Rotary tools in support of electronics, Dremel and more ..

[saturation]

One accessory that can make life easy when modifying cases, physical components in housings or parts, hacking PCBs, dead bug construction and more, is a rotary tool.  In the USA, and maybe elsewhere, the market is dominated by Dremel.

However, the years have shown a reduction in quality and materials used to build Dremel rotary tools, and many competitors either can meet or exceed its performance at a lower price, or far exceed it, at a higher price.

What models do you recommend?

Are the original accessories still better than clones or competitors?  That is bits, wheels, cutters?

As more names are gathered, I'll add it to the poll for a vote on the most often used tool among eevblog users.

[GeoffS]

The Dremel tools use a rubber mounted bearing, not so good for precision work. The major advantage is that they are stocked just about everywhere and are relatively cheap.

My preferred small grinding/milling tool is a Proxxon Micromot 50/E. A lot dearer but worth every cent (or euro or whatever...)

[Psi]

i like to use a Dremel tool but cheap 3rd party bits, the dremel bits are expensive

[G7PSK]

I prefer to use air powered die grinders and micro die grinders I have a couple of desouter and atlas copco ones they have the advantage of running cooler and being lighter and smaller.

[T4P]

Proxxon is a little bit expensive but it's the most precise you can find

[notsob]

Proxon are far better than dremel , & do not buy a dremel drill press - the mount for the dremel tool is plastic & moves when the bit makes contact & the one I had, did not even hold the dremel vertically - it was out a few degrees, I had to "dremel" out the plastic moulding to correct it.

[Psi]

yeah, i have the dremel drill press.
It's only useful for the most crude of tasks and has no precision at all. Far too many plastic parts.

[robrenz]

I prefer to use air powered die grinders and micro die grinders I have a couple of desouter and atlas copco ones they have the advantage of running cooler and being lighter and smaller.

I highly agree,  They also have higher rpm typically 40k to 90k rpm. That is very effective for tools roughly 6mm dia. and smaller.  On the other hand those speeds are an accident waiting to happen with larger diameter cutoff wheels.  That is where the variable speed electrics have an advantage with low speed torque.  Also if you are polishing with a felt buff and a compound of some sort, low rpms is a benefit in not slinging the compound off instantly.

General info on bonded grinding wheel behavior on metals. (does not apply to plated abrasive wheels):
Wheel bonds are made in different levels of hardness and there are various types of bonds used, vitrified (form of glass), shellac, rubber, etc.  Hardness refers to how strongly the bond material holds the abrasive particles to each other. Typically a hard bond is used on soft materials and a soft bond on hard materials.  The ideal hardness will have a abrasive particle break the bond and fall out when it is dull. This makes the wheel self sharpening.

Why do you care? The surface speed of the wheel changes the effective hardness of the wheel no matter what hardness it is.  Slower makes it behave softer and faster makes it behave harder.  So when you are using a wheel, if it seems like it is not cutting very effectively slow it down until you start to get some slow wheel breakdown (self sharpening). On the other hand if the wheel just seems to disappear as you try to grind, speed it up.  There are limits to how far speed can effect hardness so a wheel can be too soft or too hard for a particular material.  All of this applies to a wheel that is NOT loaded up with smeared metal or severely glazed. So use a dressing stick to clean the wheel surface before you start.

EDIT:   
When you dress a wheel you want to break bonds and remove whole abrasive particles, not gently rub the tops off abrasive particles leaving a hopelessly dull wheel.  You have to be a little agressive.

[G7PSK]

With air tools it is very easy to just throttle down the speed with the paddle lever, the down side is they sound like a dentists drill.

[bullet308]

I have a Ryobi rotary tool that runs circles around my old Dremel.

For serious work, a "super-dremel" (AKA a die grinder) comes in handy:


http://www.factoryauthorizedoutlet.com/makita/us/products/GD0800C.asp?cagpspn=pla&gclid=CNnF-9XBhbECFQgGnQodrH1Y7A

[HLA-27b]

To add a bit to robenz' write up here is a little trade secret for grinding aluminium.

