I will be drilling holes in a 18mm thick subwoofer box and only have a hand drill. Last time I did this I did it aboit a year ago on another box by eye and it wasn’t very good, this time I need to do it better as I will be using T-nuts to anchor the (heavy) subwoofer in place and if its not straight then it will make a mess of a expensive enclosure.
I have seen some “drill guides” but most are from America and cost around $70+ including shipping, so I’m just wondering if anyone has some tips and tricks they can share for drilling level holes?
You can make drilling guides yourself, just a piece of thicker paper with ahole in it at the right spot….
I made a guide out of a piece plastic from a cable canal, cut it with a knife so that it was just L form, marked the correct spots, drilled and tried if it would fit(then redrilled because I made a mistake…) The L form with a right angle is practical because you are always aligned if you press it on the side surface.
Used it for mounting handles on some closet doors…
I always use this method if I have to make a lot identical holes on more than one thing.
Maybe try to drill with a smaller diameter first…
What went wrong the last time? The position? Did you mark it with a pen before drilling? Went the drill process wrong or were your drillmarks bad?
I am understanding your problem is to make the holes perfectly perpendicular to the box. I had that problem and I did a guide with a piece of wood, I drilled a hole in a friends drill press and then I used that piece of wood as a guide to make the holes straight
Last time I just put the sub in the box and then drilled the start of the holes then took it out and drilled all the way through but even the slightest angle makes the screw go in on a angle and it presses against the inside of the hole in the subwoofer mounting.
You can see in these pics that if they don’t go in straight then its a problem as the screw’s won’t go all the way in the holes.
Also because I’ll be using T-nuts to anchor them its even more important that they are straight.
Make a quick jig using a vertical mill or drill press with a flat piece of aluminum. Get a flat piece at least 1/2” thick (larger the hole, the thicker the jig needed. 2 –3x diameter minimum). Make a few holes of common sizes you need, label them and keep it in your tool box.
Ah now I know what you mean, that is indeed a problem because there are so many holes and all need to be on the right spot and right angle.
Drilling through the subwoofer seems to be the best way, maybe clamp it down…
What about drilling a bit bigger holes than necessary for the tnuts so that you can adjust it a bit?
Slightly outside the box solution?
If you flatten the teeth on the t-nuts and drill slightly larger holes they could self align straight. A little flexible glue on each t-nut just to hold them from falling out of the holes till you tighten the subwoofer in.
You have to have a drill jig to be accurately perpendicular. You first though however have to have perfectly centered pilot holes drilled first relative to the holes in the subwoofer to even have a chance for the drill to track accurately and your t-nuts to sit level not cocked every which way. A center punch that snugly fits the holes in the subwoofer is a great way to start any of this if you decide to freehand it anyway.
I can fully appreciate what you are concerned with. You got some good advice here.
I have built many, enclosures over the years and each time I learn something new. Here is a pic of an enclosure I started to build for our home theater. I am so proud of the fact that I never finished it!
I assembled the first box and had the wisdom to realize that it was going to be too big. Here is a pic of the assembled enclosure and the panels for the second. I used 1 1/4” MDF (31.75mm)and had the panels cut at a cabinet makers shop. Outside dimensions were 21”x24”x51”. That monster has been sitting there in my shop taking up space for 7 years.
Is your enclosure for a car or home theater?
BTW, I had 12 inch speakers in my car back in 1967. NOBODY was doing that back then.
SWMBO and I help each other by spotting against either a plumb-bob string, a spirit level, or a known-to-be-plumb wall corner; one of us on the ‘x’ axis, one of us on the ‘y’ axis, just eyeballing and yelling at each other.
If you have a means of drilling & cutting thick wood reliably (perhaps a friend with a drill press & table saw?), you could take a thick piece of hard wood & bore a “perfect” hole through it. Then set your saw to make “perfect” 90° cut. Use it to cut into the hole you made, like the crosshairs of a Theodolite or rifle scope. The objective is to leave “half a hole” with each cut, which will leave you with a quarter of the hole as a “guide groove” in the corner of the wood block you just made by cutting… Obviously the cuts you make will be at 90° angles to each other and to the workpiece. Make another hole (sideways, not out the bottom) for a lanyard & paint it up so no one thinks it’s trash!!! (really!!!)
I should try to make pixtures…
The “guide groove” is only a suggestion, and it isn’t “precise”; but for the occasional T-nuts that we use, this works “well enough”…
PS: Don’t flatten the “teeth” of the T-nuts or they’ll spin & never get tight, nor will you be able to remove them after the bolts get “snug”. Gluing the T-nuts in place helps some, but only until tightening breaks the glue line. Then you’re left with the same hideous mess.
(EDIT: Perhaps loose nuts on a subwoofer will give you a nice gravelly crunch sound… A famous Bluesman used to wire empty pie tins to his speaker grill for just that reason…)
@ezarc - Those drill guides don't work as good as you expect them to. I have one and used it once to drill the dog holes in my woodworking bench. It was used once and forgotten in storage. IMO - they are a waste of money especially for $70 + shipping.
I'm assuming you're only working with sheet goods and most likely MDO or MDF type material that is max 1" thick. I would take a piece/block of wood that is cut perfectly 90 degrees from the base. You can do this with a circular saw and then make a vertical line with a pencil. When you drill use the block and the vertical line to help you stay perfectly square with the workpiece. Take a few practice cuts if you're not confident. Another trick to improve your accuracy is to pre-drill with a smaller bit and then finish off with final size bit to reduce friction but that doesn't seem to be a factor drilling into MDO/MDF.
I use a thing called a Handy Holer. It is a rectangular block of steel around 1”x1”x2” with several holes drilled through it. You find the hole that matches your drill size, set the block on the surface to drill, and use it to keep the bit straight. Bought it at a gun show years ago…
This is what I was talking about making yourself. One of these and a center punch set (or at least one that is a tight sliding fit to the subwoofer holes) and you will be golden.
