the mass is too much and block most of hte airflow. So, I need to increase the sruface area and I'm finguring 48 sq in
4" duct ~= 16 sq in ( a lil less)
good evening to all
JT-Hardinge: I'm going to make the bottom box empty (just to catch any stray particles) and to increase the surface area from 16si to 48 sq in into the top bpx that will have the pellets
Jymmm: does the air flow through the pellets or near by them?
theorb is now known as theorbtwo
JT-Hardinge: Thru them - to absorb smoke and fumes
so the problem is you don't have enough space between the pellets to pass the air you want?
correct, i *THOUGHT* I had enough room
and or your thickness of pellets is such that the frictional losses are greater than your fan pressure
s/fan/dust collector/ =)
think of it like a long skinny pipe... the longer the path the slower the flow due to friction
950 CFM in free air I bet
zero load I suspect.
So, by reducing the pellets by half, and going to 48 sq in, you think thatt'll be good enough?
if you have 12 sq ft 1" thick you get a certain amount of friction that slows down the CFM, you increase the thickness or reduce the sq ft you reduce the flow
each box held ~16lbs of pellets
a litle over 1 cubic foot of pellets
27lbs == 1 cubic foot
time to gather some empirical evidence I think
Well, even though it's just cardboard boxes, I have to cut and glue in screen, so it's a PITA
Once I get the design perfected, I'll make a permaent box out of MDF and metal mesh
do you have a way to measure the CFM?
no, just my hand to compare
so you have not tested it with live smoke?
No, but running dry with pellets in place by itself has barely any output
if I remove the pellets I get good flow.
then you have to find the balance that gives you enough flow with enough carbon
someoen else built one differently and uis using maybe .3 cf and is fine
so me at .5 cf should be ok if I can get the surface are correct, I was just trying to overenginner (as always)
more is better, not always =)
sounds like a helicopter... it's all in balancing things
heh, ok I'm off to cut some cardboard then
try and divide and see what you get
that is usually the quickest way
yeah, the greater surface area should do it too
I wonder what the huge cylinder on top of this retrofit candidate is? http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130460515726#ht_500wt_1156
it's a chimeney/smoke stack for the wood powered mill
it's where the gerbils run
poor lil gerbels
no widows to look at or nothing
Gerbils like looking at the bereaved?
[#emc] "This is the #emc channel - talk related to the Enhanced Machine Controller and general machining. Website: http://www.linuxcnc.org/,
wiki at http://wiki.linuxcnc.org/"
Bonny: for long sliders i have to fix fill/expand properties of 'control' frame
i'll play with that bit more
and why is greyed out? (can't move at all)
anyway the top one is intended to drive circle (apperture) size and other angle. Still ned more work.
Bonny: what is grayed?
I can't move slider.
they are hal scales or gtk scales?
on both lucyd and hardy
you have to add adjustments to them
in general properties in glade
other question. Is it posible to run some script with click to the button and export hal pin value as parameter?
reboting to lucyd
with a lot of work or already done and I didn't find?
adjustment's for slider are just some text command What how?
psha adjustment's is min=0 max=100 but slider goes just from 0 to 90 (90-full scale)
[#emc] "This is the #emc channel - talk related to the Enhanced Machine Controller and general machining. Website: http://www.linuxcnc.org/,
wiki at http://wiki.linuxcnc.org/"
Bonny: i don't remember how why it's going to 90. ask google :)
it's related to adjustment props like page size etc
maybe you need to set some of adjustment fields to 0
haha... Can you tell me if emc.halio->Base name for circle pins has something to do with croshair circle?
and it's doing something? :)
probably not finished ?
is CAM_view setup to find hole centers of a specific size? if i have a plate with 1" and 0.5" hole but the datum is the 0.5" would CAM_view recognize the size difference?
As I know the size is not important as camera is not calibrated.
no, basename for pins is for exporting marker, don't mind :)
So what idea you have to control crosshair circle size? (aperture circle, dual lines, square..)
