[Help] New Project - Rebuild an Old CNC Machine

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29 May 2013 08:38 #34889 by EngEC
Hi there! :cheer:
I am new to this world, so I apologize right now if I am not accurate with the questions. :silly:
I am in my final year of Electronic and Computer Systems Engineering, and my final project is to rebuild an old cnc machine.
The machine is an old Lathe (turning), so I have 3 stepper motors [2-phase Hibrid Stepper] (XZ and a tool-changer), a DC motor [3500RPM] (spindle) and an air compressed claw (that secures' the piece).

I have seen some stepper drivers, but cannot find a cheap and good driver to my DC motor, do anyone know where can I find some?

I have chose linuxcnc as my main controller because of their outstanding caracteristics, but I am new to this and I need some guidance. I've already installed the computer (I'm current waitting for the drivers), and I dont really know how the software works. Does the GUI change from milling to turning?

I've already read the manuals from tip to toe, but I haven't still done the amount of work necessary to know If I am in a good track. Can anyone help me?

I've attached a file with some photos if anyone wants to see.

Again I apologize if I am being incoherent with something I just wrote.

Thanks for every reply, and If anyone has a question, leave it here that I'll reply as soon as possible.

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29 May 2013 14:21 #34897 by cncbasher
Welcome to the world of Linuxcnc !
yes the gui will change from milling to turning , this is done in the configuration process , stepconf is the configuration setup program , which will help in at least getting started , after that you can hand edit the files as required once you learn a bit more .

we need to know a little bit more as it appears your pictures have not appeared as yet , what voltage and horsepower rating of the motor ?
what stepper drivers have you bought ?
what is the make and model of the Lathe ?

don't worry about questions , all will become clear , their are many knowledgeable and helpful people here .
that can guide you
The following user(s) said Thank You: EngEC

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29 May 2013 18:21 #34906 by BigJohnT
There are restrictions on files uploaded see this thread for info.

It would also help to know what part of the world you are from for supplier recommendations.

JT

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11 Jun 2013 18:09 #35525 by EngEC
Hi there! :cheer:
Thank you for the reply!!

Sorry for the long time, but I've been under a ton of work, still...


Components:
*******************************
2-phase stepping motor
A2578-9412
3V 4A/Phase
1.8º/Step
*******************************
2-phase stepping motor
A2578-9412
3V 4A/Phase
1.8º/Step
*******************************
2-phase stepping motor
A2583-9412
5.5V 1.25A/Phase
1.8º/Step
*******************************
DC Servo Motor
TYPE: ODM-1100
1.1kW 135V 9.2A 3500RPM (1.5HP)

OHM ELECTRIC CO.,LTD. JAPAN



Does anyone have an Idea of what drivers will I need?
I've seen some "M542H" driver, and some geckodriver's, but I am still a little apprehensive

Cheers ;)

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11 Jun 2013 19:40 #35529 by emcPT
The gecko drives (steppers) are suitable for your steppers.
The gecko drive for servos is not suitable for the servo that you have as the voltage is higher than 80V (at least when I used gecko for servos the max voltage was 80V).
You have a suitable drive available that is from granite devices. I use them and I like them. They also have solutions for steppers.

If I was you, I would buy from granite devices. My opinion.
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11 Jun 2013 21:56 - 11 Jun 2013 23:10 #35533 by EngEC
The servo it's mount as a DC motor, it's the motor from the spindle

I'll give it a look, thanks for the help emcPT

edit:
emcPT, thanks so much!
This is just the thing I was looking for... The costs of the project had diminished!

Cheers ;)
Last edit: 11 Jun 2013 23:10 by EngEC. Reason: more information, w/o reposting

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30 Aug 2013 23:19 - 30 Aug 2013 23:32 #38254 by EngEC
Hi there!

I have progressed with the machine, the hardware aint a problem now, but now I am asking some help with this awesome software. :P
I need to use PWM to control spindle, but I have a problematic situation, I achieve 3500 RPM with the motor, and have a differential encoder that turns 2 times that value, making the 7 kRPM. The problem is that the encoder is a differential encoder with index 1024ppr. Do I have a solution for the high-frequency? (I've read that the max frequency of the HAL encoder component is 10~50 kHz) :S
These PWM must be 50~95% (for CW) and 5~50% (for CCW), is there a component that I can use? [note: the 50% means that the motor is stopped]

Another thing, how do I connect the g-code interpreter with the HAL components? and this ones with the GUI?? :silly:

Thanks alot, you guys are great! ;)

P.S.- When I finish the machine I'll post it over here for those who helped me (and for those who just like these kind of machines) see the "master-blaster" :lol:
Last edit: 30 Aug 2013 23:32 by EngEC.

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31 Aug 2013 09:59 - 31 Aug 2013 09:59 #38278 by andypugh

Hi there!
I have progressed with the machine, the hardware aint a problem now, but now I am asking some help with this awesome software. :P
I need to use PWM to control spindle, but I have a problematic situation, I achieve 3500 RPM with the motor, and have a differential encoder that turns 2 times that value, making the 7 kRPM. The problem is that the encoder is a differential encoder with index 1024ppr. Do I have a solution for the high-frequency? (I've read that the max frequency of the HAL encoder component is 10~50 kHz) :S
These PWM must be 50~95% (for CW) and 5~50% (for CCW), is there a component that I can use? [note: the 50% means that the motor is stopped


I will note that both you and EmcPT are in Portugal, and you may want to talk offline or here in your native tongues, that is OK.

7krpm x 1024 ppr is 120kHz (or possibly 500kHz depending on how the ppr is measured).

It is not possible to track that with a parallel port. Two popular and well tested alternatives are:

pico-systems.com/osc2.5/catalog/product_...ath=4&products_id=30

Which connects to the parallel port and has on-board stepper pulse generators and encoder counters and misc IO or:

www.mesanet.com/fpgacardinfo.html

(look for the 5i25 / 7i76 plug-and-go) Unfortunately it is impossible to link to a product on the Mesa site in such a way as to make it possible to find the top level without guessing the URL.
However that is a similar product that plugs into a PCI slot and provides hardware step generation, miscellaneous input and outputs and also a spindle encoder input (plus spindle control voltage)

Mesa also have parallel-port connected cards (I use one myself) but the daughter card choice is wider and more confusing :-)
Last edit: 31 Aug 2013 09:59 by andypugh.

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31 Aug 2013 10:10 #38280 by PCW
a 1024 PPR encoder will have 4096 counts per turn using quadrature so ~600 RPM is about as fast as it can be tracked with the software encoder. Probably the simplest solution if you need to track higher speeds would be to swap the 1024 PPR encoder for a encoder with lower PPR, say 50 or 100 PPR. You can add hardware that will count the 1024 PPR encoder but this is probably overkill.

I do have CPLD code for a encoder divider that can divide the count by 2 to 64 (and stretch the index pulse appropriately) that could be used to lower the effective PPR of your existing encoder, if you are comfortable with CPLDs (a $2.00 part will do)

As far as the PWM goes I think that should be relatively easy using the offset parameter of the PWMGEN component (offset 1/2 way up). You will need to be careful to have the spindle enable working since the PWMgen output will be at 0 (full speed CCW) before linuxCNC starts and when the PWMGEN is disabled...

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31 Aug 2013 16:45 #38296 by emcPT
In my opinion the most simple (and less expensive) is really to use a lower count encoder, like PCW suggested.
It only makes sense to have a high definition encoder if you need to use that same encoder to move the spindle with accuracy (normally C axis). If it is only for speed, use a low cost, low definition encoder.

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