Cutting properly after debugging - Milwaukee, WI

[tnarch]

Hi everyone

What a great forum!!!

I started reading the forum sometime back in April and started construction in August. It's been a challenge and a "enjoyable" learning curve with zero metal fabrication experience. I've really learned a lot and been having a lot of fun!

Photos to follow soon.

Tuan

[tnarch]

progress

[tnarch]

not sure if someone else posted this technique for handling the clamp strip for the y-rails attachment. the steps below worked for me on the first try with great ease

1. thread a wire through the hole at one end of the tube
2. feed the clamp strip through the gantry tube leaving the end hole visible
3. feed the wire through the hole on the clamp strip
4. attach a stopper -washer in my case- to the underside of the clamp strip
5. feed the clamp strip all the way in and use needle nose to retrieve it on the other side
6. repeat 1-4
7. pull on both wires to bring the clamp strip to bring it up
8. attach fasteners for all the holes accept the end ones
9. once clamp strip is held in place, pull the wires out.

[Gerald D]

A smart fishing technique!

[MetalHead]

Very good explanation.

[tnarch]

Gerald: great analogy

Mike: Thanks for the compliment. I hope other new builders will find it helpful.

[tnarch]

need some help with cables. some of the resources i found online - charts and rules of thumb - suggested that i would need at least 16 awg to draw the 4.5 amps needed for my motors. is this really case or can i use the 18/4 that's been discussed a lot here on the forum? i'm looking to cut cost.

motors are these: http://www.kelinginc.net/KL34H280_45_4A.pdf

[MetalHead]

Did you get these already? Also if you got them from John did you get matching drivers and power supply? These motors run at over 80 volts which is to high for the Gecko Drives.

http://www.kelinginc.net/KL34H280-45-8A.pdf

8 wire version - ran Bipolar or Unipolar will run at about 48v which is better if your using the Geckos.

Wire guage I think would be 18 to 21 gauge. But I'll let others talk about that while I do aome more research.

[tnarch]

Mike, the motors are purchased. I did get them from John with 201x geckos and this for power supply http://www.kelinginc.net/KL-6520.pdf He has a MM package with motors at 900 oz-in. I downgraded the motors and upgraded the drives to 201x geckos.

As for the wire gauge, the wiring diagram for the motor specified "UL1430 AWG20# LENGTH 500+-20". I think 18-20 would work too. I thought I double check on here. However, your comment about the voltage is sending me back into research mode for the motors. Thanks Mike.

[MetalHead]

I think your motors will run on this config. They will just be derated.
This is more for Mike or Brad to talk to .

[EricW]

holy crap, another guy from wisconsin? Where are you?

[tnarch]

eric, i'm in milwaukee. you?

[EricW]

Eau Claire, but I'll be in waukesha for thankgiving.

[Richards]

The KL34H280-45-4A motors have an inductance rating of 6.8mH, which means that they can use up to 83VDC. The G201 Geckos are limited to 80VDC. The power supply that you specified has an output voltage of 65VDC, 65v / 83 = 78% of possible speed. (The power supply data sheet shows that optimum voltage for that power supply is about 52VDC, which is about 62% of the optimum voltage for those motors.) On a CNC router, that should not be a problem, unless you build a high ratio belt drive.

If you geared the motors down to 3.6:1 with a belt drive, and if you used a 1.25" diameter spur gear, you will move an axis 1.0908" per motor shaft rotation. So, 750 RPM X 1.0908" = 818" per minute or about 13" per second for your jog speed. That is plenty fast. I've never used the KL34H280 motor, but all of the motors that I have on hand can reach at least 750 RPM even with a power supply that delivers only 50% of the optimum voltage.

Normally I recommend that you select a motor based on the torque that you need (direct drive or geared), then you look for a motor that has low inductance that is able to produce that amount of holding torque. (I look for motors that are rated from 1.5mH to 3.5mH bipolar parallel or half-coil.) After deciding on the motor, you then select a power supply that give 75% to 100% of the optimum voltage (32 X SQRT( Inductance)). Add together the current requirements of all motors and then multiply that number by 66% to get the actual current requirements for a CNC router.

