Perhaps we can try to centralize some ideas about sourcing parts in Europe for the V4 build.
(I am looking for an afforable rails shipping to Belgium)
Steel rails:
https://www.jabimetal.at/ (recommended by @Philipp)
[Stahl Präzisionsrohr 32x2,0 mm rund, nahtlos, DIN2391]
and ships to AT, CZ, DE, SK
Please share your sources for rails.
For EU builders looking to get a Jackpot CNC controller board, these can be ordered from Elecrow at much more favorable shipping rates, and Ryan gets a fair compensation for each one made.
Also, your own ESP-32 dev board.
https://www.amazon.com/gp/product/B09MQJWQN2?smid=A33XZ36WFNH796&th=1&linkCode=sl1&tag=vicicn-20&linkId=24fb6cd8ce04f80a866d9434f5734483&language=en_US&ref_=as_li_ss_tl
I actually bought 3mm thick ones, but that might be overkill. I also just bought 4x1.5m because it was the same price as 3x1.5m (because 6m is a whole pipe).
And I needed it because someone was wrong with the maths (and it wasn’t me this time… 
).
I used Eurostrut Products Strut mounting systems | Eurostrut | EN when building my LR3 with Dougs hidden belt mod. I’m only just starting to build the LR4, but I intend to use the same. I also made a list of materials (for the LR3 but which will probably be the same for the LR4) in another topic LR build in the UK, which are available in the UK. These should be available elsewhere in Europe (if Brexit hasn’t screwed it up).
I also bought a Jackpot controller from Elcrow. Took 10 days to deliver but shipping was very reasonable.
I ordered electric wire tube conduit 32 OD yesterday here in UK from https://www.superlecdirect.com here is the link: 32GALV | 32mm Galvanised Class 4 Conduit Hot Dipped Galv 3.75mtr Length | 3.75m | Superlec Direct
unfortunately 3.75 m long, they don’t have shooter conduit, as well they have a next day delivery option.
A good source for pipes in Germany is Hörr Edelstahl: Konstruktionrohr.
They deliver across Europe
Another source is Gemmel Metalle, where you can find both fine-milled aluminum plates and stainless steel pipes.
Only within Germany
A great source for screws is Screwbolt, which delivers to Austria and Germany. The advantage here is that they also offer small quantities at attractive prices.
Thanks for the pipes/rails links. I will check those out.
For fastners i just stick to Wurth. Yeah the boxes are rather big quantities, but the prices are reasonable. And consistent quality.
Enough for a few builds for now 
I did use their stainless steel pipes for the Primo and the LowRider 3 and they are not completely straight, they have tolerances of 0.2 or 0.3mm which makes the bearings not always touch or be too tight.
The better choice is Präzisionsstahlrohr (DOM), though it can rust and has to be treated correctly.
Thank you, Philipp. I will choose that as well. The precision tube is also available at Gemmel Metalle: Stahlrohr | GEMMEL-METALLE
Phew, that’s only 30mm and a lot more expensive…
Gemme 4x 1500x30x2:
Preis Brutto 107,10 €
Jabimetal 4x 1500x30x2
Jabimetal 4x 1500x32x2
I am not sure whether gemme had the shipping included in the price.
Then Jabimetal is the significantly better source; the price at Gemmel for 4x 1500 30x2 is 152.25€ including shipping.
30mm steel tube source for France
This store is part of the “Kingfisher” consortium, so you may be able to find similar products in other stores like screwfix or b&q
https://www.kingfisher.com/en/about-us/what-we-do/brands.html
Philipp, what do you think of the following SS tube for the project: 31.75x3.05 mm EN10216-5 D4/T3 prec?
31.75 is not officially supported, but since the question came up more often, maybe Ryan can be swayed to add this as an option.
Since SS usually seems to be welded, I’d not use it again, though all of my bolts etc. are SS.
Is dom steel better to use then stainless? I used stainless for my lr3 since it has some better properties and I don’t like dealing with rust or rust prevention.
Thanks for the info, Philipp. It seems that D4/T3 tubes could be an option for those who want to go with stainless steel, but it’s probably more about balancing its properties against the benefits of regular steel, where rust prevention needs to be considered.
Stainless steel does have great rust resistance, but DOM steel is definitely easier to work with, as long as you don’t mind the maintenance and rust prevention. For me, the main concern is handling the heavy spindle weight, but I feel like stainless steel tubes aren’t the only factor here. The overall construction and its strength seem to matter more, regardless of which material you choose.
I believe @SupraGuy used that size in the 32mm part options and it worked well for him. Hopefully I am remembering that correctly!
It isn’t a supported size, but I used 31.75mm tube for my beta build.
It is not without issues. Mostly, the quarter mm isn’t too big a deal, but you have less leeway with tightening the strut plates, It’s easy to overtighten them, I was very careful with it. the Y clips are a bit loose. I don’t think that you get actual movement, but the Y rail does turn in the clips.
Mostly though the machine assembles as expected, and runs well. I am quite happy with mine.
