ASGS TECHNICAL DISCUSSION E-MAIL LIST

ASGS TECHNICAL DISCUSSION E-MAIL LIST

Cutting Small Diameter Quartz Tubing Lengthwise - 9/18/03

Question from Tracy Drier, University of Wisconsin, Madison

I've been trying to split a quartz tube in half longitudinally (along the axis). The OD is 19mm and the length is 24".I've been practicing with boro before attempting the quartz. I realize quartz is more brittle Things I have tried so far....

Bandsaw. My bandsaw has too much vibration. Scoring the inside of the tube with a diamond tip scribe, 180 degrees apart and pressing on the score lines. If I get a crack to start, it doesn't run cleanly down the score line. I can get maybe 8 or 10 inch sections Scoring the outside of the tube 180 degrees apart. My cut-off saw isn't adjustable to cut off the top of the blade. I feel like vibration might be a problem with that as well I can imagine that someone has successfully done this before.

If so, I'd love to hear about it. Also, what would you expect the difference between the boro and quartz to be? I've seen this done with long lengths of larger diameter boro tubing at symposiums and it seemed to go quite nicely. I'm imagining that it just tends to flex more than the smaller diameter. Ideas? Comments? Suggestions?

Thanks. Tracy

Answer from Darryl Smith, Director, Salem Community College Glassblowing Program

Hi Tracy,

This is my idea, off of the top of my head. Take a 2x4 piece of lumber (or other appropriate size). Cut a "v" groove in it. Mount the quartz tube in the groove with wax or adhesive. Flip it over and grind off half of the quartz tube on a flat grinder. May also grind on a belt sander or mount a carborundum blade along side an old metal blade from a diamond wheel and grind using the wet saw. Remove quartz from wood mount and clean off as needed.

Daryl Smith SCC

Answer from Mike Souza, Princeton University

Tracy, I used a technique somewhat similiar to what Daryl describes.

Wax the tube onto a very flat aluminium sheet stock at least 16" long w/ a slight channel or "V". (Cyrstal bond is the best)Then I jury rigged a high speed drill press w/ a small thin diamond wheel ~ 2" dia. mounted horizontal on a 3/8" to 1/4" shank. Line up the table so the jigged tubing hits the blade in the center of your tube. THen slide the block along the table down the length of each side of your tubing. The trick is to sweep across bothsides deep enough before you try cutting all the way through. Then you maybe able to get two troughs for the price of one. The fly in the ointment is that it's a messy job because you have to cool the blade w/ water. You can use gravity or siphon from a large water source or get a $30 pump. Another tip is to make your water outlets from glass luer tips. Then you can choose from an assortment of canulas or syringe needle tips of various bores and even bend them in direction that gets the coolant where you want w/o interferring w/ the cut.

I used this technique almost exclusively w/ quartz glass w/ very little failure. But I have to admit they were generally 2" or greater in diameter.

Good luck,

-Mike Souza

Answer from Dave Werth Epitronics Phoenix, Arizona

A horizontal mill with a .025 diamond wheel is ideal for splitting quartz tubes. Make a templete of the halves you wish to split by drawing a circle around the tube and then mark the template in half. Place tape on the halves that you wish to split and mark them accordingly. Then cut the quartz .030 deep using pella oil or water as a coolant and continue adding .030 until the parts split. Splitting can also be done by using the scribe method. Using a straight edge on the inside of the tube run the scribe along the straight edge. Take 3 in 1 oil and wipe inside of quartz first, this helps lubricate the scribe.Use a ballpene hammer to gently tap and crack the scribe area, as you see the crack run tap lightly just ahead of it. This procedure works well with larger bore tubing. Smaller bore tubing such as what you are using would be better cut on the horizontal mill or sent to a laser company such as GM Associates,

Davee

Answer from William Shoup, University of Virginia

Tracy,

I've had success splitting full lengths of 16 mm tubing by putting the diamond scribe marks on the outside of the tubing then squeezing the tubing at 90 degrees. I use a tool maker's parallel clamp to get the cracks started at one end. I use a diamond glass cutter (Wale 16-1655 or equivalent) with the head removed from the wooden handle, aand slide it across a piece or flat glass or plexiglass the right thickness so the diamond hits the center of the tube. The tube can be mounted any way you like just so it keeps its orientation. Hint: when initially propigating the crack, be patient, the pressure is about the same as if you were clamping your fingertip firmly but before it hurts. Sometimes it takes 10 seconds for the cracks to start & don't forget to wet the scratch. If you make the scratch in one smooth motion & there are no "skips" in the scratch, you should have success. Quartz is easier than Pyrex.

Good luck,

Willy

Last updated April 21, 2008