Hal pin or something other?
and to get correct slider reading the adjustment->pageSize must be 0
would be :)
Do yo know aprox date of release?
next week is upper bound
i hope )
waiting like a gog :D
i didint know 2.4.6 was released ;) When did this happen?
around 7 PM EST, last Friday (from the email timestamp)
davec_ is now known as Guest89982
i apt-get upgraded to 2.4.6
when i try to run it i get back to the login screen!
i just ran another stepconf wizard. nothing changed there. this is the 10.04 install from the website.
eww. sounds like it is crashing x
nVidia driver conflict?
what version did you have before the upgrade to 2.4.6?
every week i do an apt-get upgrade, dont think i have missed any upgrades in the last few months.
check dmesg for errors
I bet you got something else in your upgrade, and the emc version change is not related to the problem
if you got xorg upgrade packages, have you rebooted?
[15:23:13] <elmo40> http://pastebin.ubuntu.com/538685
there were libpango and other ones like that. dont think xorg was.
it may be nvidia conflict?
have you rebooted since the upgrades?
want me to do another?
can you run other opengl apps like glxgears?
nope :P just killed X again
ok, your X is busted
were/are you using the restricted/closed source nvidia driver?
yes. from their website.
you mean you installed the .run package from nvidia, outside the ubuntu package manager?
let me guess... a serious NO-NO.
it's no wonder the upgrade fuxxed it then. you should use the ubuntu version (or smarter yet -- none at all)
none at all is better?
that's also why you're getting the unexpected-realtime-delay errors
i have an older geForce MX 440. Any idea what i should be using?
the vesa driver probably
I don't know how to fix it. your opengl may be beyond repair. I've seen a lot of people get screwed this way.
now... how do i remove this nVidia stuff and not screw with anything else >_<
nothing lost. only a CNC machine ;)
saving your configs and doing a reinstall is probably the fastest way to unfuxx it
every time I have had open gl problems... I have not been able to recover. (like installing the closed source nvidia driver) there seems to be no going back..
their install naively overwrites stuff
but makes backups
though that is a minimal issue.
it prob affects other things kernel related
ok, so fresh install coming right up O_o
cradek: how do i select vesa driver?
[15:56:31] <cradek> http://www.linuxquestions.org/questions/ubuntu-63/geforce4-mx-420-failing-on-ubuntu-10-04-a-813796/#post4002087
(ubuntu is making it harder and harder to say which driver you want)
what is this 'nouveau' driver?
elmo40: open one for nvidia cards
apt-get install nouveau-firmware?
then edit xorg.conf?
use vesa use vesa use vesa use vesa
use swx11 use swx11
cradek: i've managed to run gremlin in touchy :)
4 gremlins :)
but there are some issues with many gremlins
isnt vesa only 800x600?
ok, vesa it is
psha: screen shot?
psha: give me a shout when you have a few minutes - I'd need a generic HAL wiget save/restore method for persistence and am unsure how to do it
psha are you angry with me or were you only in a hurry?
Bonny: i was running from work to home :)
and here only now provider fixed my link
ok I just thinking what I do wrong.. :D
also you may connect additional scale without hal pins
a bit hacky though :)
open camview-emc glade file, find slider which controls circle radius and remember adjustment name
?? I had working checkbox - move to cam offset. And button now save the coordinate into file!
then use that adjustment for you slider in gladevcp panel
Bonny: button is using LOGOPEN?
neat - I had not seen touchy translated before
looks like it's missing a few words
Actualy I tied that pin to triger o<saveXYZ>call command
and inside that 'o' is little script!
cradek: yes, some values are not translated..
net cam3 camview.hal_button1 => halui.mdi-command-02
g92 x0 y0 z0
(LOG, X=#5211, Y=#5212, Z=#5213)
(MSG, CAM position stored.)
