I recently installed Billy Dirk's conversion kit for the South Bend
1001 lathe and this video details that conversion process.
I used components that I had on hand so first we'll need to make a shaft adapter
for the stepper motors, then tear down the lathe, install Billy's conversion
kit, build the electronics, install LinuxCNC, and then maybe make a test cut. So let's
get started. To install Billy's kit I only needed to make a couple parts and these
are to adapt the quarter inch shaft of the stepper motors I had to 3/8 inch.
These are the last parts as lathe will make manually, and it's always been
pretty accurate. Next the center is drilled out and then the part is parted.
The part is put back into the collet chuck and both ends are cleaned and
chamfered. I was going to drill the holes for the set screws on the mill but
anything that's simple to do takes a long time to set up on the mill. At the
drill press we can use this center finding tool to align the part to the
spindle, spot drill, drill, and tap the holes for the set screws. Now we'll
deburr the part using the tools at hand although this probably isn't OSHA
approved. The set screws need to be shortened to about 2.5
millimeters. This grinder works great for small parts and when I was a kid I saw
my dad uses grinder all the time but he said originally it was my grandfather's.
Sometimes people ask if they should buy a CNC conversion kit or build one from
scratch. And for me, where I'm at, and amount of time that I have available, I would
definitely buy another CNC conversion kit. Beyond saving a lot of time it gives
a chance to learn from an expert. Billy has decades of experience as a machinist
and for me to review how he has constructed his kit, after having done a
rudimentary 3d printed version of a conversion kit for this lathe, I learn a
lot. So, Billy got me going quickly, at a low cost, and with great quality
components that I get to learn from. The same is true the other two conversion
kits that I've owned [and installed]. The original industrial Hobbies conversion kit and
David Clement's PM25 conversion kit. As with any conversion there's a lot of
parts to remove. Here we're starting with the cross slide
leadscrew. Some parts have already been removed such as a longitudinal leadscrew
and the threading gear pivot bracket. With the cross slide slid back
we can see the Acme nut in the channel. Now I'll slide the cross slide off of
the saddle. The apron is held in place with a couple of screws. The half nut has
already been removed and that makes removal of the apron easier. To make room
for the ball screw we need to remove the Acme nut from the channel of the saddle.
As the saddle is removed from the bed it's likely that the saddle gib will
fall. We just have to be sure it goes back in the right spot. Here you can see
that saddle gib and that the Acme nut is held in place with a screw. Just
need to take the screw out and punch the Acme nut out. The saddle has tensioners
in the front and back and you want the saddle to move smoothly on the bed but
not be loose. If the saddle is loose it'll lift from the bed under a heavy cut and
the tool will leave a phonograph pattern in the part. Now I'm removing
the longitudinal rack gear. The rack gear is in two pieces, aligned with tapered
pins and secured with screws. The first piece came off really easily
and the second piece needed some persuading. Here's the naked lathe before
installing Billy's conversion kit. I start with the headstock side support of
the longitudinal ball screw. The original tapered pins are driven through and used
to align the support. In all but a couple places on the conversion I was able to use
the original holes and screws. Billy has obviously gone to great lengths to
ensure this kit is easy to install. The only tools I needed were imperial and
metric hex wrenches. Before I install the longitudinal or the z-axis assembly I
thought you might like to see a few photographs of it.
The combination of pipe, plate, channel, and custom shapes is really clever. This
will save a lot of waste compared to milling everything from big hunks of
aluminum. Inscribing his company's name BD-Tools for Billy Dirk's Tools is a
nice touch and so is inscribing the Z and X axes names. They make sense when you
think about the mill and with respect to the spindle but I'm sure
I'm still gonna mess it up. The new apron has a little interference with the
longitudinal lock. You could probably leave this off but I decided to grind it
down. No more interference and our new apron is installed. Now I'm installing
the cross slide or X-axis assembly. You may wonder why this assembly is so long.
There isn't enough room in the channel to mount any reasonable ballnut inside
of it and there isn't enough material in the saddle to mill a larger channel.
Also the cross slide is always going to come out over the apron, so while this
assembly takes up more space in the most forward position of the cross slide, it
takes up the same amount of space in the most aft position of the cross slide.
Or said another way, the space taken up by the cross slide assembly is constant
and you're never gonna be surprised by a rapid move away from the apron. Having
said all that, I'm sure I'm gonna hook myself on this someday. A real drawback
of doing a CNC conversion is the amount of material that is discarded. OK, one last
look at this beautiful mechanics before polluting it with a bunch of wires. All
the electronics that I'm using are leftover parts from other projects. The
stepper motor drives prefer 36 volts but we can split the difference between 36
volts and 48 from this power supply by adjusting the power supply down to 42
volts. This probably isn't safe but just don't touch the metal part of the
screwdriver, and I thought it was interesting to watch the rate at which
the voltage dropped after the power supply was unplugged.
