Do you need to make adjustments to CAD for lasercut kits

[austinflyer]

I want to create an original design plane, and will be using Turbo Cad. The question I have for those who have done this "Do you need to adjust any measurements so the laser cutter gets a nice fitting kit? I have never done this before...Thanks

[Haldor]

Most likely not on balsa, sheet thickness varies anyways by a larger factor than the laser kerf itself. Plywood laser cuts are wider though and might need a little tweaking.

[vintage1]

I think the general way to proceed is to draw the plan up, then draw up all the cut parts on a seperate sheet.

Wirking with teh laser cutter, determine how much m,atreial is lost through cutting, or nees sanding off to remove scrocy marjks.

Then adjust the dawing to reflect this, and also any 'gaps' you need to stop the part falling out of the sheet.

It probably takes a few goes to get right.

[opualuan]

I have had this problem. parts do get undercut. you'll need to design in for the kerf if you have interlocking parts.

[AndyKunz]

Opualuan (what does that mean?) is right. You need to oversize parts and undersize notches. How much depends on the wood and who is doing the cutting.

Andy

[opualuan]

O is for omar (first name), pualuan is my last name.

how much does balsa vary in thickness, anyhow?

[zbrubaker]

It all depends on how the laser cutter is set up. Some systems cut right along the line that's drawn. Some systems can cut to either side of the line that is drawn, taking the width of the cut into consideration.

You'll need to discuss kerf (the thickness of the cut) and how they are setup to cut, with the person who will be cutting your parts.

The parts I've had cut, I've offset the the lines .005".

[John Boren]

I've had four models of my designs cut buy two different laser cutting officts and I supplied them with drawings that were the actual size of the part. The part fits was right on with all four models. In my experience the kerf thickness was not an issue. I would suggest you find a laser cutting service that will except your Turbo Cad drawings before proceeding, unless of course you can save your drawings in dxf format. Also every company likes their drawings with different colors for the outlines.

John Boren

[austinflyer]

Who did you use?

[John Boren]

The name of the company is laserlizard.com. You can go to Jesse's web site to check out his company.

John Boren

[Dereck]

I tried laser cutting on my last project - just the ribs. Re-arranged them to suit the cutter, didn't bother with kerfs and the accuracy was still way above what I could have achieved with my faithfull #11 knifeblade. For complex structures, this is the way to go, extravagant though it may seem.

If you're still prototyping, I'd suggest you live with ignoring the kerf issue, in the interests of faster drawings. No point in spending hours on adding/subtracting kerf allowances if you have to go back in and change the shape of the model. "Sandpaper adjustment" will be quicker overall ;)

With wood's natural variation, you still have to live with things not quite fitting - you can get your spar slots cut to exactly 1/4" wide, for example, but not all 1/4" strip is that good :(

Mine were cut as a favour by someone who has a laser, he doesn't do out-work normally. He had no difficulty producing parts off my DXF files.

I've asked hereabouts recently about laser cutting services - "AKM" @ http://www.ak-models.com/services.htm were recommended by several people. So far, I've only asked them questions on set-up and they've got back to me quickly and helpfully on all.

Regards

Dereck