... and little modified source so _CAMlog mean open for append
and thing work perfectly
skunkworks: there are tons of issues still...
one gremlin is working with only minor issues
many gremlins are horrible :(
well, seems that emc runs, no reinstall required
i went into the hardware driver thing in the top menu, removed the nVidia driver
rebooted with vesa
runs nicely now
psha something of this? <control id="circle-radius">100</control>
no, look into camview-emc.ui
psha: why would you need more than one?
skunkworks: how would you rotate it with touchsreen? :)
oh - good point. a 2 finger touchscreen? ;)
Bonn1: may you post you last screenshot from imagebin one mor time?
skunkworks: that was guessing :)
i don't know why you may use it but many gremlins are great testbed for finding bugs :)
if there is any bug in gremlin code then many screens will hit it :)
Just this once .. here's the log: http://www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2010-12-01.txt
<object class="GtkAdjustment" id="adjustment_circle">
elmo40: do you do any RIP?
use 'adjustment_circle' as adjustment name for your new slider and it will be bound to circle one
[16:44:26] <Bonn1> http://imagebin.ca/view/7cOB3L.html
it's better then hal pin since it's more responsive
... and probably not eating to much resource...
what about two lines as aperture in crosshair?
wow. max jitters in ns is 3756994 >_<
Vq_ is now known as Vq
that shouldn't be hard
yes, that should not
but you also need angle for them?
that should go to the other slider.
maybe just another control under extra menu (where label spacing and croshair circle is)
like paralel line angle then slider and button ON same as for croshair circle and distance to be stollen from circle diameter (can be both on)
elmo40: run in place? get the source from git and compile it (emc)
Bonn1: maybe it's better to use checkbox to choose aperture from 'off', 'circle' and 'lines'?
I just thinking that have 'repeated last slider' for lines http://imagebin.ca/view/oou56zu.html
but whatever... just to have chance to change angle and width.
.. and to select circle_on lines_on (or both)
question is - do you really need both at same time?
if not checkbox will be better
I don't know :D
I do not have used yet.
but probably each on/off can solve all casess
i'm trying to look a bit further
when another shape will be needed
I use just circle till now but needed lines much times.
so have to descide what to do
add them as on/off options or mutually exclusive
I think on/off can solve more problems...
but maybe I'm wrong
my friend and i are about to begin building our first CNC machine ... it will be like a plasma cutter, but we will be using oxygen/acetylene instead of the plasma cutter ... a couple of questions
(1) is a third axis absolutely necessary for something like this?
just needed to be manualy adjustable.
(to fit stock height)
must i choose one of the drivers that are listed in the "wizard" for my stepper motors? why do i need a driver that cost $150 each (like a Gecko driver)?
but if you need to expand system to plasma someday then think about Z axis
we are definitely considering expansion, but can i not purchase an additional motor and driver when we expand?
I don't know why. I just made one myself..
Yes you can....
i found a 3 driver board recently on ebay for $109
... just needed to change configuration ..
EMC can drive near ALL boards.
Maybe not trought stepconf utility but can be done!.
[17:08:44] <tlhiv_work> http://cgi.ebay.com/3-Axis-CNC-Stepper-Motor-Driver-Board-Router-Mill_W0QQitemZ330501839831QQcategoryZ71394QQcmdZViewItemQQ_trksidZp4340.m263QQ_trkparmsZalgo%3DSIC%26its%3DI%252BC%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D10%26pmod%3D330495193791%26ps%3D63%26clkid%3D5345353139210923628
this driver board seems fairly nice and is pretty inexpensive to drive 3 boards ... it has a feature that you can remove the chips too without soldering
From datasheet and images seems good one. For smaler motors up to 2.5A If you have such motors then just use it.
but that size motor will be to slow for plasma but good for oxy/acc
I have done job for friend with 8m X 2m table driven with even smaller servo.
well i have to purchase motors ... i was considering 2 or 3 of these --> http://www.automationdirect.com/adc/Shopping/Catalog/Motion_Control/Stepper_Systems/Motors_-z-_Cables/STP-MTR-23079
ok another question ... with oxygen/acetylene (and i guess with plasma too), we really need to control a couple of valves to turn the oxygen and acetylene on and off ... can EMC do this?
and if so, do i need a special driver for this too?
emc can set 1/0 on unused pins of lpt port
so if you have some - just use them
just little rearange to have checkboxes on same side and add one slider for angle.
