Hello there,
I ran across this forum section while searching for a solution for using the Dremel Drill Press with carbide drill bits.
As many here probably know, the Dremel Drill press is not the best tool for use when drilling PCB copper clad boards with carbide drill bits. It MAY work with high speed steel regular drill bits, but with carbide bits the motion has to be more precise. If there is any wobble the bit will break and then the next bit will break too, etc., so you would end up going through a lot of bits.
The problem i had was that the basket that holds the Dremel drill motor moves left and right by a good 1/16 of an inch or more, and that's not good when drilling because the bit then has the chore of keeping the whole movement in line with the hole. Since the bits can be very tiny like #75, that doesn't work and the bits break right off.
That was the problem i had and this is a fix for that problem. If you have a worn bearing or something else you would have to address that issue separately.
For this problem the solution was to first find a nut that would fit on the small shaft just to the right of the movement. It's about 6 inches long and about 1/4 inch in diameter or so. I got my drill press used so it looked like it was missing the nut on the bottom of that shaft. Yours may still have that nut, but if not, the first thing to do is find a nut that will fit and tighten it up snug. I would not go too tight though. This nut helps to keep that small shaft ridged on the side so it does not sway at the bottom or top. It stays parallel to the downward travel axis. Without that nut the next fix will not work.
The next fix is to get a small wooden wedge about 1/2 to 3/4 inch wide, and the wedge incline starts at about 3/16 inch and ends at about 1/8 inch. That means if you jam it between two objects it will wedge in there and stay put.
The idea is to jam this wedge at the bottom of that small shaft, just above the nut, between the shaft and the body of the part of the press that moves downward when you pull on the handle. It's the main part of the movement.
Once that is done, when you pull on the handle the small shaft now slides on the wedge and since it is tight in there it has very little wiggle room. As the sliding mechanism moves down, the small shaft keeps it from moving back and forth. That keeps the motion of the bit in a downward direction and no left to right swaying.
After i did this fix i had drilled several holes using some very small carbide drill bits. #66 which is good for dip packages, and #75 which has a really tiny diameter you may not even need that small of a bit. There was no indication at all that the bit would break, and after about 10 holes it was still working fine.
You may find some mods for this also like perhaps putting a little wax on the wedge after it is installed. I liked the slightly stiffened movement though it felt better that way when drilling.
The test is to try to drill some cardboard. If you drill a hole in a piece of cardboard that has a good finished surface, you can look at the hole and make sure it is not bigger than the drill bit diameter, and make sure it is not oblong. If it is distorted then that means the dill bit is moving from side to side, front to back, or both which would mean it had some precession, which would enlarge the hole. Any of that would mean the bit could break when drilling. If that is still the case, you have to find out why. Sometimes it is due to the bit not being fit into the chuck properly when the chuck is tightened. This is especially true if you use a three jaw chuck instead of a collet. A collet is probably a better option but i used a three jaw chuck and i just had to make sure it was inserted and tightened properly and checked with the cardboard test.
To recap, the most important parts where the nut and the wedge. The nut was needed to tighten the shaft, and the wedge stopped the side to side motion. This meant that when the bit came down to the surface and through the board it stayed very much vertical and did not sway in any direction.
Another tip is to lower the bit slowly until it just gently touches the surface of the board, then proceed to gently drill through the board. It becomes easier as you do a few holes.
I also used a 1.6mm bit but those are so big in diameter it's much harder to break them. If you want to you can start with a larger bit like that and work your way down to the smallest you will need. The smallest you usually need for dip packages is the #66 bit.
Good luck with it.