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Taking the CNC Plunge

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jbolt

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I cant rcall but is there anything in the uc100 config related to home limits?
 

TomS

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I cant rcall but is there anything in the uc100 config related to home limits?
I reread the UC100 installation manual and did not find any reference to configuring limit or homing switches. I did find that the I/O monitoring screen has a "home" indicator light. I'll check to see if it lights up when I home. If it doesn't then it could be a UC100 problem.

Tom S
 

TomS

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I reread the UC100 installation manual and did not find any reference to configuring limit or homing switches. I did find that the I/O monitoring screen has a "home" indicator light. I'll check to see if it lights up when I home. If it doesn't then it could be a UC100 problem.

Tom S
The homing light on the UC100 screen lights up when the switch is tripped while homing. Wasn't able to make any more progress today because the UC100 errors are back. Jeez, will it ever end!
 

jbolt

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The homing light on the UC100 screen lights up when the switch is tripped while homing. Wasn't able to make any more progress today because the UC100 errors are back. Jeez, will it ever end!
If I recall you are running the UC100 through a USB hub? If so try taking the UC100 out of the hub and directly to a USB port.
 

TomS

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If I recall you are running the UC100 through a USB hub? If so try taking the UC100 out of the hub and directly to a USB port.
Thanks for the suggestion but I was able to fix it by doing a clean boot of my computer. Evidently there was a program running in the background that was sucking up memory. Unfortunately I don't have enough computer savy to figure out what program was causing the problem.

Today was a good day. I fixed the UC100 problem and did my first CNC machining job. The mill worked flawlessly except the X and Y motors got very hot. So hot that you couldn't keep your hands on them longer than an instant. I think it may be a driver dip switch setting but will need to do more searching and reading before reaching a conclusion.

Here's my first try at CNC machining. I used a piece from my scrap bin so disregard the turned section at the top of the part. The drawing was made for a part that is twice as long as the one in the picture so that's why it looks the way it does. This is not a functional item just some g-code to see if I got the processes right.

20150531_151952_resized.jpg
 

JimDawson

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The mill worked flawlessly except the X and Y motors got very hot. So hot that you couldn't keep your hands on them longer than an instant. I think it may be a driver dip switch setting but will need to do more searching and reading before reaching a conclusion.

Check the idle current settings, maybe back down the operating current a bit and see what happens. Sounds like the motors are being driven over current.
 

TomS

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Check the idle current settings, maybe back down the operating current a bit and see what happens. Sounds like the motors are being driven over current.
Thanks for the tip. I was thinking along those lines as well. My motor voltage and current specs are 5.7V and Current 3.5A/phase. I need to check but the dip switches are supposedly set at off, off, and on for switches 1 thru 3. According to the chart on the driver these settings are for 4.9A peak and 3.5A RMS. Switch 4 is off which is the half current setting. The next lower current setting is 4.2A peak and 3.0A RMS. I'll try that and see if the motors run cooler.

Tom S
 

jbolt

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Test part looks good. Are you running any coolant?

Jay
 

wrmiller

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Congrats! Looks like you finally got this thing up and running. :)

Your efforts have given me further justification to never touch CNC... ;)
 

TomS

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Test part looks good. Are you running any coolant?

Jay
That part was cut without coolant. I've got a fog buster on my other mill that I will transfer over. Before I get too involved I've got to make an enclosure to contain the chips. Don't want any stray chips getting into the electronics.

Tom
 

TomS

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Congrats! Looks like you finally got this thing up and running. :)

Your efforts have given me further justification to never touch CNC... ;)
My goal from the beginning was to learn CNC. Still have a ways to go. Have to admit it's been a bigger challenge than I anticipated but with the help I received from forum members I was able to work through the issues. Special thanks to jbolt, jumps4, Jim Dawson and others for their guidance and support.

This thread isn't done by any means. I'm still a rookie.

Tom S.
 

jbolt

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I do like the no-fog system I made but I did learn this weekend that it is not sufficient for 5052 aluminum at high speed. It was impressive to watch a 1/4" carbide end mill at 6k load up and melt a path through some 1/8" 5052 sheet at 17 in/min. Flood coolant worked much better.
 

