Dremel 3000

[rlogiacco]

Hi everybody, this is my very first post so please, be patient.

I've a very recently bought Dremel 3000 which suddenly stopped working a couple of days ago, so suddenly I thought I had blown a fuse in the house mains.
I searched the proof of purchase like crazy, the thing is not even a month old and it was it's third use, but you got it... I didn't find it. The store, obviously, is not willing to change or repair it unless I can show the proof of purchase, they offered though to "send it to Dremel repair on me", something I already feel expensive...

I'm not completely noob in electronics (why should I be here otherwise!) and after an entire day of desperate search for the proof of purchase I decided to open it up: how complex could be this thing?

In reality I discovered it's really, really simple, so simple I can't understand what's wrong with it.

One thing to note is that my Dremel is actually capable to restart spinning by striking it on the body, but it doesn't keep running, I believe motor vibrations do break the contact.

I've completely disassembled the thing (not a complex task at all) and I've checked every connection I was able to expose and so far I've identified only one thing which seems suspicious: of the four contacts going to the motor from the potentiometer block one seems not connected, but I'm unable to disassemble the potentiometer block, or at least I'm not sure if it can be done without breaking it. The goal is to further inspect the thing to check if there's any loose connection in there.

I've attached the picture of the potentiometer block I'm talking about, the suspicious connection is the top left one.

Anybody willing to help me on this? I promise I'll pay you a beer when you'll be in Rome 

[sunnyhighway]

Maybe a bit late now you disassembled it, but there is no legal obligation for shops to even give you a receipt, let alone for you to keep it. Shops should accept any proof of purchase, like a bank statement or credit card bill.

Because of consumer protection laws in the EU the burden of proof is on the seller for the first 6 months after purchase.
So if you did not break it, the seller should (as per EU law) still fix the problem.

[saturation]

A nice thing about Dremel tools versus a copy tool from Black and Decker or nameless clones from Harbor Freight, is a plethora of parts and general schematics so its easy to DIY repair, even in the EU.

You can retrofit modern parts to Dremel models as far back as 20 years old for simpler models like 100, 200, 300.   

The bad part is modern dremels are not made as well as the old ones.  Its 1950s technology but the assembly and workmanship tends to produce many thorns in the flower bed, a common fault I find in otherwise good units is poor balancing of the rotor, causing unneeded vibration.

If striking the unit causes it too work temporarily insure that the brush springs are intact, allowing the brush to contact the commutator completely.  Sometimes its assembled incorrectly so it kinks and breaks contact, and very rarely the spring breaks.

A common bad part is the on-board variable speed switch. 

http://www.ereplacementparts.com/search_result.php?ssq=1&categories_id=15440&products_class_id=85&dsk=1

There is an embedded triac driven aka 'light dimmer' circuit in the assembly pictured, grit or heat can short the pads causing a failure of the copper tracings or break the switch tracks, or poor quality resistors or triacs burn out.    I don't recall if the 3000 has a switch cover, but you should be able to look sideways to see the tracks and electronics.

http://www.ereplacementparts.com/dremel-3000-rotary-tool-parts-c-15440_15456_205856.html

If the switch is faulty, I would check if you can use the Model 100 switch instead which is devoid of electronics.  The Model 100 is very reliable as its just a motor and a switch.   Use an external light dimmer to provide variable speed control, unlike the ganged 3000 5-speed select switch, a light dimmer it continuously variable for any speed you need.

[plesa]

I have almost the same issue with my new Dremel last year.When I unpack it and try to power it on sometime power on and sometimes not.
I found that if the pressure is applied in the area where the speed knob is, it works like charm.
Unit has been send for repair and Dremel representative appologize for that, but it is shame that brand new unit from factory has issue like this.

[Fraser]

I have heard that the modern Dremel's are prone to failure and the bushes are of questionable quality. A great pity for what was a very good quality brand.

Proxxon tools are said to be very good alternatives to Dremel but they are not exactly cheap.

I have to agree with others, I would have packaged the Dremel and sent it to your local Dremel agent with a letter explaining the purchase date, loss of receipt and fault. Many electric tools have build dates or serial numbers that provide such information. The agent can tell that the tool is less than a year old so covered by warranty. A quality brand like Dremel will often repair free of charge anyway.

