What I Did Yesterday Instead of Fishing

The cast aluminum (or maybe zamak) handle on the Y-axis gib lock busted and fell off on the South Bend SB1028F mill a while ago. I can get by without it most of the time, and if had to I could grab the head of the screw with a pair of water pump pliers or locking pliers to snug it down.

The X axis had started working intermittently at the positive end of the scale. To keep shop space clear I tend to work more to the positive end of the table, but my vise (the one that is bolted down) is nearer the center. For the most part I had no issues, but a couple days ago the DRO for X quit entirely.

I have five molds sitting on the mill table waiting on second ops. Mostly hinge pins and handles for lead casting molds. I do those operations on that mill.

So yesterday…
1. I finished my household chores
2. I chatted in the back yard with my son’s BAJA SAE race team about planned track layouts (simple easy oval right now).
3. Took my mom to a doctor’s appointment.
4. Drove partway home, and then went back to the doctor’s office so she could look for her phone.
5. Finally went home.
6. Walked back out to back field to chat with the rest of the BAJA team about track plans and track usage.
7. Finally headed in the shop.
8. A new (different style) handle for the gib lock screw.
9. Repaired the DRO.

The gib lock handle is best explained with a picture. I used a technique of plotting points on a curve and then plunging with a a parting blade to rough the shape, and then finished with a file and emery cloth. Its a very old school technique, but its the first time I’ve done it. The I do the rest of the work on the mill without a working DRO or Y gib lock. I think I used the dials on the machine for the first time since I got it.

I checked the axis by swapping glass scale cables, and the problem was not in the display head. Then I pulled the cover and blew out the scale. No luck. I loosened the screws on the read head and a shim fell out. The DRO seemed to start working again, so I tightened the mounting screws, and tested. It seemed to work just fine. Even seemed to read about right running all the way to the positive end of the table, but when I ran back it quit working again.

Of course twice I had to dig through the huge pile of aluminum chips under the machine for screws I dropped in this process.

There were two things I could think of. Maybe the glass scale was damaged (or maybe it wasn’t a glass scale) or very dirty, or maybe there was an alignment issue. I measured from the top of the housing to the top of the table with a guess-o-meter (dial caliper) and found slightly over 25 thousandths difference from end to end. I measured in the middle, and put both ends at about the same distance to the tabletop plus or minus a thousandth or two, pulled the read head up as close as I could, and tightened all the screws. Then I ran the table from stop to stop listening very carefully for any dragging. It sounded good and I got 36.45 inches stop to stop like I have written down.  Actually, I can run slightly more, but I have an electric power feed stop set at each end of the table to prevent that particular crash.

By then I was about done even though it wasn’t that late. I headed into the house and made myself a Bacardi and Pepsi Zero. I watched the latest episode of Starfleet Academy on Paramount, and fell asleep watching Fallout. I woke up just in time to see the large beastie knock the guy in the battle armor through the wall opening up the area where they were contained to the rest of post apocalyptic Vegas. Yeah, bed time.

And that is what I did yesterday instead of going fishing.