On to parts Ordering - Matthews NC USA

[qroger]

Hello all.
I have been reading and reading and reading and thinking that this might help my eventual retirement cash flow. (If I don't quit reading at work, my retirement may be sooner than originally planned!) I have started to make a list for the Kitchen Table project, trying to hold costs down. I looked at the Motion King, and the Keling, and O.M. and somehow I think I have narrowed it down to Richard-call-me-Mike's bench test setup!
4 P>K> 296 F 4.5 wired Unipolar
Gecko G-540 driver
the Avel Y236 801 Toroid with
PMDX 135-8020

I think I know that the G-540 has an onboard BOB so no need for Bob.
I feel a little guilty about taking the easy way and going for the PMDX 135-8020, but capaciters from Mouser are looking to be around $50.00. PMDX is I think $119, so $50.00 for capacitance, plus something for a Bridge and wires. I could spend as much on parts as on the 135-80, and, If I try to learn too much, too fast, I'll run out of room for the new knowledge and forget where I live.

All this looks like it could come in at around US $1000 to start. I will probably go back and look at the MotionKing Keling, Bob Campbell, etc. options but it seems what you save one place pops back up in another. For now, my plan includes belt drive reducers, so it is not the simplest approach.

All criticism, and advice will be gratefully accepted, and, as has been said many times before: THANK YOU GERALD!
roger

[bradm]

Welcome aboard, Roger!

The MK 34HS8801 might be a good choice for you (http://www.mechmate.com/forums/showthread.php?t=2622), assuming that you are going with the belt drive approach.

The bridge is a $5 part with 4 connections that can be made with easily crimped connectors. You will have to wire up about 10 connections total, instead of 6 total with the PMDX. In the context of the 50 to 100 connections you need to make for the MM, it's trivial, and you are already 80% there.

Good luck, and let us know what else we can talk you in or out of ;)

[qroger]

O.K., I sent a RFQ to MK for the 9801, that was recommended somewhere, and I guess I should ask about the 8801 as well. I just noticed the detent torque seems to be the difference between the two... O.M. is offering free shipping in the U.S. just to complicate things.

[domino11]

Welcome Roger!

[KenC]

Welcome Roger.
If you do struggle with the budget, just start with the basic configuration.

[qroger]

Ken,
Thanks for the advice. It suddenly strikes me that It might be possible to begin with 4 light bulbs instead of 4 steppers! The first step would be Mach 3, plus power supply, plus drivers. Maybe with a modification that would tell if the "light bulb motors", were running forward or backwards....

[MetalHead]

If you are building the kitchen table project on a budget. You can just buy one motor at a time. The first motor could be used to test each axis of the system. The shipping will be rough doing it all this way, but it would allow you to spread out the costs a bit.

[smreish]

or go to a local electronics place and buy a really small stepper motor and put in a really high value resistor to current limit the drive and test for about 20 bucks. A copier machine has A LOT of really small steppers in it.

[qroger]

I see people in the forum that have completed the mechanical part of their table, and are then starting to choose their electric, control, and software. I Know I can build a table, (especially with the plans from Gerald and the kit from Metalhead!). Now I am banging my head on understanding the motor - driver - power supply choices. Then, I think I have to look at the software before I hit the Go button. This is very atypical for me. My usual plan is "plunge in and hope for the best". Read Read Read, Think Think Think, lol.

[bolingerbe]

Roger,

I would not worry about the motor - driver- power supply choices. All the information is here with the people to guide you and assist along the way. This is a great project and if you do not get stressed out a very enjoyable learning experience along the way. I took my time and I am still getting the bugs out of my head to make the most of this machine when I put it to use. I use Mach 3 for the machine control software, AutoCAD to do most of the designs and V-Carve PRO to do the final work ups for depth of cut and layouts. The V-Carve PRO will generate the G-Code required to allow Mach 3 to tell your machine where to go and how deep to cut. There is a different software to allow you do the work you want with your machine and it is disused here in different areas of this forum.

