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Drilling Out Alumina Ceramic Tubing??

dazz

Stainless
Joined
Aug 20, 2006
Location
New Zealand
Hi
I ordered alumina ceramic tube for a one-off project. OD=4mm, ID=2mm.
I got tube OD=4mm, ID=1.2mm. The bore is too small.

It took over 2 months for the order to make it through the shipping process, so while I wait for a replacement, I thought I could experiment with what I have.

Is it practical to drill out the bore from 1.2mm to at least 2mm with conventional tooling (lathe)?? The bore only needs to be about 10mm deep.
The hole diameter, concentricity tolerances are wide. I want to epoxy or Loctite a 2mm pin in the bore. An oversized hole can be used to compensate for errors.

I have 2mm carbide drills but the risk of shattering would be great.

I am thinking of unconventional grinding using a soft core (plastic? matchstick?) coated with grinding paste. If the cutting end of the core is tapered from 1mm dia to 2mm diameter, the paste will be cutting over a relatively wide band.

Exotic methods like ultrasonic drilling are not viable.

Any suggestions?
 

Joe Gwinn

Stainless
Joined
Nov 22, 2009
Location
Boston, MA area
Hi
I ordered alumina ceramic tube for a one-off project. OD=4mm, ID=2mm.
I got tube OD=4mm, ID=1.2mm. The bore is too small.

Is it practical to drill out the bore from 1.2mm to at least 2mm with conventional tooling (lathe)?? The bore only needs to be about 10mm deep.
The hole diameter, concentricity tolerances are wide. I want to epoxy or Loctite a 2mm pin in the bore. An oversized hole can be used to compensate for errors.

Bore it by wet grinding it on a lathe using a 2mm diamond point, using with lots of water. The point could he held in a tailstock chuck.

Or perhaps use a toolpost grinder, perhaps cobbled from a die grinder.
 

dgfoster

Diamond
Joined
Jun 14, 2008
Location
Bellingham, WA
You will never drill that stuff. But grind it with diamond as above? Yes.

Not sure the length of the bore or the accuracy of the bore needed. I see a number of tapered diamond points in that size range on Amazon, for instance.

If you could get water continuously to the actual area grinding, that would be a real plus. It would keep things cool and flush out the sludge. A diamond point is usually on very soft steel..Bore it down the center starting at the shank end. Then hook up water to the point itself. Might be very feasible if the point were held in a tool holder rather than your tailstock. No, I have not actually done it. But that is surely what I would try. Pecking will help flush out sludge as well. Alumina is very very hard and equally brittle. That is what my TIG cups are made from.

Denis
 
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Joe Gwinn

Stainless
Joined
Nov 22, 2009
Location
Boston, MA area
Why is that ? Tungsten carbide is 2600 on Vickers scale, alumina ceramics up to 1600. There won't be a chip formation, but the drill should sort of grind its way in.

Drilling imposes far higher forces, especially in something as strong as alumina. Workpiece will likely break, and/or slip in the collet or chuck.
 

car2

Stainless
Joined
Sep 19, 2009
Location
Apex, NC
Try a smaller-dia diamond-impregnated dental type burr chucked in a toolpost-mounted grinder, ID-grinder style, with water (dentists grind alumina and zirconia restorations with those burrs all the time). I wouldn't do it on a lathe you care much about, since the alumina (abrasive) will contaminate the lathe (even with attempted careful control)--lathes ain't designed for grinding.
 

plastikdreams

Diamond
Joined
May 31, 2011
Location
upstate nj
We cut alumina ceramic cores at work with a diamond wet saw. It dulls carbide endmills quickly. It's removed from the castings with potassium hydroxide and sodium hydroxide...takes days.
 

dazz

Stainless
Joined
Aug 20, 2006
Location
New Zealand
Hi
Thanks for the advice and ideas.
Unfortunately there is absolutely no danger of getting diamond tooling where I live, and if I could, it would cost too many $$$.
It looks like any sort of carbide mill/drill won't work.

