When I begun to etch my custom pcb I felt the need to improve circuit drill tecnique. I drilled my first circuits by free-hand with my Dremel, but despite it's very fast, it's subject to errors, and it's also dangerous, because the drill bit is very narrow and weak.
I've searched a column drill as the "Proxxon Bench Drill Press TBM 115" but it's a little too expensive. I've found also a vertical stand for Dremel alt 50€, but it was a model with a single metal column as rail, similar to the most you can see with a "drill stand" search, and it had a low precision in horizontal movement of the bit. In fact you felt the head moving of about a millimeter, which is a lot when your bit is so narrow. So I decided to build it by myself.
The slide is a "macro rail" for photography which you can find on eBay at about 10$, but I already had a couple of them. The other parts you need, other than the drill, are only:
- a strong spring (but also a big elastic is good)
- some wood boards
- some screws
- a nail
- 5 inch of a little aluminium cilindrical bar (as the ones of the TV antennas)
- a wood base
- and two inches of aluminium pipe (this also isn't so essential)
This good aluminium rail has two different screws to lock the camera on the cart. One of the screws can move along the axis, so you can decide the best distance between the two connection to the drill.
Behind the rail you find the hole for 1/4" screw, I've inserted a gum disc to make the rail fixed on the column, and avoid mutual rotation.
I've used these screws to link the two half of the aluminium pipe, in which I made a threaded hole. These half-pipes are to keep the drill with the help of two nylon bands. If you need you can force the two profiles to make them with the right aperture so they suit your drill. If you have not the metal pipe you could use two metal bolts with washers and let the nylon bands pass under the washers.
The gears also has two knobs on the side. The bigger one acts to move the rail, the little one is to tighten and block the gear. We'll keep the bigger one and we'll remove the little one, using his hole for something I'll show you.
It could be useful know that in the two more very little holes are two hex screws which loosen or harden the rail flow. You would set them to increase the precision and to slow down the drill when you release the lever.
The gray plastic piece you see in the photo has come in handy to me because it does exactly what I needed, i.e. it locks together two cylindrical perpendicular beams. It's a piece of a scooter windscreen. I glued the toothbrush so that it keep close the other clamp on the metal knob. If you don't find a similar object you can link the toothbrush with a nylon band.
The little nail you see it's to stop the drill at the resting position, so that the spring remains with the right tension.
In the hole of the little knob I've screwed the blocking hex screw. To avoid it unscrews you can add a drop of glue before screwing it. You can remove it to loosen the spring and disassemble everything.
You can see as in the upper side of the wood board I've made a deep hole in which I've inserted the aluminium bar. You should bend a little the part inserted in the wood to avoid it slides. This bar already had the hole, and I bent it so that its head is in vertical axis with the rail screw. This screw, as the other one, already has an handle to help to tighten, and I've used it to join the bottom end of the spring. The other end is locked to the bar.
You could extract or insert more the bar so that you can choose the right high of the drill over the base. Unscrewing the side hex screw you can let the toothbrush making some turns. Each turn raise or lower the rail of about 1 centimeter, this is the step at which you can set the high of the drill in the resting position.
As the last thing you have to combine the column with the base. I've made it with six long wood screws from the bottom (see update). It's better you choose a wide and strong wood plate as pedestal, so it could keep the tool in steady position. Some rubber studs helps the stability.
If you want to use various dimensions bits, I suggest to add an addictional thick wood plate under the bit, and glued it on the base with a double-side scotch tape, so you can change it when the hole becomes too large.
Of course if you want to make everything prettier you could paint with black the wood parts.
You will see that the precision and stability of this tool is impressive. The only improvement I could think is to give more distance between wood column and drill, so that you can work on bigger objects.
[UPDATE: I've built a block to add distance between column and drill, so you have more space for pcb, and I also made a more nice base. I explain you the updates in next few steps]
The spacer is a wood black painted block, which is designed to put distance between column and rail, so that you can drill a bigger pcb. An horizontal hole connects it to rail with 1/4" screw, and another hole has a nut at the end, in this another screw will link the block to the column. The two vertical holes are to take the aluminium bar.
The base is made from a little wood board to cut salami, it's a good wood and it already has rounded edges and right dimensions.
I've drilled six holes to link sturdily the column. On the bottom surface of the board I've drilled with a cone bit the grooves to keep inside the screw heads.
The screws have to be long and thin, they shouldn't force the column holes, because there is danger to break the wood.
The holes are not centered on the short side of the board because pulling the toothbrush (or the lever, as you wish) you make a vertical force which has to be opposed by a larger base.
The column drill is finished (
really, this time not really, read upgrades on this new Instructable), I've glued four rubber feet at the corners, and you see I've added a thick wood plate which is handy to change when it will be a "gruviera" (swiss cheese, in Italy is commonly related with the presence of many holes, but in reality that is the Emmentaler), and I can replace it with a thinner one if I need to drill with a longer bit (it's faster than vary rail height). Don't hesitate to ask me about everything, about gruviera flavor too ;-)