The frame for this design utilises 20x20mm square 't-slot' aluminium extrusions. This is an excellent building material for 3d printers as it's strong, light, vertsatile, easy to machine and cheap. There is also a wide range of fixing options available that make building frames like this very easy.

Dimensions and cutting list:

The frame is a cube with outer dimensions of 465mm per side. it comprises of 
  • 10 pieces cut to 425mm and
  • 4 pieces cut to 465mm
Suggested orientation of these pieces is shown in the diagram below but any orientation that provides a 465mm per side cube would suffice. 
The green parts are 465mm in length, the red parts are 425mm.

 The original T-Slot Tantillus used Printed plastic corner brackets to hold the various frame components together, this approach was more than adequate for the short lengths of extrusions involved in the TST but with the Ingentis, I was concerned that they would not provide sufficient rigidity. Accordingly, I came up with a means of holding the frame together without the need for these brackets.
The solution I came up with turns out to be one that had (not surprisingly) already been developed. It involves the use of M5 Dome headed machine screws, inserted into the (tapped) end of extrusions that butt up against a perpendicular extrusion. The head of the machine screw needs to be of a size where it can slide into the extrusion's 'T-slot' from the end of the extrusion. The screw is then tightened with a hex key via a hole drilled in the wall of the perpendicular extrusion. The image below shows the end of the vertical components with the 2 intersecting horizontal pieces attached.
Please note. This approach is only viable if the end cuts of the extrusion are cut at 90 degrees to high tolerance. I would not recommend using it if the extrusions have been hand cut with a hacksaw or similar.The video linked to below demonstrates this approach. (Please ignore the orientation of the aluminium parts - I put it together incorrectly on the first attempt :) ).

So, in order to use this approach you need to drill a number of holes in the T-Slot and tap a number of ends.

Drilling holes.

All vertical components (green in the diagram above) need a 5mm hole drilled though the centre of the T-slot, centres at 10mm from each end and on both sides of the extrusion (4 holes in total).
They also require 1 further hole drilled with centre 95mm from 1 end through 1 side only (for the horizontal upper Z stage mount) Hole locations are shown in the diagrams below. Dimensions are in mm.
Side View

Front View

Tapping Holes

 All horizontal pieces (red in the diagram above) need M5 holes tapped in each end to a depth of at least 10mm - exact depth determined by the length of screw you are using.


Once the holes and tapping are complete, the Frame can be assembled. 

Step 1.Insert a dome headed machine screw into the tapped ends of each horizontal extrusion. The screws should be inserted so that about 3mm of thread is still exposed.

Step 2.Assemble the frame's left and right sides as shown in the diagram below. Each side requires 2 vertical pieces and 3 horizontal pieces, take care to get the vertical piece oriented correctly; with the hole drilled 95mm from one end located at the top of the extrusion and facing front-back.  Once the horizontal pieces have been slid into the vertical pieces, align the top and bottom pieces so they are flush to there edges are flush to the edges of the vertical pieces and then tighten the machine screws with an appropriate hex key (inserted through the holes drilled in the Vertical pieces). The Spacing between the upper horizontal piece and the horizontal piece installed to support the Z stage should be 65mm.

Step 3 Join the 2 sides together with the remaining 4 Horizontal pieces, following the same process as described in Step 2..

Step 4 Check to make sure everything is square. Use a long metal ruler or tailor's measuring tape to confirm the distance between 2 opposing corners is the same for all 4 corners of the 6 squares that make up the cube you've just assembled. This is critical to ensuring the linear motion of the x/y gantry is smooth so don't skip this. As long as you end cuts are straight and you extrusions are cut to the correct lenghts, you shoudl not have to make any adjustments. 


1 comment:

  1. Hello!
    I realy like your printer. I have reprap mendel but I think I will upgrade it to your design. Is it possible to get stl files of the gears with 4mm (or smaller) dia hole, becouse I have stepper motors with 4mm shafts.