Proxxon Micromot 60 Went BANG!!!

[RichKem]

My Proxxon Micromot 60 Drill Drill Went BANG!!!

As you can see from the photos below, it is easy to insert the power connector in reverse which causes the original 1uF Electrolytic Capacitor to go BANG! 

Not only does this scare the life out of you is also means there is no suppression capacitor on the motor which results in a less smooth and noisy motor. 

Simply replace the original capacitor with a high quality 100nf Polyester film or Ceramic Capacitor which are non-polarised (Also know as a 104 capacitor)

I found a 100nf capacitor to work best and this is a standard value for small DC motors.

Choosing a non-polarised capacitor will ensure that if you make the same mistake in future your Proxxon drill/grinder will simply rotate in reverse

Photo below shows the 1uf Original Electrolytic Capacitor next to the New 100nf Polyester Film Capacitor.

Disclaimer:

This is NOT engineering advice so do not UNDER ANY CIRCUMSTANCES follow what I do!   

[IanB]

As you can see from the photos below, it is easy to insert the power connector in reverse which causes the original 1uF Electrolytic Capacitor to go BANG! 

How is it possible to insert the power connector in reverse if there is a keyed power connector with a third pin to prevent it?

[RichKem]

@IanB - See photo below...............

Connector is inserted the wrong way but still makes an electrical connection 

[TimNJ]

A keyed designed which isn’t actually keyed at all. Nice. I wonder why they even feel the need to use that kind of connector anyway? Lock you into using their overpriced line frequency  transformer in a box I suppose?

[RichKem]

@TimNJ - The best way I can put this is that it has been PRECISION ENGINEERED to be WRONG   

Overall the quality is good and although these are expensive tools they are fantastic to use.

Just don't put the plug in the wrong way in a quiet workshop at night as you will will not only scare the life out of yourself but wake the neighbours too 

Have you noticed that if Proxxon had made the centre pin as long as the other pins then this problem would not occur?

[madires]

The first thing I do when buying a Proxxon tool is to replace that stupid connector with 4mm banana plugs. The PSU is simply a transformer with a bridge rectifier (no filter cap!).

[RichKem]

@madires

The Proxxon PSU is deliberately half wave rectified and speed control can then be achieved with a potentiometer and thyristor circuit.

If you connect a regulated smoothed PSU to a Proxxon grinder/drill which has a speed control dial on the tool itself (some models do) then you can not achieve speed control.

I chose the Proxxon PSU with the speed control on it rather than choosing a Proxxon Micromot drill/grinder with speed control on it.

Having a switch only on the tool itself was my preference.

No need to change the plug even though its design is flawed. Just change the capacitor, which is probably easier to do.

I hope this explains my rationale

[Gyro]

Overall the quality is good and although these are expensive tools they are fantastic to use.

Looking at the first photo, I'm disappointed to see that the mechanical design and build looks mediocre at best, no better than cheapies I have bought in the past. It looks as if the nose bearing has slid out of the way during disassembly, but it still uses the motor as its rear and thrust bearing. A bit sad as I bought my son one a while back as an interim spindle for a CNC he's building.

As you say, expensive, but they seem to be playing on their 'precision German engineered' tag line.

[RichKem]

@Gyro

Thanks for your input.

All read and noted.

The body and design of this tool is very good. These are about £35 without the PSU (another £50) and Proxxon also sell larger 240v drill/grinders with heavier duty specs.

However, I have found this model, the Proxxon 60, to be very quiet, smooth and well balanced.

I also have a Dremel and Parkside 'equivalent' and I much prefer the Proxxon.

If you ever get a chance to try one of these as a demo I think you will agree that they are very good tools.

I purchased a small wooden box from ebay and so I can store it safely.

See photo below.

As an aside, I pulled the workings out from the body for photographic purposes otherwise the workings are a snug fit.


Disclaimer: This is NOT engineering advice so do not UNDER ANY CIRCUMSTANCES follow what I do!   

