P3Steel version 4 modifications


A collection of useful modifications for the P3Steel v.4, as described by the basis of a draft from the P3Steel, with metal elements for X-Axis made on basis of I3 CORDOBESA Full Steel 1/8″ LASERCUT with Bowden extruder.

It is worth noting that a number of these modifications can also be applied to other cartesian 3D printers, such as the Wilson II. Some of the modifications/upgrades could also be applied to other 3D printers, such as Delta printers (i.e. Kossel) for example, the reinforced GT2 belt, and Extruder stepper with planetary gearbox.

This frame was sourced from eBay, Frame Prusa I3 P3Steel v4.0 +RODS+metal elements for X-Axis


Here is a list of links:

  • P3Steel parts by Fizzbod – The Toolsen Bowden extruder mount (see below) at the top of the Z axis, is interesting, although it is not clear if additional drilling is required from the photos

Bowden extruders


Endstops by Toolsen

Optical Endstops by Toolsen

Only Y axis, there are no X or Z axes optical endstops, as yet:

Idlers by Toolsen

Extruder by NWRepRap

Parts are listed here, on NWRepRap Prusa i3

Extruder Stepper Motor

If using a Bowden extruder, then use an extruder stepper motor with a planetary gearbox, see The extraordinary extruder.

GT2 Belt

GT2 belts with steel banding will not stretch.

Lead screws

It is probably a good idea to replace the 330 mm M5 threaded rods with superior T8 lead screws. A pitch and lead of 2 mm would be ideal, as opposed to a pitch of 2 mm and a lead of 4 or 8 mm. A 350 mm length, with a lead of 2 mm from 8mm Lead Screw Rod Z Axis Linear Rail Bar Shaft+T8 Nut For CNC 3D Printer Reprap, costs £5.28.

A pitch and lead of 1 mm could also be considered, although the cost will be higher. A 400 mm length from T8 Pitch 1mm / 2mm Lead 1/2/4/8mm Rod Stainless Lead Screw + brass color nut, costs £11.78.

Note that from this supplier, the cost of the leadscrew with either a 1 mm and 2 mm pitch/lead, is the same.  A lead of 1 mm is probably a bit excessive. Somewhat bizarrely, from the same supplier, lijieqion_0, there is a significantly cheaper leadscrew with a 1 mm lead:

It is unclear why it is cheaper – is it because the nut is copper and not brass? Or is one Acme/Trapezoidal and the other square?

See Would using a leadscrew with 1 or 2 mm lead, en lieu of 8 mm, result in a better printer?

From Accuracy vs Precision and Threaded Rod vs Leadscrews in 3D Printers. I have highlighted the relevant parts:

In general, FFF/FDM printers use relatively infrequent, small, precise movements on the z-axis and consistent, fast movements on the x and y axes. A single start leadscrew with the tightest pitch possible (highest thread density, smallest pitch) is generally going to be your best bet for the z-axis, while you may or may not need something a little steeper to get the speeds you’d like from your x and y axes. While this may seem somewhat arbitrary given the precision of movement you can get from a stepper motor, an important factor to remember here is torque.

A more aggressive leadscrew will require more torque to drive. We have one kit printer we bought a couple years ago that has an overly aggressive multi-start leadscrew for the z-axis. The small motors included in the kit do not have the torque required to reliably start upward movement of the carriage, leaving it sitting there skipping steps until the carriage is given a little upward nudge to get it going (no, it’s not a lubrication issue or a driver that needs turning up).

So, a 2 mm lead is preferable to a 8 mm lead, as not only is less torque required, but also more precise movements are obtainable.

With respect to the layer heights, I found this nugget of information, from Ditch the threaded rod in your RepRap 3D printer and upgrade to a lead screw z-axis

It’s always better to use layer heights that are a multiple of your full step. If you trust in your micro-stepping you will get poor results because torque is very poor and the motor won’t stop very precisely. Best approach is to use a lead screw (whose longer step allows the gravity to work for you and eliminate backlash) and a stepper driver configured to 1/4 micro-step for low noise, but not for micro-layering. I always use multiples of my full step and have printed 0.040 (1 step), 0.080 (2 steps), 0.120 (3 steps and so on), 0.200, 0.600 and 0.800 mm (of course using 2 different nozzles). Do you need more than that?

