Glass engraving

[julianh]

I am not sure where t put this topic, so I will stick it here unless the mods disagree.


Anyway, I am looking to etch my company logo into panes of float glass and borosilicate glass, which is tougher and much more heat resistant than float glass. The logo would be about 1"x2" tops. I also need to etch or scribe a grid into the surface of the glass that will be just barely visible against a frosted glass surface. I will use this machine 5 days a week, 10 times a day tops, always with the same or similar programing. My questions are:

A.) What machine would you recomend for somone on a tight budget to do tis job?

B.) What kind of end mills will I need?

I have been eyeing a maxnc 15 system on ebay for 1200 bucks, if that would dothe trick I would be thrilled.

[Cruiser]

You might consider just making a template for your logo & grid, then use a media blast nozzle to texture the glass within the template. All you would need for that small of a logo would be an air brush style media blast system, air, and media.

[Torchhead]

You cannot engrave glass with conventional rotary tools and spindles. You need diamond burrs and ultra high speed spindles (80,000 to 160,000 RPM)

Tempered glass is EXTREMELY brittle and any scratch or cut can cause it to easily shatter or weaken. Even using blasting media (silicon carbide) can cause problems with hardened glass. Engraving on glass has to be tightly controlled on depth so like all engraving a floating tool and adjustable nosepiece is needed.

The blast process used is "Sand Carving" and consists of using a vinyl cutter to cut vinyl or for deep etching a special thick blast resist sold in rolls. For small highly detailed etches you can use a photo method and use it as the stencil. It's detailed enough to do halftone photos.

Compared to the blast method the rotary etching is a lot slower, harder to control and uses more expensive equipment. On uneven surfaces rotary cutting is an even bigger challenge. (try it on a wine bottle!)

There are shops/businesses setup to do the sand carving. Before you invest in equipment get some samples done on the media you are going to use by a shop that knows what they are doing.

http://groups.yahoo.com/group/sandcarving/

http://www.sandcarver.org/


Tom Caudle
www.CandCNC.com

[julianh]

80-160 THOUSAND RPM? Sounds expensive. I am definately not trying to engrave tempered glass. This is just your standard float glass and also some borosilicate glass, which has less heat expansion than normal glass (less likely to shatter) and is also somewhat harder. Could a cnc machine do it using a scribe that drags instead of spins? Basicly like chucking up a bearing with an exacto knife through it, and maybe a spring for consistant pressure, except on a micro scale? What is the price range for this blasting media? It sounds like it might do the trick except that I need to be able to easily make custom "format markings", like the corners of a 4x5 centered in the middle of a 5x7. That is a pretty simple example, people come up with so really far out things to have superimposed upon their focusing screen. The surfaces I am working with are, thankfull, completely flat within 5 millions of an inch, do to flat lapping.

Thanks,
-Julian

[DMF_TomB]

they make a glass etching cream that when applied through a stencil will frost the glass with an image / letters, also there are paints the same when applied by stencil and are baked melt on to the glass (level vial marks)

i tried cutting an old sliding glass door with a grinder to make glass panels for a green house. I got about 1/2" before glass went BOOM and shattered into thousandths of little pieces. Lucky I had my face shied on. Probably it was tempered glass and I figured no problem cutting it. I can cut tile, brick, steel with a grinder............ Yep learn not to do that again. Took awhile to pick up all the glass pieces to throw in the garbage.

[cncmaintenance]

Glass can be cut, shaped and engraved with diamond coated tooling at rpms as low as 5000. The secret is keeping the part cool, using coolant designed for glass machining sprayed on the part. Glass does not dissapate heat like metal, therefore it will overheat to breaking point near the tooling. Keep the feed rate much slower than used in metal to prevent heat buildup due to tooling friction. Glass particles are abrassive and will lock up and wear machinery out much quicker than metal chips.
Google "glass machining" for more info

[gsrmmeza]

Have you thought about laser.



http://www.epiloglaser.com/glass_engraving.htm

[julianh]

Unfortunately, I think a laser engraving system is a bit out of my budget. I do like the idea of machining the glass, especialy the borosilicate, because it is VERY difficult to break borosilicate glass by thermal shock. Among its uses are test tubes that regularly get heated up well above the boiling point of water and then get plunged into ice baths. Since I also will need to machine regular float glass, my plan is to set up a good spray lubricant system so that I dont have to worry.


DMF: A greenhouse door would definately be tempered. It is impossible to cut tempered glass without anealing it first because tempering works by putting very high levels of tension on the outside layer of the glass. This layer is so thin that if you even scrore the glass with a glass cutter it will explode before you even try to break it.

[tsroonney]

Originally Posted by julianh I am not sure where t put this topic, so I will stick it here unless the mods disagree. Anyway, I am looking to etch my company logo into panes of float glass and borosilicate glass, which is tougher and much more heat resistant than float glass. The logo would be about 1"x2" tops. I also need to etch or scribe a grid into the surface of the glass that will be just barely visible against a frosted glass surface. I will use this machine 5 days a week, 10 times a day tops, always with the same or similar programing. My questions are: A.) What machine would you recomend for somone on a tight budget to do tis job? B.) What kind of end mills will I need? I have been eyeing a maxnc 15 system on ebay for 1200 bucks, if that would dothe trick I would be thrilled.

Thank you so much for the post. It's really useful.


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