[qroger]

Thanks all, for suggestions, messages of support, and a couple of facts have come in:
Motion King quotes34HS9801, x4 at $220.00 (total)
plus shipping $180.00 and Paypal Charge $20.00. Grand Total $420

PK 296 F4.5 comes in at $556, free shipping.

Dietech, with a motor similar to MK is at $192 plus $140.00 freight, as part of a RFQ that also quoted $232.00 for drivers.

Gecko G540 has a posted price of $299.00

A moment of panic when the G540 appeared to be inappropriate for the PK 296 F4.5, but I found the original set-up has a Current Limiting Resister, (which may also may be multi purposed as a coffee warmer). So 1.) $856 for "PK296 plus G540", 2.) $719.00 for a little adventure, Motion King plus G540, and 3.) Dietech motors and drivers $564 plus BOB, ($120.00?) $684.00 for more adventure.
4.) Keling comes in with a non gecko, everything including the PSU and BOB, for $899.00 all engineered with the adventure removed, (one hopes).
The big break is $137 between choices 1 and 2.

So 4 choices, most money/least money = about 2. Which should be diluted by further material costs... And except for the Keling package deal, the motors could be backed out for later acquisition, bringing the serious start budget to around $500.00, includes Power supply, drivers, Software, Used computer from the Evil Empire, Odds, Ends, bribe to better half, etc. Thinking of complicating my life using the Macintosh, I already own and Linux, which I know nothing about, etc. to keep my house pure.
Thanks again, back to pondering.

[qroger]

A copier machine has A LOT of really small steppers in it.

ANNNDD there is one just down the hall that requires a rubber band to keep the door shut so it will print! It can't be too long for this world. heh heh heh.

[bradm]

I think you want the 34HS8801, not the 34HS9901. The former is a little smaller than the latter, and may in fact be less expensive as it has less wire in it. That means a lower inductance, which means a better match for the G540. Both motors will be slightly under-driven by the G540 - and that's okay - but you might actually get more out of the smaller motor, as you aren't wasting energy on extra wire or extra mass.

You seem to have a power supply in option #4, but not in options #1-3. Add $60 to those three options.

Here's option 5:

Keling sells the G540 at $249 if you buy other items. The KL34H260-42-8A at $79 looks like it's in range when used half-coil, so $316 + $249 = $565. Add in the KL350-48 at $60 and you have a total budget of $625 + shipping.

Someone please cross check me :)

[smreish]

Brad,
My next MM will use that arrangement. I have been part of 3 MM builds thus far and the 4th (my personal) is going to be G540 + KL motors, belt drive. Then I will have built all variants!

[qroger]

Man, that seems to be getting good and without the frictional cash losses to freight.

[qroger]

Hmmm,
KL 34H260-42 8a says 4.2 amps unipolar Vmax 47v, 3 amp bipolar series, Vmax 82v would have to be limited to 50 for G540, right?

KL 34H280-45-8a says 4.5 amps unipolar Vmax 41v, 3.2 amp bipolar seris, Vmax 94v would have to be limited to 50 for G540, right?

Both motors look like if they are bipolar series they will fit under the G540 bar, but the Vmax is high. If they are unipolar, voltage is fine but the amps will need to be restrained. Is there a downside to using a current limiting resister, other than the heat it will probably dissipate?

Also I assumed freight on Keling would be minimal since one of their reply to addresses is "west of Chicago". I need to get RFQ out to them for freight quote while I am comparing.

[domino11]

Roger,
With modern stepper drivers, there is no reason for inline power resistors to limit current. The current limit is set by the driver. This is usually done with a low wattage resistor on a current setting port.

[smreish]

Roger,
if you refer to the g540 manual, pin #1 of the db9 connector allows for the current set resistor to limit the output of the drive up to 3.5 amps @ appropriate voltage not to exceed 50V.

