mini mill dc spindle speed control (newbe)

[chrisplashek]

Hello All,


First time poster short time reader.

So this whole cnc thing is all new to me. I have been reading and studying as much as possible. As I have narrowed down my first project. I feel I should first give you the story why I am here in the first place.


The robot

It started last September. I got the crazy idea that I would like to build a robotic arm like we had in shop as a kid. This project would be fun for me and my kids to play with and learn. While looking online and researching the robot build, I ended up on a cnc router page and then cnczone.

The router

the router is interesting to me. You see at the shop I work at we have 10' x 5' cnc router, so the plan changed, to a router. After much more research, a few Ebay parts and some debating, I realized that the bearing kits and slides available online were some what restricting to my limited budget and wood is out of the question.

The Mini Mill

This has brought me to the mini mill. I am sold on the Harbor Freight Central Machinery Model 47158. Though small it has the potential to machine the expensive bearing blocks for the router I would eventualy still like to build. I have 3 small nema 23 steppers, Minebea co. Type 23km-k series. I got these on Ebay for about $50 with S and H. These motors were a custom build for Kodak. Therefore the specific specs were not available to me. I emailed them on the specs and I recieved no reply. I figure they can't give out the specs because of some restrictions with Kodak. This led me to buy both a unipolar driver kit and a bipolar kit. The unipolar board with 3 drivers was a cheap buy, $26 on Ebay. The card was an old design so I decided to rebuild it. The IC's are Allegro 5804 unipolar stepper drivers. With some research I narrowed down a design for a new controler card. In the meantime, I also purchased a SteppmasterNC model SOP-2b 4 axis controler. It came a few days ago and the 5804's have gone to the back of the bench. Now this was a hare rasing event, nowing vagley that the motors were around 107 oz, somewere between 1.5 - 3 amp and no clue if bipolar or unipolar . I fearlessly pluged one motor into the SOP-2b and fliped the power switch. The initial test went good, the motor locked and no sparks flew. If it had, the $300 driver investment would have gone up in smoke, but it didn't. So I loaded Mach 2. After about 2 hours of poking around Mach 2, I finally realized that I couldn't find the manual jog controls becouse my screen resolution was set for 600x800. After reseting the resolution, I found it and yes the motor moved!!!!

So here I am Driver, motors, cam and cad softwares and ready to invest in the mill. I know the motors will be a little weak, I am already looking for new ones, Got any ideas?

This leads me to the original question,

HOW IN THE WORLD DO YOU CONTROL THE SPINDLE SPEED?!!!

I know from the PDF on the mill that the spindle motor is DC. I am thinking of just a relay to let Mach 2 turn the spindle on and off, then controling the speed (high and low) manualy. Though this seams a bit cave man to me. I have found a few speed controlers on ebay but, budget in mind, know that it will be much cheaper to assemble a variable speed spindle control. Any Ideas???

I do not, as of yet, have the specs on the spindle motor. I can assume that it is 12v-24v and 2 to 7 amp. The PDF on Harbor Freight dosn't get that specific.

Thanks for listening to my adventure so far and any feed back and advice will and is greatly appreciated.


Thanks,

Chris

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[Ninhil]

Are you talking about letting the g-code in mach3 control the spindle speed through an extra setup of electrical wiring to the spindle motor?
I would be soo interested if somebody had the solution for you, because I would also benefit.

I suppose that if the spindle was a brush motor, you could rig up a four-axis kit to the spindle motor... over at the gecko site, there exist two controllers for DC Brush motor drives!
Gecko Drive for dc brush motor

So if you did indeed purchase a 4-axis controller kit, could you make sure the MACH3 progrom recognized the the 4th axis as the spindle motor to adjust RPM only and not the typical 4th axis?!

It would look like this : Mach3 > 4-axis kit > 3 stepper motor controllers & 1 brush motor controller > 3 Stepper motors and 1 Brush motor for spindle

I am very interested to hear back! (Otherwise it would mean you would have to set up speeds manually without this spindle motor setup.)

[chrisplashek]

I was thinking really of just a MOSFET design that would plug into mach via serial or second LPT. Possiblly including some relays for limit switches and an ESTOP. Though what you are suggesting is to atatch a DC motor to my 4th axis (A) driver and to control rpms from there. It would be possible but, a least in my case the heat created from runing at high rpm would probablly burn out the driver. Mach 2 has a spindle speed control along with other varios controls through the M code. I have not played around with the program that much to tell you exactly how. Basicly what I am looking for is a stardard speed controller that goes from 0 to X rpm and has a 5v input for control and an output to return rpm readings to Mach software.

[phomann]

Basicly what I am looking for is a stardard speed controller that goes from 0 to X rpm and has a 5v input for control and an output to return rpm readings to Mach software.

Hi Chris,

Have a look at the DigiSpeed products I sell. They take the spindle speed PWM control signal from Mach2/3 and convert it into an isolated DC control voltage suitable for most, if not all spindle motor controllers.

http://homanndesigns.com/store/index...&products_id=2

http://homanndesigns.com/store/index...products_id=21

The DigiSpeed-XL includes a number of useful features such as small onboard relays that can be used to control spindle reversing circuitry and spindle brakes,etc. It also has signal conditioning circuitry for spindle speed sensors, in addition to neatly routing the index sensor signal to your breakout board via the same cable used to control the DigiSpeed.