I am going to try a bamboo toothpick, with a tapered point and automotive valve grinding grinding paste. I have those already and nothing but time to lose.
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
Hi
Thanks for the advice and ideas.
Unfortunately there is absolutely no danger of getting diamond tooling where I live, and if I could, it would cost too many $$$.
It looks like any sort of carbide mill/drill won't work.

I am going to try a bamboo toothpick, with a tapered point and automotive valve grinding grinding paste. I have those already and nothing but time to lose.

No stuff coming in from China? There's endless cheap diamond tooling and grinding pastes available off eBay and Alibaba and the like.

And how the heck did a Chinese Ecom company wind up with a name like Alibaba? Should have been 40Thieves Inc, or something like that...
 

crickets

Hot Rolled
Joined
Jul 3, 2021
Hi
Thanks for the advice and ideas.
Unfortunately there is absolutely no danger of getting diamond tooling where I live, and if I could, it would cost too many $$$.
It looks like any sort of carbide mill/drill won't work.

I am going to try a bamboo toothpick, with a tapered point and automotive valve grinding grinding paste. I have those already and nothing but time to lose.

Also check out Stefan's method for lapping such small bores :

https://youtu.be/o6UeWV_TRuc?t=1706
 

dgfoster

Diamond
Joined
Jun 14, 2008
Location
Bellingham, WA
Hi
Thanks for the advice and ideas.
Unfortunately there is absolutely no danger of getting diamond tooling where I live, and if I could, it would cost too many $$$.
It looks like any sort of carbide mill/drill won't work.

I am going to try a bamboo toothpick, with a tapered point and automotive valve grinding grinding paste. I have those already and nothing but time to lose.

Not familiar with a bamboo toothpick. But a soft( brass, aluminum, cast iron) lap charged with diamond past would get there. There are lots of schemes for making adjustable laps. I’ve made them and bought them. With coarse paste they cut quite well.

Denis
 

Conrad Hoffman

Titanium
Joined
May 10, 2009
Location
Canandaigua, NY, USA
1.2 to 2 mm is a very long ways for any sort of lapping. You need a spinning tool with diamond, lest you spend another 2 months getting the job done. Even an undersize cast iron pin with coarse diamond powder pressed in could work, though you'd need to recharge it often. A cheap plated Chinese tool would work much better. You don't want a 2 mm tool as the part will just break. Since it's 1.2 mm, start with a 1 mm tool. Hard to believe there's anyplace left without a Harbor Freight store! I'd think something on eBay would ship to you fairly quickly. You can mount a Mototool or any similar thing in the lathe toolpost to get the job done. Just shield it from the water you'll have to use to avoid electrocution. Or go with battery power.
 

car2

Stainless
Joined
Sep 19, 2009
Location
Apex, NC
Seems you'd be able to find the 1/8 to 1/4 dia diamond metal-bonded cylindrical burrs, they're sold for dremel-type rotary tools) (don't know how good those are), Big-Box stores also have similar burrs for grinding/cutting on tile and glass.
 

memphisjed

Stainless
Joined
Jan 21, 2019
Location
Memphis
Dremel engraving sets have the tiny burrs of ok quality- big box availability. Why drill, ream, grind out the hole when there is a steel pin that can be turned instead?
 

dgfoster

Diamond
Joined
Jun 14, 2008
Location
Bellingham, WA
The key things we still don’t know is how long the bore is and how accurately and precisely it needs to be enlarged. Those factors determine whether a given solution is actually practical or not. Grinding with diamond paste for 2 mm is not the same as grinding 2 inches. +/- .000” is not the same as .O02.”

Denis
 

dazz

Stainless
Joined
Aug 20, 2006
Location
New Zealand
The key things we still don’t know is how long the bore is and how accurately and precisely it needs to be enlarged. Those factors determine whether a given solution is actually practical or not. Grinding with diamond paste for 2 mm is not the same as grinding 2 inches. +/- .000” is not the same as .O02.”

Denis

Hi
From my original post:
" The bore only needs to be about 10mm deep.
The hole diameter, concentricity tolerances are wide. I want to epoxy or Loctite a 2mm pin in the bore. An oversized hole can be used to compensate for errors."
 








 
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