[CS900]

Has anyone done that yet?

[hoss2006]

Done what?
Remove the bellows?
Many do and replace them with rubber sheet or make telescoping covers.
Hoss

[CS900]

Done what?
Remove the bellows?
Many do and replace them with rubber sheet or make telescoping covers.
Hoss

sorry, I'm on my phone and it hadn't updated yet. I was wondering if people have modified the vase to get more travel, but after watching your video, it seems like I won't want it overhanging any further, which means the only way to get more travel is moving the entire column back.

Good video btw. I did the same thing on my lathe over the weekend. Felt like a fool, haha.

[CS900]

ballscrews arrived yesterday. Look nice and don't appear to be bent. Had a nick on the very end of one of them, but otherwise appear to be in good, usable shape



bearing blocks just need mounting holes drilled:

[f.jones]

looks to me like you have the pm45 don't you? jones has a similar rf45 clone which most people get 8-9 inches of travel. jones needs to rethink his design to something more conventional that allows full travel.

You guys did get me thinking about my Y travel. I inserted a 2.5 inch spacer block behind my Y mounting plate. I'm now getting 10.2 inches of y travel. I'm afraid to use a bigger spacer block or the table might extend too far and end up in my lap someday.

[CS900]

I'd be quite happy with that. I got my y axis brackets done and it looks like as is ill have around 8, but I'm fairly sure I can queeze out another inch by cutting the slot in the base forward more. Pictures to come later.

[CS900]

Also has anyone had their base and saddle surface ground to ensure flatness and remove maching marks? Only drawback I can think would be lubrication retention would be reduced, but that's not a huge deal with a one shot.

[CS900]

Ok, well got to work on the mill a bit tonight. With my Y axis ballnut bracket finished, I got a chance to mock up the Y axis a bit. I intentionally ordered the ballscrew longer than would fit normally as I want to put a free end bracket on it. So that required a little modification to the base. thanks to my cut off wheel and my dremel She now fits the ballscrew.

fancy bracket:


Base modification:



While fitting the screw I noticed that I have a lot of wasted travel in the front of the base. There is around 5" of nothing in front of the balnut cutout that I think I can squeeze more travel out of. Even once I get the second ballnut mounted I can get at least 3" more. Short of needing a spacer behind the spindle head, I don't see any downsides to cutting this area out. The table only overhangs about 1.5" right now at it's forward most position. How much overhang is too much. I'd think as long as you have more than half of the saddle supported, you'd be ok for most applications. Maybe not heavy cutting. So am I completely overlooking something obvious here? Loss of rigidity maybe?



Then once i had the saddle mocked in place, it was quite apparent that my nice straight ballscrews were indeed....not...So since I have no granite plate, I used the straightest thing I think I probably have...My brand new mill table. And with a little help from my bored companion, I measured the bend the best I could, hunting for the high spot. It's bad enough that it maxed out my poor little starrett indicator, so I had to switch over to my el-cheap-o Enco dial indicator. I measured .028" total deviation at the worst point. Then for fun I measured the X and Z as well. X measured at .024", and Z at .012"



So, any good tips on straightening ballscrews? Also, looksl ike I need to do what I've been dreading, removing the ballnut from the screw. Any good tips for reinstalling it?

[LeeWay]

Personally, I don't think that is enough deviation to worry about. Just take care to install all the bearing blocks and nut holder inline and that should be a self correcting issue. The screws aren't really long enough and your machine won't travel fast enough to induce whipping. Especially since you are nailing down the center with a ball nut or two.
Trying to correct it could also result in much worse error than what you have now.
I'd leave well enough alone and call it a non issue.

[TiagoSantos]

Couple of things.. The cutout at the front of the base - the only thing you'll have to worry about is a front way cover. The cutout, in stock form, is such that when the saddle is all the way back, the cutout is just about covered by the front of the saddle. The more you cut from that, the more exposed your ballscrew will be to chips. Not a huge problem, but you did ask if there was anything to worry about

Secondly, if I was really worried about the ballscrew not being straight, I'd measure the bottom of the races, not the tops! These are rolled ballscrews and I doubt they're really worried about what the top of the races come out like. Still, like Lee said, I'd leave it alone until it became a problem

[CS900]

so given that I don't straighten the ballscrew, how would one go about making sure everything is perfectly lined up? I was counting on a straight ballscrew to locate my bearing blocks. I suppose I could get a bit creative with a level and my calipers....and just out of curiosity I remeasured the Y ballscrew at the ball groove root and got exactly the same deviation

So if i get time at work tomorrow I should have most of my X and Z ballnut mounts done.

