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Re: Spindle Speed Troubles
« Reply #10 on: November 09, 2008, 10:34:48 PM »
Hi Again jimpinder
I had a good chance this afternoon to do some other tests and try different things. Firstly I took all the power and neutrals to the digispeed from a separate power source, no good. I am in the unique position as well were I am running two BOBs of Se perate Ports. I swapped the digispeed to the other port still to no success. I tried using different pin no.s to no avail.
I think there is something more menacing than a small glitch were I disabled the the spindle in the ports and pins motor outputs config. and the spindle still fires up with the same problem. I am really starting to lean to that the Digispeed board itself is faulty or has some glitch in it. Not sure to replace it with a C6 speed control from CNC4PC or try another Digispeed.
I can get hold of an Oscilloscope (I think if its still there)but I wouldn't have clue how to use it or what I'm looking at.

Hi,

If you can use an oscilloscope, connect it to the step input on the DC-06. Enable the spindle and set a spindle speed so you get a constant smooth step frequency.( At some frequencies the step pulse jitters about a small amount as Mach cannot produce a pulse stream at all frequencies, so adds in extra pulses where needed.)

Then while monitoring the scope, move an axis and see if the step pulse stream changes frequency.

Do the above test with the spindle drive powered up and with it turned off. Let us know what you find.


Cheers,

Peter.




Then

----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Katoh

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Re: Spindle Speed Troubles
« Reply #11 on: November 10, 2008, 12:07:17 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.
Cheers
Katoh

Offline jimpinder

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Re: Spindle Speed Troubles
« Reply #12 on: November 10, 2008, 04:43:18 AM »
I thought the CNC boards might be the problem - glad to see you have it fixed. I was on a bit of a wrong track, becasue I was thinking you were using PWM control, not step and direction - but we didn't get that far anyway.

Do not worry yourself about the "kernel speed" This is the base speed the computer runs Mach at. Mach works perfectly at 25 kHz. If your computer is capable then you can run it faster, I run at 35 kHz (I must admit, I have not seen much difference between 25 and 35).

As far as motor tuning is concerned with spindle speed, then  if you read the Mach instructions, there is a full explanation, and Mach can set your speeds automatically, if you have some form of tachometer fitted. This is a simple signal from the spindle to the computer once per rev. and from that Mach3 computes the speed.

You may need different speeds for different jobs - e.g I turn steel - 6.5 inch diameter wheels - a "slow" job. I also, on the same machine turn brass - a "high speed" job, and my machine also has a milling head so I look to 4000 rpm and maybe above for that,
The trouble is my electric motor - which is 3 phase, will only turn to a certain maximum. On the other hand, if I slow it down too much say below 50% of it's maximum, I loose torque (power) and cannot cut properly. You must, therefore make use of a gearbox or pulleys to control the spindle at speeds at which the motor is comfortable.

The speed  of each motor/pulley combination is known (certainly the maximum speed) and Mach 3 can set the output from the computer to give the required speed. It will also tell you if you are trying to go too fast (or too slow) on a certain pulley set.

Start with Pulley 1 (See Config/Pulleys) and set the speed from 0 to your maximum. Select Pulley one on the settings page. You should find that (even without a tachometer) that Mach3 has a reasonable stab at setting the right speed. If you fit a Tachometer, Mach can keep to within 2 or 3 rpm of the selected speed.





Not me driving the engine - I'm better looking.

