As i said, I made a laser printed label for a project and I had to find a way to punch some clean holes and I tried a biopsy punch. e.g.
http://www.vetlab.com/Biopunch.htm%c2%a0 Finding them might be tough. I have used a self-healing cutting mat at one time, e.g.
http://www.amazon.com/X-Acto-X7761-Self-healing-cutting-measuring/dp/B0013CKM2A%c2%a0 You need something firm and slightly soft. The biopsy punch does have an alignment issue, but it does do a really clean hole in a piece of paper/plastic. I ve not tried this method for aligning, however when I learned to do taped artwork at HP/Agilent in the mid 70's, posts about 3/16" in diameter were used to line up the artwork sheets.
I may have also did the "punching" by drilling the artwork sandwiched between two pieces of clear acrylic.
If your really worried about accuracy, of say a scribed line, one can use an optical center punch
http://www.wttool.com/index/page/product/product_id/39550/product_name/Optical+Center+Punch+Set+%28WT%29&update_continue_shopping=trueTo use an optical center punch, you position a crosshair with the base precisely wher eyou want to mark. Then you replace the optics with a center punch and mark the hole. ou would be doing this on a piece of acrylic.
I've ground 5/8" bits in the pilot point shape in 3/8" thick Lexan sheets and used the saop as the lubercant, so the method works.
Once you have your center punch mark, you can use a bit of dishwashing soap and water as a lubercant/cooler for the drill bit. This method should also make an accurate hole and you also should be able to line up all of the layers of the artwork.
I think I also used the hot pin method at one time to center the mark.
If you do any drilling in sheet stock use a "pilot point" bit. See a pic here:
http://toolguyd.com/a-few-fun-tool-closeup-photos.Some of the boards, I did I used a UV mask aligner that we happened to have at work, but I just used it for the exposure.
I also had a commercial spin coater available to make a small board. A hole in the PCB causes some minor issues when spinning on the resist, Abberations at the holes. The spin coater basically is a high speed spinning vacuum chuck with ramp-up and ramp-down rates and a way to catch the excess resist.
I'll add that a mix of vinegar and salt will clean copper very well andI used the surface tension of water rather than any sort of exposure frame to keep the artwork in contact with the PCB. Just place a drop of water between the artwork and the board.
I used ptranslucent olyester paper with the laser printed artwork, but I dont have a source for that now.
I am confident that a surgical biopsy biopsy punch can be used to make a large, precise hole from say 1.5 to 6 mm diameter. Alighnment may not be precise, but with a hole pattern as large as the punch or say concentric circles, you should be able to align things pretty well. I remember specific target patterns from Bishop Graphics that were used when layouts were taped.
You might need a jig of some sort to make a precise marks. i.e a piece of flat brass drilled with a pilot point bit and/or the use of an over/under reamer.
Don't expect a super lifetime using the biopsy punch.
A pilot point bit will drill sheet metal with a round hole and not a triangular shaped thing you would get with a conventional drill bit. Now, when I had someone drill about two hundred 1/4" holes in a thin sheet of soft Molydynium, I set him up to use a round nose mill.
The web cam probably won't be viable because you can't see depth. A stereo microscope viewer would be a better technology. You punch may deform the intended hole. Paper would be drilled. I've never used them, but their are drills for paper:
http://www.ultimateprintfinishing.com/categories/Parts-and-Supplies/Drill-Accessories/Drill-Bits/%c2%a0 ________________________________
From: crazy_geekchick <
amiegrl2001@...>
To:
Homebrew_PCBs@yahoogroups.com Sent: Thursday, August 1, 2013 1:07 AM
Subject: [Homebrew_PCBs] Re: Has anyone made a diy registration hole punch or add pins to diy exposure kit?
I have never heard of the biopsy punch before. Did you go through all the layers of the artwork at once?
I was thinking of using a replacement part for a 3-hole punch that just had the punch, spring, and frame with a hole. I thought I could use a web cam to get the alignment perfect, especially between the different layers (copper/solder mask, front/back).
The tack into the pcb through the artwork sounds interesting.
Thanks btw
Switch to: Text-Only, Daily Digest • Unsubscribe • Terms of Use • Send us Feedback
.
[Non-text portions of this message have been removed]