Simax Glass question

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jlangridge
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Simax Glass question

Post by jlangridge » Sun Dec 30, 2007 10:01 pm

Let me apologize in advance if I have posted this to the wrong forum.

I am working on a ion gun project for a non-Fusion device that utilizes a glass tube interface between air and vacuum. The glass I have purchased is Czech made and Kavalier is the manufacturer. It is sold under the name of "Simax" and is the hardest stuff I have ever tried to work with in my life! Does anyone have any recommendations on how to cut this stuff? It is far too hard to cut with a standard glass tubing cutter and carbide blades seem to work in a limited capacity but are so rough that they end up breaking and flaking the glass during cutting. This tubing is 34mm in diamater with a wall thickness of 1.4mm.

I am limited in my tooling at this time but have historically had good luck with a triangle file, and tubing cutter combo. From time to time heat stress fracturing has worked well, but not with Simax. I am open to buying a diamond saw but I wonder if there are any recommendations, tips or wisdom that anyone might have to offer me when working with such a hard piece of glass.

Thanks,

John Langridge

Raymond Jimenez
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Re: Simax Glass question

Post by Raymond Jimenez » Sun Dec 30, 2007 11:24 pm

Hi John,

From my experience Simax is equivalent to normal borated glass/Pyrex. I've been working it all the time here, breaking it using the normal triangle file-pull-and-break method. It has the same working point too, in terms of lampworking.

Raymond J.

jlangridge
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Re: Simax Glass question

Post by jlangridge » Mon Dec 31, 2007 5:37 am

Raymond:

Thanks for the response.

I suspect one of the problems with what I have is the wall thickness and trying to cut it too quickly.with a dull tool. I did find today that my triangle file was virtually edge free after an attempted (and failed!) cutting session yesterday. The technique I am using is to lay a scratch all the way around the circumference with the file and once I have a groove I continue to pull the file through the groove until I think I am far enough to snap or pull apart. I haven't actually succeeded in snapping or pulling the pieces apart. Recently I have been resorting to the heat fracture method after a lay a deep scratch but the material never seems to break cleanly as I am told it is supposed to. I will try again with a sharp file and see if I can get all the way through.

Again, thanks for the response. I will stand down on the diamond saw purchase until I try a new file.

John Langridge

Richard Hester
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Re: Simax Glass question

Post by Richard Hester » Mon Dec 31, 2007 6:29 am

You may actually have a variant on fused silica rather than borosilicate. Most normal glasses are about as hard as a file. Fused silica is much harder, and its lower coefficient of expansion makes it less amenable to thermal stress fracture. You may have to use a diamond tool in the end.

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Carl Willis
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Re: Simax Glass question

Post by Carl Willis » Mon Dec 31, 2007 6:34 am

John,

The technique I was taught (my first job during high school was in a scientific glass shop, although I was not blowing glass) was to make a single short heavy stroke with the file, then wet the cut with a damp finger, then snap. The wetting seems to be important to the reliability of the method, though I have no idea why. For bigger tubing, like above 1/2", I saw the glassworkers heat the tip of a little piece of glass cane and apply the glowing tip against the end of the file stroke to move a crack around the circumference of the unheated tube in stages. That seemed to be a more controlled method.

Mike Donovan, an occasional forum poster out here in Albuquerque, has a lot of glass experience, and is quite the lampwork artist, and maybe he will comment.

-Carl
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DaveC
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Re: Simax Glass question

Post by DaveC » Mon Dec 31, 2007 8:39 am

John - Sounds you have fused quartz. As to the diamond saw.... McMaster -Carr sells a very useful small diamond band saw. We have one in the work lab and it works wonderfully well. Not too expensive... $300 - 400. and extra blades are around $100 each. But it will cut quite literally, anything, quartz, ceramic, ferrites,... like butter. Has a self contained water reservoir... the blade runs in the water and lubes itself.

You might want to check that out. Otherwise... diamond tools will cut it. Dremel has diamond grit cutoff saws for their "Moto-Tool" high speed grinders. But you probably need to work these dry.

Dave Cooper

jlangridge
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Re: Simax Glass question

Post by jlangridge » Mon Dec 31, 2007 3:52 pm

Gentlemen:

Thank you for the replies. Could someone give me their impressions of whether they think ebay item 180200024626 could do the job with this glass?

This is an Inland DB100 wet/dry diamond bandsaw. It looks to be marketed to the stained glass folks. The blade clearance looks to be more than enough for my tube.

Any opinions?

Thanks again for the input. I really appreciated it.

John Langridge

jlangridge
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* * * U P D A T E * * * Re: Simax Glass question

Post by jlangridge » Tue Jan 01, 2008 1:34 am

* * * U P D A T E * * *

After sending my previous post, I communicated with my associate and it appears that he had purchased a diamond blade for his scroll saw that did the trick. It is a slow process but results in a very clean cut.

Thanks again to all of you who provided information on this topic.

Best Regards,

John Langridge

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