Offline Katoh

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Re: Spindle Speed Troubles
« Reply #13 on: November 10, 2008, 08:01:52 AM »
Hi Jimpinder
Many thanks to yourself , Hood and Chip for the replies and suggestions.
The spindle is running as Sweet as Sweet can be.
Just so I ramble on a bit I should start another thread but Ill keep going with this one.
To those who are interested My Machine is.
3200mm long x 1800mm wide by 1200mm high moving gantry router.
Its X axis has a cut of 2700mm Y, 1250mm and Z, 260mm
It is run by 5x 900z/In steppers run by G201 Geckos and fed with 40amps of 48VDC.
Its constructed of Steel framing with Aluminum Gantry and aluminum parts machined on a Friends CNC also running Mach.
The spindle is a Fimec 3.5Kw (5hp) 380volt direct drive controlled with an AcTech VFD.
The machine is very happy running at 3000mm/min (118"/min) and is capeable of 6000mm/min(236"/min) without loosing steps.
the X axis is driven by Duel Rack and Pinion, the Y and Z 3/4" ball screws.
All three Axis are guided by Igus Drylin-W linear glides. (100%dust resistant and extremely accurate.)
Its Taken me just over one year to build and still not complete as I have plans for a 4th axis and Vac Table.
The Machine weighs approx. 1100Kg (2420Lb)
Ill postsome photos at completion. If any one wants more info about it please just ask me Ill be more than happy to share what I have done and learnt.
Cheers
Katoh

Offline Hood

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Re: Spindle Speed Troubles
« Reply #14 on: November 10, 2008, 08:12:53 AM »
Sounds like a nice router, looking forward to the pics and you dont have to wait until its finished, its often nice to see machines as they progress :)
Hood

Offline Katoh

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Re: Spindle Speed Troubles
« Reply #15 on: November 10, 2008, 08:32:52 AM »
Thanks Hood
Ok Ill Take some pics and post them tomorrow night. If I can work out how to get the pics on the forum.
Cheers
Katoh

Offline Hood

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Re: Spindle Speed Troubles
« Reply #16 on: November 10, 2008, 08:37:40 AM »
On the reply page you will see an additional options tab (lower left) you can use that to browse your drive for the images.
Hood
Re: Spindle Speed Troubles
« Reply #17 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.
Regards,
Ray L.
Re: Spindle Speed Troubles
« Reply #18 on: November 10, 2008, 08:14:36 PM »

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.

Regards,
Ray L.

Hi Ray,

When I way developing the DigiSpeed DC-06,  I designed in circuitry that eliminates the step pulse from affecting the output voltage. The charge pump of the 2907 reacts to the energy in the step pulse, so if the step pulse is fed directly into the chip and the pulse width varies, then so will output. To eliminate this the DC-06 feeds the 2907 with a constant step pulse width regardless of the pulse width sent from Mach3.

When setting the max velocity of the Spindle axis in setup tab, a common problem that many do is provide too many steps, resulting in the maximum output voltage being reached before the maximum RPM setting in Mach is reached. This is then seen as a non-linear response in the actual vs desired speed.

The way to tue a DC-06 correctly is to do the following;

1. Determine the maximum speed of your spindle, for this example assume 10,000rpm.
2. Set your Max pulley speed in Mach to 10,000
3. Set the steps/unit  to 1000 in the spindle axis of the motor tuning tab and set the velocity to its max value allowed
4. run the spindle with the desired rpm set to 10,000. This will run the motor as fast as possible.
5. Adjust the output voltage attenuation potentiometer so that the output voltage is set to the maximum recommended for the VFD or motor controller.
6. leaving the desired speed set to 10,000 go into the motor axis tuning tab and start reducing the max velocity until the motor rpms start to drop.(you will need to in and out of the motor tuning tab to do this.

The point at which the rpms just starts to drop is where the output control voltage is just managing to reach the 10V required to drive the motor at max speed. With this setup you should get a reasonably linear relationship between the desired and actual speed.

Also note that these speed controllers are basically open loop and can be affected by external factors. For example a cold motor/drive-train may have more drag on the system than one that is warmed up, and therefore the speed my read slightly less until it has been running for a while.

I hope this helps,

Cheers,

Peter.

----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Katoh

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Re: Spindle Speed Troubles
« Reply #19 on: November 11, 2008, 03:26:49 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.
Cheers
Katoh