Most steppers will be rated to work well into the 80+ DC voltage. Though, practice shows that 35 to 56v is a more common DC voltage.

I know that Brad and others have had great success with the G540. Good luck on your choices.

Sean

[bradm]

Roger, check out these for background (http://www.mechmate.com/forums/showthread.php?p=41983&highlight=bipolar-series#post41983) perspective (http://www.mechmate.com/forums/showthread.php?p=41793&highlight=bipolar-series#post41793), or even this loudmouth (http://www.mechmate.com/forums/showthread.php?p=37489&postcount=28) in an otherwise helpful thread.

You are likely going to want to run those motors (bipolar) half-coil, and don't be tempted by a larger motor. Once you understand the distinction between series, parallel, and half-coil (all bipolar), it will be easier. As Sean points out, voltage is not an absolute; any of these motors would run on 12V or lower. More voltage assists you in getting more energy into the motor, for more torque (good), and more heating (bad). For the G540, and Geckos in general, pay attention to the inductance of your chosen motor and wiring.

You're getting close, keep reading, it'll click in :)

[qroger]

Ahhhhhgggggghhhh half coil, full coil, 1 stack, 2 stack, three stack, uni polar, heh heh heh, it's making me bipolar! (the old schisophrenic, or crazy).
Thanks for your confidence. I feel I am getting closerrrrr.

[qroger]

*Furthermore, Unipolar motors may be used in 2 different configurations-- One, simply ignore the center taps. Two, use half the coil only by using the center tap and one of the terminals. This will produce less hold torque but allows higher top speeds because of the lower inductance.*

http://www.stepperworld.com/Tutorials/pgBipolarTutorial.htm

Closer!, g'nite.

[domino11]

Roger,
Look for posts by Mike Richards, he talks about the different configurations in many threads here. Half coil would probably be the way for you to go with the G540 due to the lower voltages required. Half coil also has better low speed torque. A plus for our application.

[KenC]

Roger,
Threat each phase has 2 coils, each half is an individual coil. when connected in series, they become a long coil & slender coil when connected in parallel the become a short fat coil...
Think of it as horse pulling carriage, Half coil is a single horse carriage, full coil is two horse in series with one pulling another, & parallel the coil is having 2 horses running side by side. In our application a single horse carriage is enough to get you around productively.
Once it clicks, everything will fall into their prospective. Keep reading.
If you get too frustrated, no worries, just stick to half-coil & get it running 1st.
Unless you have the means to measure the torque, speed characteristics, the bottom line is only one thing. That is as long as it work!
remember, for the motors, all those numbers you get from the formulas are just some reasonable guide lines. Don't loose hair over it if you don't get everything spot on. +/-15% are good & even 50% variance can still work you will not kill them instantly!. What you really must watch out is heat when you switch them on. If you don't, you will get smoke & fire...

[qroger]

Thank you all, once again. I now know what wiring 1/2 coil is and I am a little closer to choosing my configuration but... I have to go back to Gecko white paper Introduction to Steppers and find out why you wouldn't just look for a motor half as big!

[KenC]

I did have the same question when I finally realise what half coil is...
There are no straight answer to it, it is a compound factor to it, one of which is the iductance of motor coils, space required to house the bigger wires to hold the current, another is the size of the rotor & stator to accomodate the chracteristics we need.
Bigger motor stops faster, smaller motor with the same performace stops slower due to elctromegnaticsm, mechanical & physical characteristics...
At the end of the day, Nema 34 is the framesize we need...

Happy learning

[bradm]

Roger-

I think that question means you've got it! You would look for a motor 1/2 as big - except that you won't find one. The motors are manufactured to standard sizes, and generally they cram as much wire as they can into a given size to get the best performance and be competitive. Half coil is a clever tactic for getting a smaller winding in a larger frame without a fully-custom motor order.

