still kicking

[rweigel]

pictures of flex shafts and controller

 

[Sinterklaas]

I stand corrected.
I guess I at least got the bit about the unruliness of a flexshaft right..

I am curious, if the slower RPM and higher torque is more manageable for cutting stone seats, how does a micro-motor perform when cutting other more brittle mediums? such as glass, eggshell, mother of pearl, or abalone?
This may be a unusual question, but have you ever used it to try and remove a broken screw or tap from a hole? I'm curious of other advantages of the torque over RPM and if, with appropriate technique, there is any true benefit to higher RPM..

For brittle stuff it works also. At low speeds. But then I would use diamond burrs. They have no teeth so they won't really start to run off on you.
I have also used either carbid or diamond burrs to remove broken burrs and taps. It work well. Just go slow so the tool will stay cool. And will keep its cutting properties much longer.

Dentist use high rpm tools. But they are always watercooled. The dental machines all have a water jet shooting at the burr to keep it cool and maybe to prevent dust that is breathable.

_________________________
Dani, Another problem might be how you hold the tool.
If you hold the motor to far back it will run off.

I hold the micromotor at its very tip. Just like a pen. And I even have 1 finger against the shaft of the burr. And an other finger on the metal. So I have good control close to the cutting action.

 

[Meshach]

For stone setting I use only flexible shaft tools at low speed. Position of the stone marked with a deep dot from a scriber, I drill first a 0.5 mm hole through the metal with a spiral drill. For the rest of the work I use round dentaI reverse the direction of rotation. Build a special controller for this, with a selector switch for my 5 flex shafts. The burr will still remove material if rotated in the wrong direction, but much slower and without chatter. I set down the burr on the metal and start rotation slowly with the foot pedal. Thanks to Ganoksin for the “reverse rotation” idea…
...
I mounted 5 flex shafts (4 of them light and small like the Dremel flex shaft) onto DC motors with different max. speeds, which I control all with one foot pedal with selector switch.

Reverse direction.. .. at first I missed the part about having mounted the flex shafts to dc motors and was dumbfounded how this could be done but upon checking the 2 foredoms I have access to I found that one is indeed AC 120 but low and behold the other is a 120v DC motor .. I believe this could be adapted for reverse with a simple pigtail with an inverted plug at the footcontroll... And after reading the post in this thread, perhaps I will be starting down another rabbit hole of tools..
This .470 inch (12mm) flex shaft still seems less than optimal for handling with fine inlays, perhaps I just need to 'relocate' it to the engraving bench to try some finer work with it.. the picture you provided appears to have different sizes of flex shafts, is that just an optical illusion or are there indeed various sizes (diameter) available?

 

[rweigel]

Hello Meshach, I use different styles of flex shafts. One standard size came with the big green-gray motor, the other standard size shaft (the red one) I bought as a spare and connected it to a really slow DC motor. Both accept exchangable handpieces of european style. The red flex shaft is especially usefull for the setting hammer handpiece.
The smaller flex shafts got non-exchangable handpieces that accept collets from 0.5 to 3.5 mm, and with an adapter piece also small jacobs chucks with the same diameter range. They come from the european company “Proxxon” and are comparable in size to the ”Dremel” flex shaft. Many goldsmiths dismiss them as “toy”, but I have good experience with them. Bought most of them at ebay, cost me 10-20 Euro per piece, 2 of my purchases did not work or had exessive tolerances. Overall, a good deal. Setting is not hard work for the flex shaft, they do not wear out from it. They are about 50% of a standard flex shaft in shaft and handpiece diameter.

 

[Meshach]

They are about 50% of a standard flex shaft in shaft and handpiece diameter.

That sounds MUCH more manageable for detaild work! Thank you for the info I believe I will have to try out one of those tools.
.. for better or for worse I believe I am becoming a tool addict.. hehe

 

[Dani Girl]

for this kind of work I would advise against a flex-shaft tool, they have plenty of torque and power but are harder to control and still pull a lot because they are a low speed tool.
I haven't done a ton of stone setting but what I have done was done with an ultra-high speed air rotary tool, the power carver 400xs is an example and what I have used for stone setting, unfortunately they are fairly expensive (looks like it's on sale for $400 from $550 at https://scmsysteminc.com/power-carver/ ) however if you look around there are sever other brands out nowadays and I seem to remember coming across a web post a year or so ago comparing 5 or 6 different brands some of which (if memory serves correct) were close to a quarter of the price of the 400XS, also you may look into a rotary dental tool as it may be a cheaper option but I'm not sure..
I have used (for other projects) one of these 65,000 RPM hand tools that you can get for about $20 on Amazon.. https://www.amazon.com/Air-Powered-...pcontext&ref_=fplfs&psc=1&smid=A1NE1K2SUI6UFL
and they are OK but for this type of job you will fight them.. if you learn to control it right (which for extended projects will cause a lot of strain and cramping in the hands...) then the next biggest problems is finding burs that are fine enough to do this detailed work as they use .125 inch shaft tools and most of them that I have used are rather large in the bur..
I also use a Foredom flex shaft tool pretty much daily for stock work and other heavy duty projects, they CAN be used for decent detail work but the shaft is far to stif and unrully to want to do any detailed setting work for long periods of time in my opinion.
Admittedly I don't know if there are or have experience with higher speed smaller flex shaft tools..
I believe the thing you want is RPMs in the range of 150,000 + you can stall it out fairly easily because it doesn't have a lot of torque, but at that speed it feels more like drawing with a pencil then cutting with a rotary tool and you can make those fine cuts and inlays without it grabbing and running away. it is designed to cut at high speed so rather then putting a variable foot controll on it what I have done is just put an on-off foot pedal on it's airline to make it more easily manageable. another cool thing about those ultra-high-speed tools is that you can use them to cut on glass and eggshells and many other surfaces that are nearly impossible to cut otherwise.. also you could use it to do some of your background removal that you mentioned in another of your posts..
you can find dental burs online for them at a reasonable price, you just need to look for anything with an "FG" size shaft which is .0625 inch they make them with pointed tools, cylinder shaped tools with round or flat shaped ends, round burs that can go althe way down around .020 inch (.5MM) in diamiter.

is that stainless or silver you are inlaying into? looks like a silver chain with stainless pendent. I know that rolling those prongs in stainless without breaking them is a tricky job from hearsay and from how it reacts engraving, but I haven't done any setting in it so I'm not likely to be a lot of help advising with that one..

Edit:
I also know of people who use a drill press with a stop set to get uniform sets for stones too so it's not like any one tool is the only way to go, but there are certainly tools that are better suited for any particular job..
As I said in the start, I don't have a lot of experience setting stones but that's my 2 cents and I'm sure we can get some input from some other folks too

silver fill I engraved on the back of it, not stainless

 

[Dani Girl]

I guess no harm in drilling some holes and seeing if I can hold onto it better. I can run the micromotor in reverse too. fast or slow? 0-45,000rpm I think it goes.

I had a little super fast air one once but the bearings died on it and replacement ones lasted minutes. tried to fix a few times. wasn't grs branded but looked like the same thing. I haven't heard any bad experiences about actual grs branded ones yet. should I save up?

in stone setting youtube videos they go really slow taking tiny nibbles with the handpiece held vertically into the drill hole and using a round bur only spinning a few rotations at a time