Best CNC KIT

[cotang]

Hi, I'm not sure if this have been asked. I did a search and didn't come up with anything (although I should've shorten the search...) anyways, I'm wondering what some of you guys think is the best CNC kit for a X2 that doesn't require modifying the X2 itself (as in drilling and tapping new holes). I know some of you will say build it yourself but I'm a newbie and I wanna get a feel of how a conversion is done before attempting to design something on my own.

Thanks.

[Smitty911]

I looked at Hoss2006 post and he did an excellent job.

There is CNC fusion - Looks nice and well done also.

KDN tools - I just recieved mine today. Ground screws and ball nuts. Ken claims backlash at less than .001. So I spent the extra money. I have to re-assemble my mill now so I cannot speak to the accuracy of the claim.

Smitty

[askman]

cnc fusion kit requires 1 hole to be drilled and tapped. pretty easy to do though. if you are going to ballscrews, go with preloaded.

[tai42]

KDN tools - I just recieved mine today. Ground screws and ball nuts. Ken claims backlash at less than .001. So I spent the extra money. I have to re-assemble my mill now so I cannot speak to the accuracy of the claim.

I was just looking at their site. I see where they offer rolled, and "precision rolled" ballscrews for their X2 kit, but I didn't see where they had ground screws. Is this something you had to request custom?

[Smitty911]

I was just looking at their site. I see where they offer rolled, and "precision rolled" ballscrews for their X2 kit, but I didn't see where they had ground screws. Is this something you had to request custom?

My Mistake;

They offer the precision rolled. How 'bout they just look really nice. Haven't taken them out of the shipping tubes yet. Maybe this week.

Smitty

[cotang]

So is ball screws better? Has anyone use cncfusion? Do they know if the backlash is a problem.

[KOS]

i went with KDNs kit...second one I have purchased from them and their service and quality is awesome! and yes when I got my preloaded ball screws they are very accurate...I am very happy with them and have no problem reccommending them at all.

[ataxy]

So is ball screws better? Has anyone use cncfusion? Do they know if the backlash is a problem.

yes its better
no i havent
any slack, loose, wobble you can get on cnc is a problem

[Smitty911]

There was a whole thread on cold fusion conversion, I believe it has to do with using a clamp to set pre-load. I believe they have since changed there design to use a nut to pre-load. This eliminated one (1) source of the backlash.

From my research most of the rolled screws will have .003-.005 backlash. Than any mounting issues would make it worse. The KDN claim is alot less than that.

I just went and bought the one I felt would deliever. I don't have the time to worry about this that and the other, design, make, check, do over (which I'm quite good at). Seems the second/third/ninth time I do something it comes out quite well.

Smitty

[alexccmeister]

I keep reading about preloading of ballnut. Can someone explain what this is all about. Thanks. I am in the process of converting my mill also and willbe ordering some ballscrews and ballnut. I would like to have preloaded ballnut but what do they mean?

I thought it had something to do with them loading the ballnut onto the ballscrew. Cos doing it myself will be difficult.

[tai42]

Easy to think about this way. When you move the handle on a manual mill, you are putting the nut under a "load" in relation to the screw. You can stop, and start again, and as long as you are going in the same direction you continue to have a load on the nut and therefore no backlash. However, as soon as you start moving the handle the other direction, you remove the load from the nut on one side and start applying it to the other. This transition is where the backlash occurs. Now if you have a nut that has a "load" in both directions without moving anything at all, then you have a "pre-loaded" nut. In principle, the transition from moving in one direction to the other never removes the load, and therefore you have no backlash. The one caveat is that the force you put on the nut cannot exceed the pre-load. If it does, then you will be back to the same situation as before, and the potential of backlash will be there again.

That is the principle of pre-load, but there are various ways of making it work. One way is to use two ball nuts screwed together in such a way that they create a load on each other. This is what you find in more "high-end" system. The amount of pre-load is adjustable depending on how tightly you have the nuts screwed together so you can set it based on the characteristics of the machine. Another way is to use slightly larger balls in the raceway of a single nut. This is a little tricky and tends to be a trial and error sort of thing. Because the balls are a little too big, the nut squeezes them in on the screw creating the load. This method is common for the smaller conversion kits, but isn't adjustable like the two nut approach. However, it is also a lot less expensive to implement, and doesn't limit the travel as much as having two ball nuts might. (Something important on the smaller machines many of us are converting.)

[The Blight]

There is a third option. This ballnut uses the same principal as the oversized ball option, but instead of making the balls bigger, you compress the casing. I have tested these and there is less then 0.01mm of backlash in it (0,00039").