[Menacer]

OK so I'm working on switching my Taig to ball screws... I love this forum and should try to give something back... A ball screw conversion is lacking here.....BIG TIME, so I'm going to try and post as I can... Sorry for the video as I don't have time to script or Re-take/edit, so it is what it is...

I just uploaded the video to youtube. I will add pics to this post later...

WATCH IN HD!!! If you can..



[ame="http://www.youtube.com/watch?v=idg2iMtdLkg"]IMG 0829 - YouTube[/ame]

[xnthn]

Hey Menacer,

Just checked out your video. I've been trying to figure out how to do this myself. Looking forward to seeing how you've done it and how much it costs to do such a retrofit.

I'm not concerned about speed, but mostly accuracy, as I'm doing mostly small detailed work in all sorts of materials. I currently just can't it right. I'm about off by 0.003-0.004".

Keep us posted!

[bjm323]

I'm very interested in this also. Please keep us updated.

[BAMCNC.COM]

I'm in! I have a Taig CNC backlash video on YouTube.

[900steve]

Nice. Thanks for posting. Looking forward to the pics.

[xnthn]

Menacer,

Any updates on this? Where did you get your hardware for the retrofit? I'd love to here how much this costs, and what's involved in this mod.

[Menacer]

Hey guys!

Glad you're all interested in sorry it's taken me so long to reply, but because of work and family I'm not sure if I'll be able to post a lot, therefore I'm hoping that anybody with experience in converting their Taig CNC mill to ballscrews will be willing to jump in and share any information ideas or experience doing so.

I actually ordered these ballscrews for a different project but after talking to a friend I got the courage to convert my mill itself.
Please keep in mind that I have not completed this project I currently have my Z axis converted.

Okay for some info.. After searching for weeks on the Internet for different types of ballscrews there's everything from $16 ballscrews to $300 ballscrews. I try to get in contact with big ballscrews manufacturers
like NSK and others but it just seems like they're not willing to speak to little guys like us (who just need 1-3 screws/nuts ) eventually I came across www.homeshopcnc.com they seemed to have a easy way to order ball nuts "Zero Backlash" and the screw size and length that I was looking for.

Here are some pics of what I had to do to make this ballscrew fit on the z-axis.



Okay so with this picture basically shows is the taig stock screw on the upper left and the ballscrew on bottom. After trying to cut the ballscrew with my lathe I found out that the interrupted cut / gap between threads plus general hardness of the screw was going to be a real problem so I decided to grind the threads down.



With a standard grinding will that you might get from Home Depot and using water for coolant I was able to grind
off all of threads in 10 to 20 min. "You don't want to let the screw get hot or you could reck it". After giving up attempting to cut this ballscrew with my small lathe I took it to a buddies shop where he
made quick work turning it down to the proper size " THANKS! Shannon!!!!!!!!! " with his larger lathe.

Will continue tomorrow!

[bebob1]

any plans on modding the other axis also? might require a bit of workaround for those cause there isnt much space?

[Menacer]

Yes definitely! Your right on space but I'll have to take a second look after I get home tonight... But I'll make it work.

[Menacer]

After returning home to check to see if the parts fit I needed to thread the end ( used to die ) and clean up the keyway my friend cut into the ballscrew with the slitting saw. I used my old Harbor freight 7 x 12 mini lathe with the grinding attachment. Here are some before and after shots.

( If you ever do this cover your ways as you don't want grinding dust particles sanding them down. )

[Menacer]

So here are some other pictures of the new ballscrew assembly and stock bearing housing.

[Menacer]

Here are some pictures of the spindle mount milled down about .330 thousandths. I also had to mill a small channel for the ballscrew, next I drilled four holes flipped the spindle mount and counter bored the other side.

[BAMCNC.COM]

Good pictures!

[Menacer]

I hope your not kidding.., My phone is the only camera I have right now. I do wish the pics had more light.

[fretsman]

I can't imagine him joking with you as the pictures really are very nice, thanks for sharing-

Dave

[BAMCNC.COM]

No, very good, they are a tutorial all in themselves. Thanks!

[handlewanker]

Hi, when you bought the ballscrews, did you get the ground type or rolled?

If you bought the rolled it would be interesting to see the effects of moving forward and back to zero to see if you get any backlash due to the nature of the screws production......the ground type will be a lot more expensive but much more accurate.
Ian.

[Menacer]

ok cool..., Glad the pics worked out. I will post more this week. I have the mill turn down as I have to model the Z column and new bearing block I'm working on.

Handlewanker,

Hi, when you bought the ballscrews, did you get the ground type or rolled

www.homeshopcnc.com only has rolled polished ballscrews with an error rate of .0018 per foot, so as long as my backlash is low I'm sure I'll be able to live with this especially considering the size of my machine.

If you bought the rolled it would be interesting to see the effects of moving forward and back to zero to see if you get any backlash due to the nature of the screws production......

Now I don't know if you watched the video I was pretty happy with my results with not much setup in Mach 3. The Z got back to zero without any problems but with the the weight of the motor it's kind of unfair to assume that I will have the same results with the X and Y. In the video I was using a test indicator that only measured .0005 after little eBay searching I managed to get my hands on an indicator that measures .00005 also the motor is set up in a direct drive fashion which I will be changing for acceleration reasons.

I will test my results and post them but first I need to complete the bearing block and cog gears for the Z.

[handlewanker]

Hi, a lot depends on the weight you are moving when you do the dialing tests......IE, when you come down onto the table you are virtually under no load conditions, but when you reverse and go back up you first have to overcome the weight of the head before the load moves, which translates to lost steps from your stepper motor.

Although it's not the same, I have this problem with the down feed on a surface grinder head.

The weight of the head is counterbalanced by a set of springs that are designed to always pull the head up against the screw thread when you reverse the up feed screw so that you always have a positive drive to the screw in both directions, IE no backlash.

The previous owner of the grinder had the counterbalance wire pull up mechanism fail and it meant when he down fed the head it hung there against the friction of the slideways and a tight gib, but at some point he slackened the gib to ease the down feed and it became unstable and the head fell when the screw was fed down......job flew off the mag chuck etc.

In this case the solution would be to fix the compensating mechanism or apply some force to the gib to hold it against gravity and ensure that you always have pressure on the screw when downfeeding, and this means you are actually preloading the screw until the head moves.

This is similar to the move you are making with the mill head, IE the weight on the ballscrew going down and with weight on going up....you have a certain amount of loading to overcome before you get movement on the up, which means you get lost motion......(at all points along the screw), and as it's equal all along the screw you can program it out....probably 2 or 3 steps to move it back up.

If you have a ballscrew for head moving that has preload abilities then the lost motion is non existant.
Ian.

[bjm323]

Any updates?