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Old 3rd May 2003, 12:11 PM   #1
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Default PCB drilling alternatives

Hi all,

I've been making pcbs at home for years. Drilling the pcbs after etching is always very boring... A couple of years ago I decided to buy a Dremel professional (electronic readout, multispeed) and Dremel's drill stand, the 212. They were quite expensive but after several years using a hand PCB drill I decided that it was worth it.

The Dremel is a nice tool - I've used it for a couple of other light tasks - but it is used for pcb drilling for most of the time.

It's the stand that has caused the most annoyance. Despite Dremel's assertion that it is a 'precision' drill stand it is anything but! When new it was ok but over time it has developed significant play. The whole drill moves approximately 0.5 - 1mm off line on a downstroke (mostly in the last 5mm before contacting the board.) For a lot of hobbyist purposes I guess this wouldn't matter. However when trying to drill into pcb pads which are already spotted with a 24th hole this is a real pain. It's not that there's been a lot of wear and tear - I've only made about a dozen pcbs since I got it.

The tolerances of the stand just aren't up to the task I think. When using tungsten carbide drill bits this movement on the downstroke leads to breakages. I've been very pleased with tungsten carbide drill bits - they are a significant improvement on HSS, especially if you purchase CNC regrinds - Rapid Electronics in the UK (and other places) do 10 bits for 12.70 UKP. In addition the Dremel drill itself has several annoying resonances up through its rev. range. These blur the drill and make it harder to position and also I guess make the breakage risk higher. To cure the vibration I need to up (or down) the speed.

This morning I've already wiped out a couple of bits and I'm only on the second pcb (out of 16). I think it's time to replace at least the Dremel 212 drill stand with something else. If necessary I'll replace both the stand and the drill. I'm also willing to consider a more expensive solution provided it's reliable and easy to use. Over the long term it might even pay for itself in terms of reduced bit breakage.

I've also had many PCBs made by various UK houses over the last 10 years but am not willing to send out all my pcb designs. It's much quicker to head for the back yard with a dish of ferric chloride than to prepare Gerber and Excellon files...

Let me know of your experiences with different PCB drilling solutions.

Thanks,

James
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Old 3rd May 2003, 01:00 PM   #2
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Default get a mill

I suffer the same problem with broken (expensive) carbide bits and the Dremel -- one of the solutions is to use more steel bits and just throw them away when done. You just buy 100 pieces of 0.033" at a crack.

at any rate, I now have a mill which is in the process of being converted to CNC by one of my kids (actually an architecture student -- he wants to use it for models). I am intending to use micro-router bits with the CNC and go directly from Gerber files to prototype.

oh, btw, if you have the patience surface mount saves one heck of a lot of time -- see the thread on the Quadruple Gainclone in which the input, feedback resistors etc. are smt.
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Old 3rd May 2003, 01:15 PM   #3
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Thanks jackinnj,

Strangely it's the bigger bits I'm breaking - 1.6 mm. Haven't broken too many of the smaller ones (0.7 & 0.9mm). I've already decided to go back to HSS for the larger sizes. However, the stand problems just multiply when using smaller diameter bits - you can miss the pit by the width of the drill.

I've had a quick look at mills in the last day or so - see:

http://www.techsoftuk.co.uk/page49.htm

but I see a number problems with them. Firstly is they are quite expensive to buy. Secondly, they seem to need special laminates which don't blunt the tools as quickly - may be expensive, may not. Thirdly and most importantly, the one above requires you to use their own software. I've been using the same PCB design package for the last few years and don't want to change. If the solution accepted Gerber files then this would remove this objection.

I use surface mount components where possible - however for power amps, power supplies etc. it's very difficult to avoid the use of some through hole components which brings us back to the problem of drilling.

Can you tell me some more about your custom mill?

James
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Old 3rd May 2003, 01:20 PM   #4
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nemestra....could I make a suggestion for you....first of all I use my dremel alot...great tool!!!!...what I did was went and bought a small table top drill press for my proto work....what I bought was a small collet to fit in the chuck to hold the very fine bits and I insert them so there is only 6mm of the bit protruding out making it very stable and less likely to wander as that is why most break to begin with...another thing I do is keep a bottle of alcohol and spray the bit it keeps it from bulding up crap when doing numerous holes....another trick when doing very small pads is to tap a little centre punch on it....this really helps to keep the bit aligned on the cntre of the pad................hope this helps you as we have all been there!!!!!


Cheers!!The DIRT®
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Old 3rd May 2003, 05:28 PM   #5
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Have you tried PROXXON tools?
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Old 3rd May 2003, 06:22 PM   #6
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Thanks for the tips guys.

Hadn't thought of using alcohol to keep the swarf down.

Hadn't heard of proxxon tools before. Very interesting web site. Like many DIY types I have to control a latent fetish for tools. Would need to see the proxxon stuff first of course. May contract the UK distributor. I'm convinced that if I had all those minature machines I could turn out something like the quality Peter Daniel does ...

James
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Old 3rd May 2003, 06:55 PM   #7
tom1356 is offline tom1356  United States
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I just bought one of these. Purpose designed and built for PCB's.
It should be here next week. Any idea how long it takes to learn to use it?
Attached Images
File Type: jpg cnc2500.jpg (7.4 KB, 598 views)
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Old 3rd May 2003, 07:10 PM   #8
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Hi tom1356,

looks nice, but what is it? Manufacturer? Model? Website? And ... gulp ... price?

James
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Old 3rd May 2003, 11:30 PM   #9
tom1356 is offline tom1356  United States
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It's a MINITOOL Model 2500 CNC

http://www.minitoolinc.com/microdrillingandpunching.htm

retail is $14,250
I bought it used.
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Old 2nd April 2008, 01:27 PM   #10
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Default An old thread is better than a new thread....

I just purchased a Craftsman "Rotary Tool Drill Press" for $40 and can't believe I've went this long without it. The stress this device relieves is worth ten times what it cost.

I've drilled about 20 or so test holes in 2oz FR4 using a 0.0135" #80 carbide bit and it hasn't broken yet.

It did require one small mod to get its tolerance in check. I had to place one layer of packing tape on the main shaft where it sits in the base. It fits like a glove now.

Click the image to open in full size.
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