Bonn1: this widget (unit controls) is generated by camunits and listing all controls found
i've no way to control it
psha: i assume the driver board i just posted for the motors can't do that can it ... i would have to have another driver board for this right?
but first two tabs are mine
ahh I will just wait as you are smart one and problem will be solved soon. :D
the nice thing about that driver board is that has the parallel port attached to it, so "splitting" the cable might be my only option
A SSR driven from spare pins on the LPT port would do for driving the valves
that board has the pins you need exposed, you would still need a relay to drive whatever valve you use
Full access to all unused DB25 pins connector via terminal block, easy connection for prototyping work
so you probably need one transistor as realy probably need more current that CNY17 optocoupler can give.
but you can use that for valves.
how big table you plan?
atmega: would the "current" from the I/O be enough to activate the relay?
i know that i could run the valves off of 12V or 24V, but i need (like you said) a relay to pass that 12V or 24V to the valve, and i need something to activate the relay ... i'm guessing that the I/O on the computer will not do that
sure it will
Bonn1: i think 8'x4'
if the relay draws too much, add a transistor
atmega: do you have a sample relay in mind? :-)
I drive an SSR directly from mine, it only takes a few mA
hmm then chose better motor. If you have plan to cut thin materials then you will be to slow.
as I read that manual the 'free' pins are just routed to headers without optocouplers..
Bonn1: i don't know much about choosing motors for sure
[17:28:53] <atmega> http://www.opto22.com/site/pr_details.aspx?cid=4&item=240D10
AC only output
Basic problems is that 'gantry' wil be heavy
and with underpowered motor you can get high speed but acceleration is low.
and that corrupt all edges as speed decrease here.
Bonn1: gantry shouldn't be any heavier on a 8'x4' than a 4'x4' should it?
it should just move twice as far
atmega Seems to be TTL output (direct printer port pin)
Bonn1: you could add an opto or a transistor... or not.
gantry is same but all pipes come's heavy
opto and transistor for sure!
if you are going to the trouble to make something that big, why skimp on cheap motors and drives
In start I just check and recheck why motor stall on one side of machine but work ok on other..
have find no defects...
atmega: on that SSR you just sent me, you activiate it with pins 3 and 4, connect +24V (or +12V if i use a 12V valve) to pin 1 and connect pin 2 and 0V to the valve?
Bonn1: what pipes?
... but then just for test removed all pipes (gas/oxigen) and works.
oh it's hose right?
so problem is wey hiden.
well yes hose...
hose is not heavy :-)
I think too. But result is different.
I lost few day on that..
3 to whatever pin you use on the p-port, 4 to ground, 1&2 are the swtich to the valves, need to be AC vavles though
a 120D3 would be fine for a pair of 120vac asco's or whatever
valves are tipicaly 24V here.
i would think a basic solenoid valve would be DC
and can be AC or DC. Just use proper snubber.
because they are SCR's any only turn off on the zero crossing
that's just what I'm using for spindle control... you can get a DC SSR
atmega: i don't understand ... isn't pins 1 and 2 just opening or closing via what happens on pins 3 and 4?
If you use regular relay then doesn't matter AC or DC. For SSR you must check datasheet what can use. (DC SSR's are wery rare)
it shouldn't matter what you put on 1 and 2
i mean i have 120V and i don't mind using it, but i just don't understand ... i would think pins 1 and 2 are just like a regular switch ... and the switch is controlled by what happens on pins 3 and 4
it's not a mechanical relay, it is an SCR
i guess i'm not familiar with a SCR
atmega uses electronic relay and that isn't same as ordinar realy.
SSR means Solid State Relay
well i think i need an electronic relay because i'm gonna want to switch it with the LPT output
And is tipicaly made with photocoupler and thryac.
You can use photocoupler too.
what about something like the HDD-06V75E on this page --> http://www.power-io.com/products/hdd.htm
I mean here the DC SSR are way to $$$$ is cheaper to use one photocoupler and relay.
oh wow ... $86 :-(
[17:43:31] <atmega> http://www.opto22.com/site/pr_details.aspx?cid=4&item=DC60S3
that's pretty cheap i think right?
yep... $10 on ebay
hehe ... now i just need to find a couple of valves to use with this
10mA@4V is out of reach for most LPT ports I see.
that one draws 10?
mine is more like 1
the 10mA is in link.
I think somewhere up to 5mA is ussable for most LPT ports. (but some can draw over 30mA) so must know the port.
