Messages

1471

General Mach Discussion / Re: Can someone explain the current draw of these stepper motors, please.

« on: November 11, 2008, 12:05:39 PM »

You need to be looking at power, not current.  You will never be drawing full motor current, at full supply voltage. The motor is rated at 4.17V, 2.8A.  Power is voltage times current, so the max motor power is 4.17 x 2.8 = 11.7W.  your power supply is 36V, and you're measuring 0.5A, so the power is 36 * 0.5 = 18W.  Close enough.  You are running at, if not above, the max ratings for the motor.  Two of these motors would double the power, to 36W.  If your 6A motor is also rated 4.17V, then its power will be 25W.  Your power supply is rated 36V, 8.8A, which is 316W.  All three motors combined draw 18 + 18 + 25 = 61W, so your 8.8A supply should be more than adequate.

Regards,
Ray L.

1472

General Mach Discussion / Re: What to do after a loss of Power?

« on: November 11, 2008, 11:04:00 AM »

Pete,

   This is something you have to think about up-front.  You should always assume something *will* go wrong, and provide a means of re-zeroing the machine after a position loss.  This can be something as simple as putting a hole in a known location, or referencing your "zero" point to a corner or two edges of the work piece.  I will often put a 1/4" hole in my pieces, in a location that will NOT get machined off until the last operation.  If I lose position, I can move the machine until a 1/4" rod in the chuck will just drop cleanly into the hole, then set the DROs to the known position of that hole.  You can do the same by using an edge finder on any two perpendicular edges of the workpiece.  All my fixture plates have the front-left corner milled to a perfect right angle for this purpose.

    If you haven't made a provision for this in your current part, you need to find edges or holes you can use, and look at either the G-code or CAD drawing to determine the exact locations of those features.

Regards,
Ray L.

1473

General Mach Discussion / Re: Spindle Speed Troubles

« on: November 11, 2008, 10:10:40 AM »

G'Day Ray
Just as Peter describes setting up the spindle speed is spot on. Jimpinder sets it Exactly the same.
what I did I set The the steps in the motor tuning tab (spindle) to 1000 and then used Max velocity The step size I left at 2us and Dir at 2us which is recommended to run your Geckos. I found if you change it in one area Say spindle it will change them in all of them Xaxis, Yaxis Etc. So I left them at 2 for each Step and Direction.
Next Go to pulleys set it at your max speed ( I Dint Know your Set Up So Ill Speak For Mine Only) in my case 14700 min 0 the ratio 1.
Through mach I set spindle speed max (MDI Area) type s14700 <enter> then type M3 spindle enabled speed at max. I went to the Digispeed and measured the voltage coming out, I adjusted the "adjuster Have a mind blank cant think of The name of it" on the digispeed itself to give me 10v. Then went back to mach and set speed at S7350 exactly 1/2 went back and measured the voltage it was around 9v. Then went to motor tuning Spindle and decreased the Velocity only. 1st try was around1/2 velocity went back and checked what the voltage was it was about 4.6 set at 7350 via mach. getting close.
Do you get the drift just kept going back and forth only changing the velocity setting in the motor tuning till I got 5v at 1/2 speed 7350 and 10v at max speed 14700. then did a check went from 1470 speed gave me 1v, 2940 speed gave me 2v and so on till I got to max speed.
Took me about 6 goes but all I changed was velocity in motor tuning spindle that's all. (in my case for a router spindle speed +/- 10% is nothing but I got it down to nearly exact.

That's pretty much what I went through on mine.  The only added confusion was I have a SmoothStepper.  It first took a while to realize the step pulsewidth timing in Mach3 had no effect, and then a bit to find a good pulsewidth setting in SS config.  The tuning can actually be done with either the pulsewidth or the steps/unit, since both have a similar effect (the C11 is basically integrating the pulses, so either more pulses, or wider pulses will have the same effect).  Once I got the pulsewidth into a reasonable range, and understood how the C11 and the SS worked, it was not terribly difficult to get the result I wanted.  The only problem now is some days it does not work correctly on power-up, and seems to need some time to settle down and start operation correctly.  That I still need to sort out.

Regards,
Ray L.

1474

General Mach Discussion / Re: Greetings from a newby--- please help :(

« on: November 10, 2008, 10:07:26 PM »

Do the axes move the right direction when you jog?  Are you aware that movement is based on the tool, not the work?  i.e. - moving -X will move the tool to the left, or the table to the right.  Moving -Y will move the tool towards the front of the machine, or the table towards the back of the machine.

How about posting your updated code?  Sounds like you're close...

Regards,
Ray L.

