How to Spec. a Laser Cut Box for Vendor?

matthew_stacy

I would love to hear recommendations and best practices from the Onshape user community regarding how to specify a plywood box for laser cutting.

This simplified model has a front panel and right side panel, finger-jointed together.  The front panel includes engraved text.  How would you communicate this design to a laser cutting vendor?  My understanding is that laser cutters typically work from DXF files but that different types of cuts would be segregated on two or more layers:

• Thru cuts
  
• Partial depth cuts (w/ some way to differentiate between vector-perimeter cuts and raster-area cuts)
  

But unless I overlooked the obvious, OnShape does not offer layering.

I would be happy to share the document directly with anyone who wants to roll up their sleeves and collaborate on this.

So far my work flow is to:

1. Create the parts and flat layout in a Part Studio
2. Create an assembly from the layout
3. Create a drawing from the assembly (delete all border entities, resize background to large format, 1:1 scale)
4. Export drawing as DXF

DXF units, or lack thereof, seem to be a whole 'nother can of worms with potential for designer/vendor communication errors. 

dirk_van_der_vaart

I think the best way is not to think for the "lasercutters", they have their own way of doing thing,s.
So give them a drawing of the assembly specify the depth of engraved text and name all part's A,B,C,etc., export the flat's direct out of the partstudio name them A,B,C, etc.
Don't worry about layer's , outline's and compensation for the fitting of the part's, don't think about nesting as well, the lasercutter know best, it's their job.
Ask your lasercutter about how he like the corner's of the part's, sometimes it is better, faster to avoid sharp corner's.

dirk_van_der_vaart

Forgot the most important thing, let them create a free account of Onshape, so you can share the document for viewing and exporting of the flat's

michael3424

I've done a bit of cutting of parts like that with a CO2 glass tube laser.  The finger joints need to allow pretty accurately for kerf and I use the Laser Joint Featurescript to create the slots and tabs and adjust those dimensions for the kerf.  The type of laser I use typically has about a 0.004-0.008" kerf and I usually cut some small test pieces in a new material to find an acceptable kerf value to use for that material.  The commercial laser cutters probably have their own preferred way deal with kerf so my approach probably doesn't have much merit for your use.

matthew_stacy

@michael3424 what is the thickest plywood that you have cut?  Is the kerf width fairly consistent through the material thickness?

michael3424

The thickest that I've cut with fingers is 1/4" Baltic Birch plywood.  The kerf is always a bit tapered with a laser cutter, at least with the the glass CO2 tube that I've been using but that hasn't affected fit or integrity of glued joints with both plywood or acrylic and I've never tried to measure it.  One of the joint projects serves as a shield over the exhaust ducting that leads out the overhead door in the garage where my laser is located.  I've lowered the door on that shield a couple of times with no damage to the shield so the fit and glue up seems good enough..

 

michael_denault

Typically we use different colors to differentiate the different process types.  For example

CUT= Black line color
ENGRAVE = Blue line color
GREEN = Ignore

each color can be given a different process setting, the particular color doesn’t matter as long as you send them a key.

typically we include a border around the whole document with the “ignore” color in case it needs to be resized.  That way the entire document can be selected and scaled properly using the binding box.  You can also include design notes in this col

That’s how you can work around layers.  Generally using a different color is preferred since most cutting software doesn’t play well with layers.

michael_denault

Typically we use different colors to differentiate the different process types.  For example

CUT= Black line color
ENGRAVE = Blue line color
GREEN = Ignore

each color can be given a different process setting, the particular color doesn’t matter as long as you send them a key.

typically we include a border around the whole document with the “ignore” color in case it needs to be resized.  That way the entire document can be selected and scaled properly using the binding box.  You can also include design notes in this color as well or part labels that you might not want to be engraved or cut.

That’s how you can work around layers.  Generally using a different color is preferred since most cutting software doesn’t play well with layers.

matthew_stacy

michael_denault said:

Typically we use different colors to differentiate the different process types.  For example

CUT= Black line color
ENGRAVE = Blue line color
GREEN = Ignore

each color can be given a different process setting, the particular color doesn’t matter as long as you send them a key.

typically we include a border around the whole document with the “ignore” color in case it needs to be resized.  That way the entire document can be selected and scaled properly using the binding box.  You can also include design notes in this color as well or part labels that you might not want to be engraved or cut.

That’s how you can work around layers.  Generally using a different color is preferred since most cutting software doesn’t play well with layers.

@michael_denault do you implement this workflow in Onshape?  If so I'd love to see a simple example (shared as public document).