Bonn1: so i should be looking for 5mA needed to activate the SSR (to be safe)?
i don't even see your 10mA listed on the specs page for that SSR
driving a valve is probably one of the more minor things
do you need an O2 compatible/clean valve for the o2?
i really don't know ... i know little about oxygen/acetylene ... i'm going to rely on my friend who uses such things daily for that expertise
if you wanna to connect laptop then some of them can give only 1mA @ 3V (mine here is such animal)
all i know is how it works ... the ignited acetylene heats up the steel and the oxygen blows through it cutting it
O2 valve MUST be compatible with O2!!!!
Or you can get fire!!!!
o2 fires are impressive
For oxy torch you need at least 3 valves.
Bonn1: one for oxygen, one for acetylene, and one for ... ?
for O2 for burner and for acitylene and another for O2 to blow
When such thing start the O2 supply is low, but when preheating is done then O2 start to blow with power to oxidize iron and to actual cut.
ok ... time to go teach class ... back later ... thanks for all the help folks
I use a lot of O2, and mostly O2 compatible stuff :)
Near all stuff are compatible with pure O2
... ie near all burn :D
I have one o2 solenoid valve that is actually made for o2 use (gas path, wetted surface, seals)
I have seen how valve explode.
yeah, I've seen the resulting fire involving an oxygen booster, pretty impressive.
(regular valve with O2 pasing trought)
... hard to belive how danger O2 is.
Hi all in the Warm USA -7°C Germany
800km south from you is -5°C and snowing near all the day
im soth of you if u are in the city named your nick
no. I'm from Slovenia. Osterich betwen us
psha has probably the coldest reading here now.
IchGuckLive: and ~2k km to the east it's -20 :)
thats cold but try
psha do you have some improwment?
then weather report here lie. It say -12 for Moscov
it was 18-20 today with strong wind
[18:19:22] <psha> http://pogoda.yandex.ru/27612/details/
oh including winshill its -25 nearest station 25km
this one is pretty correct for local weather
probably the reading from the best hour.
what is psha working on
cnc router ß
at least numbers are arabic :D
IchGuckLive: no router :(
skunkworks: what would i use RIP for?
psha thats bad
you shoudt make one out of an old tatra
I hope on something to improve http://imagebin.ca/view/khfbuQrY.html
i'm too lazy to do something with hands :(
Bonn1: i'm on crosshair now
so hope it'll land in ~30 minutes
[18:25:19] <pcw_home> http://www.opto22.com/site/pr_details.aspx?cid=4&item=DC60S3
needs only 3mA
But for gas valves you better have a chargepump or watchdog of some sort
Bonn1: what is the cam for inspecting via cnc routing
I don't inspect vias...
pcw_home: those relays look awesome. it would work well with a plasma gun.
elmo40: running the development version or modifying source
but i dont program...
* elmo40 will brb, restarting X
By for me today :D :D
pcw_home: I love opto22! They are cheap and work great.
I think our Opto22 compatible pin-out dates from our 8255 parallel cards we made in the 80s
still works great
we are using 2 of the 24 port boards - It is awesome to be able to set whatever we want as input or outputs.
(and 3 16 port boards)
(but those required some creative cabling)
still pretty painless though - just required crimping some different ends on the 50 pin cable.
[18:36:03] <skunkworks> http://www.electronicsam.com/images/KandT/conversion/16io.JPG
2 50 pin plugs go to 3 16 port i/o boards.
I guess I could make a adapter PCB for that
Bonn1: as usual i have no place for controls :)
:D make smaller :D
but for now only way to change shape is via plugin tab
wait for it to land :)
I think that should be here?
and you'll see
what to prepare?
and while you are playing with it i'll try to fit combobox somewhere
Bonn1: lucid and hardy versions are done
hmm did you know the angle property name?
I mean adjustment
click on slider and look into 'adjustment' field
or just look into list of adjustments and guess :)
im on hardy can't click
glade doesn't work here
and camview-emc.ui seems old one..
so corect one is somewhere else
you may open it with vim/gedit and look in the end
I can't find file!
the correct one...
I install package not updated with git
and now have ^&*(^%^%@
where that file reside?!?
you may check list of files with dpkg -L camview-emc
[19:21:29] <Bonn1> http://imagebin.ca/view/ec_WLdA.html
just alignment of angle is little to coarse.