1475

General Mach Discussion / Re: Greetings from a newby--- please help :(

« on: November 10, 2008, 07:58:51 PM »

Lotsa stuff in there that is not G-code.  It's a mish-mash of G-code and non-G-code.  Specifically, the following words are NOT G-code:

Tool#
RAPID
LINE
FEED

MeshCAM should offer different posrt-processors to output G-code to suit different machine controllers, and there certainly should be one specifically for Mach3.

Regards,
Ray L.

1476

General Mach Discussion / Re: Motor won't turn

« on: November 10, 2008, 11:48:27 AM »

Hi! I'll send xml later, I'm at work at this moment. I started to look closer LPT connector and noticed that connector's pins are mirrored on pcb! So pin #1 is actually #13 and #14 is #25 etc.  I don't know is this done by purpose but pins would be ok if connector is soldered from bottom of pcb. I think that BOB designer has done mistake here.
Can I change Mach pin order so I can use this BOB anyway?

Mikko

Good grief!  What BOB do you have?  That is a MAJOR screw-up!

Regards,
Ray L.

1477

General Mach Discussion / Re: Spindle Speed Troubles

« on: November 10, 2008, 11:45:57 AM »

Hi Peter
After a lot of searching and reading through different forums, I came across something interesting not directly related to my components but put me on the right track. Firstly I hound with the C10 CNC4Pc BOB pins 1 14 16 17 only will give you an off/on control they dint have full motor functions. I tried pin 8 off BOB1 for the step comment to the digispeed and "SUCCESS the spindle speed will not fluctuate with axis movement. Now I'm left with the tuning of the motor in regards to the 0-10v output from the digispeed. I have set the motor tuning to 1000steps and velocity to 1450 which is nearly max.
I used 1450 as my spindle has a max speed of 14500rpm. In pulley setup i used pulley one min speed 0 max 1450 ratio 10.
The only trouble I have now is when you set the speed at max 1450 you get 10v, but when you set the speed at 725 1/2 speed you get 9v to confuse me further set the speed at 145 1/10 and I get 1v. can anyone tell me if and what Ive done wrong.
I also asked a question Earlier about Kerniel speed and what that should be set at? Or how do determine whats the correct correct speed 25kHz 35kHz 60 KHz ect.

I spent a lot of time setting up my spindle with a C10, and found the setting rather "fiddly".  Pulsewidth setting will significantly affect the response, as will steps/unit, and you have to play with both to get the response you're after, and to get the "S" values scaled as you desire.  In my case, I wanted the "S" values to range from 0 to 900, corresponding to 0Hz to 90Hz on my VFD.  I did eventually get there, albeit with some non-linearty.  But, on the days it beahves well, the error is less than 10%, and that is mostly at the very low end, where it's really not critical.  In the more usual operating range (40-90 Hz), the error is typically only a few percent.  Sounds to me like you may be getting a fairly linear response except at the top end, which suggests you're reaching 10V output well before an S value of 1450.  You can re-scale that response by reducing the steps/unit, so the output reaches 10V at an S value just short of 1450.  You'll have to determine the correct value mostly by trial and error.

Regards,
Ray L.

1478

General Mach Discussion / Re: manual feedrate override pot

« on: November 10, 2008, 11:37:05 AM »

Hood,

    Actually, you could do it with a normal selector switch as well, using diode logic, or a few logic gates.

Regards,
Ray L.

1479

General Mach Discussion / Re: manual feedrate override pot

« on: November 10, 2008, 11:00:34 AM »

Hey hood, (I hope to get this in while there are still signs of activity) he he

With the 3 momentary switches, I assume I would need 3 input pins. ? ? ?

With the rotary switch, would I need 1 input pin for each position ? Not sure.

Thanks,
RC

You can reduce the number of input pins required by using a rotary switch with binary or BCD coding.  That would allow, for instance, a 16-position switch to use only 4 input pins.   You'd then create a brain with 16 "lobes".  Each "lobe" of the "brain" would have to look at all four values to determine the switch position.

Regards,
Ray L.

1480

General Mach Discussion / Re: Z AXIS KNEE

« on: November 09, 2008, 02:54:41 PM »

My size 42 stepper drive BP sized CNC mill has Z on the quill, but my 55 year old back is tired of cranking the knee up and down so I'm adding an 1800 in-oz stepper motor to the knee also. I'll configure two start up files so I can use the knee for Z for heaving milling (quill locked) and the quill for Z for drilling, tapping, light milling.
So I'm going to have my cake and eat it too.

Ray L., I'd like to put some gas springs on my knee like you did, to you have any model numbers and the supplier info for the ones you bought?

Thanks,

Paul T.

Paul,

   The gas springs are from McMaster-Carr (www.mcmaster.com).  Just search on "gas spring".  I used two of the longest, heaviest ones they had - only $20 each!

Regards,
Ray L.