TomS

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I do like the no-fog system I made but I did learn this weekend that it is not sufficient for 5052 aluminum at high speed. It was impressive to watch a 1/4" carbide end mill at 6k load up and melt a path through some 1/8" 5052 sheet at 17 in/min. Flood coolant worked much better.
I'll keep flood coolant in mind when I'm building the enclosure. So you were plowing instead of cutting? Lol
 

coolidge

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For CNC I vote flood coolant and not some dribble pressure but a good proper blast to knock the chips out of the way. Remember to plumb a hose with a nozzle for machine clean up, that's one really nice thing about flood coolant you can hose down the entire machine which makes quick work of cleanup. Another is not having to worry about anything rusting. About the only place I had rust issues was under the Kurt vice.
 

coolidge

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I do like the no-fog system I made but I did learn this weekend that it is not sufficient for 5052 aluminum at high speed. It was impressive to watch a 1/4" carbide end mill at 6k load up and melt a path through some 1/8" 5052 sheet at 17 in/min. Flood coolant worked much better.
I was once milling a mold in some wood on my cnc mill...with the end mill rotating backwards, it was smoking and making a mess and I was cussing thinking I had bought a bad end mill...DOH!
 

jbolt

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It was more like friction milling. A cocept that never took off.

I like the mist for drilling and light work so I dont have to keep the enclosure closed.
 

TomS

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Did you figure out the motor heating issue?

Jay
Not yet. Wife and I have been out of town for the last two weeks. Will get to it today.

I thought about this a lot the last two weeks and it hit me that my power supplies are running on 220V. Could it be the driver dip switches are set for 110v thus drawing twice the necessary current? Seems to me I read in jumps4 build he had the same problem with the motors drawing way too much current.

Been watching your router build. The finished product looks nice. Hope you figure out the electronics soon so you make make chips.

Tom S
 

TomS

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Changed the dip switch settings to the next lower amp rating and the X and Y axis motors are still overheating. Set them two amp ratings lower and motors still running extremely hot; so hot you can't hold your hand on the motor for more than a second or two. The power supply rated output is 60VDC at 5.85A. I checked them with a voltmeter and both were 61.4VDC without the motors turning and 69.6VDC when running g-code. These power supplies have an adjustable voltage setting so I turned them down as low as they would go. The X axis PS is putting out 63.6VDC and the Y axis 61.8VDC. The voltage didn't change between static mode and run mode. Not sure if my initial readings were bad or the readings after the voltage adjustment are bad. Could the high voltage situation be the cause of the motor heating problem? As it is now I'm reluctant to run g-code for more than 45 minutes.

BTW - I cut a 2" nominal hole is some 3/8" thick aluminum plate and am extremely pleased that the is less than .001" out of round. Hole size was a bit off at 2.005" but I think I can fix it by recalibrating the steps/per.

Tom S
 

JimDawson

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Take a look at the idle current setting on the drives. It sounds like they are not switching down to idle current. That is way to hot, something is not right. The high voltage may be the cause, but the drives should limit the current.

Measure the end mill you are using. If it is oversize 0.0025, your hole would be oversize by 0.005. Most end mills are not exactly on size. You are correct in that you may need to fine tune the calibration.
 

jbolt

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I believe your X & Y motors are Wantai 85BYGH450C-012. The website says the operation range is -20c to 50c (-4f to 122f) with a max temperature rise of 80c ambient. If I read that correctly the max temp is 130c (266f) which I understand is the max temp rating for the wire insulation.

Have you measured the heat of the motors? My X & Y motors run between 100f and 115f.

What is switch SW4 on the driver set to, on or off?

Jay
 

TomS

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Take a look at the idle current setting on the drives. It sounds like they are not switching down to idle current. That is way to hot, something is not right. The high voltage may be the cause, but the drives should limit the current.

Measure the end mill you are using. If it is oversize 0.0025, your hole would be oversize by 0.005. Most end mills are not exactly on size. You are correct in that you may need to fine tune the calibration.
Jim - I've attached the driver manual and included my motor and driver specs for reference. When you say the "idle current" setting is that the same as the "standstill current" setting referenced in the manual? Currently my switch 4 is set to half of the selected dynamic current.

Stepper Motor

Technical Specifications

Part No: WT85STH151-3004B dual shaft 85BYGH450C-012B

Frame Size: NEMA34

Step Angle: 1.8 degree

Voltage: 5.7V

Current: 3.5A/phase

Resistance: 1.9 Ohm/phase

Inductance: 22 mH/phase

Holding torque: 11.3N.m/1600oz-in

Rotor inertia: 3600g-cm2

Number of wire leads: 4

Weight: 5 kgs

Length: 151mm


Note: Nema 34 stepper motor with 1600 oz-in holding torque on single shaft, front shaft length is 37mm with 25mm flats length, the diameter for motor shaft is 14mm.


RED = A+

GREEN = A-

YELLOW = B+

BLUE = B-


Stepper Motor Driver

DQ860MA

Introduction

The DQ860MA is an economical microstepping drive based on patented technology of Wantai Motor. It is suitable for driving 2-phase & 4-phase hybrid stepping motors. By using the advanced bipolar constant-current shopping technique, it can output more speed and torque from the same motor compared with traditional drivers, such as L/R drivers. It’s 3-state current control technology allows coil currents to be well controlled and with relatively small current ripple, therefore less motor heating is achieved.

