Has anyone made a 4 stroke CAM grinder using LINUXCNC. Apparently positioning
the head is not the way to go. From what I was told the head needs to be
positioned with acceleration rather than absolute position. It sound a bit odd
but apparently if you have done this before, you have an idea of w
I don't see a problem with using the standard PID loops. I did something
similar to this with my lathe for turning some non circular parts. I
couldn't use a very high spindle speed but I'm sure it was faster than
you would need while grinding.
Les
On 29/05/2013 12:13, Marshland Engineering wro
On 29 May 2013 12:41, Les Newell wrote:
> I don't see a problem with using the standard PID loops. I did something
> similar to this with my lathe for turning some non circular parts
http://www.youtube.com/watch?v=FpP7iTKuWpw
--
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/M
Yup, that is pretty similar to what I did only in my case the parts were
tapered and hexagonal.
Les
On 29/05/2013 12:48, andy pugh wrote:
> On 29 May 2013 12:41, Les Newell wrote:
>> I don't see a problem with using the standard PID loops. I did something
>> similar to this with my lathe for tu
On 29 May 2013 13:00, Les Newell wrote:
> Yup, that is pretty similar to what I did only in my case the parts were
> tapered and hexagonal.
I have a HAL component that allows me to say how many facets I want on
my polygons. It is actually in the system all the time, but is rather
rarely used. Par
I do make camshafts for living, and I'm controlling a cam grinder with
LinuxCNC but only for positioning, since the grinder uses a master to make
the lobes. I'm always thinking about using cnc to make the profiles and
don't use the masters anymore. Because the lack of time, I couldn't even
start wi
My HAL component used a simple lookup table that mapped spindle angle to
X position. The table was generated by SheetCam so I could cut any shape
I could draw. It's still on the machine but it has been so long since I
last used it I can't remember how it all tied together.
I also have a SheetCa
How fast do you turn the cam while grinding?
Les
On 29/05/2013 13:23, Leonardo Marsaglia wrote:
> I do make camshafts for living, and I'm controlling a cam grinder with
> LinuxCNC but only for positioning, since the grinder uses a master to make
> the lobes. I'm always thinking about using cnc to
About 120 RPM for the first tenths of milimeter, and then 50 rpm for the
last turns to finish it. This machine has no VFD, it uses a two speed
electric motor and I use it as it was originally. I can make it go faster,
but approximately that's the velocity I use to make them based on the
diameters I
Did you just use a boring bar with your routine to do that?
Very slick.
How fast did you run the spindle when you did that?
Dave
On 5/29/2013 8:12 AM, andy pugh wrote:
> On 29 May 2013 13:00, Les Newell wrote:
>
>> Yup, that is pretty similar to what I did only in my case the parts wer
I don't see any problems with that sort of spindle speed. The normal PID
loops will maintain pretty good tolerance. If your X axis is heavy you
will need a reasonably powerful motor to provide the acceleration.
Les
On 29/05/2013 13:36, Leonardo Marsaglia wrote:
> About 120 RPM for the first ten
Yes, thinking it fast I assume that a 4 kw servo motor and ballscrew will
do it. Also there's the possibility of using the same hydraulic piston that
the machine has but with a servo valve and a linear way. I've seen that a
guy here on the list did that to a intetrior grinding machine and It worked
Leonardo Marsaglia wrote:
> About 120 RPM for the first tenths of milimeter, and then 50 rpm for the
> last turns to finish it. This machine has no VFD, it uses a two speed
> electric motor and I use it as it was originally. I can make it go faster,
> but approximately that's the velocity I use to
Doing that with hydraulics would be very, very expensive compared to an
electric servo. You would need a constant pressure pump, accumulator,
and a very expensive servo valve to get that
kind of speed. Big $.
Dave Cole
On 5/29/2013 12:18 PM, Leonardo Marsaglia wrote:
> Yes, thinking it fast
The maximum lift we are machining is about 12 mm and maximum diameter is
about 45mm . And may be some eccentrics on some camshafts but nothing too
big.
