Cutting Alumina

For posts specifically relating to fusor design, construction, and operation.
Post Reply
Jeff Robertson
Posts: 58
Joined: Tue Jul 19, 2011 11:58 am
Real name:

Cutting Alumina

Post by Jeff Robertson »

Hey all,

I recently bought one foot of alumina tubing off McMaster. I don't have the exact measurements on me but it's about 1/8" thick, around 1" outer diameter. I need to figure out how to cut this down so I can place it over the electric feedthrough inside the vacuum. The problem is I'm an undergrad with access to only basic machining tools (milling machine, bandsaw, etc). I talked to the on-campus machinist and he doesn't have anything diamond-tipped, or suitable for cutting ceramic.

Any ideas for how I can cut through this alumina? I only need about 4" of tubing, with a pretty lax tolerance (like +/- 1/8"), so any crude "by hand" methods would probably work just fine.

All of this, naturally, is to avoid dumping money into any additional [unnecessary] parts. If people tell me that there's no way around it, I'll bite the bullet and buy a diamond tipped bit or something. Just wanna see if people have found alternative solutions to dealing with alumina.

Cheers,
Jeff Robertson
David Housley
Posts: 32
Joined: Sun Feb 20, 2011 5:07 am
Real name:

Re: Cutting Alumina

Post by David Housley »

I'm not sure exactly where you are located, but I suspect you have something similar wherever you are. Basically, a Dremel type rotary tool with a cheap diamond cutoff wheel should do the trick, especially if you drip water on it as you cut to keep it cool. Here in the US, we have a "cheap tool store chain" that imports from China, called Harbor Freight. They carry the cheap diamond cutoff wheels I mentioned. They work great on ceramics--they may not hold up for production stuff, but for amature one's and two's they will work fine. This is how I cut the alumina tubes if I want a clean cut.
Good Luck!
Jerry Biehler
Posts: 975
Joined: Tue Nov 24, 2009 3:08 am
Real name:
Location: Beaverton, OR

Re: Cutting Alumina

Post by Jerry Biehler »

Any diamond wheel will cut it. Maybe look at craigslist and see if there is an old tile saw.
Andrew Seltzman
Posts: 815
Joined: Sun Feb 01, 2004 8:02 pm
Real name: Andrew Seltzman
Contact:

Re: Cutting Alumina

Post by Andrew Seltzman »

Use a dremel with a diamond cutoff wheel. A tile saw would be too big and would not have enough control. I have used a dremel to cut 0.75" OD 1/8" thick alumina and it worked very nicely.
Use a 0.75" to 1" diameter cutoff wheel that is as thin as possible (larger diameter wheels will just require more torque and cause more vibration; do not go with the 2" wheels they are hard to center on the mandrel. You should also buy a right angle adapter for the dremel, or the thickness of the motor will force you to cut at an angle.

Water cooling while cutting is mandatory of the wheel will melt. You can run a flow of water over it or wrap it in a wet paper towel(less spray).

Examples of cutting alumina:
http://www.rtftechnologies.org/physics/ ... jector.htm
http://www.rtftechnologies.org/physics/ ... d-grid.htm

Buy these wheels or something like it:
http://www.ebay.com/itm/5pc-1-DIAMOND-C ... 230f9ca89b

and this adapter:
http://www.ebay.com/itm/Dremel-575-Righ ... 43aedc6146


good luck,
Andrew
Andrew Seltzman
www.rtftechnologies.org
Conrad Farnsworth
Posts: 135
Joined: Wed Jul 07, 2010 9:35 pm
Real name: Conrad Farnsworth

Re: Cutting Alumina

Post by Conrad Farnsworth »

On this topic (mostly), how does one go about cleaning off embedded grime that comes with handling the tubes?
Andrew Seltzman
Posts: 815
Joined: Sun Feb 01, 2004 8:02 pm
Real name: Andrew Seltzman
Contact:

Re: Cutting Alumina

Post by Andrew Seltzman »

Acetone cleans the tubes nicely. You can also heat them to white hot with a torch and that will remove all volatile grime.

Andrew
Andrew Seltzman
www.rtftechnologies.org
Tom Dressel
Posts: 287
Joined: Fri Jun 22, 2001 4:44 pm
Real name:

Re: Cutting Alumina

Post by Tom Dressel »

If you are making only one cut, you can go to tile store near you and they will probably cut it for you. To cut my feedthrough, I went to a Color Tile shop and they did it for nothing.
Tom
prestonbarrows
Posts: 211
Joined: Sun Jun 24, 2012 1:27 am
Real name:

Re: Cutting Alumina

Post by prestonbarrows »

Wet tile saws with diamond blades work great. Just go slow and light and let the tool do the work.

You don't need a fancy one but they will cost a few hundred new. You could probably rent one on the cheap for a day from a home improvement type place if that is all you need. Also can try asking around at local glass shops, especially stained glass studios as diamond cutting tools are common for both.
092333771856lg.jpg
092333771856lg.jpg (17.59 KiB) Viewed 15001 times
I imagine any small diamond grinding wheel or diamond embedded scroll saw wire would work in a pinch. The key is to continually flush with water so the tool does not get loaded up.
Dan Knapp
Posts: 402
Joined: Wed Aug 06, 2008 8:34 am
Real name: Dan Knapp

Re: Cutting Alumina

Post by Dan Knapp »

Harbor Freight sells a small tile saw with sale price of about fifty dollars. With a coupon, you can get it for about forty dollars.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Cutting Alumina

Post by Richard Hull »

Harbor freight is a great place to buy tooling. It is 100% chi-com and you will not pass the tools down to your children, but for the price and particular service the average home owner might expect from them, they are great! I retain and use virtually 100% of all the freebie and 20% off coupons my wife cuts out for me.