Once I was involved in design and production of a new façade for an office building which consisted of nearly 20 tons of aluminium sheets welded up - all welds to be ground flush and polished to match the original finish. My guesstimate is that we removed close to a ton of aluminium by grinding alone. So I had enough time to go though all of the Murphy's laws concerning aluminium and its grinding.

Aluminium is very nasty to grind with abrasives as it fouls up the abrasive immediately and once fouled the stone (or flap disks in our case) can not be recovered. One little known remedy is to use lard as a lubricant. Yes, common lard and I know it is 21'st century. Liberal amounts of animal lard  is applied to the part being worked and the grinding medium. As the part is being worked it heats up and melts the lard which then flows and lubricates and almost totally prevents fouling up of the grinding medium. I've experimented with most other substances out there and nothing works anywhere near as good including all sorts of oils greases emulsions suspensions old wife remedies and what not.

It makes an absolute horrid mess as blackened drops of molten lard sling all around and solidify as they hit the wall and ceiling, so be warned this is not something you want to try in the living room. Wear goggles and some old t-shit you don't like.

Lard is a hard white substance with consistency reminiscent of soap or candle wax (i.e. it is purified not raw). It should be available in hardware stores if lots of aluminium is being worked around the area. It is also raw material for common soap.

[robrenz]

I use Johnson's #140 stick wax.  It is made for this and behaves exactly like the lard including the horrendous mess.  Also works well for using carbide burrs on aluminum. You can dip the running burr in the wax. My tube of it is probably 30 years old but it is still available. 

HAL-42b,  I am glad we can count on each other to get OT in the machining direction

[HLA-27b]

I use Johnson's #140 stick wax.  It is made for this and behaves exactly like the lard including the horrendous mess.  Also works well for using carbide burrs on aluminum. You can dip the running burr in the wax. My tube of it is probably 30 years old but it is still available. 

I'm kinda glad that we don't have "everything brand name" around here yet. Most things are sold as bulk commodity. Or maybe it is simply due to the quantities that I am used to deal with.
 

HAL-42b,  I am glad we can count on each other to get OT in the machining direction

It's a pleasure

[SeanB]

One of the hardest things to machine is soft silicone.

PTFE is a far second, and Vesconite is great to machine bushes out of. Much better wear properties than bronze, and nice to work with, though you have to be careful with thin sections, you need sharp tooling and multiple small passes to get to the final size.

[T4P]

As for picking the right rotary tool ... Forget about dremel
If anything avoid the ones that look like the dremel normal series
Go for the ones that have a 25mm chuck or a 6mm chuck
PS: I'm throwing out my dremel clone that hardly works anymore once i get a new die grinder

[G7PSK]

I use zirconium flap disc's for grinding aluminium no need for any lard or wax as the material is made non clogging. There is also a special aluminum grinding wheel which is silver in color and does not need lubricant as it contains it already.

[ErikTheNorwegian]

My tip is..

don't rotate it, vibrate it (any woman knows that!)

From a older tread..
https://www.eevblog.com/forum/general-chat/cutting-square-holes-for-instruments/msg108707/#msg108707

[Dawn]

Somebody put Foredom in the list. Odd though that nobody has mentioned flexible shaft tools. These blow a typical dremel tool away both with precision and flexibility. They aren't cheap, but a good one with a Jacobs chuck/handle will last a lifetime with occasional replacement of the flexible shaft and brushes. I've owned a Vigor that I bought from a Jewelry tool supply and some other quality miniature tools about 35 years ago that works just as good today. Unlike a Dremel, these generally don't use collets unless you specifically buy a collet style handpiece. It's always hanging there ready to use rather then digging it out of a box or kit. Most of the Chinese knock offs are crap, but a few of them are actually very well made. You don't see these too much outside Jewelry repair, but they are one of the essential must haves in my book. One particular Chinese made unit that was sold by craft suppliers was housed in a blue or green plastic housing that was excellent. The shaft was supple as a hose and the handpiece was a near identical copy of the Jacobs #30 and the foot pedal while plastic was a very smooth speed control, much better I think then mine. These were selling for about $50USD and less at places like Harbor Freight. Most places replaced these with a metal housed unit that's garbage with a stiff shaft and shitty handle, but the Blue one is still around and a much better deal then a Dremel.

