Mini-drill

A mini-drill is an essential tool, it’s often the first one bought. The simplest are actually made up of a motor, a switch and a chuck with collets. In my opinion, the main selection criteria are:

This last point is not essential for hand working, but very important if the drill is mounted on a stand.

That point made me eliminate a Dremel drill: the collets (aluminium, therefore too soft) did not rotate smoothly! I preferred a Proxxon model, which for years, although not free from defects, has given me satisfaction.

Proxxon Micromot 50/E

Drill equipped with collets

Drill equipped with collets, the chuck is in front of it.

Characteristics

Power supply 18 V CC max
Maximum speed 20,000 rpm
Maximum power 40 W
Collar diameter 20 mm
Equipment Steel collets ø 1 - 1.5 - 2 - 2.4 - 3 - 3.2.
Optional: chuck ø 0.3 to 3.5

Operation

The control is made by a turning knob, potentiometer type, with integrated switch. This button is graduated in rotation speed, but if you connect the drill to a direct current source, you will find that it is impossible to vary the speed by turning the knob!

To actually vary the speed, there are three solutions:

Connector

The connector is a specific one. If you choose the third option, there is obviously no problem. In the other cases, you have to tinker with an adaptation. If, like me, you don’t want to cut the cord, you can connect it into a terminal block, ideally with a 12 mm pitch. Personally, I have adapted, by forcing a little, a 10 mm pitch withdrawable block.

Terminal block based connector

In the foreground, on the left: “normal” white block, at the exact spacing of the Proxxon connector pins. In the background, withdrawable block a little too narrow, but it fits…
On the right, the power supplies female blocks.

The center pin is only used for coding and is not to be connected: a cut in the insulation of the terminal block gives it a place. I have generalized this solution to all sources of direct current or even DCC, obviously taking precautions of polarity and coding.

The good choice?

After all this, one wonders whether it’s not better to choose a drill that connects directly to mains, like the FBS 240/E! Apart from perhaps the price, but if we take into account the power supply, we end up with about the same price to pay. I still see a disadvantage: the minimum speed of this drill is 5000 rpm. It’s still too much for delicate freehand drilling (see above).

Disadvantages

There are not many disadvantages. However, it is regrettable that the shaft locking pusher is in the gripping zone of the tool.

But there is still a more annoying defect which, in my opinion, is a design flaw: to work with the chuck, you have to unscrew the ø 20 metal collar which allows to fasten the drill in a stand. As a result, it is impossible to work with the chuck on a stand!

Close-up view of the chuck

From left to right in the foreground: the collet nut, the ø 3,2 collet, the unscrewed collar. Notice the position of the shaft lock pusher.

According to the Proxxon catalog picture, the model 50/EF doesn’t have this disadvantage: it can be seen with the chuck and collar, which is cylindrical. This seems to be the only difference with the 50/E, except that the latter is sold with a series of collets, while the other is sold with a chuck.

Comparison of drills 50E et 50EF

Left, model 50/E; right, 50/EF.

The revelation!

As I’m writing these lines, I have a sort of illumination: why not cut off the annoying front part of the collar? No sooner said than done: the conical part must be reduced to keep only a maximum total height of 9.6 mm.

Drill with reduced collar and chuck

Note that the chuck is fully tightened to ensure that it will not rub against the collar.

With a lathe, it may be feasible in a few minutes. I don’t have one, but since the piece is made of aluminium, there is no difficulty in cutting it with a hacksaw, then rectifying it with a light milling.

But how didn’t I think of it earlier? But why, at Proxxon’s, have they made two different models for so a little difference? Conclusion: it is better to buy the model 50/EF with chuck plus a set of collets, rather than the model 50/E with collets plus a ref. 28941 chuck, although it costs a few euros more!

Micromot 50/E ref. 860-28510
34,20 € — price 2015
at micro-modele.fr

Micromot NG/2 ref 28706
23,08 € — price 2015
at micro-modele.fr

Micromot NG 5/E ref 28704
56,19 € — price 2015
at micro-modele.fr

Proxxon Micromot 50 ref 28500
30,20 € — price 2015
at micro-modele.fr

12 withdrawable terminal
blocks ref. 0 342 53
at Legrand

FBS 240/E
59,20 € — price 2015
at micro-modele.fr

Set of Micromot collets
ref. 28940 - 9,53 € — price 2016
at micro-modele.fr