Building on what Ken said, the MechMate design uses NEMA34 for it's physical size, in particular the 1/2" shaft that is much more robust than the NEMA23's 1/4" shaft. As it turns out, we use the smallest size NEMA34 motors, so we can't get a motor half as big without dropping down a frame size. It would probably be possible (actually I think someone did it) to use a largish, double or triple stack NEMA23 instead, but you would need different motor plates, etc.

[qroger]

By Jove! I think he's got it! he he he. I went back to the intro to stepper sites and I found that using 1/2 of a big motor's windings still uses all of the rotor, bigger bearings etc. The low speed current is already controlled by the driver, so the low speed power is also set by the driver. And, as you point out, just because you can identify the ideal, doesn't mean anybody makes it for you. Thanks again. Now ON TO FINDING THE MONEY!

[qroger]

Here is my present situation. I found a scrap metal yard that had partial reels of heavy stranded copper wire. Probably AWG #4 through #10. Had I known the wire that I will need, I would have been able to buy the wire, possibly at scrap price. I am pretty sure eventually the scrap yard will supply me most of the steel, the power supply panel, the wire, and I noticed a couple of coffins in a warehouse there.

So, now I am starting to look at the plans for wiring the kitchen table project and the control box. I may learn something. A bill of materials or recipe might tell me that I needed 3 meters of 7mm stranded wire, and after converting to a more normal measuring system, I would go to the electrical supply house, purchase the wire, and never think about it again.

It is a little like the saying of give a man a fish, and he will be without hunger for a day. Teach the man to fish, and he will never go hungry again...(Unless the factory ships come and take all of the fish out of the oceans.)

[Red_boards]

Roger,
When my motors arrived they had a nice picture that gave different wiring configurations. After comparing the pictures to ones on this site I was able to identify which I wanted (I have 8 wires from the motors, so I plumbed for bipolar parallel for optimal speed/torque). I could simply wire the correct colored wires to A; /A; B; /B - all marked on the Geckos. Easier than it looked at the outset.
My kitchen table project has a fair number of masking tape connections. But having assembled a Heath Robinson effort I'm much clearer about the connectors I need for the control box proper.
Just a note on the computer. Mach3 needs at least 1GHz clock speed. My 640 MHz machine just falls over, so I have to upgrade.

[qroger]

Thanks for the note. I was figgering on working the comp specs back from the Mach 3 recs. He reccs 1.0ghz single core chip, 512 ram, separate Video Card w/ 32 mb ram, and a recent flavor of Windows. Up to now I have managed to keep wintel out of my house, but it's probably easier than learning how to get linux onto a Mac, then EMC to function there, then get that to talk to yet to be built cnc router.

It's funny, at work after upgrading from a single core box to a dual core box, my GIS software actually slowed down because the software didn't know how to talk to two cores at once.

Your Heath Robinson reference tripped me up for a second. I was wondering if you were refering to the old Heathkit tube equipment; then I found that Mr. Robinson is a close to cousin to Rube Goldberg.

[qroger]

This is the kitchen table I am currently considering.
I purchased an eBay torroidal transformer, Antek 6435 that is labeled:
IP: 115V, 115V, OP 35V, 35V, 18V, 12V.

For motors, I have about decided on 4 x MK 34HS 8801. Wired 1/2 coil I think these are 4 amp, 0.7 ohm phase resistance, 3.0 mh Inductance. IR = rated 28V.

Driver(s), will be Gecko G-540 which would actually like no more than 3.5 amp (this can be remedied in the driver) and 18V to 50V; .

Power Supply should be between 3 to 20 times rated voltage, or 8.4V to 56V.
(I wonder if the current is limited to 3.5 amp, is that number to use in the power supply calcs, yielding 4.9V to 49V?)

3.5 amps times 4 motors gives me 14 amps needed.

If I use one of the 35V outputs from the transformer, times 1.414 for 49 V DC that should be sufficient. A 25 amp x 140V rectifer, Mouser 512-GBPC 2502, and a Mouser Cap, 100V 10,000, mf, Mouser 539-CGS100V10,000, I'm hooping nothing will explode.

