1 inch =25.4mm

In the cad system that I'm familiar with, I would import the DXF (as inches), then switch display units to mm, before re-exporting to DXF.

I'd do ONE first to check that the laser cutter can open the file and that it is correctly sized. Some systems might only accept older DXF versions.

I'm surprised that the laser cutter can't do the conversion – either in CAD, or in the CNC control software.

The laser cutting company (online quoting and ordering), I use has an online drawing editing feature that pops up if the DXF I submit contains any errors that might cause the cutting process to throw a wobbler. One can then correct small errors (or design simple parts from scratch)

The submitted DXF's must have all the cutting lines on one layer, must have no text or dimensions and all lines must be unbroken ie converted to 'polylines' (in Acad).

I send plain DXF files and do not need to state any units. When I first began using the company I put one major dimension in my drawing name but then did not bother because found that the website quoting software shows a little drawing of each part and states the X and Y sizes.

Online quoting means one can change material type, grade, thickness and other factors and immediately see the most cost effective method (where appropriate).

Ian P

If the holes are much smaller diameter than the material thickness then presumably they will at least put a centre mark/divot so you dont have to mark out the positions.

Ian P

Glad to hear you're sorted. If you need to do it again, or to modify the plans in other ways, QCAD is both free and full-featured. You can download a full Trial Version of the commercial product which works for 30days or so. It's reenergised by either coughing up for a full licence or by switching the application into Community Mode. Community mode is plenty good enough for most 2D purposes. Many other free or trial packages have the poke necessary to scale drawings.

I wouldn't recommend getting CAD in unless several drawings need converting because there's a steepish learning curve, not worth it unless the software is used for other stuff.

Once understood well enough to find the buttons, your conversion is done in QCAD by opening the drawing, selecting everything, and scaling by 1/25.4. Simply changing the base unit doesn't do any converting. Worse, my experiments found some issues, such as managing layers (if used), and what happens when the drawn dimensions aren't scaled with everything else. They end up 25.4 times too big!

Good luck with your Shay. Will you share some photos as the loco develops please? Always good to see what other folk are making.

Dave