They do sell a set of diamond high speed Dremel type cutting wheels. Hamfests also have tool dealers that sell sets of diamond cutoff wheels for Dremels.

I have three lathes. One has a 6" 6 jaw chuck and an overbed swing of 10". I also have a K9 Southbend with a 6" 3 jaw chuck. In addition, I have a micro lathe used in my model railroad work. I would say 95% of my work involves spinning and working something under 2" in diameter and under 6" long, often under 1" long! As such, I am always working right at the headstock/chuck with a small workpiece in a giant twirling 6" diameter chuck! I doubt if I have used the lathe's tailstock in 8 years, save for boreing.

Harbor freight has had a 3" overbed lathe with a 3 jaw chuck that can chuck up to a 1.5" diameter piece. It is well made and has a continuous, electronic variable speed motor. It is real nice and I have mulled over this $500.00+ lathe for the past 5 years, wathcing its price go from $490 to its current $569. About three months ago they had a super sale and for one day only they offered a first time ever 25% off coupon!!!

I took this coupon and got my $143.00 savings. It is in my lab now and I rarely turn on my big lathes anymore. I give this lathe a triple A rating if you are doing a ton of occasional small stuff, like me.

I find the same stuff at Northern Tool and Equipment a bit over priced, though I did by a drill press from them at a good discount due to its being damaged....Which was an easy fix for me.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Andrew Robinson
Moderator
Posts: 688
Joined: Sun Aug 11, 2013 1:54 am
Real name: Andrew Robinson
Location: Raleigh, North Carolina
Contact:

Re: Cutting Alumina

Post by Andrew Robinson »

Richard Hull wrote:Harbor freight is a great place to buy tooling. It is 100% chi-com and you will not pass the tools down to your children, but for the price and particular service the average home owner might expect from them, they are great!
Except when it comes to multimeters Richard haha ;)
I can wire anything directly into anything! I'm the professor!
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Cutting Alumina

Post by Richard Hull »

The Harbor Freight multimeters are highly accurate at the list price of $5.99 each. (or free)

Andrew refers to a weekend test at a friends home. He noted that the meter on the AC range read voltage from a battery. There is no problem here of course. The solution is simple...Never read a DC battery voltage on the AC range. Try using the DC range were the battery's voltage will be accurate to about +/- .004 volts. This is the average of 5 of the harbor freight meter's error against a Weston standard cell that I ran. My $250.00 fluke was no more or less accurate when run against the cell. I suggest reserving the use of the AC range on the meters to measuring AC voltages where they perform just great.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Andrew Robinson
Moderator
Posts: 688
Joined: Sun Aug 11, 2013 1:54 am
Real name: Andrew Robinson
Location: Raleigh, North Carolina
Contact:

Re: Cutting Alumina

Post by Andrew Robinson »

Haha yeah. Why was he measuring with the AC setting to begin with? I'm guessing he just wasn't paying attention to the meter setting?
I can wire anything directly into anything! I'm the professor!
AFW
Posts: 157
Joined: Sun Dec 10, 2006 5:51 pm
Real name:

Re: Cutting Alumina

Post by AFW »

Do you have a campus glassblower? If so, he will probably have a diamond saw suitable for the diameter of your tubing.
Tony Webb
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Cutting Alumina

Post by ian_krase »

You might be able to just burn through it at the cost of inexpensive normal cutoff wheels. Or score and snap it, potentially.

Also, concentrated NaOH (drano?) will dissolve alumina though I suspect this would be very slow even if heated.
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Cutting Alumina

Post by Dennis P Brown »

For small diameter Alumina (3/8 inch and under) I have never bothered to use my diamond band saw - rather, I scored it with a triangular file, and broke it by a forceful pull and bend. I then obtained a nice break that just needed some clean up using sand paper on a solid surface. So, methods do depend on size.
User avatar
Rich Feldman
Posts: 1470
Joined: Mon Dec 21, 2009 6:59 pm
Real name: Rich Feldman
Location: Santa Clara County, CA, USA

Re: Cutting Alumina

Post by Rich Feldman »

Welcome to the forums, Ian.

Ian and Dennis, thanks for hint about familiar score-and-break method on narrow alumina tubes. I've seen video of an expert snapping a large (maybe 2" diameter) glass tube that way.

Here's a older forum thread about ceramic and handyman tools. I bet the McMaster alumina tubing cuts about the same as old porcelain sinks. In my limited experience, it never hurts to use plenty of water with abrasive wheels on ceramic. viewtopic.php?f=18&t=9988&p=67082
All models are wrong; some models are useful. -- George Box
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: Cutting Alumina

Post by ian_krase »

Isn't alumina-silica or other type of ceramic usually significantly softer than straight alumina?
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Cutting Alumina

Post by John Futter »

Ian
I think you should be posting in the new user area
you are not adding very much to this old thread
Alumina alumina silica are just about as hard as each other, alumina silica has better resistance to thermal shock
Both need diamond tools to do a GOOD JOB and as has been mentioned a good supply of water to keep the tools from burning up
Post Reply

Return to “Fusor Construction & Operation (& FAQs)”