spindle, against the torquing of the draw bar which meant that the drawbar was
never properly torqued, and the Tormach TTS tool would pull out under heavy load. With
the spindle lock, I can lock the spindle in place, insert the tool, and properly
inside of the head. It's held in place with a couple of set screws. A pin slides
through main body, the main body is attached to the side of the head, and the
pin threads into the main body, locking the collar in place and keeping the spindle
need to thread the locking pin, simply push it forward into the collar. The
new design also adds a plunger switch which is used to detect when the pin is
pushed into the collar and the plunger switch sends a signal, indicated by the
red LED, to LinuxCNC that inhibits the motion of the spindle and
the table. If a program is started while the spindle is locked, nothing happens
until the spindle is unlocked. The spindle comes up to full speed
first part to be made is the main body, and this will be made in three setups. The
hole being bored is where the locking pin will slide.
After the part is flipped, the new origin will be against the face of the fixed
jaw, the parallels, and the contoured side of the part. A gauge block is used to
offset the contoured side.
I like using the face mill because it removes a lot of material fast and leaves a smooth
floor. I'll use it even in a case like this where side milling could be done. I've
found that on the less rigid PM25 that side milling a decent amount of material with a standard
endmill, that I have a hard time maintaining tolerance on depth. The mill is flexing
somewhere and the screw-like forces from the standard endmill are causing me to
lose control over the depth, just a few thousandths. This can be worked around with
careful control over the amount of material left during roughing for
finishing. With insert tooling I don't notice this problem even after roughing,
the floor is pretty smooth. Traditional endmills do work well for finishing
vertical surfaces. Just keep it a few thousandths off the floor. The third
setup is to drill a hole for the plunger switch, and it starts by placing the bottom
of the part against a known angle created by angle blocks.
This piece will become the collar for the spindle. The spacing operation is
using a neat feature of the CNC lathe which is constant surface speed which
changes the RPM of the spindle relative to the cutting diameter. The maximum
speed of this spindle is 2500 rpm and the spindle drive has only a small capacity
for absorbing the momentum of the spindle, so the spindle slows down slowly.
Close enough.
To begin the boring operation, the center is first drilled out. After making a
single pass of the boring bar, I'm now measuring the bore and I'll use that
number to touch off the boring bar in LinuxCNC.
glued to the outside of the collar.
The brass knobs that come from McMaster are pretty rough so I just face them to
clean them up. The locking pin is turned from half-inch cold rolled steel rod.
This is the first locking pin that I made of the new design, and found that I
wasn't thinking about the plunger switch right. For a detent I only need a narrow
groove. I wanted to learn as much as I could from the prototype so I filled the
wide groove with J-B Weld, let it cure, and then turned it. This actually worked
really well and let me use a prototype to find out what else I didn't know. The
position of the detent is important and we can get an exact position by using a
transfer punch through the main body onto the pin. The depth of the detent is
less important than the preload of the plunger switch. There's a pretty narrow
acceptable range and too much pressure and the switch can be damaged. These
pictures are from my original spindle lock video and they're just showing how
I did layout and modified the head.
The spindle collar needs to be positioned so that the locking pin will
be square to the head. A little bit of filing might be easier than pulling the
spindle back out.
Using transfer punches here for marking out screw holes for the main body.
I don't have video showing the assembly of the new spindle lock but I think you
get the idea. Like I said earlier, just be careful with setting the preload on the
plunger switch. You don't want it so tight that vibrations set off or its
life is shortened. This is the HAL code that connects the spindle lock to
spindle lock. That's attached to the input pin of a debounce component that
inhibit and this connection is given spindle-lock signal name. When this
signal is high the spindle is not allowed to move even though it may have
motion-feed-inhibit true when the spindle is locked and the program is
running. In my HAL code I've already assigned this pin to the run-on signal.
attached to the input pins of an and2 HAL component. Finally, the output pin of
combination that allows the motion to be stopped by the spindle lock if running
locked. This code adds an LED panel component to LinuxCNC Axis. The
side to the interface side. And this is the interface ID with the spindle lock
being toggled. Now with the spindle locked I'll start the program. And
but what do you think? The next video I plan to make is a spindle encoder for