It is still worth a try if you have not damaged ant security seals/labels.

Aurora

[Balaur]

Proxxon tools are said to be very good alternatives to Dremel but they are not exactly cheap.

Big Proxxon fan here, but I just ordered some Proxxon stuff for the company and I'm hugely disappointed by the latest evolution in their manufacturing quality. "Precision" vise with a huge (~ 1mm) gap with the jaws closed because of misalignment; a drill stand incorrectly assembled by the factory, Proxxon labels askew, harsh movement and so on.  Frankly, the quality is on par with LIDL products that cost 2-3x less. Oh well...

[rlogiacco]

Big thanks for all the replies. I didn't break anything, there was no seal whatsoever, the only thing that might report some sort of opening are the labels on the side, but nothing some usage wouldn't have done itself. I'm trying to contact the local Dremel support, but no joy so far, they are probably on holidays as it's the season here in Italy.
I already tried to check the brushes and the contacts of the slider, everything seems fine. I can see the triac, but my tester doesn't report any shorts and the device is quite clean as it has been used three times only.

If you feel it will help I can post pictures of the disassembled parts for you guys to visually inspect in case I missed something, but as I said the thing looks very simple... No comment regarding the failing contact on the pin?

Do you guys have any electric schematic we can check for possible sources of problems?

Thanks again!

[ModemHead]

I had a Dremel give me fits once with intermittent operation.  Turned out to be the connections for the field coil assembly.  The magnet wire is brought out and pulled into some insulation-displacement type connectors (basically little slits).  One of the wires had been effectively cut by the connector and was making intermittent connection.

[ElektroQuark]

It looks like there is a new player, BOSCH GRO:



I have a DREMEL Professional and a PROXXON IBS/E. I like the PROXXON over the DREMEL, but the BOSCH is tempting.

[saturation]

The Dremel is an mains powered electrical device driven by 110 or 220Vac, so take due care.  The troubleshooting step is bypass the switch and if the unit works at top speed, clearly its the switch unit. 

The schematic is basically a motor with a switch.  The switch itself is just a simple triac dimmer akin to this, there may or may not be a fuse [ usually thermal in the Dremels].



If the resistor to adjust speed Rp or triac burns out it will fail OPEN, and the unit will not work or at the least, spin very slowly.  Details from a review here with extensive photos:

http://www.amazon.com/gp/customer-media/product-gallery/B002BAHF64/ref=cm_cr_dp_cust_img_see_all_txt

I already tried to check the brushes and the contacts of the slider, everything seems fine. I can see the triac, but my tester doesn't report any shorts and the device is quite clean as it has been used three times only.

If you feel it will help I can post pictures of the disassembled parts for you guys to visually inspect in case I missed something, but as I said the thing looks very simple... No comment regarding the failing contact on the pin?

Do you guys have any electric schematic we can check for possible sources of problems?

Thanks again!

[wagon]

I've got a $50 'Chinese Dremel' (copy) that I've had for years.  It's been pretty good for the money.  I'm surprised the 'Dremel' product has gone downhill.

[saturation]

Yes, I'd say brushes are no better than anyone else but this is near a century old motor brush technology and has all its pitfalls.

Many  'dremel' clones are competitive, but they often have a fatal flaw somewhere over dremel.  For example, in Black and Decker models like the RTX, they often stop providing or don't make any brushes at all.  Dremel brushes are $5/pair delivered and they've supplied them for over 30+ years. 

Dremel like tools are not routers or miller grade tools albeit folks use it as one, and its not in the precision league as Proxxon.  A big flaw is that it was originally a small hand tool for craft level work, and users are applying it to larger tasks, like home repair.  If used for electronics work: repairing PCBs, cutting traces, chassis, cleaning grime, its perfect; for fixing a chair or removing grout in the bathroom, you risk burning it out.  That's why over the years the more expensive units have gotten bigger and more powerful,  but then Dremel steps into the territory of Milwaukee or Makita tools, who have far better reputations for that type of work.

