I just thought I’d tap into the collective wisdom and experience of the community here and ask a couple of questions about and gather more experienced people’s thoughts on using the laser cutter for making router templates, which I’m sure many members have done before.
Mostly, my questions relate to the issue of the laser cutter’s ‘kerf’. Obviously the laser cutter has an effective kerf, as it burns away a small amount of material in order to make any cuts. From my experience with the laser, that kerf is of the order of 0.1 mm, or thereabouts. I assume (perhaps wrongly?) that the laser cuts on the effective middle of the lines in your vector design, so the cut design typically comes out to be half the kerf’s width smaller.
Now, for most cases in woodworking that sort of discrepancy between the vector design and actual cut piece is negligible, but let’s say I want to use the templates for cutting an inlay and I want to cut both the positive and the negative templates on the laser cutter. Due to the kerf, simply making the cut once means that the inside (‘positive’) bit that was cut out is actually going to be very slightly smaller than the outside (‘negative’) template.
I am assuming that the correct thing to do in this case is to cut one of them again separately, with the kerf’s width adjusted for. For example, by cutting the inside bit again, but with the vector design path offset by the width of the kerf. I am wondering if, in people’s experience, this actually matters and is the kerf something that should be adjusted for when making such templates?
One more thing I wanted to ask about - the laser cutter doesn’t cut perfectly perpendicular walls, due to the intrinsically hourglass shape of the beam. In theory, this could mean that a flush-cut router bit could cut differently depending on where along the laser cut template’s wall the bearing is riding on. But again, my main question is whether people have found this to actually be a significant effect in any way? Additionally, if so, how would one mitigate it - choice of template material, fine-tuning laser cutting settings, or something else?
Yes, the laser follows the center of the line (it ignores the width of the line).
The kerf value is discoverable using a kerf testing tool (search on the page).
The angle of the cut depends on the thickness of the sheet.
I also believe that the angle is greater on clear acrylic than on ply (anyone agree/disagree?)
I never noticed that kerf testing tool and instructions doc, it basically just answered 80% of what I asked in this thread - thanks for that!
I would definitely still be interested in hearing about people’s thoughts and experiences with the angle of the cut and how (or if) it affects the router bit bearing
In terms of actual functionality, there’s not really anything the laser does in this context that the CNC wouldn’t. As Brendon said, sometimes the geometry is not permissible for CNC routing, but then you could still use the CNC to make the templates as Paul mentioned above.
Really, the main reasons for going the laser route are just speed and simplicity. And also I’m not inducted on the big CNC yet haha
I’ve used a laser-cut router template in the past to add an extra pickup cavity to a bass guitar. You’d have to do a lot more disassembly and work mounting and lining it up than it takes to tape on a template that has centre lines already marked.
Of course, if you’re starting from scratch you can do the whole thing with CNC much more easily!
I found holding a router for hour was less fun than watching a robot do it for me. But very nice that it was mobile and less setup. Pretty slick workflow.
It’s kind of a different tool. I wouldn’t use it to cut big panels out but it’s portable and packs away easily.
It’s brilliant for fitting hardware. It’s great for cutting small details on things that would be hard to fit into a big CNC machine. I used it recently to cut repair panels in a door - used the same file to cut a block then slowly opened up a corresponding hole until it fitted exactly.
Fantastic for repairing solid wood flooring.
I have to engraved details on 48 oak sleepers for a job. They won’t fit in my CNC router without rearranging the bed but I could make a mask with Shaper tape on it that will drop over each sleeper in turn and then I’ll engrave each one separately. Haven’t decided on the approach yet!