The DigiSpeed-GX is a much more minimalist controller, just producing an isolated control voltage.

Cheers,

Peter.

[chrisplashek]

Peter,

I looked your XL board over and I think this is a good starting point. I will have some dificulty with the wiring. The speed controler on the mill has a high and a low setting. I glanced at the wiring diagram (of the mill) and some how I will have to "tap in" after the on-off switch.

Here is the PDF at Harbor Freight:

http://www.harborfreight.com/manuals...7999/47158.pdf

I have limited abilities with advanced wiring. Could I bypass everthing past the 12vdc transformer/on-off knob and route it to your board?

This mill also has no RPM sensor what would I need for one?
Would I be able to control this with a standard DB-9 serial port or would I have to control it by a second DB-25?

Sorry for all the questions, this is uncharted teritory for me. I can see everthing is there on the DigiSpeed-XL , just implementing it into the existing controls will be a very big task.

Thanks,

Chris

[phomann]

Peter,


Here is the PDF at Harbor Freight:

http://www.harborfreight.com/manuals...7999/47158.pdf

I have limited abilities with advanced wiring. Could I bypass everthing past the 12vdc transformer/on-off knob and route it to your board?

This mill also has no RPM sensor what would I need for one?
Would I be able to control this with a standard DB-9 serial port or would I have to control it by a second DB-25?

Sorry for all the questions, this is uncharted teritory for me. I can see everthing is there on the DigiSpeed-XL , just implementing it into the existing controls will be a very big task.

Thanks,

Chris

Hi Chris,

Apologies for the delay in repling.

Firstly, the RPM sensor. I've had good success with the omron EE-SY672 sensor. It is a reflective one. On my Taig mill, I point it at the aluminium spindle pulley and have segments drawn on it with a black permanent marker pen. The good thing about this sensor is that it has an inpuilt amplifier with a sensitivity control and a LED indicator to show when it detects the segments.

Mouser has them for about $25.00

http://www.mouser.com/catalog/629/1537.pdf

http://www.mouser.com/search/Product...ey653-EE-SY672

Also they have matching connectors and cables EE-1006

http://www.mouser.com/search/Product...key653-EE-1006

This is as close to plug and play as you can get.

Other sensors can be used with the DigiSpeed-XL though as it has its own index signal conditing circuitry on board so that a more basic sensor can be used. I know that the Sherline Tacho sensor works using the DigiSpeed-XL.

As to using the DigiSpeed-XL to control the Mills spindle I have no boubt that it can be done. The schematic in the PDF file is not clear. Basically it would replace the manial Speed pot connected to P1,P2 and P3 on your controller.

The existing potentiometer has a switch in it. Is it necessary to turn the switch off and then on when turning onm the mill so that it doesn't start unexpectantly?

The DigiSpeed has a "Zero Speed" relay that is active when the speed is zero. You may be able to use it in place of the one in the potentiometer.

Cheers,

Peter.

[chrisplashek]

Thanks a lot Peter. I think I am sold on your XL board. I will be buying the rest of my components in the next few weeks. Any Idea on the shipping time From Aus to Michigan?


Thanks for all the help

Chris

[phomann]

Thanks a lot Peter. I think I am sold on your XL board. I will be buying the rest of my components in the next few weeks. Any Idea on the shipping time From Aus to Michigan?


Thanks for all the help

Chris

Hi Chris,

Order to the USA are sent via registered Airmail. Delivery is 10 to 14 days.

Cheers,

Peter.

[joroqui]

Hello everybody:

This is my first post since I have registered as a member of CNC Zone because my English is very poor. Sorry.

I am a mechanic hobbyst and I live in Argentina (Buenos Aires city).

Because I am an electronic engineer, the mechanic is not my job, but I like it so much.

This is the reason because I have bought a 7x10 mini lathe and a mini mill.

I am learning how to use this machines and I am practicing with them.

Because I have read that the mini mill gear's breaks frequently, I have decided my first project will be to convert my mini mill gear's in a pulley-belt one.

I have made 2 pulleys with the mini lathe and all the mounting system for the motor.Then, I replace the mini mill spindle gear's with them. I can't believe how good it works.

My next project is to make a torch using Luxeon white power led's controled by mean of an electronic constant current circuit.

Thanks and good by.

Jorge

[Ron111]

Joroqui,
Welcome aboard!!

You will be happy to know that we have a mini-lathe forum also. I have also enjoy lathes and have converted a couple to cnc. Lots of good reading there on modifications to manuel lathes.

Take care

Ron

[tpworks]

http://www.cnc4pc.com/Store/osc/prod...roducts_id=149

[jheyne]

Thanks a lot Peter. I think I am sold on your XL board. I will be buying the rest of my components in the next few weeks. Any Idea on the shipping time From Aus to Michigan?


Thanks for all the help

Chris

Chris,

I was wondering if you ever got a solution to work for you on the motor control wiring. I'm in the process of a conversion of the same machine you are using and investigating options for the spindle control. I'm using a china 5 axis cnc controller that I got off of ebay and mach 3. Any information you could pass along about wiring up the spindle would be greatly appreciated. Thanks