[mredican]

Here is my problem:

I'm trying to engrave glass plate with my cnc router. I have a dremel 35,000 rpm and dremel engraving bit. When I start out the first letter--1.5 inch high, parkavenue font--turns out great. However, by the second letter the bit is "scratching the glass" not "frosting it".

Some things I tried:

1. Changed Z axis.
2. Tried different bits--dremel brand engraving.
3. Changed feed rate up and down.

Any hints or tips would be greatly appreaciated.

Matt

[mredican]

bump

[ger21]

Try using some water or some other coolant?

[Geof]

If you Google 'cnc glass engraving' this is one of the links you will get.

http://www.2linc.com/glass_engraving.htm

I have been doing some searching for info on glass engraving and based on what I have found so far I think your Dremel engraving bits are not up to it; are they diamond tip?

[ViperTX]

Personally I'd use diamond, or corundum based stone.

[cbass]

I haven't done any engraving yet (heck, I don't even have a machine yet!) but I know there's a difference between diamond coated and diamond impregnated bits. When the coating on diamond coated bits wear down, the bit is pretty much toast. On the other hand, diamond impregnated bits last much longer (and cost much more) because as the material breaks down, fresh diamonds are revealed.

Do they make impregnated 'engraving' bits?


Carlo

[CJL5585]

Matt:
---------------------------
Question:
Is your work surface Parallel to the Dremel Tool? It will have to be Parallel to less than .001 inch to perform the task. Otherwise the cutter will not be able to engrave and will just scratch the surface.

Jerry

[Aksess]

I have done some engraving on glass. I made my own springloaded tool holder. the problem is the rpm's are to high you need to be turning around 2000-5000 for glass then the cheaper bits will last a lot longer.

[mika28au]

I've been in the glass industry for the past seven years and in my spare time I mess around with the cnc engraving and so on, I don't actually have an engraving bit but I use a diamond embedded router which works well always with water for coolant otherwise it just burns with the heat, and an even surface is crucial. unfortunately I don't have any pics from the work by the router, but I do have some pics of some brilliant cutting I've done and so on.
.....http://weekendoutdoors.awardspace.co...20waterjet.htm
I also have a site where I post free creative dxf files
.....http://flashanims.awardspace.com/
I don't charge for these files but if you want to earn me some beer money ha ha
you can click on an ad or two they are relative adds so they lead to interesting sites. also being as this is a hobby for me if anyone has a request I'm usually happy to draw up a dxf file in my spare time and post it.

[santiago lisboa]

I have done some engraving on glass. I made my own springloaded tool holder. the problem is the rpm's are to high you need to be turning around 2000-5000 for glass then the cheaper bits will last a lot longer.

Can you share the springloaded toll holder desing?

[tracyranson]

Here is my problem:

I'm trying to engrave glass plate with my cnc router. I have a dremel 35,000 rpm and dremel engraving bit. When I start out the first letter--1.5 inch high, parkavenue font--turns out great. However, by the second letter the bit is "scratching the glass" not "frosting it".

Some things I tried:

1. Changed Z axis.
2. Tried different bits--dremel brand engraving.
3. Changed feed rate up and down.

Any hints or tips would be greatly appreaciated.

Matt

You might want to purchase and industrial grade diamond engraver from Granger or mcmaster carr. I have had great success using a 30 deg carbide v-bit that I purchased on eBay.

[roonie]

this could be a problem of flatness of the table, if is not flat it will never be able to carve in the glass the way it should, take a big diameter tool a thick sheet of plexiglass and do an area clearance so it will make your table flat and then you should not have any problems the tool should do the job perfect

[wildwestpat]

Hi Matt

If this is a one off and you don't want to go to the expense of diamond tooling can I suggest you try this:-

Build a dam around the part of the sheet to be engraved using strips of metal and sealing on the outside with plasticine / modeling clay. The dam will be used to hold the coolant and abrasive so it only need to be a 1/4" high. Make up a tool out of soft copper with a flat end and required diameter. Mix up carborundum grit with a mixture of olive oil and turpentine. The amount of carborundum to the olive oil turps mix should be visibly thickened by the addition of the abrasive but the aim is for it to be liquid with the grains in suspension. Start with a 50% mix olive oil to turps but you will have to do some experimenting on a bit of scrap glass of the type you are using. The grade of carborundum grit determines the degree of frosting.

Place sufficient abrasive mix within the dam over the point at which the first figure is to be cut. The mix should be thick enough to stay put on the glass without spreading over a wide area. When you plunge the cutter into the mix the puddle will rotate and a slow speed of 1000 rpm would be a starting point - raise when you have the pecking sorted. Use a lift shift and repeat step as in peck drilling to allow the abrasive to be replaced before the copper contacts the glass. Diamond dust or diamond lapping compound will also work.

I have used this method for cutting holes and making decorative spots on glass plate.

Hope this helps - Regards - Pat