Bellingham Makers

Learn how to use the Bellingham Makerspace X-Carve CNC router. An introduction to CNC using Easel (software) and the X-Carve (hardware). The class will cover laying out projects in Easel - using some of its numerous functions and features - as well as importing 2D CAD (dxf) and Inkscape (svg) projects into Easel. The class will then use the X-Carve to make a project.

Participants are encouraged to register at Inventables, watch the Learn Easel in 4 Minutes video and bring a simple project or idea. One project will be chosen and used to show how to setup and use the X-Carve, everyone else will leave with a ready to route project. The fallback project will be carving a signboard made in the Intro to the Woodshop class. Topics will include router bit selection, hold down clamps, fixtures, waste-boards and the dust collector.

When: First Friday of the month, 6-8pm
Cost: $33.46
Available discounts: member/volunteer, scholarship and audit
Min/max registrations: 2-4
Links: registration, class webpage
If you'd like a 50% scholarship discount (no questions asked) or would like to see the class offered at another day/time, email davelers@gmail.com

What to bring: A laptop PC if you have one
Related and useful classes: Vector Graphics 101 and Intro to the Woodshop
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The new dust collector swings out of the way for easy bit changes and provides good cut visibility. It is not KISS, there are three important aspects:

• The acrylic plate needs to be set just high enough to clear all clamps.
  
• The space between the router and the plate needs to be >= depth of cut.
  
• The side knob needs to be tightened with the red lines aligned.

In the example the plate is relatively high because it needs to clear the knobs (bad idea), luckily there was enough clearance to make the desired depth of cut... There are some new low profile hold down clamps to help with potential clearance issues (in bit box)... Added a rotational stop to simplify alignment.
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The fixture is a combination square and spoil board that allows routing multiple pieces using the same home position. While the square is not particularly square, it does allow for reasonably accurate repetitive (re)positioning. The example is one of three marble mazes that were routed with a bullnose bit and then repositioned and through cut with a straight bit.

The fixture has 5mm holes on 75mm centers (same as the X-Carve) that allow positioning and clamping anywhere on the table. There are also some special 2 hole clamps for clamping 1/4 and 1/2" stock to the fixture (example stock is 3/4).
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Polylines (12min) cut cleaner and faster than segmented lines (32min). In Easel, the only way to cut inside or outside of the line is with closed polylines. Polylines show up as an unbroken path when Simulate is clicked in Easel. Hidding the material and tilting the preview should show a single vertical start/finish line.

While Inkscape has a Path Combine/Break Apart that looks like it works, and that I thought had worked for me in the past, nothing I tried in Inkscape got me an unbroken path in Easel... The DXF Segmented Line Fix in Inkscape video shows a couple of ways to fix/join segmented lines. The shift-select adjacent segment, box/select node, shift-J to join method may simpler to do in CAD (e.g. clicking adjacent segments can fix or join them, depending on the tool selected).

Another solution, in this case, is to open the dxf or svg in (the free version of) QCAD, add a layer and use the polyline tool to rebuild the shape as a closed polyline. Delete the layer 0 shape, save and import into Easel. For shapes with curves, I use an old CAD program (AutoSketch 9) to join the segments into a polyline (save as dxf and import into Easel). Apparently QCAD can do this, but not with the free version.
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The default Easel origin is the bottom left of the material. Centering any multiple object drawing on the material can be a PITA, especially when text is involved. While using a center origin is not visually intuitive, it is relatively easy to setup. The easiest way is to select all the objects in the drawing (Ctrl A), select the Shape tab, click the center circle and enter 0/0 for X/Y. While this works in simple cases, it is not very precise (center circle and origin are not aligned) and probably won't work as expected when text is involved.

The problem with text is that it doesn't center (its bounding box does) or center isn't the best place for it. For precise center origin alignment of text, or any set of objects: add a square to the drawing, set Cut to Outline and Depth to 0, set Shape to a Size that's bigger than all bounding boxes (blue lines), e.g. material size (if that's big enough). Use Edit > Center to Material to center it on the drawing, select all objects and (as above) set Shape position to 0/0 (center circle selected). While the added perimeter shape shows up in the drawing, the depth was set to 0 so it won't be cut/visible in the preview/simulation (deleting it is optional).

Mark the center of the material with a pencil, align the router bit over the mark and hit carve. Center origin is also handy if you want a reference point that can be used on both the X-Carve and the laser, e.g. route paths/pockets and then laser cut and/or engrave the part (or vice versa). If one or the other operation will cut away the pencil mark, do that one last. While the laser default origin is the top left, it has a center-center option.

Note: the only reason for work area and material dimensions is for visualization and to insure everything will fit. The only information sent to the X-Carve is how and where it should move the router (example image). When designing stuff in Easel (do not do this on the X-Carve PC), reducing the Machine Work Area dimensions to match the material dimensions will make previews and simulations easier to see (set to 1x1mm for the example image).
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Generally, cutting wood works best with straight two flute bits and plastic with single flute up-cut spiral bits. Down cut spiral bits can provide cleaner cuts in wood and may be worth the extra cost in some applications (I'm not sure the X-Carve is rigid enough for them to make a difference). Compression (up/down spirals) bits are worthless on the X-Carve, they are only beneficial on single pass (full depth) through cuts.

Wood pocket cutting works well with a 3/8" T-slot cutting bit. The primary reason is the relatively large cutting surface on the bottom of the bit. Most specialty surfacing/bottom cleaning bits are too big for the X-Carve. While 1/2" open center mortising bits are another option, they are typically significantly more expensive and the current Easel algorithms favor 3/8" (over 1/2 and 1/4").

Inventables bit articles:
Carving Bits 101 - Bit Basics
Carving Bits 201 - Feeds, Speeds, and V-Bits

Cheap Bits:
AliExpress : Milling Cutters
single flute   single flute 10pcs (e.g. 1/8 carbide $6+)
straight two flutes   straight two flutes 10pcs (e.g. 1/8 carbide $9+)
1/4" shank, 3/8" pocket cutting
The straight two flute HUHAO (Hozly looks very similar) brand is better than Fdit (Walfront looks very similar). Both the tip and edge grinding is simplified/slightly flawed/cheaper on the Fdit's. More facets on the ground shape generally means higher quality and a few bucks more... That said, the Fdit's seem to cut fine. The Weix spiral two flute bits are ground well (better than Kitbakechen).
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