hmm well.. I usually need to drill the small pilot holes before i bore something larger..
smallest, 2mm.. biggest, hmm about 25mm.. im thinking of doing a "swing" table on a sleeve and a rack and pinion to be able to rise and lower the table. Ive found this old 3kW electric motor, that is 3 phase lying around in the garage from some other project so im thinking belt drive and a three speed controller for the motor..
3 kW is a lot of power for a drill press. Most commercial units covering that range would have a motor between (about) .38 and .57 kW. Too much power will make drilling with small (say < ø1 mm) bits more difficult (they break with too much torque).
The
swing I was referring to is the distance between the centerline of the chuck and the edge of the column. This measure is usually rated as the largest diameter of (round) part to which you can drill to its center. Being able to reach 200 mm from the column to the center of what you are drilling is (generally) called a
400 mm swing.
I would actually recommend using a cable drive system with pulleys and a counterweight for raising and lowering the table. (1) It is simpler to build and (2) it is (usually) easier to operate.
i have a hard time to wrap my head around that "spline drive" thingy. I cant really in my head see how it should be able to spin and move up and down at the same time..
In commercial practice, a
spline-shaft is essentially a long spurgear. The driving side is a
spline-drive that is essentially a round OD part with a mating
gear-shaped hole broached in it. The drive-belt turns the
spline-drive which, in turn, spins the
spline-shaft -- which can move (axially) up & down with respect to the
spline-drive. Whatever the Norwegian equivalent of
Machinery's Handbook will have information on these types of parts.
Now it is true that a spurgear type of interface is going to be the most efficient of this type of drive interface. However, a reasonable equivalent can be made by using a square or a hex shape. These are much easier for the home-shop type of equipment (and, usually, skills) to make. The closer you come to a true circular interface, the less shaking will be induced by the eccentricity of mass. A square shape interface will drive more power, but it will shake (induce more vibration) into the drive than a hex shape interface. An octagon shape interface will drive less power than a hex shape interface, but it will vibrate less. (Etc.) Another
alternative approach is to run long keyways on the shaft that can be driven by keyseat broached or cut (i.e. filed) into the drive hub.
I would (generally) recommend a hexagon drive interface.
Anyway, fixed head and moveable drill table i think its the best way to go about this. I need about 100mm of travel for the drill but the table need to be lowered for larger stuff.
If your
I think about it and XXX throw is about right number is 100 mm, then I would
design for 150 mm of throw as that should not add too much trouble or expense and will save your bacon when you discover you need that extra 10 mm! More is almost always better in this regard!