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View Full Version : Question RE Y-Axis Ballnut Mount



BobWarfield
08-16-2008, 08:28 PM
I've got the IH kit and am just starting to assemble. First thing is the Y-axis. First thing there according to the instructions is to lop off the flange on the ballnut mount to maximize travel.

That leaves 2 bolts instead of 4 to hold the bracket in place, and they're off center. Somehow, that didn't sit too right with me. First, it's a CNC'd part, they could've just made it without the flange. But second, I've been granite filling the base and want as much rigidity as possible. Seems like 4 bolts is better than 2 for that!

So I got looking, and I don't understand why the bracket doesn't flip the mounting flanges around 90 degrees so the flange is left and right of the bore rather than above and below it. Sure looks like there is plenty of clearance on my mill to accomodate this. It means making a new mount, but that is pretty darned easy. The part is not complex at all to make.

I've been looking for interferences, but I don't really see any. The only change is I now have flanges left and right, but they are low profile. Any ideas why this wouldn't work? Seems like a straightforward "mo betta" design change.

Cheers,

BW

dnelso
08-17-2008, 10:37 PM
Bob,
Here is the mount that i made. The aluminum was weak looking and i also wanted 4 bolts. I also made a support bearing for the end of the ballscrew.
It made no difference in the machining or accuracy but it did make me feel better. I can remove the ballnut for cleaning by removing the four bolts on the side and not worry about alignment problems.
Later

BobWarfield
08-18-2008, 01:03 AM
Looks good dnelso. Did you simply modify the bracket by lopping off both flanges and building brackets to bolt into it or did you make an all new bracket?

Just curious.

I'm most of the way through making a new bracket. Started this morning and would've finished but got distracted onto 2 other projects helping people out. I should finish it the next time I go out into the shop.

Cheers,

BW

PS: Almost finished. The old vs the new:

http://www.cnccookbook.com/img/MillStuff/CNC/YMount/P1010838.JPG

Threaded:

http://www.cnccookbook.com/img/MillStuff/CNC/YMount/P1010847.JPG

Got interrupted by 2 other projects or I'd be done. Shouldn't take long next time I have some free time in the shop.

IHCNC
08-18-2008, 01:09 PM
Hi Bob;
We Use all 4 bolts on the Y axis ball nut mount. Not to lose any travel we Cut out a little of the front casting as we need to gain enough for 13+ inches of y travel. This saves all the work that you did to make another mount. These mounts are the same ones as on our H/D CNC Mill. They are more than strong enough for the Standard Mill. Anyone with a Kit please feel free to call IH for any questions like this.

dnelso
08-18-2008, 09:09 PM
Bob,
I made the whole part from steel. I have been very happy with the mill. I think you will be to.
Later Dave

BobWarfield
08-18-2008, 11:50 PM
Gene & Tommy, thanks for your update.

You might consider updating the install instructions on the IH web site to reflect cutting the front casting. Currently they tell you to slice off the flange. I would definitely have considered your other alternative had it been in the directions, although I'm not so sure I wouldn't still have felt this was the better way to go.

You should also consider whether a design change makes sense. All other things being equal, the CNC to make a bracket like mine has got to be identical in terms of your costs to making your existing bracket and you wouldn't have to cut the front casting which has to cost you (or your customer installing a kit) more in labor.

dnelso, no worries about liking the IH mill. I've had one for a couple years and love it. I write about it frequently on CNCCookbook.com. In fact I like it so much that I own two of them. This gives me the luxury of doing all this work on the one while still having the other operational.

Cheers,

BW

Runner4404spd
08-19-2008, 06:36 AM
Bob as an FYI the kit actually uses 3 bolts. one from the top and two from the bottom. i have all three installed in my kit and have had no rigidity issues and i routinely cut steel. one thing i did have to do (or want to do) was to shim the y axis mount so the screw came through the hole in the front of the cast down the middle of the hole. i had to add an 1/8 in. this was probably not critical but i didn't want to take any chances rubbing.

BobWarfield
08-19-2008, 10:15 AM
Yep Runner, I was familiar with that bolt from the top, it's in the directions.

Rigidity issues are of course relative. Clearly the mill cuts steel, I do it all the time. The question of rigidity is one of improving surface finishes, feeds, and speeds. Since I have 2 of these mills, it will be interesting to compare whether the mods done to this one give it any advantages over the other one.

I intend to do a test similar to the one described here on the two mills:

http://www.mmsonline.com/articles/100501.html

It's a good way to find the best feeds and speeds for a particular machine and tooling anyway. I think it's also an interesting way to compare the relative performance of 2 machines.

I'll keep an eye on that clearance issue. I'll assemble it dry and check it. It's no biggie to align things twice if I have to back out the bolts and retighten with loctite the second time. Just takes a little more time. The directions also show a bit of grinding on the base to clear the ballnut, but OTOH my saddle casting is a little different too than what's pictured.

Cheers,

BW

BobWarfield
08-25-2008, 01:12 AM
Finished up the mount:

http://www.cnccookbook.com/img/MillStuff/CNC/YMount/P1010855.JPG

The little hole in the center carries oil down onto the ballscrew.