converting to ball screws without CNC?

[JeffG519]

Has anyone done a ball screw conversion to the mill without doing CNC? I have a lot of backlash in my X2 and I am hoping to get rid of that problem before I convert to CNC

I would prefer to buy one of the off the shelf kits for this, as making precision plates and holders would be an act of extreme frustration until I solve the backlash issue.

Thanks.

Jeff

[ataxy]

the problem with converting a manual mill to ballscrew is that you will loose the friction of the acme screw wich prevent the table of moving to easly, you are better up getting some anti backlash nut

[JeffG519]

So I think what I am hearing is to just do the complete CNC conversion at one time.

Thanks.

J

[ataxy]

yes if this is what you intend on doing in the long term yes if in short term you just want to get rid of the backlash then some backlash nut would be a better choice

[BobWarfield]

You can switch to ballscrews without CNC, but you do need to deal with the friction issue that was mentioned. If you don't, the very low friction will let forces on the table move the screw, depending on your ballscrew.

The latter is very important. There are rules of thumb for how much lead the ballscrew can have without this being a problem. You'll need to go research that information. I would take a look at ballscrew conversions for Bridgeports, for example. There are lots of them out there, and they don't require CNC.

Cheers,

BW

[sansbury]

How much backlash exactly are we talking about, and which axes does it occur on?

[JeffG519]

I am getting a lot of play in both the X and Y axis.

I have measured backlash in the X axis between .013 and .018 and the Y axis of .008 and .011. I have not measured the Z axis for backlash there.



I am hoping to convert the whole thing to CNC in the end, I was just wondering if I should spend the time cleaning up the backlash before I do the conversion. I know that most of the conversion swap out the leadscrews, so I guess it would be mout to fix the backlash, and then change out the leadscrews.

I guess I just need to pony up and order everything at once.

J

[blades]

Jeff, it sounds to me like all you really need to do is spend some quality time adjusting the backlash. There's no reason you should have to live with any more than .005 on this machine, unless of course you've plum worn it out.

Ball screws are very nice to work with, a worthwhile upgrade, especially with an eye towards a future CNC conversion. The drag issue is really not addressed properly here. Too little drag can commonly be an issue also with the standard acme leadscrews.

It all depends on the machining circumstances at any given moment. Many times it is advantageous to "ride the brake" when machining. It can help reduce or eliminate cutter chatter, improve surface finish, improve cutter life, and if you happen to be climb-cutting, it's imperative to ride the brake, else your cutter will grab & pull the table along, putting the backlash on the wrong side of the screw. It begs repeating: It all depends on the machining circumstances at any given moment.