1 degre seems to much.
should be 1/10 of degre...
.. at least
still i don't find place where to put combobox:(
it's not bat where is.
is not it too far?
well can be closer but not needed so many times..
sizing aperture and angle is most used.
can be combobox linked like sliders?
just one thing...
they may share liststore but not active value
the aperture size slider has to much gain.
ie when is in half the aperture is already bigger that screen.
The best should be to be that slider percentage of current screen width.
maybe you are right..
the one bug. The value in emc.halio tab (enable logic XOR checkbox) are not saved..
and emc.croshair tab XOR too are not saved.
they are saved...
but then overriden :)
... hm that's same as not saved for me :D
second build gone
fixed xor save, angle step (0.1) and aperture combobox
that's some development cycle!
step 0.1 doesn't work!
I can move with mouse in 1 deg step but with keys doesn't work at all. (can't move)
try on lucid
atmega: pretty small cycle :)
the digit's was 0 so no decimals at all.
Just set to 1 and works
[19:54:00] <Bonn1> http://imagebin.ca/view/egfGr-rh.html
it's easy fit to center.
Bonn1: you told me that you thought perhaps i might want faster motors ... do you have any suggestions?
looks nice :)
Bonn1: is color button working?
color, not xor
croshair color work
hmm some extras.. tooo
color's are saved ok.
just little funny is when selecting color in [main] the color is applied to DRO and croshair.
it's feature, not bug :)
I didn't say bug. Just funny as I didnt expected that.
psha thanks... had to go..
hahaha. an Amazon.com negative comment about a seller: "They cancelled my error due to there mistake."
I wonder whoose misteak it reely was
psha: back (with a petiit sauvignon ;-)
mhaberler: rewrite for you is ready
i'll push it in a minute
btw link from dev channel: http://psha.org.ru/tmp/touchy-gremlin.png
so on next gladevcp push one will be able to add live plot into touchy :)
psha: exactly how many balls are you currently juggling ?
hi folks ... i was planning to purchase these for a 8'x4' CNC table, but Bonn1 told me they would likely be quite slow. --> http://www.automationdirect.com/adc/Shopping/Catalog/Motion_Control/Stepper_Systems/Motors_-z-_Cables/STP-MTR-23079
any suggestions what motors i should use on a 8'x4' table?
mhaberler: merge psha/gladevcp-persistence
that's wip and not final version though
There is a guy on here with a Mechmate 8x4 (ish). I can't remember who it is. I think he is using some fairly big NEMA 34 motors with rack-and-pinion drive.
mhaberler: unfortunately i'll won't be able to do much work on emc till next wednesday...
Nema 23 are a bit slow on my 2' lathe. They would be hopeless on something with 8' travel I think.
sure, I'm slow :)
i'll have only small netbook with me
without emc on it...
what a life
so at least i'll push all intersteing branches to my repo
andypugh: wouldn't it depend on how they are geared?
But then what gearing you can use depends on the cutting forces you need to resist, and the mass of the parts you are trying to move.
andypugh: well it's for a oxygen/acetylene/plasma cutter
You need to start with the basics, forces, masses and accellerations, then work out the torque you need (and the torque-at-speed)
davec_ is now known as Guest36728
In that case you don't have any cutting forces (though you might have to drag cables/tubes around). However, you need to move fast enough for the cut.
andypugh: so if we decide to go with a 4'x4' table, would you still advise against these motors?
Consider the smallest radius you want to cut in a cutting-speed X+ to cuttin-speed X+ move, and the mass of your gantry, and F=ma etc. A spreadsheet might help.
8x4 and 4x4 and 800x4 are all much of a muchness.
And I don't advise against those motors, I advise working out what motors you need :-)
andypugh: this is difficult to determine since i myself have little experience with oxygen/acetylene torches and no experience with plasma cutters
The spec sheet has speed-torque curves. Those are a good start.
my brother-in-law (who we are building this for) has much more experience in these things, but i'm not sure he would know how fast to advise
Work out what sort of rapid-speed you would like, and how long you can imagine a sensible accell-decell taking.