I'm using a simple parallel port breakout card I think is called a Nextrox
parallel port breakout, it's like the cheapest one that Amazon sells but
it supports five axes, limit switches, and has a relay for a spindle control. You
could even put displays on it and use it as a remote DRO. And everyone knows that
electrons flow with less resistance in braided wires. The computer was being
used as a MythTV DVR but I haven't had time to watch television since my son
was born. I'm adding a low profile PCIe parallel port card. It's especially hard to
find one that works with Linux reliably. I want to show you a little bit of the
installation of the CNC controller, LlinuxCNC. The disk image can be downloaded free
from the LinuxCNC.org website. It's a modified Debian installation and adds the
LinuxCNC components and real-time extensions. Most of the setup is pretty
obvious, you just keep hitting continue. This computer wasn't on the network
while doing the installation but afterwards plug the Ethernet cable in
and it uses DHCP to get its IP address. With the network enabled, I'll use an NFS
share to copy g-code files from my modeling computer to this computer. This
setup works well on my CNC mill. On my Industrial Hobbies mill I used Mach3
as a controller but that was probably eight years ago. Being pretty familiar with Linux,
when I got the Precision Matthews PM25MV CNC mill I wanted to use a LinuxCNC on it.
LinuxCNC took me longer to learn how to operate them Mach3, but that's
because LinuxCNC is enforcing procedures that are more common to
industrial controllers and for someone who's learning that may enforce good
habits from the start. What I'm doing now is upgrading LinuxCNC. The disk image
that I downloaded had a date stamp of 2015. After opening the Debian Update Manager,
first uncheck everything and then go to the bottom of the list and select only
the LinuxCNC components. That may be all the third-party updates. Do not update
the kernel or any component that would update the kernel because that will
likely cause LinuxCNC to stop working. I assume updating the kernel kills the
real-time extensions at LinuxCNC is dependent upon. Now I'm going to map out
the parallel port card. I'm going to do that by downloading a tool from LinuxCNC's
website. There are two files that we need to download: the XML file
defines the user interface of the tool and the HAL file defines the pins on
the parallel port card and how they connect to the widgets on the user
interface.
Before we can use the tool I need to find the memory address of the parallel port
card. In this case the address is E010.
Now I'll modify the HAL file to use a parallel port at that address.
With this tool we can toggle the state of each output pin on the parallel port
and read the state of each of the input pins. Unfortunately we can't latch a pin
or hold a pin at a state and this particular breakout board uses pin 1 as
an e-stop out. We need to hold pin 1 high in order for the breakout board to come
out of e-stop. To create latching pins I'll change all of the buttons to check-buttons
by modifying the XML file. This is a little bit convoluted but it also
shows how easy it is to change a LinuxCNC tool to your needs.
While measuring the voltage of a pin on the breakout board, I toggle each of the
parallel port pins until I find the one associated with the breakout board's pin.
After mapping the breakout board I use StepConf to create a configuration
file for LinuxCNC. Instead of doing this completely from scratch, I'm going to load one
that I've previously built. StepConf is only suitable for parallel port breakout
based systems so if you have different hardware you'll need to use a different
tool. This is the configuration for my system but it's really easy to assign a LinuxCNC
function to a parallel port pin. And this is also where you set the
parallel port base address. On an earlier screen is where lathe or mill machine type is
selected. The last two screens are for configuring and testing the lathe axes. At
a minimum to configure an axis you need to know steps per revolution of the
motor, pulley ratio, and leadscrew pitch. Travel distance is obviously important
and later you should optimize maximum velocity and acceleration.
Now inside of LinuxCNC, take it out of e-stop and start the machine. And then
jog each of the axes. With these small 157 ounce-inch
stepper motors, the Z-axis has a small amount of binding on the tail stock side.
One of the pieces of the apron is slightly rubbing the bed and a small
amount of filing solves the problem. Billy has made his conversion kit to a
standard which is probably higher than the factory had for the lathe and with any
conversion kit there's gonna be small things like this that you have to solve but
the hundreds of hours that are saved make a conversion kit well worth it. This
is a simple pawn piece that I made in Fusion360. The LinuxCNC turn
post-processor isn't built into Fusion360 so I needed to download that. This is
the very first part that I cut after installing the conversion. There
were no rehearsals.
Okay, obviously that wasn't the right tool to be using. I've never operated a
CNC lathe before let alone owned one and there's a lot of learning that I have
to do. Even the simplest procedures like spindle alignment and tool touch off are
new to me. I mentioned in the video that I prefer
buying a conversion kit over building a kit, and with Billy's conversion kit the
entire conversion process took less than a day. So unless you love the process of
designing a kit, consider buying one and use that time saved and your CNC
conversion to build something that no one else has seen yet. Okay, thank you for
watching and we'll talk again soon.
you
you
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