Features

Low cost and good high-speed torque

◆14 selectable resolutions

◆Supply voltage up to +80VD

◆Suitable for-2-phase and 4-phase motors

◆Output current up to 7.8A, 5.86A rated current, 256 Microstep.

◆Dip switch current setting 8 different values

◆Optically isolated input signals

◆Pulse frequency up to 200 KHz

◆Automatic idle-current reduction

◆Small size (107*97*48), Weight: 0.6KG

I'll measure my cutter but you raised a good point. It could also be my asian set screw holder has some runout. I'll also try my collet and see what happens.

Tom S
 

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JimDawson

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Jim - I've attached the driver manual and included my motor and driver specs for reference. When you say the "idle current" setting is that the same as the "standstill current" setting referenced in the manual? Currently my switch 4 is set to half of the selected dynamic current.
Yes, Idle current = standstill current. In the manual is also a reference to: 4) Semi-flow function: Semi-flow function is that there is not step pulse after 200 ms, the driver output current automatically reduced to 40% of rated output current, which is used to prevent motor heat. I'm not exactly sure how this is implemented, or if it it overridden by SW4:confused 3: The manual is a bit vague on this subject.

I have two of almost the same setup on the bench right now, same drives, but 1200 oz/inch, 5.6 amp motors. They're getting ready to drive Alloy's Shizouka tool changer and variable speed control. I'll pull one of the drives out of the panel tomorrow and see how it reacts. We are a couple weeks away from firing it up, and I need to test the new tool changer gearbox on the bench anyway.
 

TomS

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Yes, Idle current = standstill current. In the manual is also a reference to: 4) Semi-flow function: Semi-flow function is that there is not step pulse after 200 ms, the driver output current automatically reduced to 40% of rated output current, which is used to prevent motor heat. I'm not exactly sure how this is implemented, or if it it overridden by SW4:confused 3: The manual is a bit vague on this subject.

I have two of almost the same setup on the bench right now, same drives, but 1200 oz/inch, 5.6 amp motors. They're getting ready to drive Alloy's Shizouka tool changer and variable speed control. I'll pull one of the drives out of the panel tomorrow and see how it reacts. We are a couple weeks away from firing it up, and I need to test the new tool changer gearbox on the bench anyway.
Thanks Jim. I'm going to change switch 4 to "ON" (full current) and see what happens.

Tom S
 

JimDawson

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OK, I ran some tests on the bench.

Equipment:
Wantai WT86STH118-6004B 1200 oz/in stepper motor 5.6 amp
Wantai DQ860MA Drive
60 Volt Power Supply
Stepper Speed Controller
3M Infrared thermometer

Conditions:
Motor clamped to a wood bench with a C-clamp, 3 sides exposed to still air
800 Step / Rev, SW 5 OFF, SW 6,7,8 ON
5.6 Amp, SW1,2,3 OFF
SW4 OFF
Power Supply voltage = 60.0

I took a temperature reading every 5 minutes during the test
Ambient temperature at START of test = 77 F
Starting temperature of motor case = 88 F
The first 10 minutes was Power ON, Motor OFF to test standstill temperature rise.
At 10 minutes I turned the Motor ON, about 1 REV/Sec (equivalent to 12 IPM on a 0.200 pitch leadscrew)
Maximum temperature was at 55 minutes (45 minutes running time) = 161 F
The last 15 minutes (55-70) was power ON, Motor OFF to test standstill temperature again.
Ambient temperature at END of test = 80 F

As you can see, the temperature rise was pretty constant as long as the motor was running. I don't know what the max safe operating temperature of the motor is. The high temperature is due to running current, not standstill current.
Step Thermal.jpg

The only suggestion that I have is to turn down the current to the minimum that will run the machine.

.
.
 

TomS

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Thanks Jim. I'm going to change switch 4 to "ON" (full current) and see what happens.

Tom S
Well, that didn't work. The motors got hot without much movement. Did some web surfing on stepper motors running hot. Found lots of comments but no real answer on how to address it. Comments included adding cooling fans to installing heat sinks. I'm more interested in fixing the root cause. What I found interesting is some commentors say 100 to 110C is considered normal. That's 212F to about 235F! Harbor Freight has a non-contact infrared thermometer for $12. Might give that a try to determine how hot my motors are actually running.

Tom S
 

TomS

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Just posted then I saw your post. Were you able to hold your hand on the motor longer than a few seconds? I've read that 140F is the maximum pain threshold. If this is true then my motors may be running about the same temperature as yours.


Tom S
 

TomS

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Towards the end of the test I really didn't want to touch it, pretty hot.
Maybe I don't have a problem. I'm off to Harbor Freight in the morning to buy the thermometer. Thanks for your help.

Tom S
 
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