[G7PSK]

You can get flexible shaft tools in varying sizes as well I have seen monsters with 5KW 3 phase motors for grinding. There used to be a very good make called Flextool I have not seen them around for a while another good make was Wolsey they made flex shaft tools as well as sheep shears.

[nanofrog]

Somebody put Foredom in the list. Odd though that nobody has mentioned flexible shaft tools. These blow a typical dremel tool away both with precision and flexibility.

I've an old Dremel of this type I inherited. Much easier to work with than the non-flex shaft versions IMHO as well.

Not sure how it stacks up with Foredom or similar though, as I've not had access to them.

[nukie]

Proxxon, I have a few models they have bearings made in heaven. Drills 0.25 mm holes without breaking carbide drills, the drill stand is available from amazon cheap and very useful and very rigid compared to Dremel toys. Once you tried a Proxxon, you will never look back, Dremel is immediately at the bottom of list, it has shitty bearings. Foredom is too expensive.

Many has converted Proxxon tools into cnc.

Flex shaft is not the answer to precision stuff, and it requires regular maintenance.  It is not as flexible as holding the Proxxon Micromot. It is a low voltage and lightweight tool it provide full freedom.  I feel that flex shaft is always fighting me whenever I want to change angle. It is especially useful for micro engraving PCB, it works really well. Despite being an AC motor, you can power it from your DC power supply albeit with less torque(unless you build a PWM). It starts with a gentle hum from 6V you can use it in the silent of the night but don't let this little gem fool you it's bloody monster when it's at 15V. I fit a 2mm endmill to mill aluminium block quite slowly.

The advantage of bigger brother mains powered Proxxons over Dremels are their precision bearings and balanced motors. Other than that, I don't see much different. Proxxon has very little vibration which makes them a fine tool. Just think about it the next time you use your Dremel. The Dremel is like a tool trying escape from your hands when it's on. My biggest regret is buying a second Dremel. Get a Proxxon you won't be disapointed.

Finally not everything is good with Proxxon, I find some of their engraving bits quite 'unfinished'. Dremel makes very fine bits.
On the right is a factory Proxxon bit that I fixed manually.

[Fallingwater]

My "good" rotary is a mains-powered Black&Decker RT650. Back when I bought it a Dremel would have cost me neatly twice as much (they have come down in price since). I often read bad opinions about B&D, but I've gotta say the RT650 is a good tool. It has torque to spare and I've had no trouble with the bearings. I put a drill-style chuck on it because I was tired of losing the little triwing collets every time I had to change bit size and it's been my main rotary tool for the last decade.

I also have a nail-art rotary I got from a friend after she gave up on the activity and sold her gear. It looks a lot like this, except for the color. The motor is much smaller than an ordinary Dremel; it's about the size of one of those pistol-grip cordless Dremels, but without the grip part. It has impressive torque for something that small and that, uh, pink.
The collet has a twist-grip arrangement that works really well at releasing bits, and the base has a variable speed setting and lets you change direction, though there's little point in running it reversed. It's also surprisingly quiet considering its power. Torque-wise it obviously can't match the mains-powered RT650, but for precision jobs it blows it into the weeds - bits meant for grinding stone-hard nail-art gel and acrylic have little trouble eating through relatively soft materials like plastic, and can go through harder stuff given enough effort.

I also have a couple of cordless cheapies with nothing interesting to remark on. I use them for low-power jobs around the house.

[saturation]

Thanks everyone for their insight into so many rotary tools of use in electronics.  Please keep them coming, I think this thread is one of the better ones on the net, as it covers so many types of tools in one spot, very well described and detailed.

Eyeballing Proxxon reviews on Amazon.com, for 115/E and IB/E units, ~ 25% complain [ 3 star or less reviews] of early failures with motors smoking as a fairly common symptom.  Anyone experience this?

[T4P]

I only know dremels suffer from premature brush failure, fake or not.

[robrenz]

Eyeballing Proxxon reviews on Amazon.com, for 115/E and IB/E units, ~ 25% complain [ 3 star or less reviews] of early failures with motors smoking as a fairly common symptom.  Anyone experience this?

The parts listing on thier website shows a geared drive.  That is why the spindle is offset from the body.  It does not look like it would be very robust.