Screw nut ball CNC

hello community.

I have found out that there are screws for the CNC with balls which allow the nut to have no play, to give the CNC more precision.

I have a CNC3018 PRO (https://aliexpress.com/item/4001097302113.html).

The idea is to change the screws for ball screws to give it greater precision, it turns out that there are an infinity of these screws and since I am new to this world of CNC I do not understand the difference much.

I need a screw that is compatible with my machine, I measured the screws it already has and the measurements are as follows.

Length
40cm x
30cm and
10cm z

8mm (diameter)

My idea is to buy it through one of these sales pages like aliexpress, alibaba, ebay, amazon, etc. I would like you to guide me on what type of screw will work for a CNC3018 PRO, I am trying to find the best quality and low price, some material that is better than another.

The models I have seen are SFU and SFK

Quote:

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Originally Posted by Andrewxxd1

hello community.

I have found out that there are screws for the CNC with balls which allow the nut to have no play, to give the CNC more precision.

I have a CNC3018 PRO (https://aliexpress.com/item/4001097302113.html).

The idea is to change the screws for ball screws to give it greater precision, it turns out that there are an infinity of these screws and since I am new to this world of CNC I do not understand the difference much.

I need a screw that is compatible with my machine, I measured the screws it already has and the measurements are as follows.

Length
40cm x
30cm and
10cm z

8mm (diameter)

My idea is to buy it through one of these sales pages like aliexpress, alibaba, ebay, amazon, etc. I would like you to guide me on what type of screw will work for a CNC3018 PRO, I am trying to find the best quality and low price, some material that is better than another.

The models I have seen are SFU and SFK

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Yes there are different grades of Ballscrews, but you won't find a replacement off the shelf for your machine in a different grade, they are almost always custom for each machine type, the part that is different is the end of the Ballscrew machining which is custom to most machines, so even if you can find one that is close you will have to have the ends machined to the same as what you have installed on your machine

So you need a complete drawing of each of your Ballscrews the size of the support Bearings they are are using etc. so every dimension of the Ballscrew before you could even start to look

You may need to take into account the length of the ballnut as it can be quite large and it's size prevents the machine travelling the full length of the screw.Which means that to retain the amount of travel you have now you may need to buy a screw a bit longer than you have stated and installing it may need a bit of fabrication on your part.

OP:
It is perfectly possible, but probably much more involved than You think.

The yoke is the part that connects the screw to the machine.
This needs to be made, or you need to find one that You can modify to fit.

The yoke is the hard part, all else is brackets and flat parts you can cut to fit, in steel.
Then drill and tap as needed.

If you can/could find a similar sized machine with ballscrews, you could buy and fit their screws onto your machine, bought as spare parts.

You will spend more than 220€ to get ballscrews fit onto your machine.
And they wont be zero-backlash, nor will they have the bigger balls to preload the nuts.
Nor will they have proper bearings on the screw mounts.
Proper bearings alone will cost about 80-120€ extra for 3 axis.

Thanks for answering, I think the information I gave you is a bit vague, so I will try to give you more specific questions.

I have found some models with the SFK and SFU series, do you know anything about that? is there any concrete difference in them?

Within the same screws that I have found SFU there are versions where the Screw ends in thread and others where it ends smooth, I think they call it machined or not machined.

If we put ourselves in a case of any CNC, which would be the best option or the most versatile one that is mechanized or not mechanized.

Finally, I have found some abysmal price differences, between screws with practically the same characteristics. SFU. and from what I saw I don't find a noticeable difference. Share links

expensive version https://es.aliexpress.com/item/4000169265420.html

economic version https://aliexpress.com/item/1320917366.html

If you know of an American company that sells these threads at a good price, I would appreciate if you could give me some company names

Quote:

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Originally Posted by Andrewxxd1

If you know of an American company that sells these threads at a good price, I would appreciate if you could give me some company names

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Rockford Ballscrews are in the same grade that you are looking at

You will need a Ballscrew with machined machined ends the same as what you have, unless you have someone that can machine the hardened ends for you, they are not easy to machine and Grind to size

I am curious for the material of the screw nut ball. Is AISI 52100 bearing steel good for it? If not, what is the best or other options?