]

I didn't even know about the deburring tool. Sandpaper worked fine for cleaning up the edges though.  Now I'll know what to do next time when I do another project like this. I just wish I knew all this before I did the holes in my case but I guess its all part of the learning experience.   

[bregez]

I didn't even know about the deburring tool. Sandpaper worked fine for cleaning up the edges though.  Now I'll know what to do next time when I do another project like this. I just wish I knew all this before I did the holes in my case but I guess its all part of the learning experience.

Another trick is to take a countersink bit and use it to deburr the small holes.   In the case of the cornet, use a 1/2" bit to deburr.  It is desired to use a larger bit compared to the hole as long as the tip of the bit fits in the hole.  You want to only remove the burrs and not machine a countersink.  Do this by hand, do not use a drill.  Just gently turn the bit 1/2 turns without pressure, the small burrs should fall off.  It leaves a nice finished hole.