Rotating Ballnut - design ideas

[mutzy]

Hello Jonathan, how are you today? Wow, you certainly created a great thread here. I can't seem to find distributors that have this size bearing to bore out. Do you have any suggestions of who might sell them? USA would be best for shipping. Once again thank you.

[Boyan Silyavski]

I made it a couple of times. If Johnathan could not, i could do it. Plus i have it from my drawing on my machine and is working perfectly fine.


Though last time i did it, i said i would not do this again for the money i charged then. In short only parts are worth ~200euro, as i have to have them at hand as all is not available locally and shipping costs are included that raise the price,

+answering to 50 emails, 3-4h redrawing for different motors and mounting, 8h to make parts and 2h for 2 people to put them together, 2h packaging, 1h sending . Plus while you are making them you learn from small mistakes.

So if you have 500euro prepared for them, then PM me. Thats the reality folks for bespoke parts. Mind that the cheapest servo motor with hole in shaft is 1500euro plus 400euro for drive, and you need 2x.


What i am saying here is i am just trying to help, not sell. So if sb could do it cheaper, go with him. If not- call me, i will do it.

[Jonathan]

+answering to 50 emails, 3-4h redrawing for different motors and mounting, 8h to make parts and 2h for 2 people to put them together, 2h packaging, 1h sending . .

I know the feeling....

Having said that, I did start making a few some months ago, but got distracted by another project:



I already have the bearings etc. I'm willing to finish these off and sell them, as I have a bit more time now. Silyavski's price is about right, maybe a little less - fortunately I bought the bearings before the £ crashed!

[Black Forest]

What exactly would be included in the units you would sell Jonathan?

[Jonathan]

What exactly would be included in the units you would sell Jonathan?

That's up to you, but in the past:



So the mount, including pulleys and belt. You just add the motor and ballscrew.

[mutzy]

Jonathan, i would like to purchase some of the bearings from you. how much are they. 30t 5m bored out to correct size.

Thank you
Mutzy

[Jonathan]

Jonathan, i would like to purchase some of the bearings from you. how much are they. 30t 5m bored out to correct size.

Is that just the pulleys you're after, or bearings and pulleys? For the bearings, I got the last lot from here:

https://www.aliexpress.com/store/pro...053270817.html

[It may help to order 2 at a time to avoid customs charges. Not sure how it works in the USA, but I ordered two with no charges, then got taxed a lot when I bought 10 :(]

Regarding the pulleys, I can get 30t 5m HTD for about £6.30 each. Boring them accurately then drilling/tapping the setscrew holes takes maybe half an hour, so I'd be happy to sell them for £10 each plus postage.

This weekend, I made some progress on the six mounts I'm making:



I'm away racing next weekend, but after that I should have time to finish these ... at last.

[richienz]

Impressive nuts! I just took a look at your e-moto webpage quickly too , wicked. Great project and racing at Isle of Man wow respect that place is nuts.

Hey I have a large router that is running well but I want to upgrade the main screw to a fixed screw rotating nut design. The screw is 40mm dia 10mm pitch and 3m long so its heavy. Running a 940W AC servo and a Grantite Devices VSD-XE servo drive, and 80VDC supply, I'm getting good response now with 8m/min velocity and about 400mm/s/s acceleration. This took a long time for me to work out the servo tuning but I got there in the end. I'd like to remove the rotating mass to improve my accelerations. The gantry it moves weighs around 150KG I estimate.

So I am wondering are you interested in building me a ball nut for this? Happy to pay market rates of course and if it helps fund any of your emoto projects then all the better. Please contact me if this is interest to you.

Below is my final servo response I got recently which I am really stoked about it, but to speed up my jobs I really want to up the accelerations.

cheers
Richard

Is that just the pulleys you're after, or bearings and pulleys? For the bearings, I got the last lot from here:

https://www.aliexpress.com/store/pro...053270817.html

[It may help to order 2 at a time to avoid customs charges. Not sure how it works in the USA, but I ordered two with no charges, then got taxed a lot when I bought 10 :(]

Regarding the pulleys, I can get 30t 5m HTD for about £6.30 each. Boring them accurately then drilling/tapping the setscrew holes takes maybe half an hour, so I'd be happy to sell them for £10 each plus postage.

This weekend, I made some progress on the six mounts I'm making:



I'm away racing next weekend, but after that I should have time to finish these ... at last.

[Jonathan]

Great project and racing at Isle of Man wow respect that place is nuts.

You can certainly say that of the riders!

I'd like to remove the rotating mass to improve my accelerations. The gantry it moves weighs around 150KG I estimate.

With that size ballscrew then you do have a problem with the rotating inertia, not so much the 150kg gantry. Can you measure the ballnut - approximate it as cylinders, then we can work out the inertia of the ballnut compared to the ballscrew to see what you could gain by rotating the nut.

So I am wondering are you interested in building me a ball nut for this? Happy to pay market rates of course and if it helps fund any of your emoto projects then all the better.

My PhD studies are taking up a lot of time at the moment (need to catch up after all the racing!), but I do intend to have time to finish some rotating nut assemblies soon.

Below is my final servo response I got recently which I am really stoked about it

What else can you plot from your system - can you plot the motor torque in addition to the speed response? If so, that's another way to work out the inertia and get better insight into how the system will behave.