I'm building a new printer after having an Anet A8 for about two months and getting a feel for what I want. I'm planning to buy a P3Steel frame; but can't decide which version to get.

There are one or two prints I would like to make that are larger than 20 cm in length; but I could always do these in multiple pieces.

What I'm wondering is how serious are the trade-offs I would be making for a larger bed? I would think I would need thicker linear rods for the 510 mm length y-axis; and the bed would also have a large amount of inertia so that could slow down printing. Does anyone have any experience with this size bed in a moving y-carriage scenario? Also how thick of rods should I get? Orballo printing is saying 8 mm is fine but the research I've done implies that you shouldn't really go over 200-250 mm unsupported for that width.


1 Answer 1


Go for the P3Steel v4 (20x30). The extra print area is worth it. There is a Polish supplier, Printo3D, on eBay that has the cheapest frame, and parts - cheaper than the Spanish supplier. That is where I got mine from. See Frame Prusa I3 P3Steel v 4.0, 300mm x 200 mm, which costs around £80.

This kit uses 10 mm smooth rods for the Y axis:

Smooth stainless steel rods:

  • 2x Ø8x385 mm for X-Axis
  • 2x Ø8x320 mm for Z-Axis
  • 2x Ø10x520 mm for Y-Axis

Threaded stainless steel rods:

  • 2x M5x300 mm

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 choose1, 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 20x30 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.

As an aside, I built mine sourcing all of the parts separately. It was a bit of a task, but an educative one. The process certainly made me understand the ins and outs a lot better than purchasing a ready built, or complete kit, 3D printer.

I have written up some blogs regarding the kit that I purchased, see P3Steel from Poland – A tale of despair, dismay and woe. Ignore the depressing title, it really isn't that bad.

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.

You may also find this question of mine useful, Z axis top brackets, of P3Steel, differ between v1.x/2.x and v4.

There are a number of modifications to the standard P3Steel, that may well be worth considering. In particular, you should note the Toolsen Edition MK2, see P3steel toolson edition MK2 (in German), and P3steel - toolson edition. I have written about these, and more, see P3Steel version 4 modifications. In summary, these are:

  • Bowden extruders
  • Endstops
  • Endstops by Toolsen
  • Optical Endstops by Toolsen
  • Idlers by Toolsen
  • Extruder by NWRepRap
  • Lead screws
  • Aluminium/Composite Y-axis carriage

1 I got the Rattm 17HS8401 steppers. See RepRapWiki - Nema17. The recommended steppers are high torque:

  • Kysan 1124090/42BYGH4803;
  • Rattm 17HS8401, and;
  • Wantai 42BYGHW609

However, motors close to NEMA 17 size, with approximately the following specifications, can also work:

  • 1.5A to 1.8A current per phase
  • 1-4 volts
  • 3 to 8 mH inductance per phase
  • 44 N·cm (62oz·in, 4.5kg·cm) or more holding torque
  • 1.8 or 0.9 degrees per step (200/400 steps/rev respectively)
  • $\begingroup$ thank you, this is exactly what I was looking for. And I suspected that steel carriage would be overly heavy; thank you for confirming. $\endgroup$ May 4, 2017 at 6:49
  • $\begingroup$ Do you know what specifications the stepper motor would need for the y-carriage? I bought a working but otherwise terrible 3dprintersonlinestore.com/full-acrylic-reprap-prusa-i3-kit off a friend for 60$ with the idea of using the non-frame parts for my p3steel build. I'm not sure what the specifications on the motor are though; or for that matter what the desired specifications are. $\endgroup$ May 4, 2017 at 6:57
  • $\begingroup$ @JonathanBayer - I got the Rattm 17HS8401 steppers. See Nema17. The recommended steppers are high torque (44 N·cm (62oz·in, 4.5kg·cm) or more holding torque): Kysan 1124090/42BYGH4803, Rattm 17HS8401, and Wantai 42BYGHW609. I have updated my answer with this information. $\endgroup$
    – Greenonline
    May 4, 2017 at 9:09

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