Gecko has redesigned the G201 drives and replaced them with the G201x; however, the G201 should work just fine. I have four G202 stepper drivers on my test bench as well as a bunch of G203v stepper drivers. The G202, which is a slightly updated G201, works very well for me. Be sure to add a 470mF capacitor to the power terminals on each stepper driver.

Wire gauge is kind of a black art. The charts give two ratings, chassis and power transmission. 18 gauge wire is rated 16A for chassis wiring, but only 2.3A for power transmission. I have never used anything heavier than 18 gauge on my machine and I've never had any trouble.

[tnarch]

Mike

Thank you! Having an experienced builder saying there "...should not be a problem" is comforting

I plan to eventually gear the motors. The goal at present is just to get the machine cutting. One question about the ipm calculation: how did you get the 750 rpm?

I did go through the math you described in your recommendation after reading about it in one of the posts on selecting motors or power supply. Perhaps this is the reason I'm not too far off from optimal specs even though the choices were made based on cost.

As for the drives, is the use of the capacitors to regulate to voltage coming from the supply? How did you calculate 470mF (milli-Farad)?

I will follow your lead on wire/cable.

New question: I'm planning to buy this contactor since I'm using a 220V 20amp supply. Does this check out? http://www.factorymation.com/s.nl/it...=2&category=16

[MetalHead]

That contactor is a whole other question

I have a Basic Starter Setup listed here.

http://www.mechmate.com/forums/showt...7&postcount=36

It uses the CU-22-F6 contactor. I have been studing this and see that just because you feed 220v to your machine does not mean you need a 220v contactor coil. You can pull off one of your legs to power the coil. In file Part4 drawing 1070130CA (page 3) you will see a 220v feed and a 120c contactor. it is rated at 16 in that drawing but the 22 is what I have here in my BC01 kit.

You can break a contactor down into three parts (in this format without the thermal overloads added) .

You have the following

1. Coil
2. Input/Output (L1,L2,L3 and T1,T2,T3)
3. NC/NO switches on the side of the contactor.

I am working on a write up of how the contactor works.

[Richards]

Tuan,

750 RPM is just a 'standard' figure that I use to that should work with most motors. (When a motor is wired half-coil and the motor/power supply/stepper driver are matched properly, the torque curve usually still has usable torque at 750 RPM.) With a Geckodrive stepper driver, 750 RPM eqates to 25,000 step pulses per second, which should work even with Mach 3 used in evaluation mode.

I assume a 1.25" spur gear (which is 25-tooth with the rack on my old Shopbot). So:

1.25 inch X PI = 3.927 inches per shaft rotation

3.927 / 3 gear ratio = 1.309 inches per shaft rotation with 3:1 belt drive

750 X 1.309 = 981.75 inches per minute

981.75 / 60 = 16.36 inches per second

You caught a 'typo' in my post. It should have read 470uF instead of 470mF. The 470uF capacitor is required with G201 stepper drivers (page 2, 3rd paragraph of the REV: 16, August 6, 2009 Geckodrive instruction sheet).

The power supply should have a large filter capacitor(s). You can determine the value of that capacitor with this formula:

(80,000 X Current of all motors) / Voltage = Capacitance (in uF)

For example, assuming 4 each 5A motors, you would need:

4 X 5A X 66% = 13.2 A

(80,000 X 13.2A) / 48VDC = 22,000 uF

Depending on your actual 'load', you might be fine with a 10,000 uF capacitor, but 22,000 uF would be best.

I agree with Mike (Metalhead) about the contactor. I use 120VAC contactors in my designs; however, the model that you specified should work just fine if you want to use 220VAC to activate the coil. That contactor has the required aux. switch so that it can be wired to self-latch (see Gerald's schematics to see how to wire a contactor to self-latch).