The subject I am worried about the most is the one about how to generate
the g-code, because if I want the X axis to follow the profile on the cam
I've done a machine with linear servos and they would be perfect for
what you want to do if you can get them with a high enough force rating,
but they are very expensive in longer travels.
Since you have a very short movement range you may want to check on some
pricing.
Dave Cole
On 5/29/2013
The problem with the short travel on the machine is that, it's fine for
making the camshafts, but as the wheel get's smaller because of the
dressing passes I need to move the X axis closer to the workpiece.
Anyway I don't see too much room for a linear motor since the machine now
has a piston, I
On 29 May 2013 13:24, Les Newell wrote:
> My HAL component used a simple lookup table that mapped spindle angle to
> X position.
After much messing about I found the maths to be fairly simple.
Here is the comp, it goes in between the axis.0.motor-pos-cmd and the
PID/stepgen.
It needs connections
On 29 May 2013 18:49, Leonardo Marsaglia wrote:
> Anyway I don't see too much room for a linear motor since the machine now
> has a piston, I don't know if there is in existance a linear servo motor
> with the shape of a piston, all circular or something like that, they must
> exist anyway.
The
do you have a master cam? if so you could just build a cam duplicator
On Wed, May 29, 2013 at 2:24 PM, andy pugh wrote:
> On 29 May 2013 18:49, Leonardo Marsaglia
> wrote:
>
> > Anyway I don't see too much room for a linear motor since the machine
> now
> > has a piston, I don't know if ther
http://www.youtube.com/watch?v=88CgdUkrk3s
here like this . if you set ti up to use a master lobe you can machine the
lobe on a cnc mill then machine it off the master lobe and produce any cam
you want
On Wed, May 29, 2013 at 3:38 PM, jeremy youngs wrote:
> do you have a master cam? if so you
I make the master cams (lobes) with one of my machines since it's built for
the purpose too. Then I use the same masters on the other machines. The
pivot lenght is practically the same, I think the worst case is 1 or 2 mm
of difference between machines. Also, I use the same range in diameter for
th
Looks like you chaps were busy chatting while is was sleeping piecefully and
waking to a nice first this morning.
The CAM grinder was a discussion I had with my local CAM grinder yesterday
and from the replies, it looks like LinuxCNC will be able to create working
solution.
Thanks for the repl
Here's something that looks like the perfect thing for moving the grinder head
on a CNC cam grinder.
http://www.youtube.com/watch?v=9WIMscMFLAA
Instead of connecting the two eccentrics to one motor and manually adjusting
it, use two servo motors which would be independently controlled to
conti
On 30 May 2013 08:42, Gregg Eshelman wrote:
> Here's something that looks like the perfect thing for moving the grinder
> head on a CNC cam grinder.
> http://www.youtube.com/watch?v=9WIMscMFLAA
Clever, looks like fun to control.
I guess that any of the steam engine valve-gear mechanisms would wo
I did an interesting exercise today. I received a DXF from the cam grinder
with 360 line segments. I imported into SheetCam and then exported it to
GCode.
I looked at the GCode and couldn't believe my eyes. It was only 7 arcs long.
SheetCam must have joined the lines together and created arcs.
So
the line segments will give a more accurate following of the area under
the curve of your cam profile. if it is an engine cam .014 could make a
dramatic difference in functionality. i would want to know if you can
adjust the parameters of sheet cam to out put segments at .001 resolution
to get a m
That mechanism is interesting, thought non-linear. You'd need to maximize the
connecting rod lengths and then probably do some linearization in software to
get the output to deliver uniform incremental displacement.
N. Christopher Perry
On May 30, 2013, at 3:42, Gregg Eshelman wrote:
> Here'
I'm getting to the point where I need my own camshaft grinder.
The question I have is the G-code. The grinder has 2 basic components, a
rotary operation to turn the cam and a linear movement to move the grinding
head. For simplistic sake, say the G-code is 360 deg with the corresponding X
travel.
Have you considered external offsets for this? I have had moderate success
turning low lift cams with this feature.
I'm preparing the retrofit of a cylindrical grinder with LinuxCNC to
achieve camshaft and crankshaft grinding. With external offsets you don't
need a really precise servo spindle. A
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