I'm pretty sure I left something out,,,,Vmax? I'// be back shortly. Thanks, in advance, for helps, comment.
roger

[qroger]

vmax, (for motor?) = sqrt (impedance)x 32 sqrt (.7) x 32 = 26.7
Back to the reading..

[qroger]

Hmm, pretty sure that I have this v max convused with power

[bradm]

32 x sqrt(INDUCTANCE) = 32 x sqrt(3) = 55.4256 So you are very good at 49V.

8.4 to 56V for the motors was correct.

14 Amps, only if all motors drawing max at once. Experience tells us this doesn't happen, and 300 to 400W power supplies are adequate. Rough check then is that 300W / 50v = 6 Amps. If you're supplying above that, you should be in good shape.

Last question then is do you have enough capacitance in 10k uF to smooth things out.
See the helpful spreadsheet (http://mechmate.com/forums/showthread.php?p=15996&postcount=17) from MikeR, which recommends about twice that (two capacitors in parallel), if you are engineering conservatively.

I think you'll be just fine as specified above. Note that each of the 36V windings on that transformer furnishes half of the rated current, so if it's 8.6A, you'll get 4.3A from each winding. You probably want to wire the two windings in parallel. Careful doing this; one way they work together; the other they short each other out.

[qroger]

Now I have to go to the transformer and find out where you got 36 from and why 35+35 doesn't = 70. Dude! It's 'lectricity! It's not supposed to make sense! hehehe.
No Worries.
roger

[bradm]

36 is a typo. I meant 35. If you take the two windings and wire them in series, then 35V+35V = 70V at 4.3A. If you wire them in parallel, 4.3A + 4.3A = 8.6A at 35V.

[qroger]

Thank you. I believe this has me squared away so I can order some parts! :)

[qroger]

Yesterday I spent more money! hehehe. Ordered the capaciter(s) from Mouser as well as the rectifier. There was only one screw-type available so I went ahead and got the snap cap version, (so I wouldn't be back-ordered), and it was about 1/3 the cost for the same spec screw type.

I have to admit I wish I had had an electronic bill of materials on hand while I was ordering. Mouser has a project manager that would allow me, or admin, to post a project list, from which items are then checked off as ordered. I probably could have gotten some switches, etc, but now I will be forced to get organized for next time.

Can someone rec a suitable wire size to connect the caps, the torroid, the rectifier, and items between the power in and the flexible cable riding in the cable carriers? Or is that a stupid question? I have a shopping trip to the scrap-yard planned for the weekend. Or there is this: http://charlotte.craigslist.org/tls/1931210450.html on the local craiglist. Cheap but big and would need a door. Check out the color though!:eek:

Anyway the power supply parts are now on order, and as soon as the stock broker coughs up a check, I can plunge in for the rest of the kitchen table project. Man I hate letting a Windoze comp into the house, but the alternative would be tooo much distraction. There does not appear to be an easy Macintosh option, so Windoze it is, meh.

This thing I came across is currently a key part in my fantasy of turning the MM into a cash machine:
http://www.david-laserscanner.com/
current fantasy: 3d scan into 2d slices into 3d form into 3d object into money.

Getting Excited Now, lol.

[bradm]

Roger, a quick approach would be to match the gauge of the wires coming out of the toroidal transformer. Otherwise, you want to work out the amount of current you expect to use, and apply that. In a MM, you should be looking in the range of 14,16, and 18 gauge wires (15A, 13A, 10A as some safe working values).

[qroger]

Thank you. I think I remember that bigger wires have lower resistance and less line loss, so, in general there should be no harm in erring on the slightly bigger side #12awg?
Thanks again
roger

[bradm]

There is no electrical harm in using larger wire, as long as you dont create a situation where a large wire feeds an overly small wire. A common term for this is "fuse".

Larger wires don't bend as well as small ones.

