Archive for January 10th, 2009

Adjusting Sherline Mill Column Gib

This is a nuisance you gotta do once in a while. The symptom today was that the mill axis didn’t line up at all with the laser aimer I have mounted on the ceiling; it’s supposed to point right down the spindle bore, but the bore wandered all over the place. Took me a while to realize it was really that bad…

Basically, you must take the headstock off, unplug the axis motors, and put the mill on the workbench so you can get convenient access to the back of the column. Unscrew the cap screw holding the Z-axis backlash lock plate and disconnect the saddle nut. Make sure the lock doesn’t engage.

Loosen the gib lock, remove the gib, clean the crap off the mating dovetail surfaces & gib, add a touch of their approved silicone lube, slide the gib back & lock it in place. Slide the saddle up & down (that’s why you want the saddle nut disconnected) and tweak the gib until it slides more-or-less freely along the entire length without binding or being too loose. My saddle gets stiff near the very bottom of the column, but it never gets that low in actual use. Make sure the gib lock is tight.

Run the saddle nut to the top of the leadscrew, slide the saddle in place, back those two tiny setscrews out, secure the saddle nut to the saddle with a short cap screw, then turn the setscrews until they just touch the nut.

At this point, the nut should be in its nominal position, centered on the leadscrew and aligned concentric with its axis. If you turn the Z-axis knob and it binds, then you get to loosen the cap screw, futz with the setscrews, tighten the cap screw, check for binding, and iterate until it works properly.When it’s OK at the top, crank it all the way to the bottom and verify that it doesn’t bind elsewhere.

Mine took one iteration this time, which is just sheer blind good fortune. Or maybe the saddle nut is wearing out and getting sloppy?

Then adjust the backlash lock to reduce the backlash to whatever you think is appropriate. My Z-axis has a few mils unless that thing is way too snug.

Sherline’s instructions for aligning the saddle nut screw that connects the leadscrew to the saddle are on Sherline’s site, hidden in the instructions for the “new” Z-axis backlash adjustment: http://www.sherline.com/4017Zinst.htm.

Memo to Self: do this more often.

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Mysterious USB Disconnects

For the last few months, one of the USB hubs in my PC has been disabling a port connected to an external USB hub. The external hub re-establishes communication with all the devices, but the X server doesn’t take kindly to having devices yanked out from underneath it. After this glitch, my left-hand trackball and tablet are dead in the water; the only way to get ‘em working is to log out, restart X, and log back in again. Not pleasant.

Oddly, the keyboard continues to function.

Note that it’s the hub in the PC that’s complaining, not the external hub.

USB connections at PC

USB connections at PC

I’ve tweaked the obvious things: switched USB ports on the PC, replaced the external hub, powered and un-powered the external hub, rearranged the devices on the hub, moved other devices away from the hub, and so forth and so on.

Now it’s time to start taking notes. The current external hub is a cheap, no-name gadget direct from China that bears a striking resemblance to the tchotchke HP-branded “Made In China” hub a friend picked up at SC06.

Both hubs have a cut-out in the case for a power plug, but the internal circuit boards lack the requisite jack to actually make use of external power.

Here’s the current dmesg dump.

[ 2917.702975] hub 1-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
[ 2917.702986] usb 1-2: USB disconnect, address 3
[ 2917.702989] usb 1-2.2: USB disconnect, address 4
[ 2917.712300] /build/buildd/linux-2.6.24/drivers/input/tablet/wacom_sys.c: wacom_sys_irq - usb_submit_urb failed with result -19
[ 2917.787223] usb 1-2.3: USB disconnect, address 5
[ 2917.831161] usb 1-2.4: USB disconnect, address 6
[ 2918.002420] usb 1-2: new full speed USB device using uhci_hcd and address 7
[ 2918.165658] usb 1-2: configuration #1 chosen from 1 choice
[ 2918.170675] hub 1-2:1.0: USB hub found
[ 2918.172533] hub 1-2:1.0: 4 ports detected
[ 2918.502967] usb 1-2.2: new low speed USB device using uhci_hcd and address 8
[ 2918.662816] usb 1-2.2: configuration #1 chosen from 1 choice
[ 2918.679915] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.2/1-2.2:1.0/input/input10
[ 2918.721211] input,hidraw2: USB HID v1.11 Keyboard [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.0-2.2
[ 2918.751759] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.2/1-2.2:1.1/input/input11
[ 2918.793088] input,hidraw3: USB HID v1.11 Device [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.0-2.2
[ 2919.010108] usb 1-2.3: new low speed USB device using uhci_hcd and address 9
[ 2919.165963] usb 1-2.3: configuration #1 chosen from 1 choice
[ 2919.187020] input: Kensington      Kensington Expert Mouse as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.3/1-2.3:1.0/input/input12
[ 2919.244778] input,hidraw4: USB HID v1.10 Mouse [Kensington      Kensington Expert Mouse] on usb-0000:00:1d.0-2.3
[ 2919.465338] usb 1-2.4: new low speed USB device using uhci_hcd and address 10
[ 2919.617208] usb 1-2.4: configuration #1 chosen from 1 choice
[ 2919.625530] input: Wacom Graphire3 6x8 as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.4/1-2.4:1.0/input/input13

