my first cnc project from the start. as i type i am formating a pc that will be dedicated just to cnc.
my board came today from ebay :smile: very fast delivery 2 days.
i will post more as i get on.
Attachment 3498
Attachment 3499
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my first cnc project from the start. as i type i am formating a pc that will be dedicated just to cnc.
my board came today from ebay :smile: very fast delivery 2 days.
i will post more as i get on.
Attachment 3498
Attachment 3499
Ah, the ubiquitous TB6560 3-axis board from eBay... If you haven't already, you might want to search for TB6560 and look at other threads related to these boards...
i have but pressed the buy it now!! i hope it gives me some probs so i can help others :)Quote:
Originally Posted by irving2008
well got the pc up and running and the steppers all wired up plugged in and running :smile:
no probs as yet :smile:
http://www.youtube.com/watch?v=rTwB0BJCjt0
The motors make useful hand warmers this time of year :-)
Mine run on the edge of too hot to touch and I haven't had any problems yet - 80 degrees C above ambient seems a common maximum.
hahahah!!! nice one chris... its ages since i was in that position watching them motors turn on the road runner g-code
it was all magical mystical shit to me (still is a bit)
iv got the 5 axis version of your board, my motors are a bit bigger than yours and dont really get hot at all on 24v, iv heard plenty of people reporting how hot the motors get, i think in some cases its pretty normal
What motors are those Chris?
I hope not... 85degC absolute case temp is the maximum recommended temp you should run a stepper at - higher than that and you risk internal breakdown and demagnetisation.... remember inside its going to be a lot hotter!Quote:
Originally Posted by FatFreddie
an 85degC case is too hot to touch for most people. Maplin do a cheap £19 multimeter with a temp probe thats a useful bit of kit for playing with electrics...
Quote:
Originally Posted by irving2008
Bipolar NEMA 23 case size. Rated current 1.2A, holding torque 0.314Nm(3.2kg-cm). Rotor inertia
0.55kg-cm2. Detent torque 0.0492Nm(500g-cm). 4-connections flying lead 115mm long terminated with a .1"
pitch SIL header type socket. Output shaft 6.3mm dia x 19mm long. Body 56.5mm dia x 40mm long with 57mm
square mounting face haveing a 5.2mm dia mounting hole in each corner on an approx 47mm square.
Chris... just what do you plan to do with those motors?
nothing atm irving i think my 1st thing i will do is convert my milling mc to cnc :)
oh right, just those are very lightweight motors and I was wondering about your expectations of them...
Sorry, yes - 130 degrees max internal which is about 85 degrees on the case. This website seems to think 70-80 degrees is normal - bit of a useless temperature that - hot enough to want to avoid touching but not hot enough to make tea.Quote:
Originally Posted by irving2008
80 degrees above ambient is pretty tepid in my garage at the moment so I don't think it will be a problem for a while :-)
well i tested the temperature 54c
Attachment 3513
my 24v supply turned up :smile:
when its all running should it sound like 56k modem?
can any one recommend a program to start with for gcode.
Hot enough if you're 6700m above sea level!Quote:
Originally Posted by FatFreddie
My motors (3nm size 23, 4.2A on 75v) rarely got hot. The vast majority of the time I can barely feel any temperature rise. It's only when the machine has been running for a long time that they start to get hot. I think the drivers reducing the current to 50% when stationary helps here.
It makes me wonder if I can up the current a bit and get a bit more torque/speed. It's on 4.09A, could try 4.64A. That'd be up to 30% more heat I think (I^2*R), or 20% above rated power.
Yes, mine does too. Could get it to play a tune if you tried...know the frequency from the step rate. Got three 'instruments' (motors) so could even do some interesting harmony...Quote:
Originally Posted by h4ppy-chris
There have been some Christmas tunes on the zone in the past.Quote:
Originally Posted by Jonathan
Phil
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what motors should i be looking for? the board i bought is the 2.5amp and 24v PSU.
Depends greatly on the size of your machine, are you using ballscrews/ACME etc. With only 24v you want a motor with very low inductance to get any reasonable speed.Quote:
Originally Posted by h4ppy-chris
reccomended v=32*L^0.5, so rearranging that:
L=(24/32)^2=0.56mH
So your looking for a motor with an inductance ideally lower than 0.56mH, and sufficient torque...you'll be lucky to meet those criteria so just find as close as possible.
Hope that helps...
sort of helps, from this which would you say is the best to go for?
http://www.savebase.com/InfoBase/SAV.../nema23_56.png
this is my MC that i want to convert to cnc
Attachment 3514
iv got the 5 axis version of your board and im using 57BYGH76-401A steppers (at the bottom of your posted table)
im pretty happy with them at the mo
i get 1500mm/min on a pretty heavy gantry
nowhere near as fast as jonathans but good enough for the price :)
not sure youll get 1500mm/min pushing that back n forthQuote:
this is my MC that i want to convert to cnc
im guessing you will have to use belts and pullies to up the torque
Out of those motors I'd go for the last one, with the biggest torque. Except your driver is only 2.5A...I think that's near enough though. Definitely get a 4 (or 8) lead motor. Your milling machine is very similar to mine and I found that when I started with 1nm motors they just didn't have enough torque to go above a few mm/s and required pulley reduction, so I upgraded to 3nm motors from Zapp, with their 70v drivers which works very well.
