X axis drive

[petesos]

Hi All
Does anyone know where or the best place i can get a complete replacement ball screw for my 3040t cnc , tried contacting the company i purchased it from but like a lot of these people on flee bay as soon as they get your money they don't want to know you
Pete

[Sterob]

Is it removed from the machine?
Whats wrong with it?

Probably easiest thing to do would be to take some measurements and do a search online.
If your lucky it will be a standard size.

[Doddy]

Just to re-iterate Sterob's recommendation - the 3040's and similar out of China are not a single design - so there's no easy answer to your question than to measure and search for a suitable replacement.

If you've not played with a ball screw before, be aware that you're probably better to getting the nut as well - and that removing the nut must be done with care if you're not going to lose any bearings in the process (e.g. if you need to swap the orientation of the nut) - google that for more info. Also, when you say "complete replacement" - just what do you mean by "complete"?, screw?, screw+nut?, screw+nut+bearing-blocks? etc. I guess the screw+nut, but it's unclear from your post.

If you post a good picture of your screw we might be able to identify it. Common size for a ball screw would be 1605 (16mm diameter, 5mm pitch) then you just need to specify the lengths of the machined ends. But many of the cheaper 3040s are on trapezoidal/acme threads, rather than ball screws.

[Sterob]

Nicely put Doddy.

[JAZZCNC]

But many of the cheaper 3040s are on trapezoidal/acme threads, rather than ball screws.

Many with ball screws also don't have end bearings as in BK type or angular contact. They are often just standard cheap n nasty deep grove bearings machined into the end plate with a very sloppy fit.!! so the end machining will be custom rather than a standard BK12, 15, etc type machined screw.

Contact Fred at BST and give him the sizes and accurate dimensions of the machined end and he will make one for you.!

[petesos]

HI Guys
Thanks for the replys, have attached a few photos so you can see the type it is , i would rather buy the complete unit threaded bar bearing nuts the whole lot as the hands are not steady enough now to put together but i could manage to put the whole lot in together already built.
The instructions say it is 1404 double thread trapezoidal screws and about 420 mm long .
There is a bit of backlash on the x axis just now and thats what i want to get rid of as its about 1mm

[Doddy]

That looks like it's got a few miles on the clock, but - if you'll forgive the impertinent question - do you know that the backlash is because of the screw / nut? Have you checked the mounting of the nut to the bed?, and have you checked the mounting of the screw and the coupling to the stepper motor? if the problem is elsewhere than the nut you could save yourself a lot of hassle.

If you're confident it is the screw/nut - then from what I've read in the last 10 minutes some of the 3040/trapezoidal screws use a delrin (plastic) nut - and that (rather than the screw) is likely to be the cause of the backlash - although 1mm is pretty horrendous - surprised the nut is still holding together with that. I'd expect if it is the nut that it's got progressively worse to the position that you find yourself in today. If it is delrin then it's not hard to re-cut a new nut using a bit of heat, delrin, and the original screw. Otherwise...

Eyeballing the photos you've provided - it looks as though the nut is attached to the carriage with two M4 or M5 bolts - use a hex key/drive to unscrew those and you should be able to persuade the nut from the carriage - then you can properly assess it for backlash. I've spent a short time googling/ebaying/amazoning and the T 14 4mm p2 trapezoidals are not immediately obvious from the "usual" sources. It might be worth looking to see if you can get similar, even if not the same. Maybe the Chinese suppliers (including Jazz's recommendation) may be able to source a nut.

I'm purposely ignoring for now your reluctance to perform a lot of disassembly/reassembly - that might be unavoidable.

[petesos]

Thanks guys for the help
And yes i am going to replace it all with better quality fixings as and when they need replacing , going to start removing x axis tonight and will post photos and dimensions so i can source a supplier . Jazz have you got a number for the engineer you mentioned .
And by the way guys i work in the urethane industry so if you need bar or sheet urethane drop me a line

Pete

[routercnc]

. Jazz have you got a number for the engineer you mentioned
Pete

Fred is at BST automation on Aliexpress over in China. You are dealing directly so would need to be happy with how Aliexpress works, and create an account. Send him an email to make sure he can help with that type of thread first.

[petesos]

Right guys
You guys been in this game for a long time so am asking for your recommendations ,
The x axis screw on this cheap chinky machine is 12 mm diameter trapezoidal and am looking for a good replacement ballscrew as i will replace all the ballscrews as they wear .
What would be the best upgrade { ballscrews } from the cheap screws that are on there already, any ideas please