glass cutting on a shopbot

[paul60]

http://www.cncinformation.com/CNCBlog/cutting-glass-by-scoring-it-on-a-cnc-router/

[beacon14]

Amazing. Who would have thunk it?

[br928]

Who makes the cutter? What does the depth setting do? Apply more pressure?

[knight_toolworks]

Yes I was going to ask about depth too. it looks like the cutter was just modified.

[myxpykalix]

What i have a question about is what is controlling the glass cutting insert to make it turn or is that inconsequential to the cutting? Is the tip just like an engraver with a point or does the cutter look like a round wheel?

[oddcoach]

its not the same tool that is in the video but you can use Russ Todd's spring loaded engraving tool. it has a diamond tip. the the tool in the video follows the path is it has a caster angle . the point of contact is behind the point of motion. same thing that lets your car drive in a straight line when you take your hands off the wheel. the vinyl cutter works the same way

[widgetworks_unlimited]

Thanks for the plug John...

I just posted to another SB thread about using the WidgetWorks Unlimited Diamond Drag Engraving bit for cutting glass with your CNC machine, so I don't want to add too much here, but I do have a few comments/answers to add to the discussion...

As John mentioned, the cutter in the video appears to be a "drag wheel" design. One of the challenges of designing a drag style bit is dealing with the "blade offset" distance. The offset needs to be large enough to control the cutter angle, but larger offsets result in less accurate cuts.

In this case, the offset is quite large. I'm not trying to insult anyone with that comment - it may need to be large to work for glass cutting (the bit that we designed uses a point, not a wheel, so I don't have direct experience here,) and the loss in cut accuracy may not be important since the mirror's edges are generally hidden. But, if you were cutting letters or graphics with that offset the loss of accuracy would be quite noticeable.

Depth of cut for our diamond bit is fine tuned using spring pressure and a floating-head design. I don't see this in the video, but it should work for their design if they decide it's needed.

Conceptually, it's fairly easy to design a bit that will "float," but accuracy is always a concern with any floating head design. Critical portions of our bits are machined to .0001" accuracy - a number that few of my friends outside the SB community can really appreciate!

Anyway... from one tool maker to another - keep up the good work! I'm glad to see that I'm not the only one using these machines to do things that Ted never intended. :)

[knight_toolworks]

I tired cutting class with a diamond tipped drag point and it did not work. the diamond only lightly scores the glass. did you need to make multiple passes? I have never cut glass before so I may be missing something. I was also told the glass would wear the diamond tips fast.

[mezalick]

Steve,
You're not really cutting the glass but scratching it.
More than once causes problems.

Here is a vidoe that's okay in explaining the process.The second half is better than the first.
Michael
http://www.thisoldhouse.com/toh/video/0,,1631599,00.html