[CS900]

OK...

So got the X axis block finished. I ended up boring a 1.43" hole all the way thru it, but of course you can never get a drill to go straight. So I ended up doing a bit of creative fixturing to square the block to the drilled hole. I ended up putting a ground dowel (use to be a piston rod in a shock) thru the hole and propped it up on vblocks to hold it parallel with the table, then just clamped it down in the vice. Worked better than I was expecting!


Also did a bit of creative fixturing to cut the chamfers on top, but my little Taig powered thru like a champ.


Finished!


So just need to bore the hole for the ballnut in the Z axis block and it'll be done as well.

[LeeWay]

Thats using your noodle. Looks great.

[CS900]

so I'm a dumb arse...After finishing my Z axis block and going to test fit it, I realized i drilled it for the 20mm ballnut instead of the 25mm that I have....blond moment...But at least i have more material to make another one.

Anyone using 20mm ballscrew for their Z axis want a really good nutmount?

[LeeWay]

Ouch! Welcome to humanity. Measure twice, cut once.

[CS900]

i did measure twice...just used the wrong measurement

Oh well, a minor setback, but not the end of the world by any means.

[CS900]

ok, so long time since an update, and I'm afraid I haven't gotten nearly as much done as I would have liked.

Any ways, Got the new Z axis block made and fitted. Hand filed it down to fit a very slight press fit. Also got the Z axis bearing block bolted down, so now all my bearing blocks are finished! I also modified the base to extend the Y axis travel. Not sure how well it'll work as the saddle hangs off the base quite a ways at the extreme travel, but I do now have 12" of saddle travel

So how all the pieces sit as of now:


and the modified base. Not the cleanest thing you've ever seen, but not the worst either:


Still have yet to fabricate the servo mounting brackets, and do a few modifications for the oilier system.

[CS900]

ok, so long time since I updated, but I could use you guys help for a bit. I finally got my other ballnuts in from china, and upon inspection I noticed the balls were quite crappy. So I ordered new high precision and heat treated ball bearings, polished the inside of the ball nuts, deburred the track transfer inserts, and repacked everything back together. Installed them on the ballscrew and she runs great.

So first issue, the new ballnut I got the the Z axis has 4 tracks of balls unlike the original one which only has three. The 3rd track , when loaded is very notchy, more noticeable in one direction than the other. I even tried swapping the track transfer inserts, but still had the problem with the 3rd track. So not a big deal, I just didn't load the 3rd track, when I installed it on the screw. Ran fine until I applied the anti-backlash preload. Just a VERY light notchy feel to it now, but not nearly as bad as before. Added a bit of oil hoping it would help, but it didn't really.

Did the same thing to the X axis next. Installed both ballnuts and they ran great. I can hold the ballscrew upright, and gravity will (quickly) spin them down. Then the same problem. Added preload and one of the ballscrews is VERY notchy in one direction.

So what the hell am I doing wrong? Preload is around 360lbs right now, which is WELL below the working load of these ballnuts. I see jid2 had the same problem at first. Seems he "fixed" it, but just removing preload until it was smooth. So is my preload too much?

On the bright side, all the servo mounts are fab'd, and I've started wiring up the servo controls.

[SCzEngrgGroup]

Cheap rolled ballscrews will wear in with use and get a LOT smoother. When I did my first conversion (and X2), it was very "crunchy". After a few weeks use, it was smooooooth as can be.

I wouldn't worry about it until you've run them in for a while.


Regards,
Ray L.

[LeeWay]

The opposite is true for good ground ball screws. When one of mine got crunchy, it was time to replace the balls.

Some of them were more football shaped than they were round.