[qroger]

After removing the cubic foot or so of copper, + iron, I got an unused, air tight, transformer box at the scrapyard. (pictures to follow). I ordered the Gecko G540. Asked for a final official quote from MotionKing for the 8801's.

There is something i worry about: From Gecko:
"]If your motor is below 3.5A, you can use the above drives as well as the G250, G251 or G540 drives.

If you need an all in one solution then the G540 is the drive for you. It has a built in breakout board, short circuit protection, opto-isolation, parallel port connection and four axis operation via DB9 motor cable connectors.[/

[COLOR="Black"] If I read the Gecko correctly, current set resistors are used to make the Gecko suitable for amps below 3.5. For motor current above 3.5, (such as the MK 34HS 8801, what must be done to make everybody play nice together? I guess I should ask Gecko.

[Kobus_Joubert]

Roger, do you mean MotonKing 9801... I don't know the 8801

[qroger]

http://www.motionking.com/show_products_detail.asp?ID=12&fenlei_ID=2

We will see if the link works.
I believe the advantage is supposed to be that the lower inductance will get the motor down into g-540 range.

All advice is gratefully accepted.

[qroger]

I found out the effect of too many amps for the Gecko. In my case if a 4 amp motor is used with a board with a 3.5 amp reccommendation, the torque is reduced, in this case 3.5amp/4 amp = 87.5%.

[qroger]

I found this link Kobus. There is more to it than just the author, but I forget what. I think it is partly cost.

http://www.mechmate.com/forums/showthread.php?p=39065&postcount=15

[qroger]

http://s226.photobucket.com/albums/dd128/qroger/?action=view&current=ElectricalBox.jpg

In inches, it is, 20 high, 16 wide, 10 deep, with removable panel, 17 x 13. It was 1/2 dollar per pound.

[qroger]

I am trying mightily to get a photo in here. It is in the manage attachments slot, so far, so good...
Oh!! Happy Day!

[qroger]

I have on-hand, quotes from Motion King for the 34HS9801, the 34HS8801, and have a request in for prices on the 34HS6803
Specs are as follows and all I think are half coil.
Motor length Current, (A) Phs Resistance Phs Inductance (ma) wt

6803 66 2.7a 1.2 ohm 3.5 mH 2.0 kg
8801 78 4.0a 0.7 ohm 3.0 mH 2.5 kg
9801 98 4.0a 0.98 ohm 4.1 mH 3.0 kg

Kobus has run the 9801 with success.
The 8801's have been kicked around in the forum but 1.) I don't find a record of anybody useing them, and 2.) MK says no availability for 3 weeks after payment.
So My question is:
For a belt reduction option, wouldn't the 6803's come closer to the G540 ideal?

Thanks,
roger

[bradm]

Roger, I think you want to underdrive a larger motor, rather than overdriving (or just driving) a smaller motor. Otherwise, you're giving up torque you could have had.

[qroger]

I'm wondering if belt drive reduction would take care of the torque issue. I think the lower induction, (relative to the 9801), maintains the torque out to higher rpms, so that's good for the belt drive, right? The little motors save a kg each for reduced momentum so that should be good, but probably not really significant.

Other than putting together a system that won't explode and burn to the ground, my other concern is that I have ordered the G540, and I have the power supply parts in hand, so I will need motors that fit within those constraints. From my point of blessed ignorance, I think any of these motors should work.

I would have more confidence if Motion King had a conventional shopping interface. I presume they will eventually produce an invoice I can paypal off of.

Thank you for your review, and as of now no motors have been purchase.
roger

[hutchcj]

My mate has just got a quote back from Motion King about the 34HS6803 motors with a gearbox. They come in 5:1 or 10:1 reduction. The price we got is USD$115 for the G5 and USD$130 for the G10.

This would take care of the torque issue rather than putting a belt on it. At half the cost of the OM's they seem to be priced right.

Does anyone know about the quality of these motors with the gearbox?
Has anyone put these motors on a MM build?