I came here a few weeks ago to update things, but then got distracted by the holidays, and some of the parts of life that don't involve the shop.
The first big thing to report is that I got over the operation that scared me the most: drilling a 1/8" hole 4" deep into the cross slide and intersecting another 1/8" hole to bring oil from that hole to the surface oil grooves.
I had concluded that I'd drill a larger diameter hole and only finish out the last inch or so with the 1/8" bit. There's no reason not to use the recommended tap drill for the larger first hole - it's going to be tapped for the oil fittings anyway, so I settled on using that. Some tables say to use a Q lettered bit, others said R. I ended up drilling the 4" deep hole with R, 1/4 and 1/8, but the 1/4 wasn't really necessary. The cavity from the bigger bits will fill with oil and the only difference is the larger amount of oil in the larger R drill profile. I drilled most of the way using the mill as a drill press, clamping the table to a vertical fixture - pretty much an angle plate.
The last inch was drilled by hand since it was too deep to use the mill, and this is it when the drilling was just completed. The 6" long 1/8" bit wanted to flex and move around more than I was comfortable with, so I turned that little piece of aluminum you can see in the hole with a 1/8" hole centered in it, to help me keep the bit from wobbling too much. Once this was drilled, if everything was cool, I should be able to shine a flashlight in the side hole that this long hole is supposed to intersect with and see light.
With the long hole out of the way, I could work on adding all the fittings, but they were on order. I figured I'd move on to the ballnut removal because that's the main thing stopping me from putting the system back together. I had a bad experience with the ballnut removal tool (which I'll call the BRT). Briefly, I had made a tool out of Delrin and ended up tearing it up trying to shave off some a section of the wall down about .015 thickness. I only had the one piece of Delrin, and since the wall thickness was the problem, I thought I'd make a BRT out of some 12L14 steel I have in my junk box. I ended up tearing that up on the lathe, too.
While trying to figure out a way to get a BRT that worked, it occurred to me that if I had a piece of the threaded portion of the ballscrew, I wouldn't need a tool. I could just unscrew the nut onto the small piece and then re-screw it back into place on the real ballscrew once it's in the base. All I needed to find was a 5" long piece of RM1605 ballscrew. I asked on Hoss' forum on CNCZone, and was told by one of the guys (not Hoss), "You're way over-thinking this. When you buy a ball nut separate they come with a cardboard tube inserted into the nut to keep the balls in place. " Cardboard tube? Like this?
The writer went on to say, "Without having the original cardboard tube, I have simply taken a piece of paper, formed it into a tube, and then wrapped it with masking tape to build the thickness and diameter to where it needs to be and then slid the ball nut off of the screw and onto it". I thought one of those terrible thoughts, "how hard can it be?" In the engineering world, this considered on a level of pure badness about equal to "all you gotta do", which is the most horrifying phrase in all of engineering, and usually precedes the worst times in your career. Indeed, "how hard can it be?" preceded the worst moment in this story.
Realizing I only need about a .012 to .015 wall, I wrapped three turns of printer paper around the leadscrew, ran masking tape down it, then tried to unscrew the nut. Didn't work. It started binding and when I unscrewed it back off the paper tube, I could see the same problem I had with the first two tools - the balls were trying to create matching screw threads in the paper. So I pulled most of the tape to make the tube thinner and started again. This time it was unscrewing onto the paper without binding. I guess I thought, "holy crap! it's actually going to work." and kept going. A few seconds later, I heard the balls falling into the folded over paper end I was holding in my left hand. At this point, it was over. I unscrewed the leadscrew the rest of the way and found that the last few threads in the nut were exposed and the balls fell out of that. I
think I caught all the balls and none escaped, but I won't know until I put it back together. I put tape over both ends of the ball nut and paper cup (folded over paper tube) so that the balls don't escape.
Since I wasn't sure I didn't lose a ball bearing, I ordered some from a seller Hoss recommends on eBay.
Meanwhile, my oil fittings had come in and it was on to preparing the cross slide for the fittings, which brought its own problem: a bad tap. I had a 1/8-27 NPT tap in a my Horrible Freight tap and die set, and quickly found the cast iron in the table cut away the tap faster than the tap cut threads! After some searching, I found a better tap locally (Ace Hardware) and was able to resume working.
Here's a view of the cross slide, right side, before tapping for the oil fittings:
The two holes for fittings are the big hole upper right, and one between the two big cap screws, but below the bottom of the section those screws are on. This next view shows the one in the middle of the front, too.
The two facing to the right are straight fittings and the front fitting is right angle. I will use Tee connectors to help distribute the oil around between fittings. The X and Y ball screws have press on, "barb" fittings, and there's another right angle connector on the left side that has the same function of the straight one on middle of the bottom of the right side of the slide. Eventually, there will be six oil tubes on this side and the whole thing will look pretty similar to this:
This portion of the modification is on
Hoss's open web site, not on the copyrighted DVD that I bought, so I assume I can link to it. You can see this picture is a screen capture from a
YouTube video here.
The cross slide is now set for the oiling system, so I need to drill and tap the channels for the Z-axis and headstock area. I should be able to take that off the base and finish that once the X and Y axes are moving.
Which brings me back to the problem of repacking the ball bearings into the ballnut. It's harder than it looks
online. That video gives me hope of being able to re-pack the balls without needing a BRT. My problem is that I need the BRT for about 5 minutes. If I rebuild the nut on the screw, like most repacking videos show, I need a fancy BRT to remove it from the ballscrew. But the nut is off the ballscrew already. If I could rebuild the ballnut on something simpler like a piece of doweling or something to hold the balls in place, then put the ballnut onto the screw, I'd be better off.
And there you go. Just about a full month in the shop. It's a lot but not enough. I want to get this project completed.