Rotating Ballnut - design ideas

[Voicecoil]

+1 The advantage of roller bearings is the huge radial load they can take, in this case the axial is more significant I think. However there are one or two sizes of tapered rollers that are easily available at a very attractive price which might swing it ;-)

[Boyan Silyavski]

+1 The advantage of roller bearings is the huge radial load they can take, in this case the axial is more significant I think. However there are one or two sizes of tapered rollers that are easily available at a very attractive price which might swing it ;-)

If you will be milling steel using 3 inch cutters yes, not in a 3m woodworking machine case scenario. But don't listen to me, put that bearings there cause they are cheap.And see what happens.

[JAZZCNC]

If you will be milling steel using 3 inch cutters yes, not in a 3m woodworking machine case scenario. But don't listen to me, put that bearings there cause they are cheap.And see what happens.

I agree with Boyan and we Both have experience of using rotating ballnut design, so you might want to listen. That design and those bearings are not good for this application because of things which have been stated. They will work ok, but they won't last ok, the forces are in all the wrong places so between this and the heat generated because these ballnuts are being run in ways they where not designed to run it will impact the life and performance.

But you could say what do we know.? In which case go for it.!

[Voicecoil]

Well, this one was bugging me today, so I did some digging and the good Mr NTN came up with the info.
edit I guess it's friction/heat that's the issue?? OK angular contacts may not have the load capacity of rollers, but usually have lower coefficient of friction (1.2....2) than tapered rollers (1.7....2.5). I did see that there's been some recent advances in roller bearings pushed on by trying to get better efficiency in automotive, but they don't seem to be generally available at a nice price

[Heavyweather]

What do you think of that design for a 16mm ballscrew? Maybe the pulley should go on the right between the bearing and locknut so I can use a smaller pulley.
The bearings are double row 3805 2RS 25x37x10 spaced 35mm apart.

It is just a copy of the Fenergy angetriebene Mutter and I will probably buy that one anyways.
I just extended the spacing of the bearings and didn't copy other stuff that well.

https://www.google.com/search?q=fene...h=566&biw=1280

[Boyan Silyavski]

What do you think of that design for a 16mm ballscrew? Maybe the pulley should go on the right between the bearing and locknut so I can use a smaller pulley.
The bearings are double row 3805 2RS 25x37x10 spaced 35mm apart.

Why do you need a rotating ballnut for a 16xx screw? This should say it all. Did you read anything at all from that thread and the forum?

[Heavyweather]

Why do you need a rotating ballnut for a 16xx screw? This should say it all. Did you read anything at all from that thread and the forum?

Several times the last 6 or so years.

Why not? I got a 2m belt on belt drive now and 2m 2005 screws but the 16mm is cheaper and easier to do.
Plenty of machines that use it up to 3m (https://www.cnc-aus-holz.at/index.ph...6525#post16525) and some that sell it, some mostly/only the 16mm.

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

https://www.ems-moederl.de/ws45.html
(Uses 2 on Y and one on X)

https://schulze-leistungselektronik....ne-kus-mutter/
https://schulze-leistungselektronik....ne-kus-mutter/

http://cnc.a-ueberbach.de/?s=angetriebene%20mutter

[JAZZCNC]

Several times the last 6 or so years.

Why not? I got a 2m belt on belt drive now and 2m 2005 screws but the 16mm is cheaper and easier to do.
Plenty of machines that use it up to 3m (https://www.cnc-aus-holz.at/index.ph...6525#post16525) and some that sell it, some mostly/only the 16mm.

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

https://www.ems-moederl.de/ws45.html
(Uses 2 on Y and one on X)

https://schulze-leistungselektronik....ne-kus-mutter/
https://schulze-leistungselektronik....ne-kus-mutter/

http://cnc.a-ueberbach.de/?s=angetriebene%20mutter

Just because someone else uses it doesn't mean it's good or should be used, not every one who builds a CNC is good at it or as the experience to know better.!! . . .For instance one of those guys built his machine from wood which says it all really.!

Also just because a company as designed and sells a product doesn't automaticly make it a good product. I've experienced many products from suppliers like Haase that seem to look good only to find in practise they have some serious flaws, whether that be instantly obvious at time of fitting or appear over time in use.

With some experience of rotating ballnuts then I see such issues occuring over time with this narrow unbalanced design, but you take your chances and time will tell.

My point in this post is to say don't be fooled by what your seeing and reading, because most of those singing the praises are the designers and often those that have bought them won't admit they have issues or even have the experience to know they have issues or what the issues are over time.! . .Often blaming other areas of the machine when things do start going wonky.!

[Heavyweather]

You probably didn't understand the name of the site where the bamboo machine is shown.
I don't see anything wrong with combining wood with a 3m screw driven nut. The nut is a proven design running in EMS machines for years.

What's wrong with 16mm screws?

[JAZZCNC]

You probably didn't understand the name of the site where the bamboo machine is shown.
I don't see anything wrong with combining wood with a 3m screw driven nut. The nut is a proven design running in EMS machines for years.

What's wrong with 16mm screws?

We will have to agree to disagree regards a wooden CNC machine.!!

Regards the 16mm screw then it's too flimsy over 3mtr and thou it it doesn't rotate it will still vibrate at higher feeds. Now you probably don't believe me because your thinking well it's under tension how can it.? But let me assure you that it will vibrate because even the 25mm screws I fit and put under heavy tension still vibrate at high feeds when the machine approaches the ends of travel and changes direction quickly. A 16mm screw will twang like a skipping rope.!!