 

I have heard that the modern Dremel's are prone to failure and the bushes are of questionable quality. A great pity for what was a very good quality brand.
Proxxon tools are said to be very good alternatives to Dremel but they are not exactly cheap.

[amyk]

Many  'dremel' clones are competitive, but they often have a fatal flaw somewhere over dremel.  For example, in Black and Decker models like the RTX, they often stop providing or don't make any brushes at all.  Dremel brushes are $5/pair delivered and they've supplied them for over 30+ years. 

Brushes aren't exactly high-tech... any blocks of graphite of the right composition and size will work. If you can't find ones of the exact dimensions buy slightly larger ones and sand them down to the right size.

[grenert]

I belive that Bosch and Dremel are both under the same ownership, so on the inside, that Bosch is probably the same as a Dremel.  It looks like the Dremel 8220:
http://www.dremel.com/en-us/Tools/Pages/ToolDetail.aspx?pid=8220#

It looks like there is a new player, BOSCH GRO:



I have a DREMEL Professional and a PROXXON IBS/E. I like the PROXXON over the DREMEL, but the BOSCH is tempting.

[saturation]

Yes, but you can rig any brush to fit as a hack, but there is more to brushes than a rod of graphite, here are the specs, which one does it use?  Do it wrong and you'll get the unit to work but as the pdf shows, it can lead to a lot of issues, often wearing out the commutator or creating a spark/fire hazard. 

http://www.mersen.com/uploads/tx_mersen/5-carbon-brush-technical-guide-mersen.pdf

But the bigger point I make is some makes like B&D makes little effort to supply spare parts, so you are on your own, its not just the brushes.   

Brushes aren't exactly high-tech... any blocks of graphite of the right composition and size will work. If you can't find ones of the exact dimensions buy slightly larger ones and sand them down to the right size.

[robrenz]

I got an inexpensive but full size flexible shaft for Christmas this year. Basically a Foredom copy and Foredom handpieces fit it.  I am surprised but my many dremels are collecting dust now. Having foot speed control and lower min rpm is priceless in many situations. As is being able to get the tool in position on the part not running then slowly advance the speed to your liking.  The handpieces just snap on and off the shaft so I have three different ones. One drill chuck style with 1/4" capacity, the 5/32 capacity drill chuck style that came with the unit, and my favorite is the Foredom H28 collet style handpiece (pic below). The basic flex shaft was $70.00 $80.00 at my local flea market and is pretty decent quality.

After my 8 months of industrial use I now highly recommend a flex shaft over a dremel.

[Zucca]

Thanks Robrenz,

To me it looks like the Foredom is like a Ferrari, the rest seems to be BMW/Mercedes level (just an example... please excuse me to be so rude...).

Very tempeted by this (220V, be aware!):

eBay auction: #201130399786

[robrenz]

The 2 hand pieces in that kit are the ones I would choose.  You can buy additional collet sizes to fit them if they don't come with all sizes.  You wont regret it

[rlogiacco]

Quick update.

Dremel has been acquired by Bosch as someone previously suggested and the Italian Dremel support was so kind to accept to repair my unit without a Proof of Purchase: they were happy enough to see a manipulated print screen of my online banking statement (I blurred out transactions not related to my device for privacy).

Now my concern is related to the fact I actually opened the device in the attempt to repair it myself, even if I'm 100% sure I didn't break anything and I was cautious to properly reassemble it.

I'll let you know if they decide to charge me and the technical details, if they will share.

Wish me luck!

[rlogiacco]

For anybody having a Dremel out there: they sent me a brand new Dremel 3000 with 25 new bits at no charge! 

I'm really pleasantly surprised by the outcome of this: I started thinking I got busted by my new Dremel and I ended up with a new unit and some free bits.... Wonderful!

[Fraser]

Nice to see some good customer support and service.

I have met other tool companies that provide a reconditioned (repaired?) drill as a replacement rather than a brand new one.

Well done 

[wagon]

I know this is digging up an old thread, but I just repaired one of these tools for a customer. (So, apologies in advance!)

One half of the field coil assembly measured open circuit.  Upon inspection, the winding was broken very close to the terminal.  I scraped away the insulation on the winding, soldered on a short piece of winding wire, then put the IDC-style terminal back together.  Worked well!