I guess one big factor will be the sliding friction of the guides.
i think this is where experience likely has much advantage over what i can work out
i don't mind doing the math (i mean i do math for a living -- i'm a math professor), it's just that i presume there are other factors that others have encountered that i would almost certainly not consider
Have a look at http://www.mechmate.com/forums/forumdisplay.php?f=26
I know that Mechmates work, and are about that size (or perhaps bigger)
you could find some specs of some other similar machine and copycat whatever has been used in it
I think you will need to register, and I can't be bothered.
Yes, the maths is easy, but knowing what you want is less so. What units do you think in?
well i don't mind either ... English units are my native units, but SI are almost just as natural
tlhiv_laptop: it's rarely true for opposite direction :)
I tend to guess in imperial and calculate in SI.
psha: i agree
i've used SI units so much in math and physics courses, that they don't scare me at all
Lots of chatting to my thoroughly imperial dad, while being taught metric at school.
So, handwaving, I would say that more than 2 seconds end-to-end is a bit slow
hehe ... i don't think that's slow at all
speed is less of an issue for us
And taking more than 6" to get up to traverse speed is probably rather slow too.
well i don't think moving from one end of the table to the other (8 feet) in 30 seconds is that slow
this machine will not be used often enough to where speed is much of a consideration
My lathe (which is the sum total of my experience, to I am hoping others will speak up) goes from stopped to half full speed in about 1mm, but then it has to for threading applications.
Top speed isn't all that high, as a lathe needs plenty of force.
after 100-200mm it'll get enought speed to go to geostationar orbit!
I built a machine once that went from rest to 100kph in 10mm.
But I digress.
when you consider what has to be done with these things we will be cutting after they have been cut, the amount of time needed to cut them out is likely insignificant (no matter what speed) to the rest of the fabrication time
OK, so perhaps you don't need all that much speed, so the next question is how sharp you need your corners.
we're looking to build a machine that can do things that we cannot (namely automatically cut out things that we either cannot reasonably cut out or would take us LONG periods of time to trace and cut)
There are people on here with plasma cutters, I am surprised they are not saying anything.
well that depends on the size of the tip on the torch ... i think probably 3/16" diameter circles are how thick the cuts would likely be
Do you have any feel for travel speed?
again, i don't think travelling 8 feet in 30 seconds is unreasonable
You might when you are watching the machine home :-)
but it's only 30 seconds to "start our project"
after we spend lots of time preparing the project (i.e., designing, converting to g-code, loading into AXIS, etc.), 30 seconds seems small
Maybe compromise, buy the NEMA23s , but drill the 34 mounting holes too.
modifying an exisint setup is trivial ... after all, we're building everything from scratch :-)
[22:49:59] <andypugh> http://www.youtube.com/watch?v=-cGSlkjMGlE&feature=related
my brother-in-law is a pretty good fabricator
Perhaps guess some speeds and cutting rates from that?
You can probably go slower than that one, but I would assume that cutting too slow causes problems?
so you said that we should decide how fast we would like to get from one end of the table to the next ... that should help us estimate the maximum velocity, but i'm not sure that helps with acceleration
i would assume you would want something that gets from 0 speed to max speed in perhaps 1/6 of the length of the table
Maybe a bit quicker, but that would be my theoretical starting point.
fenn: cory doctorow new free book 'little brother' ... funny i just re-read 1984
if we say 15 seconds to run 8 feet, that's an average speed of about 0.5 feet per second
The max velocity tells you at what motor speed you can afford to stop accelerating. EMC2 controls acceleration but not jerk, so you need enough torque to accelerate at the set rate at the max speed.
And stepper motor torque is a strong function of motor speed.
if i want to get to that max speed in 2 seconds, then that would give an acceleration of 0.25 feet/s^2
is my math sound? :-)
You might find yourself solving simultaneous equations (possibly graphically)
You tell me!
assuming linear acceleration, 0.25ft/s^2 gets me from speed 0 to speed 0.5 ft/s in 2 seconds right?
A different gear ratio might give you more force, but then you will find that the motor is going faster, so the torque is lower by more then the ratio change....
or v^2 = u^2 + 2as might be more useful if you want to get to .5f/s in 1'
Just this once .. here's the log: http://www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2010-12-01.txt