MK3 MK4 X-Axis M3 Thumbwheel Rod Puller

Both the puller body and the thumb-wheel use a standard M3x6mm hex spacer rather than just an M3 nut, which  might deform under pressure.

Two M3 mudguard or nylon washers improve operation smoothness, transferring the pressure to a larger surface area.

An additional slider is used to maintain a stable contact with the X-Axis printed parts.

Required hardware:    

2 * M3x12 Screw + Nut
4 * M3x25 Screw + Nut
2 * M3x6 Hex spacers
2 * M3x9 Mudguard or Nylon washers
1 * M3 Cap Head fully threaded long screw

Note the requirement that the screw be fully threaded. (Many long M3 screws are only partially threaded)

Any screw longer than 25mm will work but the pulling travel would be restricted for only marginally longer screws. I used an M3x70, going for the longest I could find, as it had to buy 10 to get what I wanted. 

The pulley body consist of a front and rear held together by 4 x 25mm screws which clamp onto the rods.

Assemble the long screw and one M3x6 hex spacer into the rear of the body, tightening the screw firmly.

The front can then be fitted using the 4*M3x25 screws, after placing the rods in the two channels.

Note the operational tip of wrapping the rods where the clamping happens with cling wrap to assist in preventing slipping during pulling.

The thumb-wheel has the second M3x6 hex spacer pressed into its centre.

Screw the thumb-wheel onto the long screw to a convenient position, fitting one M3x9mm mudguard or nylon washer on each side

The slider consists of two identical halves, held together by two M3x12 screws.

Fit the two slider halves over the thumb-wheel and two M3x9mm mudguard or nylon washers, after placing the rods in the two channels.

Firmly secure the two halves using the M3x12 screws.

The tolerance around the rods in the slider is increased to intentionally allow the rods to easily slip through while providing a stable face to press against the X-Axis printed parts.

Rotate the thumb-wheel to increase the gap between the body and the slider.

There are two versions, for the MK3 and MK4.

The only difference is the spacing between the rods.

While the MK3 version is sat at 45mm spacing, the MK4 version is set at 40.05mm, the diagonal distance between the rods. The puller will be slightly angled when fitted to an MK4.

Note that while I do have two MK3 printers, I do not have an MK4 to do final testing. I am hoping an interested MK4 owner will confirm the operation on the MK4.

UPDATE: 

I used this on my MK3S+ when replacing the rods and bearing.

What I noticed when turning the thumb-wheel  was a clicking noise about every ¼ turn.

The noise was not coming from the puller. 

It was the bearing holder slowly letting go of the rods.

So don't be surprised when you hear this noise when turning the thumb-wheel.

I have also uploaded an additional photo of the puller being used.