[tnarch]

16/7 Helukabel F-CY-JZ (gray colored) for e-stop and other controls
14/4 Flex-cable for servos (black colored) to be used on spindle
16/4 Flex-cable for servos (black colored) for motors hook up

the strand count for each core of the flex cables is 90! is that good or bad?

[tnarch]

Z-slide and stop block are fabricated. The electronics also came in Tuesday. Took the machine down for painting.

The task list for the up coming weeks:
-Finish painting
-Reassemble
-Las Vegas
-Start control box wiring (aka kitchen table project)
-Buy water pump, test VFD wiring and cooling system for Spindle
-Connect motors (waiting on xlr connectors)
-Fine tune (and debug?) Mach 3

I am hoping start cutting by mid January. Lets hope I'll be bringing some luck back from Las Vegas!

[smreish]

I like your adaptation of the stop block. Simple and as long as your nuts seat flat, your fine - or you could tap them if it did.

Nice work.

[tnarch]

Thanks Sean. I had some angle left from the rails and decided to use them for the stop blocks. The blocks are tapped. I added to bold for extra threads with the intention of welding them to the block before I paint.

[tnarch]

Hi all

I have one of those water-cooled Chinese spindles and got a cooling flow rate from Keling specs for 20-26 gph. To be on the safe side, I'm thinking about getting model Epp315 from this site because the max lift height specified is well clear of the highest point of the z slide. Will this work with running a water line ~24' inside the cable chain? I'm searching the web for water flow calculation but haven't found something easily digestible for my primer-fume-clogged brain

[KenC]

The spindle only need very little flow rate to keep cool... in fact I worked the spindle at 14000rpm for over an hour before I remembered to turn on the pump... Still surviving...

[smreish]

Ken,
That's what the VFD aux contact closure is for! When ever VFD on....pump on....might help you in the future for the cost of a little relay.

Keep up the great work.

Sean

[KenC]

LOL!
Procrastination working its best on me...
I still haven't got my y stopper, z-stopper, limit switches, VFD aux contact, joypad HID, x-y lazer zeroing, disco light, vacuum table, belt reduction boxes... even the cover for my collant reservoir made
Only managed to conjure enough energy to set up the Z-axis auto touch off & dust collection system...
Lucky me... Still managed to churn out enough production to fulfill orders...

[tnarch]

Sean & Ken, thank you for the tips. They will be very helpful with wiring coming up next.

An update picture to show the color scheme:
- matte black for all large/frame components
- shiny fire engine red for all other components

Kind of like that Ferrari I always wanted

[tnarch]

another update photo.

a bit apprehensive as the electronics is up next. any advice?

[smreish]

Kitchen Project Thread. Read it 3 x before proceeding. Then dive in head first! Ask if you get into any challenges.

SEan

[riesvantwisk]

Tuan,

my advice is : if in doubth, don't do it
Don't hurry the kitchen table project and make sure every cable and wire is properly attached and makes good contact. Electronics my die when connections come loos between stepper and driver.
When firing things up (turn on) don't look at your computer screen but at your electronics teh first 10 seconds. Your motors will settle quickly when powered up. Just look around all wires and stuff to see if you see smoke
Make sure you have everything fused, preferred even a lower amp quick fuse then the 'standard' fuse.
Take a look at your drivers and see if they turn green, your manual of teh drivers will tell you what's a good situation and what's a bad.

When that's all fine measure some voltages and see if they are what they suppose to be.

Then you are ready to configure your computer and attach your parallel port.

[tnarch]

Thanks Sean and Ries for the advice.

The first picture shows the current configuration of the control box components. Any potential problem? The door mounted on-off push-button have momentary contacts. Is this right?

The second picture is a gantry e-stop enclosure. Do I have my contacts right? I'm not sure about the contacts for the PMDX e-stop circuit.

Going to the shop to connect some wires!