The external hub is on the white cable (a USB extender cable, which may contribute to the problem) plugged into the port at the far right from the network cable. But i’ve used an external hub with a different and very official USB A-B cable.

The USB connections on the back panel:

Top row: Zire 71 PDA cradle | External USB hub (the offending one)

Bottom Row: Logitech trackball | Dell 2001 monitor hub | empty port

What I changed after this glitch:

HP SC06 hub replaces no-name hub.

Update: Time passes… and it craps out twice.

The dmesg dump:

[10625.203907] usb 1-2.2: USB disconnect, address 8
[10625.970605] usb 1-2.3: USB disconnect, address 9
[10626.865087] usb 1-2.4: USB disconnect, address 10
[10627.880887] usb 1-2: USB disconnect, address 7
[10638.410365] usb 1-2: new full speed USB device using uhci_hcd and address 11
[10638.579231] usb 1-2: configuration #1 chosen from 1 choice
[10638.582167] hub 1-2:1.0: USB hub found
[10638.584118] hub 1-2:1.0: 4 ports detected
[10638.898574] usb 1-2.1: new low speed USB device using uhci_hcd and address 12
[10639.035458] usb 1-2.1: configuration #1 chosen from 1 choice
[10639.038484] input: Wacom Graphire3 6x8 as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.1/1-2.1:1.0/input/input14
[10639.301891] usb 1-2.3: new low speed USB device using uhci_hcd and address 13
[10639.445768] usb 1-2.3: configuration #1 chosen from 1 choice
[10639.466865] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.3/1-2.3:1.0/input/input15
[10639.505029] input,hidraw2: USB HID v1.11 Keyboard [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.0-2.3
[10639.525686] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.3/1-2.3:1.1/input/input16
[10639.572404] input,hidraw3: USB HID v1.11 Device [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.0-2.3
[10639.777083] usb 1-2.4: new low speed USB device using uhci_hcd and address 14
[10639.917975] usb 1-2.4: configuration #1 chosen from 1 choice
[10639.934026] input: Kensington      Kensington Expert Mouse as /devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2.4/1-2.4:1.0/input/input17
[10639.971692] input,hidraw4: USB HID v1.10 Mouse [Kensington      Kensington Expert Mouse] on usb-0000:00:1d.0-2.4
[10962.110496] usb 5-5.2: new high speed USB device using ehci_hcd and address 8
[10962.219819] usb 5-5.2: configuration #1 chosen from 1 choice
[12290.756701] usb 5-5.2: USB disconnect, address 8
[54272.946992] hub 1-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
[54272.947001] usb 1-2: USB disconnect, address 11
[54272.947003] usb 1-2.1: USB disconnect, address 12
[54273.003212] usb 1-2.3: USB disconnect, address 13
[54273.071171] usb 1-2.4: USB disconnect, address 14
[54273.214485] usb 1-2: new full speed USB device using uhci_hcd and address 15
[54273.383873] usb 1-2: configuration #1 chosen from 1 choice
[54273.386778] hub 1-2:1.0: USB hub found
[54273.388736] hub 1-2:1.0: 4 ports detected
[54273.699213] usb 1-2.1: new low speed USB device using uhci_hcd and address 16
[54273.840096] usb 1-2.1: configuration #1 chosen from 1 choice

So replacing the hub seems to have not done anything useful, as expected.

Next step: plug the hub cable into the right-hand port on the bottom row.

Update: Time passes and another disconnect pops up. I’d just poked the USB button on my pocket camera’s cradle. Coincidence? Sometimes it disconnects when I sit down, which suggests a static discharge.

