CNC height detector

[basem2b2]

Is there is any CNC router machine can detect sheet thickness during the action ?
because I'am working on 3mm Acrylic sheets which its thickness is not all the same and that makes bad results.
thanks in advance .

 

[letterman7]

Sounds to me that your cutting bed isn't flat. If it's 3mm acrylic, it's 3mm acrylic. Those tolerances usually don't vary from a manufacturer. But to answer your question, it all depends on what machine and software you're running. Some programs have a built-in Z zero setting, but it won't self adjust while it's running. I can't think of any that would since the programming would need to adjust on the fly.

 

[GVP]

It kind of depends on what you are doing. If you are just cutting out shapes, you would zero the z-axis to the top of the bed (i.e. the underside of the acrylic) all cnc software should allow you to do this. Since the zero point is now set to the machines table, any small fluctuations in the acrylic thickness shouldn't matter.

 

[basem2b2]

thanks for the response

thanks for the response
cutting bed is flat but the sheet it self is the problem, the thing is, I am doing some V carving 150 degree
so when the thickness is not all the same, that gets me uneven and disturbed shapes
that's why I am looking for some techniques to get the machine go along with the sheet thickness
View attachment 92782

 

[letterman7]

Hmm.. v-carving in 3mm. That creates problems all it's own. Unless the acrylic is textured in some way there still shouldn't be any issue. It's possible that the heat from the bit is warping the acrylic on deeper plunges, and that may be affecting the immediate area, but other than that I have no suggestions. Flat sheet is flat sheet - if yours isn't to spec and flat, why are you trying to rout it? Send it back or try another sheet. There are no programs or techniques that will allow the bit to follow the uneven contours of a sheet. You either need to check your sheets at the beginning with a straightedge or deal with the problems of trying to rout material so thin.

 

[basem2b2]

Hmm.. v-carving in 3mm. That creates problems all it's own. Unless the acrylic is textured in some way there still shouldn't be any issue. It's possible that the heat from the bit is warping the acrylic on deeper plunges, and that may be affecting the immediate area, but other than that I have no suggestions. Flat sheet is flat sheet - if yours isn't to spec and flat, why are you trying to rout it? Send it back or try another sheet. There are no programs or techniques that will allow the bit to follow the uneven contours of a sheet. You either need to check your sheets at the beginning with a straightedge or deal with the problems of trying to rout material so thin.

true the sheet it self is the problem, the variation in thickness could reach 0.5 mm of 3 mm, and that's a lot so I probably will look for new supplier thanks for you help

 

[SebastienL]

That's some mighty cheap *** acrylic you got there if the variation in thickness varies up to .5mm. That's .019". That's way outside most manufacturer tolerances. Personally, I'd return that crap and get decent acrylic.

My guess is your table is not flat or the material is not laying flat on the table.

 

[CanuckSigns]

We've had issues with 6mm p95 acrylic not being the same thickness from one end to the other, it wasn't a big deal for us, but annoying none the less

 

[basem2b2]

That's some mighty cheap *** acrylic you got there if the variation in thickness varies up to .5mm. That's .019". That's way outside most manufacturer tolerances. Personally, I'd return that crap and get decent acrylic.

My guess is your table is not flat or the material is not laying flat on the table.

going to take your advise and throw the dealer and the acrylic.
about the table, I had installed an MDF wood sheet over my machine table and then used a 20 mm flat drill bit to level the entire sheet of any disturbing in thickness, that's why I'am surprised of the result of the work that came not like expected.