[RichKem]

@Gyro

I wanted to add to my comments above in response to your comments about the design.

I totally agree with you that this tool looks like it lacks robustness and I like your comment about the its reliance on the motor as a rear (thrust/radial) bearing.

However, the case is made of very robust and very accurately manufactured injection moulded parts.

It is surprising at how well it performs as a complete design.



Disclaimer: This is NOT engineering advice so do not UNDER ANY CIRCUMSTANCES follow what I do!   

[madires]

I chose the Proxxon PSU with the speed control on it rather than choosing a Proxxon Micromot drill/grinder with speed control on it.

My setup is a little bit different. I have multiple mini tools and built a PSU with sufficient power providing AC, unfiltered DC and filtered DC to support all possible types. One PSU instead of buying several expensive vendor specific ones (also less wasted workbench space).

[RichKem]

I chose the Proxxon PSU with the speed control on it rather than choosing a Proxxon Micromot drill/grinder with speed control on it.

My setup is a little bit different. I have multiple mini tools and built a PSU with sufficient power providing AC, unfiltered DC and filtered DC to support all possible types. One PSU instead of buying several expensive vendor specific ones (also less wasted workbench space).

Do you have any photos?

If so don't keep telling us how good yours is! - Post some photos! 

[madires]

Sorry, haven't taken any pictures. It's nothing special anyway, just an aluminium enclosure, a toroidal transformer, a homemade PCB, a few switches and 4mm binding posts.

[RichKem]

Sorry, haven't taken any pictures. It's nothing special anyway, just an aluminium enclosure, a toroidal transformer, a homemade PCB, a few switches and 4mm binding posts.

Come on! Let's see those photos! You have me interested now! 

[tooki]

Looking at the first photo, I'm disappointed to see that the mechanical design and build looks mediocre at best, no better than cheapies I have bought in the past.

Remember that you’re looking at their entry level line. Even so, it may be plastic, but it’s good plastic. They’re better than the Dremel tools, and certainly better than cheapies.

If you go up in price to their top model standard tool, the IBS/E — which, I will add, still costs less than the top of the line Dremel — you’re looking at die-cast metal for the important bits, and a spectacularly precise build with essentially zero run-out. Dremels feel like ruffians with gravel for bearings in comparison to the IBS/E. (This is the model I have.)

It looks as if the nose bearing has slid out of the way during disassembly, but it still uses the motor as its rear and thrust bearing. A bit sad as I bought my son one a while back as an interim spindle for a CNC he's building.

The IBS/E is the lowest model you should even consider as a CNC spindle.

As you say, expensive, but they seem to be playing on their 'precision German engineered' tag line.

IMHO the German precision is there, and frankly I don’t think they’re very expensive at all.

[RichKem]

@tooki - Thanks for your input.

I didn't want to sound too opinionated so I thought I would leave someone like yourself to say all this 

Ultimately I agree with what you have said.

The Micromot 60 is more of an entry level tool at £35 but good quality as you have said.

IBS/E is a fantastic tool but just bigger than I wanted.

Overall the size and performance of the Micromot 60 is fantastic.


Disclaimer: This is NOT engineering advice so do not UNDER ANY CIRCUMSTANCES follow what I do!   

[IanB]

Just don't put the plug in the wrong way in a quiet workshop at night as you will will not only scare the life out of yourself but wake the neighbours too 

I think the capacitor should not blow up if one just momentarily puts the plug in the wrong way. It normally takes time for the pressure to build up before a capacitor goes bang. Are you saying the explosion happened within a second of reversing the plug?

[RichKem]

I think the capacitor should not blow up if one just momentarily puts the plug in the wrong way. It normally takes time for the pressure to build up before a capacitor goes bang. Are you saying the explosion happened within a second of reversing the plug?

Ian, if you were unaware that you plugged it in the wrong way like me then the time issue is a little bit of a moot point as the only time you find out is when it goes Bang!! 

The only pressure that built up was across my heart!!! 

I would say a matter of 10 seconds or so.