By all means try using the driver you've got, it'll work and if you don't mind it being a bit slow that's fine. I do advise getting quite big nema23 motors though. They'll serve you well if you get a better driver.
will they be ok with my 2.5 amp board or should i get the 3 amp board?
Quote:
Originally Posted by blackburn mark
The difference here, in addition to mass, is you have nice linear bearings, not a heavy dovetail with lots of friction.Quote:
Originally Posted by blackburn mark
They would work on 2.5A, just with slightly less torque.Quote:
Originally Posted by h4ppy-chris
thanks alot guys for your help :)
Chris,
Have a look at the tutorial I wrote here... will give you some insight into your needs.... you have to start with what you are trying to move... then decide how fast you want to move it and how you are going to move it... that tells you what you need to move it with... and then you can decide what motor/driver package will work...
BTW what mill is that? looks similar to my Warco, but older...
thanks irving had a look at your tutorial it was a very good read.
am not sure of the make of the mill no markings on it :( but would love to know.
Jonathan is quite correct about friction, a really important mod is a one shot oil system. This will reduce the wear and reduce the friction its the only way to get the lube in just where its needed, just a PITA to do.Quote:
Originally Posted by Jonathan
Phil
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I have a similar mill,i have 70v ps running at 6 amps rapids at 2000 mm pm motors are 4Nm I would say that to be the minimum spec.Quote:
Originally Posted by h4ppy-chris
Increasing the power via belts will also reduce the max speed unfortunately speed costs money.
Phil
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Well, having done the calcs on my mill, and measured the actual friction coefficient with a digital spring gauge, I know the likely motor is going to be in the order of 3Nm to achieve 1300mm/min cutting and 2500mm/min rapids. If I hadn't measured it then the estimated friction coeff of 1.1 would have suggested a 4Nm motor. I'm working on 36v @ 4A as I have a 36v, 12A PSU to hand.
The point here is that every mill is different. You need to weigh the table and measure the friction coefficients to avoid overegging the solution. I am not fussed about cutting speeds as long as they are reasonable... its still going to be faster/more accurate than I can do it by hand and since I dont have suds or one-shot oilers I'm going to have to be there to spray/oil as it runs.... Its not going to be working hard enough to justify doing those mods...yet...
Those numbers are similar to what I got on my milling machine with the same motor. I've never cut at over 1000mm/min, and that was with a big cutter (http://www.youtube.com/watch?v=iC7lX..._order&list=UL). The 2150rpm spindle limits the feedrates I can use. I started off with 2500 on the X axis (see http://www.mycncuk.com/forums/showth...ll=1#post12790 post #19), but have gradually reduced that to 1800 over time. Now I've taken the motors off to use them on the router. It will still do more than 1800, but not 2500...I think the ACME screw or something has worn a fair bit. Time for ballscrews perhaps-that should make it a bit faster due to the efficiency.Quote:
Originally Posted by irving2008
Attachment 3516
Looks like a Clarke MD25 - Similar to the Warco MD30/Minor i have.... tho mine has a longer table... I wont be using the original screws but some ballscrews I got off Robin..... the top speed of the spindle is limiting, I have a VFD to go on so plan to increase the belt ratio to up it to 3000 or so... tho running at 1800mm/sec with a 6mm cutter would ideally like 5000rpm on the spindle... not sure the bearings will like that much tho...
If that's mine your referring to then it's a Clarke CMD1225C from Chronos (though I got it second hand). The castings look pretty much the same. Agreed with the 5000rpm. I'm thinking either mount a separate spindle to the side of the main one (i.e. my 6000rpm 6kw-ish brushless motor), or put that same motor in place of the 750w original motor. I was about to ask you if you thought the bearings would take that rpm! They allready sound a bit rattly and the spindle pulley gets warm - maybe that's normal. How long is your table and what are the travels just out of interest? I get 350x141x92mm.Quote:
Originally Posted by irving2008
What diameter are your ballscrews?
The table on the MD30 is 675 x 205mm approx and the travels are 490 x 195 x 105mm approx. The ballscrews are 16mm dia. I'm pretty sure my quill bearings won't like 5000rpm, they get warm on 2150! I was considering a secondary spindle based on an ER collet chuck, belt driven 1:2 or 1:3 off the main one, similar to what Robin's done (but probably nowhere near as neat :lol:).
Can you not up the frequency instead ?Quote:
Originally Posted by irving2008
I renewed my bearings with SKF they are rated at 7K
I have run mine at 3.5K but I need to change the belts as I have the twist lok type and you can see the effect of centrifugal force. Scary
I do intend to go to 5K
Phil
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i have some worn A-belting... its starting to fray :lol: yes I can take the motor higher on the VFD but not from 2150 -> 5000 using the same pulley set. You can over rev the motor maybe 10 - 15% say 2500, but what I plan to do is put a new small fixed pulley on the motor and run a single belt (with an idler to get round the column) using the largest pulley on the spindle.
Irving I am gonna have to disagree.
My motor speed is 1400 and as you know they also come in speeds of 2800 so it depends on the stock speed
I have run it at 100Hz for long periods the motor does not get warm in the slightest.
Who told me I could do that, the company who sold the motor inverter package to me.
The motor upgrade was forced on me due to the fact that the original motor over heated and was poorly balanced.
So it turned out a blessing in disguise.
Phil
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