T3P3 Kossel Mini Kit Release 3

Assembly Instructions

Chapter 7 - Frame Assembly

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701 Frame - Parts needed

Base assembly

Tower extrusions 650 long x 3

M4 x 10 button head screws x 6

M4 T-nuts x 6


Top assembly

M3 x 40 socket capscrews x 3

M4 x 10  button head screws x 3

M3 full nuts x 3

M3 penny washers x 3

M4 T-nut x 3

Carriage adaptor assemblies x 3

Endstop assemblies x 3


702 Fit towers to base

Insert a tower extrusion into one of the motor brackets and push/tap gently until it reaches the bottom or will go no further. If you need to hammer on the end of the extrusions to make them go in, then either use a rubber/wooden mallet, or protect the end of the extrusion with a block of wood to prevent damaging it.

Repeat for the other 2 corners.

Invert the frame and push or gently tap the frame extrusions into alignment with the bottom of the printed motor bracket.

Turn the frame on its side. Insert a T- nut in the top nut channel of the extrusion from either side and push both nuts into the bracket until they align with the bolt-holes.


Insert an M4x10 dome head socket screw in each hole and tighten.

Remember to check that the T-nuts have rotated into the correct position in the slots!

Repeat for the other 2 frame base corners.

703 Identify X Y and Z towers

From this point on in the assembly, we need to identify the 3 towers individually. As shown, the front left tower will be X, the front right tower Y and the rear tower Z. The motor brackets in the picture have been labelled accordingly and the extrusions joining them will be referred to as X-Y, Y-Z and X-Z.  X, Y and Z-stickers have been provided in the kit if you want to label your towers.

704 Fit carriage adaptors

First make sure that the 3 captive nyloc nuts are in their nut traps. Ease a carriage adaptor assembly onto the top of a tower (plastic facing inwards). You may have to loosen off the tensioner bolt before it will go on.


Tighten the tensioner bolt to apply a small amount of preload to the rollers, while ensuring the adaptor can run smoothly and easily up and down the tower extrusion and is just able to fall to the bottom of the extrusion under its own weight. Repeat for the other two towers.

705 Fit endstops

Fit an endstop to the top of each tower above the carriage adaptors, facing inwards. For the moment, tighten it about 80 to 100 mm below the top of the tower.

706 Fit top frame

You will need to place the frame base on a fairly low support to gain easy access to the top of the towers.


Fit the top bracket to the towers. Make sure the nut traps for the belt tensioning bolts are on the bottom of the printed corners.

You may need to tap the printed corners  gently in turn with a hammer and block of wood.

Push the top brackets down the towers until 12mm of extrusion is protruding above each bracket (picture shows 15mm). It is important that they are all the same.  

Turn the frame on its side, fit an M4 T-nut into the channel, as you did for the base, and align it with the bolt-hole. Fit an M4x10 dome head socket screw, but do not tighten it fully yet. Repeat for the other 2 top brackets.

If you want to protect your work surfaces from possible damage, now would be good time to pad the base corners of the frame with the neoprene foam supplied.  This will make it slightly more difficult to fit the timing belts, though, and can be deferred until Chapter 18 - Tidying up.

If you decide to fit the padding now, then use the frame as a template to mark out the shape for cutting.

Cut out the 3 corner pads with scissors.

Remove the paper backing from the self-adhesive side of the pads, and fit to each corner.

Turn the frame upright again. Fit an M3 x 40 bolt with penny washer into the angled belt tensioner hole in the top of each bracket.

Fit an M3 nut onto each bolt from underneath and tighten just enough to draw it into the nut trap without raising the bracket on the pillar.

Now go on to the next Chapter.


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