Gear reducing kit recommendation

[JAZZCNC]

I have also seen vertical cnc machine you have put together, really nice work. I was surprised that that long screws worked that well, until then I thought that screws on machine that big are ridiculous, but you managed it with high pitch screws to avoid whip.

Those screws where 2525 with 2:1 ratio using 8Nm 3phase closed loop motors and mains drives. They also had fixed ends at both ends of the screws and where preloaded slightly to tension the screws.

I have also seen design for rotating ball nut made by forum member Jonathan. Those seem really well made and simple. I have sent him the PM if he is willing to sell me 3 of those. But he has not been on forum for about 6 months, so I don't know if that will happen.

I don't think Jonathan does much with DIY CNC anymore as he's working now he's left university. I bought the last 6 sets he made. These are what I used on the 10 x 5 Router.

You are probably right about those Chinese gear reduction units. They are one piece units, yes, which is bad. And even if I get a high quality rack, there is no sense in getting a low quality gearbox.

No probably about it, I'm 100% sure because I've worked on them, only last week I converted a router which used them and it was sloppy as hell. Just about every Chinese router I've worked on uses them.

My thoughts about servos are the same as yours. They have their place, but for my purposes they are overkill and added complexity (and cost). With proper steppers I should get if not same then very close results. If my steppers are missing stepps while carving or routing, then something else is wrong. And high rapids are not so important to me.

Exactly, I've built quite a few large machines now that use 3 phase closed motors with mains drives and never had any issues with reliabilty or setting up with more than enough power and speed for even large machines, they are pretty much plug n play fit and forget.

I also have 600w Chinese servos fitted to my plasma machine which are way more powerful than required and nothing but a pain regards tuning.
If I was fitting servos to a router that used Rack n pinion then I'd only fit higher quality servos like, yuskawa, Mitsibishi or panasonic which provide tuning software to help with setting them up, esp with dual axis motors.

I like the idea of using ball screws with rotating nut, but have trouble finding them. But what is high precision in this case?
I was looking at a C7 grade 2525 ballscrew with machined ends. Price with delivery for 2 of those (3m) is 800 Euro (C7 grade, accuracy 0.05mm/300mm). From here:
https://www.tuli-shop.com/ball-screw-shaft ).
Will this be precise enough for 3d carving? This site does not offer more precise ballscrews with that high pitch. 3232 ballscrews would be about 100 Eur more (C7).

In terms of precision then yes 0.05mm will be more than enough for 3D work in woods. If all you are cutting is mostly woods, plastics etc then I wouldn't get bogged down with chasing high precision because it's pointless in materials that can't hold it anyway.

I would pay the extra 100eur and go for 32mm, it will be worth it and lower the chances of whip if your rotating the screw.

Another option I was looking for were racks. Was looking for Q6 or Q7 racks. Found Q6 racks here (with predrilled holes which is bonus), mod2
https://www.damencnc.com/en/straight...2010-6mm/a2687
They would cost me about 180 Euro/m

I was thinking about using their anti backlash worm gearbox with double pinions (ratio 5:1). But they are quite expensive (360 Euro per piece for gearbox + mounting plates for nema34).
https://www.damencnc.com/en/r-p-driv...15t/a554?c=364

Whole setup with a straight rack from this shop would cost me about 2300 euros for the x and y axis.

I would avoid these, I have worked on a machine that used those anti-backlash untis and was not impressed at all. They where difficult to setup and where constantly needing adjustment. They also caused premature wear on the rack/pinion. The Rack was low quality and wore out within 1 year and as been replaced with helical rack I believe.

I have not looked into helical racks, if you know where to find suitable ones, please let me know. But I see that they are pretty rare in DIY router versions. And so is rotating ball nut.

They are rare in DIY because they are not cheap but most good engineering suppliers will be able to supply them.

Rotating ballnuts are not so common and might require you have your own made. This is the only other place I have seen rotating ballnuts. Use google translate.

https://team-haase-shop.de/maschinenelemente.html