Cutting the sled (metric system, s'il vous plait)

Ok. Maslow is assembled and calibrated (w00t). Next step is to cut the sled.

Makercam is down. The alternative site needs Flash (who even does that anymore?), and Easel wants me to create an account.

So, how do I convert the sled drawing to a gcode file? I’m using an 8mm router bit, so a pre-made file for a 1/4" bit isn’t going to work.

I tried Freecad, which looks promising, but imports the DXF without reading the units, so my sled is 9mm in radius…

It also messed up the position of two of the brick mounting holes, which ended up way over on the left.

Someone has written a Maslow post-processor for Freecad, which makes it even more appealing, but only if I can read the DXF properly. The SVG files don’t work either.

QCAD is nice, and has a CAM module. Hmm.

Anything else (that isn’t from Autodesk)?

At the absolute minimum, can we have a dimensioned drawing (mm/in.) of the sled in a PDF file please? Naturally I could print it myself, but my drawing would show that indeed the sled should have a radius of 9mm. With a dimensioned drawing I could do my own CAD and then generate the CAM file, and verify my final output against the original dimensions.

Thanks in advance!


Replying to self because I can pretend to be someone more knowledgeable.

I have found a lot of Freecad resources in these very forums, including a Freecad sled model. So you can all stop looking now. Thanks.

Memo to self: first search, then ask for help.


It’ running here. Also there is


Flash! Ah-aah! Saviour of the universe.

Unfortunately that only works in the movies. In real life it’s really not a good idea to run it.


As a Linux guy, my choice had to be FreeCad

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I think you are missing a link for “here”.

Here was related to my testing location. ( makercam worked)
Both worked from this side of the globe or plane.
I would like to take the opportunity to Thank You! for your work benefiting the community.


Ok. It’s not working for me. I downloaded the “Sled with holes and tabs.FCStd” file but it seems to be a finished job, which I don’t know how to edit.

What I need is either:
a) instructions to change the cutting bit to 8mm diameter in that file (which I don’t think is possible as the outer slot is set to 1/4" so can’t be re-cut at 8mm as the tool is too big)


b) a dimensioned drawing of the sled so I can make my own model and set up the cuts myself (because Freecad won’t read the supplied DXF or SVG files). I’m going to need this skill later anyway.

Actually, I think I can use QCAD to read the DXF, and make a dimensioned drawing from that. Which I can then redraw in Freecad.

If I’m missing the simple-and-obvious solution please enlighten me (and no, acquiring a 1/4" router bit is not an option- you don’t get off that easily).

Thanks in advance.

I checked the file.
I think you could delete the job and material, make the “body” visible by selecting it and hitting the space bar.
Then edit the sketches that need to be adjusted and create a new job.
I prefer to separate the different cuts, as I like to test them on scrap material first.
I ‘stitch’ them together with a text editor once they are confirmed to be OK.
Let me know if this works for you.

Edit: Are you using 0.17?
Just in case you haven’t already seen that gigantic fishing-lure

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Ok. Freecad will need some sitting down and figuring out. In the meantime I installed Flash (against my better judgement) and used makercam (it’s working for me now, and partkam too).

There are some errors in the instructions for makercam, so I’d like to list them here. If they are genuine errors I will update the wiki, but if they are my own errors then I’d like to understand them anyway.

The instructions are here:

The first oddity is Step 3: a note about preferences
It says I should change the SVG Import Default Resolution to 96, but it doesn’t say why. In the dialog in makercam it says illustrator should be 72 and inkscape should be 90, but we should know where the figure of 96 comes from, and how we know if that is the correct figure.

Next is applicable to Step 4, 5, 6, and 7. Holding the CTRL key to select multiple objects doesn’t work. This makes it very tedious to set the cutting parameters for each hole.

Finally, step 8. Adding tabs by clicking the green line doesn’t work. There are only green lines above and below the straps for the bricks. Other lines are blue. I wanted to add tabs around the perimeter of the sled, but I couldn’t.

Exporting the file and loading it into Ground Control worked, however, due to an oversight, bad things happened. Which are mostly fixed now.

Anyway, if my observations are genuine I will edit the wiki to fix the mistakes.

From this point I still want to produce a dimensioned drawing, which I will do with QCAD. I’ll also use QCAD’s CAM module to make another gcode file and compare it with makercam’s output. I actually prefer QCAD. Freecad is too much work at the moment, and makercam uses Flash, so I do not want to use it again.

Another thing. The three holes to guide the position of the ring. The lower two are on a radius of 6.251" [158.78 mm] (which I guess is supposed to be 6.25" [158.75 mm]), but the top one is not on the same radius. It is 0.05" [1.27 mm] lower, or a radius of 6.201" [157.50 mm]. Is that right? If not, should it be on the same circle as the lower two holes?

Also, the holes are placed at 113° either side of the vertical. Which is fine, but I would have assumed 120° by eyeballing it.

And, just for sanity’s sake, the sled has an outer radius of 9" [228.60 mm], right? And the inner hole has a radius of 1.5" [38.10 mm]?

Ok. I looked at makercam’s gcode output and the width of the sled is 457.2 mm, corresponding to a radius of 228.6 mm. I am satisfied that I have followed the steps properly and produced sensible looking output that matches the expected size of the sled with the specified router bit diameter (8 mm).

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Can’t help on makercam as I’m not using it.
The dialogue says 90 pdi for Inkscape as that was the default years back. Inkscape has changed it to 96 to meet a css standard as far as I remember.
SVG can be created with several programs, but what to put in the wiki? All programs that we know are used? Illustrator, Inkscape, LibreCAD, QCad?
I think a sentence like “set the resolution matching the output dpi of the program you used to create the SVG” could be confusing or even intimidating for a new user.

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