See also Reddit – Lead screw opinions:

  • The general consensus is that a 2 mm lead is preferable to a 8 mm lead.
  • Lower the lead the better for an Z-Axis screw to allow for more precision
  • No need for anti-backlash nuts for a Z-Axis if it has a decent amount of mass/weight to it.
  • 1 mm will slow the printer down, but provide 0.005 mm (5μm) vertical movement.

That’s going to be awfully slow when homing. While you really don’t need speed for the z-axis, there’s not much point in going with such a low pitch… you won’t be printing anywhere near the layer heights that can achieve. In the end I guess it’s not a big deal, but I don’t see any reason to go below about a 4 mm pitch. A 1 mm pitch with a 1.8° stepper gives you 0.005 mm increments. Anything under 0.02 mm (which is sort of ridiculous anyways) is just unnecessary. Just my thoughts.

  • An 8 mm lead can result in the weight of the X-axis gantry (especially in a P3Steel) overcoming the idle torque of the stepper. As a result of this, the X-axis gantry can end up sliding down the leadscrew, in particular at power down:

I have lead screws on my Z and it readily falls down if you kill the power. Regular threaded rod is much better at keeping it in place without power.


That’s one of the problems with 8mm lead 😉 With 2mm lead it will hold itself. The stepper motor provides a fair amount of resistance even when powered down.

Aluminium/Composite Y-axis carriage

With respect to the Y-axis carriage, the steel carriage does add a lot of weight/inertia, you are correct. This may or may not be an issue, depending on your steppers motors that you chose, and their torque. That said, the 3 mm steel print bed/Y-axis carriage, is ridiculously heavy, and it would be most wise to substitute it for an aluminium, plywood, or some other lightweight solution.

Apart from that the 3 mm steel frame is fine and as solid as a rock. There are a number of aluminium 20×30 print beds/Y-axis carriages available on eBay and Amazon. A thorough search should reveal a few. There are also composite Y-axis carriages, I found a supplier in the Ukraine,tehnologika_net, who, last year, had a number of different types at a reasonable cost – in fact they were the cheapest that I found.

See also Heatbeds. At the bottom there are some links to various alternative Y-axis carriages. However, some of the links/items may no longer be available.

Thermal Fuses

From Build a 3D printer workhorse, not an amazing disappointment machine:

It’s rare, but 3D printers can catch fire. Use the safety features provided by the firmware, but don’t solely rely on them. Both plain MOSFETs and solid state relays typically fail in their conducting state, which can result in runaway heating with disastrous outcomes. Thermal cutoff fuses are $1 components, but they are well able to prevent a runway heated bed from turning your workshop into a crater.


From Build a 3D printer workhorse, not an amazing disappointment machine:

Enclosing your printer in a box prevents draft and the retained heat allows you to print larger objects from ABS with fewer distortions. The enclosure itself can be anything from a large enough box or a beautiful acrylic printarium. As long as the heat stays inside, it will just work. Keep the electronics of your printer outside the heated build chamber to prevent overheating of the motor drivers and power supply. Mind that actively heated build chambers also require actively cooled hotend-heatsinks.

Linear Bearings

Use tribological, polymeric slide bearings instead of linear ball bearings. From Build a 3D printer workhorse, not an amazing disappointment machine:

As long as your build doesn’t exceed the typical size and weight of a desktop 3D printer, avoid using linear ball bearings in the X and Y axis, as they are a very common failure point. Their quality varies greatly depending on the manufacturer, and even if the cheap shot works seemingly great in the beginning, they won’t last for long. 3D printed plastic debris and even fragments of their own assembly will sooner or later cause them to block. Tribological, polymeric slide bearings are the way to go here. They are self-lubricating, maintenance-free and virtually last forever, at least by the standards of linear ball bearings. They are also available in Japan standard compatible form factors as drop-in replacements for the commonly used LM8UU.

The LM8UU and its tribological counterpart
The LM8UU and its tribological counterpart

Some examples of these LM10UU bearings, called Igus Drylin, are:

Some examples of these LM8UU bearings, called Igus Drylin, are:

Use longer bearings instead of two. From Build a 3D printer workhorse, not an amazing disappointment machine:

Don’t use multiple linear bearings in line to increase the angular stability of a carriage. There are prolonged versions available for almost every linear bearing type , for example, use the LM8LUU form factor instead of two LM8UU.

Instead of two LM8UU, one LM8LUU is often the better choice.
Instead of two LM8UU, one LM8LUU is often the better choice.

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