The dmesg dump:

[ 1275.088536] hub 3-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
[ 1275.088547] usb 3-2: USB disconnect, address 5
[ 1275.088549] usb 3-2.1: USB disconnect, address 6
[ 1275.132321] usb 3-2.3: USB disconnect, address 7
[ 1275.220223] usb 3-2.4: USB disconnect, address 8
[ 1275.371502] usb 3-2: new full speed USB device using uhci_hcd and address 9
[ 1275.541198] usb 3-2: configuration #1 chosen from 1 choice
[ 1275.544148] hub 3-2:1.0: USB hub found
[ 1275.546102] hub 3-2:1.0: 4 ports detected
[ 1275.856554] usb 3-2.1: new low speed USB device using uhci_hcd and address 10
[ 1275.993439] usb 3-2.1: configuration #1 chosen from 1 choice
[ 1275.997194] input: Wacom Graphire3 6x8 as /devices/pci0000:00/0000:00:1d.2/usb3/3-2/3-2.1/3-2.1:1.0/input/input10
[ 1276.259871] usb 3-2.3: new low speed USB device using uhci_hcd and address 11
[ 1276.406735] usb 3-2.3: configuration #1 chosen from 1 choice
[ 1276.423836] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.2/usb3/3-2/3-2.3/3-2.3:1.0/input/input11
[ 1276.469640] input,hidraw2: USB HID v1.11 Keyboard [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.2-2.3
[ 1276.490647] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.2/usb3/3-2/3-2.3/3-2.3:1.1/input/input12
[ 1276.545539] input,hidraw3: USB HID v1.11 Device [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.2-2.3
[ 1276.746036] usb 3-2.4: new low speed USB device using uhci_hcd and address 12
[ 1276.896906] usb 3-2.4: configuration #1 chosen from 1 choice
[ 1276.912985] input: Kensington      Kensington Expert Mouse as /devices/pci0000:00/0000:00:1d.2/usb3/3-2/3-2.4/3-2.4:1.0/input/input13
[ 1276.960781] input,hidraw4: USB HID v1.10 Mouse [Kensington      Kensington Expert Mouse] on usb-0000:00:1d.2-2.4
[ 1280.734257] usb 5-5.2: new high speed USB device using ehci_hcd and address 7
[ 1280.843575] usb 5-5.2: configuration #1 chosen from 1 choice

Next step: rearrange cables thusly…

Top row: Zire 71 PDA cradle | Dell 2001 monitor hub

Bottom Row: Logitech trackball | External USB hub (the offending one) | empty port

Methinks it’s time to start yanking the SD card out of the camera and poking it into the PC’s media reader. That should eliminate one possible source of bus confusion.

Time to reset…

Update: time passes and it’s been working OK… up until I zapped the desk lamp with a teeny static spark, at which moment dmesg reports this:

[49077.518404] hub 3-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
[49077.518413] usb 3-1: USB disconnect, address 2
[49077.518416] usb 3-1.1: USB disconnect, address 3
[49077.562470] usb 3-1.3: USB disconnect, address 4
[49077.658411] usb 3-1.4: USB disconnect, address 5
[49077.805865] usb 3-1: new full speed USB device using uhci_hcd and address 6
[49077.974924] usb 3-1: configuration #1 chosen from 1 choice
[49077.982443] hub 3-1:1.0: USB hub found
[49077.983860] hub 3-1:1.0: 4 ports detected
[49078.302253] usb 3-1.1: new low speed USB device using uhci_hcd and address 7
[49078.439141] usb 3-1.1: configuration #1 chosen from 1 choice
[49078.442156] input: Wacom Graphire3 6x8 as /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1.1/3-1.1:1.0/input/input10
[49078.709567] usb 3-1.3: new low speed USB device using uhci_hcd and address 8
[49078.853443] usb 3-1.3: configuration #1 chosen from 1 choice
[49078.875540] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1.3/3-1.3:1.0/input/input11
[49078.920499] input,hidraw2: USB HID v1.11 Keyboard [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.2-1.3
[49078.941372] input: Microsoft Comfort Curve Keyboard 2000 as /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1.3/3-1.3:1.1/input/input12
[49078.999851] input,hidraw3: USB HID v1.11 Device [Microsoft Comfort Curve Keyboard 2000] on usb-0000:00:1d.2-1.3
[49079.212710] usb 3-1.4: new low speed USB device using uhci_hcd and address 9
[49079.351593] usb 3-1.4: configuration #1 chosen from 1 choice
[49079.367726] input: Kensington      Kensington Expert Mouse as /devices/pci0000:00/0000:00:1d.2/usb3/3-1/3-1.4/3-1.4:1.0/input/input13
[49079.411112] input,hidraw4: USB HID v1.10 Mouse [Kensington      Kensington Expert Mouse] on usb-0000:00:1d.2-1.4

So it looks like there’s really something EMI-ish going on. Perhaps it’s time to look into grounding all the exposed metal around here.

Update: It really was static electricity. More discussion there.

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