Taz 6 specific External Belt Tensioner

This project is an externally accessable M4 bolt driven Y axis belt tensioner for the Taz 6 series printer.

Co designed by Kevin Davis.

It will not work with any other Taz. For older Taz, or to see the general idea of how this works, check out the Taz 1-5 Variant here: https://www.thingiverse.com/thing:1656341
Taz_6_external_Belt_tensioner_base_1_0_a.stl (122 KB)
Basically you will need 1 m4 bolt , 1 m4 washer and M4 nyloc nut, 2 M3 heat set inserts, 3 1/4" smooth threaded spacers (probably the 1 inch long ones), 6 6-32 1/2" long bolts to fit those spacers, 3 6-32 Washers, and the stock idler hardware from your Taz. You will also potentially want 4 long-ish M3 metric bolts and nuts to temporarily bolt the drill guide in place and an at least 4mm drill bit.

One spacer gets bolted to the middle of the base, with the bolt head recessed. so as to not hit the mounting plate. The other two replace 2 of the stock M3 bolts and heat set inserts.


  1. on the Idler mounting plate stripped of hardware, bolt the drill guide to the outside of the plate using M3 bolts and screws and drill an at least 4mm dia hole (as long as an m4 bolt can pass through here you are ok)
  2. Use the M4 bolt and washer to pull the nyloc m4 nut into the new tensioner nut socket. then remove the bolt.
  3. Assemble the idler pulley hardware.
  4. insert the 2 heat set inserts into the baseplate
  5. Bolt one of the 1/4" threaded spacers to the center-ish hole using one of the 6-32 bolts in the recess (after cleaning the hole)
  6. bolt the base plate to the idler mount plate using 2 of the stock m3 bolts in the heat set insert holes, and 2 of the 6-32 bolts and nylon spacers in the other two holes.
  7. Put the tensioner on the spacers, adjust for fit as needed.
  8. thread the M4 bolt and washer from outside the plate into the tensioner.
  9. Assemble the belt as usual, then use the M4 bolt to add tension
    Taz_6_external_Belt_tensioner_Tensioner_1_0_a.stl (142 KB)
    Taz_6_external_Belt_tensioner_drill_guide_1_0_a.stl (288 KB)

A slight remix (with Tim’s cooperation).

1/4" 6-32 spacers don’t seem that common on the eastern side of the pond so I remixed this for 6mm nylon spacers (zillions
on EBay link to the ones I used at the bottom of this posting) with through bolts and nut traps instead of heat-inserts (heat
inserts seem to come in different sizes and the ones I had didn’t fit Tim’s model).

In addition to the spacers you’ll need 4 M4 12mm or longer to temporarily mount the drill guide, 2 M3x12 socket heads for the left hand side of the plate mount (don’t be tempted to go longer as you’ll foul the Y limit microswitch) and 3 M3x40 socket heads to go through the spacers.

As everyone likes build pics :slight_smile:

Remove the standard bearing mount and bolt on the drill guide:

Then carefully drill two 3mm holes.

Remove the drill guide and re-drill the RIGHT hand hole with a 4mm drillbit (you can go up to 4.5mm with this if you like). If you have trouble working out which is the RIGHT hand hole look at the drill guide :slight_smile:

Use a couple of M3 screws to draw plain M3 nuts into the nut-traps on the mounting plate and a nylock M4 into the adjuster nut trap.

Loosely attach the mouting plate and tensioner assembly like so:

Reinstall the bearings, install the M4 adjusting screw a couple of turns into the adjuster (hand tight is about right then it’s not quite going into the nylock bit until you actually tension it up), reinstall the belt

Tension the belt as normal and then tweak the belt tension with the adjusting screw

Job done. Many thanks and qudos to Tim Pierce (piercet) for the original.

PS - If you’re planning on using Tim’s Y axis Openbuilds mod, you’ll need to modify the front end plate from that project to clear the new adjusting and mounting screws. Takes around 5 seconds with a round file. Tim did produce a modified plate to clear the adjuster screw on his version and uploaded that to his TAZ 6 adjuster Thingiverse project https://www.thingiverse.com/thing:2612555

[1] Nylon Spacers: https://www.ebay.co.uk/itm/Black-Nylon-Plastic-SPACERS-Standoff-Washer-M2-M3-M4-M5-M6-M8-M10-M12-Pack-of-12/301400291143?ssPageName=STRK%3AMEBIDX%3AIT&var=600390239108&_trksid=p2057872.m2749.l2649

Hmmm… this forum software gets very shirty when you try to edit a post with inline pictures :confused:

STL files here:
Tensioner Body.stl (217 KB)
Mounting Plate.stl (167 KB)
Drill Guide.stl (312 KB)

Nice work! That came out clean! Are you planning on uploading it to thingiverse as a remix? Remixes give more visibility in ranking to original projects anyways so i’d be fine with that.

If not, would you mind if I uploaded it and the pictures giving you full credit for the remix?