[Fastest1]

Much lighter and streamlined!

[hoss2006]

Much lighter and streamlined!

Saves me some weight to help with what comes next.
Hoss

[mwood3]

Saves me some weight to help with what comes next.
Hoss

such a tease

[Fastest1]

Let me guess, a toolchanger? Or maybe a 3D printer head alongside the spindle? Oh yeah that isnt ready yet.(chair)

[rwskinner]

Hoss,
I loaded oversize balls into my X&Y nuts and they worked out pretty good, < 0.001". For some reason I forgot to measure them on the Roton 0.750" nut, I guess I was in a hurry.

Do you remember if they were 0.1250" as well from Roton? I have like 0.012" backlash in my Z axis.

I run a double nut on the Z Axis as well sprung with 200# of wavy washers but I can tell that sure isn't enough when the gibs are snugged down. The second nut just shifts back and forth and the first solid mounted nut has all the backlash.

Thanks,
Richard

[photomankc]

Hmmm. I'd look hard at everything in there. I have no oversized balls or double nuts and my backlash on Z is 0.0015" using Roton screws and nuts. With as much as you are seeing there I would suspect that some part of the mount is moving. You should not need oversized balls for a double-nut arrangement I wouldn't think.

[Starleper1]

You are right you don't need oversize balls for a double nut setup. The spring preloads both nuts.

[rwskinner]

I put a DTI on the AC bearings and they aren't moving, and when I put it on the end of the shaft the shaft moves less than 0.0005" so it's in the nut or mount.

I backed the gib off a lot and I can still see the spring loaded nut move up a ways before the Z Axis starts moving. That says a couple of things in my mind, not to say it's correct.
1) Springs aren't stout enough for the wweight and drag of the head.
2) the top nut for sure has lots of play.

I didn't really want to use Hoss's thread my my issues but I thought he knew what size balls were in his. On the Z, a single nut with oversize balls would be much simplier and I wouldn't have to worry about the spring pressure.

[hoss2006]

The Z ballnut has .125 balls too IIRC.
Never added oversize balls to mine yet so I don't know if it takes the same size I used on the X and Y.
Your Z is for an RF45 though isn't it?
I believe my ZX45 head weighed about 250 lbs so it makes sense that 200lb springs aren't enough
in your double nut setup.
Hoss

[rwskinner]

I looked up the part number I installed to make sure.
I went with 12 of these springs
McMaster-Carr
rated at 28# each for a total of 346#

I cranked down on them more and I'm down to 0.002 backlash but the gibs are pretty loose. I'll keep checking to see what else may be moving.

[hoss2006]

Thought I was going to finish the latest project tonight but my back is aching.
Did get the tricky part done and machined the z slide hub smaller.
I could have taken it flush and added a spacer to do the same thing but this way left
me with more threads on which to purchase.
Should wrap it up tomorrow.
Hoss

[gun_mike]

Very cool Hoss,
I'm interested in how you programed this with your CAM system. Did you interpolate using G18? or did you trick the machine? by switching Z----->Y and Y----->Z?

Mike

[hoss2006]

Very cool Hoss,
I'm interested in how you programed this with your CAM system. Did you interpolate using G18? or did you trick the machine? by switching Z----->Y and Y----->Z?

Mike

Thanks, yeah, just swapped the Y's and Z's in notepad.
Hoss

[hoss2006]

We have a 5th Axis. (the 4th's are on the shelf next to the mill)
Still tweaking the pulley ratios to get the most out of the 570 n23 but I may splurge for a nema 34.
The head retains it's original pivot location, keeps the tool to pivot distance as short as I can.
The spindle motor and pdb add a lot of offcenter weight but I may counter balance that a bit
rather than move the pivot up and lose the Z travel I gained from before.
The pdb needs stiffer springs to counteract the side flops, dang gravity.
Lots more playing to do.
Hoss

[ame="http://www.youtube.com/watch?v=A5ykOUgxDHU"]G0704 5th Axis Intro - YouTube[/ame]

[Winnfield]

I have one set up exactly like this on one of my Taig mills using a Sherline table. What kind of rotary table did you use, and do you have a way to lock it in place when you aren't using it?

[hoss2006]

I used this 6 incher from Wholesale Tool.
Rotary Tables (WT)
Went thru it and added bearings here and there.
Backlash is adjustable with it and it has 2 locks, I have a third if needed but probably won't,
it's very stiff.
The center bolt can be tightened down to lock it in place if needed.
Hoss

[Fastest1]

I cant wait to see all of that going on at once! Toolchanger too? I wouldnt even know where to start in developing a toolpath.

[hoss2006]

Yeah I always said this would be the easy part, now to learn the software.
I got the latest version of CNC Toolkit and GMax, looks a lot better than what I dabbled with years ago.
Hoss

[WTX]

very cool

[hoss2006]

very cool

Thanks!
Hoss


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