Sunday, June 11, 2017

LinuxCNC installation lessons learned

I'm posting this on the chance that somebody has similar troubles that I had this week getting LinuxCNC running again on a computer I had working before the hard drive crashed.  Hopefully someone with the same problem will find this page on Google.

It worked best for me to use the LinuxCNC 2.7 bootable DVD image and install in Failsafe mode.  Unfortunately, the defaults for "Guided partitioning" recommended for most users did not setup any partition to be "bootable".  I wasted more time than I like to remember figuring that out.  That's a problem if this is the only operating system the computer is using.  I wonder if this is some kind of inferiority complex that leads the authors of this Linux installation DVD to assume everyone who wants to use Linux still wants Windows on their computer, too.
I had to select Manual Partition instead.  I used Ext4 for Linux partition, making sure the partition was set to be "bootable". I also chose to format the partition and set mount point root "/".

The updates wouldn't install so instead I ran ...$sudo apt-get update

I have this CH352 PCI Parallel Port card:

I installed the parallel port driver from the CD that came with the card.  I created a file called parport_pc.conf in /etc/modprobe.d with one line:
install parport_pc /bin/true

When I ran ...$lspci -v
this was in the output:

00:09.0 Serial controller: Device 4348:5053 (rev 10) (prog-if 02 [16550])
 Subsystem: Device 4348:5053
 Flags: medium devsel, IRQ 17
 I/O ports at c880 [size=8]
 I/O ports at c800 [size=8]
 Kernel driver in use: serial

Even though it says serial, it's parallel.  Go figure.

To test the parallel port, I downloaded ptest.  Instructions for using it are found in the same link.
I replaced the address in ptest.hal with the second address above (0xc800) . I made sure the parallel inputs function.

Finally, I ran the stepconf Stepper configuration wizard.  I remembered some settings and had to rediscover others.  The way mine is set up, to home an axis to zero from positive positions (X & Y) I needed a negative homing velocity and then find the unlatch position in the opposite direction.  I have Z axis homing to zero from negative positions, so the homing velocity is positive.  My max velocities (0.3 inches per second) and accelerations (2 inch/s/s) are much slower than the defaults.

I am hopeful that someone finds these discoveries helpful, because it took me a week to figure this stuff out in my spare time, and I would love to save someone else some of that frustration.

CNC router: Upgrading the Z-axis - Alignment

I have noticed recently when planing a surface with a cylindrical cutter, there is a step of about .020 inch per inch in the Y direction.  My Z axis is not quite perpendicular to the Y.  I already want to redesign and rebuild the z axis because it is not stiff enough to resist cutting forces in the Y direction to my satisfaction.  As I design a new base for the Z axis, I need to get the mounting holes in the right place to correctly orient Z to Y.  My solution is a test plate with the following pattern:
The program puts center points for the two mounting holes along with a set of horizontal lines.
The G-Code is so simple, I just wrote it in a text editor.
I used the program to cut a piece of hardboard:
Then my computer crashed...
A week and a $10 hard drive later (Thanks, Habitat for Humanity Restore!), I drilled out the holes and mounted the board on the saw.  Then I fixed a pencil in a board and drove the y-axis to mark a line across the board:
As you can see by the angle between the pencil line and the horizontal groove, there's a bit of error in my original measurements, so this will help me get it right.

Wednesday, May 31, 2017

Shopsmith Hack #2: A More Stable Table!

A new Shopsmith Hack from Chip's Wood Shop- a more stable table!  I have been using this brace on my table for a few months now.  After a few minor tweaks, I have published a "how-to", complete with drawings, photos and a video in which I demonstrate the effectiveness of the brace by measuring the deflection I get in the table before and after applying the brace.
Some key benefits of this design include:

  • Easy to lock and release - two nuts that can be turned with a single wrench from where you stand to use the saw.
  • Automatically adjusts to any position you use the table, including tilted 90 degrees for the drill press.
  • Out of the way when you don't need it.
Click the photo above to open the instructable.

Sunday, April 30, 2017

Corner Bench Installed with Lids

Now that the corner bench is in its new home with trim and lids installed, I just wanted to share a couple of photos.  The bench is six feet along one wall and about 11.5 feet along the other.  

 The lid supports hold the lids in whatever position you put them:

There is more to come, but so far we're pleased with the results.

Stay tuned for the hows and whys when the last touches are finished.

Saturday, April 22, 2017

The sanding war-wagon

Now that the corner bench is finally going in, I am so pleased with the results that I want to share what is for me a delightful discovery: the orbital sander with vacuum attached.

I know, "Big Deal! Orbital sanders have been around a long time.", but this is working out so much better than my previous experience with orbital sanders, that I think it should be shared. I have been using a 1/3 sheet orbital sander for more than 10 years, but I didn't have great success getting it to work with the vacuum.

Because of my bench project, I invested in a cheap 5 inch (12.7 cm) round orbital sander with hook and loop sanding pads. It didn't really connect well to my shop vacuum either, but I salvaged a duct from an old vacuum cleaner that serves well as an adapter. After some trial and error, the results have been great! I get almost no dust up in the air when sanding. Far less, for example, than with hand sanding.

A few lessons I have learned: 
Make sure you line up the holes in the paper with the holes in the sander (approximately).

You can use a painting edger to protect adjacent perpendicular surfaces.


Contrary to the instructions that came with my sander, I only turn it on when it is already in contact with the surface because, in addition to orbital motion, this sander allows rotation. Due to the inevitable  imbalance in the pad, the orbital motion is converted to rotation rather quickly when it is free-running in the air. It builds up so momentum so fast that it damages the surface when it first makes contact.

Finally I want to say that I love using it with the shop vacuum in the following "war-wagon" configuration:
This makes it very easy to sand all over the place with the vacuum following along.  Notice that the sander cord is wrapped around the vacuum hose then plugged into the extension cord (orange). The vacuum cord is only unwound from its storage coil enough to reach the end of the extension cord. The extension cord is loosely tied to the vacuum handle in sort of a lark's head.

This setup has really proven itself in my bench project, where I have sanded over 100 square feet  (9 square meters) with multiple grits.  Not only does it almost eliminate dust in the air, but it improves sanding by pulling the dust off the surface so the sandpaper has better contact with the workpiece.

Thursday, February 2, 2017

Beveled Edges - A New Instructable in the Woodworking Elements Series


https://www.instructables.com/id/Woodworking-Element-2-Beveled-Edges/

This time I explained how to use the scrap from cutting a beveled edge of a board to check the accuracy of the angle.  I use compounding error by  stacking up segments of the scrap to exaggerate the angular error to make it easier to see how much to correct and to make it clear when your angle is close enough to what you want!

Tuesday, January 10, 2017

Build-a-bench

More instructables and videos are in the works, but for the last few weeks I'm spending my free moments building a corner bench for the dining room.  Here are some sneak peeks which I hope to explain in more detail later.  I love this photo of the bench in progress because it illustrates the challenge of doing woodwork in a limited space:
This is the reason (almost) everything in my shop is on wheels.
Here's a preview of some tricks I want to share soon:



 The bench has lids with piano hinges that needed to be trimmed with beveled edges:

I'm match-drilling and pinning the seats to the base so I can dress it all up in the installed condition in the garage, then tear it down and reassemble in the dining room later.


Chip's wood shop selfie- actually I'm using the phone to sight holes from underneath that I can only reach with one arm:

As I say, more to come, but I wanted to let interested people know that Chip's wood shop is busy getting lots more ready to share!