Drill jig advice

[MrStab]

Caution with the X Y table, the backlash will probably be great if it only costs $30.00.

From a professional standpoint, I was surprised my dad suggested an AliExpress listing.
From a personal standpoint, he has always been a sucker for marketing.

The cross slides do intuitively make a lot of sense to me, though, if the accuracy can be guaranteed. I've adjusted the PCB so the holes are 24mm apart, so no awkward decimals.

Whatever you decide to do, it's better to start with a small guide hole, like 3mm and then use a step drill. No need to start  big.

I guess the crux of all this is that I struggle with high, repeatable accuracy of my punch and pilot holes, especially when it amplifies to this scale.

Last year, Hammond had a paint-flaking issue with their 1590SBK enclosures (acknowledged and resolved now, by Hammond, Rapid Online and Mouser). So I have 4 or 5 dud 1590SBK enclosures I could use to practice on. Finally, some use for them!

[stallik]

Masking tape helps with my punching accuracy. I hold the punch at 45 degrees so that I can set the point exactly on the mark, then raise the punch vertically. The masking tape stops the point moving.

My punch is one of those auto things so it's one handed, leaving my other to guide the point with a finger.

[davent]

Caution with that paddle bit, it will break your arm when it breaks thru.
Caution with the X Y table, the backlash will probably be great if it only costs $30.00.

Yeah, with step bits widely available and doing a great job doing what they were designed to do, it makes no sense to try drilling with a bit ill suited for the job, just asking for trouble.

If you need an in between sized hole, drill small and finish to size with a handreamer, you can creep up to a perfectly fit symetrical round hole, trying to file will lead to a distorted off centre hole unless you're a file master or get lucky.

[bluelagoon]

Make yourself a Template from acrylic 1/4 inch with the 2 x 22mm holes next to each other.
If there were difficulty to make such a template accurately, then send off the drill plots to Tayda drill service on one of there box enclosures to be used as a sacrificial template at reasonable cost. At least you know you would have the 2 holes in alignment perfectly distanced with a CNC Drill cutout from Tayda.

Then mask off where your holes on actual enclosure are to be position cut those holes 20 - 21 mm out using a step bit,
Then place over your enclosure the template aligned exactly where you require the 2 x 22mm holes, its easily done with double sided tape to hold the template against the enclosure .

Then if you have a table top router preferred or even a plunge router you can trim the excess alloy from the holes to exact alignment with the 22mm hole template. See router bits suitable that use a bearing guide to exactly contour to the shape of the template .

Just be careful, and know the correct direction to move the router or the enclosure on the router table.

I have trimmed aluminum before this way, so long as you take very small bites at the material at a time until you get to the template finished result, it works without drama. Some router experience is useful.

[Phend]

In the process of making 4 effects.
Will make this template out of acrylic.
It will locate pots, switch and led. Plus.
First I will tape it upside down to the 1590BB box and drill 2 of the 4 corner holes.
Then open and tap those 2 holes.
Flip the template right side up and attach with 2 screws and drill / tap other two holes.
Fasten it down with 4 screws and drill locations of pots, switch, led and other.
Will use a small drill for all of this locating.
Then remove template and open holes with a step drill.

[MrStab]

Will make this template out of acrylic.

A physical guide for the pilot/punch hole itself. I like it. One of those things that jumps off the page to me.

Thanks guys!

[bluebunny]

FWIW, I'm doing the exact same thing as Kevin.  And if you're really channelling your inner NASA, you can make a pretty precise "first guide dent" with something skinny like a needle before bringing the auto-punch onto the masking tape.

[stallik]

^ Great tip Marc

[davent]

I use an optical center punch, makes it harder to screw things up. This is the one i have but it's no longer available, others are out there.

https://www.diystompboxes.com/smfforum/index.php?topic=104168.0#msg1220418

[Phend]

That is quite the precision locator. High teck.
How do you find / locate the place(s) to center punch ?

[davent]

That is quite the precision locator. High teck.
How do you find / locate the place(s) to center punch ?

Me?

Printout of a CAD drawing attached to whatever it is i'm drilling.

To accurately attach a printout say to the face of an enclosure, as accurately as i can draw the two center lines on the enclosure, the printout has centerlines to match, i then use a paper punch to put a hole through each of the four center line segments of the printout so i can so i see to match up the printout's center lines to those on the enclosure.

[Processaurus]

This was a production jig I made, an attempt at better registration on holes than paper templates and center punching, it's a 3D printed jig with these hardened steel 1/8" doweling hole jig inserts that woodworkers use. They're on the big side, but MUCH cheaper than industrial ones from McMaster. One of the nice things about the 3D print is the jig matches the tapered sides of the hammond box.

One of the issues that came up, is the first print had terrible dimensionality; while the printer is very good at knowing where it is as it prints, the whole scale changed because the plastic shrinks as it cools. The shrink is expressed as a percentage, so with bigger parts like this it adds up. I had to make a second one scaled from the errors of the first one.  In the end it worked fine, but it still wasn't like, +/- .005" accuracy. In the future I think I might do a hybrid approach, 3D printed sides, but maybe send out for an acrylic laser cut plate for the top, or maybe the aluminum PCB. The nice thing about the doweling hole jigs is the thing they are attached to can be soft.