From the Loftsmith Workshop

Square tube marking sleeve for 45 and 90 degree cuts

A sleeve that slides over square or rectangular tube from 10 to 100 mm and gives scribe edges for 90 and 45 degree cuts on every face. One end is square for 90 degree marks. The other end is cut on a single 45 degree plane, so the lines you scribe on all four faces meet, and the engine measures that angle at exactly 45.00 degrees. There is also a drill guide centred on the face (bits from 3 to 10 mm, guide at least 1.6 times the bit diameter) and an M4 thumb screw to lock the sleeve. Sliders set the tube's outside width and height, sleeve length, fit clearance (0.2 to 1.2 mm total), drill size

1 part · 17 g · 77 × 52 × 33 mm

by Loftsmith Workshop

Square tube marking sleeve for 45 and 90 degree cuts
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No adjustable sizes

Ask for the sizes you want to tweak, e.g. “make the width adjustable”.

Change it in the Studio

Parts

  • sleeve · PETG · Standing on its square (90 degree) end with the 45 degree end at the top; no supports. 76.5 mm tall at the defaults.

    PETG because it holds the heat-set insert well and copes better than PLA with a warm drill bit and a hot workshop. PLA also works. About 17 g and 34 min at 2 walls and 15% infill at the default 40 x 20 mm tube.

Print settings

Layer height
0.2 mm
Walls
2 walls (default); 3 walls for a stiffer boss
Infill
15% (default)
Supports
None
Notes
At the default 40 x 20 mm tube: about 17 g and 34 min at 2 walls and 15% infill, or about 22 g and 44 min at 3 walls and 15%. Measure your tube with calipers before printing. If the first layer squishes inwards (elephant's foot), turn on your slicer's elephant-foot compensation so the square end sli

Hardware

  • M4 heat-set insert (5.6 mm OD, 8.1 mm long) · Pressed into the side boss with a soldering iron.
  • M4 thumb screw or socket screw, 10 mm long · M4 x 10 reaches the tube at the default clearance. With clearance over about 0.8 mm the check asks for M4 x 12.

Assembly

  1. Measure the tube's outside width and height with calipers and set the Tube width and Tube height sliders. Choose whether the 45 degree edge should run across the width or the height, depending on which way the frame joint turns.
  2. Print the sleeve standing on its square end.
  3. Press the M4 heat-set insert into the side boss with a soldering iron until it sits flush.
  4. Thread in the M4 thumb screw, slide the sleeve onto the tube and tighten the screw lightly. It pushes the tube against the opposite wall.
  5. Scribe along the square end for a 90 degree cut, or along the 45 degree end for a mitre. The four lines meet around the tube. The V notches at the square end mark the centre of each face.
  6. To make a hole, put the bit (or a centre punch) through the guide on top. The exit hole in the opposite wall lets a bit come out the far side of the tube.

Good to know

  • This is a marking guide, not a saw guide: scribe or mark along its edges and cut freehand or on a saw. Don't run a blade against it.
  • The drill guide is plastic. Use it to centre-punch or drill pilot holes, and don't let a spinning bit rub in it for long, or the bore will wear and melt.
  • The fit was checked against a model of the tube, not a real one. Real tubes vary by a few tenths of a millimetre and can have weld seams, so print a short one first and adjust the Fit clearance slider (0.2 to 1.2 mm total).
  • Mark against the inside edge of each end. The outer edges are chamfered, so don't use them for marking.
  • The 45 degree edge suits a mitre on one pair of faces. For the other direction, print a second sleeve with the other option, or turn this one 90 degrees on a square tube.
I printed this Remix

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