Gecko G201s or G251s UBOB? Plasma Decision

[Wolfesmetalfab]

I dont have much time, as im trying to make a decision before geckos sale ends. I am building a 4' x 3' plasma, Gantry weighs 50lbs, and I am using 3tpi ballscrews for x & y. Speeds I am looking for are normally 40 - 80 ipm with jogging and maybe some thin metal cutting @ 250-300 ipm.

I am debating between the g540 $300 (includes BOB), g251s $150 (need BOB) , or the g201s $288 (need BOB).
Ok, so time ran out, and I went ahead and ordered the G201s as I think its the best option even though it costs a little more (worst comes to worst, I can give a forum member the sale price when the prices are normal!!! LOL)

I think I finally understand the volts, amps, inductance relation, as well as the torque curve somewhat.
I have calculated I have 3 tpi drive, that takes 600 pulses to move 1". I am am wanting 300ipm max, then 600 pulses * 300 inches = 180000 pulses per minute, or 3000 pulses per second. For the normal working speed, figure approx 50 ipm which doing same calculating gives 500 pulses per second (or divide 3000 by 6).

With the G201s, I think I have the most options in motors and changing in the future, as well as getting the best performance out of my motors.

Handy Torque Convert Calc
Looking at the torque curve of the first motor link below i get 2.1nm (297.3oz) at 500pps .7nm (99.12oz) at 3000pps. Is this a little lower than I want, or decent? I realize that the running torque and holding torque are much different, but this much? Or does that have to do with the speed might be a little more than ideal? Power wise 32*(sqrt6.8mH) = 83.4 volt and 2.8amps * 3 motors =8.4amps. 80 volt or just under for safety at 6 amps (gecko formula 8.4 amps * .67). Hope I make sense to more than myself.

Taking a look at the Nema 34 640oz curve, i find that 500pps (50ipm) i get 4.25nm (601oz) and at 3000pps (300ipm) i get 3nm (424oz) Much better option, or excessively large? Power wise 32*(sqrt2.2)=47.4 volts. Amps 6.3* 3 motors=18.9 then by gecko formula *.67 =12.6 amps. So a 48 volt 13amp supply would work well here.

However, I am not adding in any variables for resistance of the 50lb gantry. (haven't figured that one out yet, nor do I know if it makes much of a difference)

These are some of the motors I am thinking of as options. Suggestions always welcome. Is 8 wire better for flexibility, or does it not matter if I have the G201s and can buy whatever PSU I need.

nema 23 425oz 8 wire
torque curve nema 23 425oz

nema 23 495oz 4 wire
nema 34 400oz 8 wire
nema 34 465oz 4 wire

nema 34 640oz 8 wire
torque curve nema 34 640oz

more thoughts on motors. Will the nema23 with 80 volt supply give me better results, or the nema34 with 48 volt supply? I am thinking the 34, as I dont think speed will be a problem at the 48 volts, but Im a newbie with only a couple weeks research, so help me out! Also apart from performance, which will be more reliable and less likely to burn out or break down? Price is also a factor, but if its not a whole lot more in the long run, I might as well not be skimping, right!?


BOB
Campbell designs $130
CandCNC UBOB1 $84 may have to add extras to it
CNC4PC C1g $42 (if this will do well, I like the price!)
CNC4PC C11g $109 (if ^ not good, then maybe this one)
PMDX-122 $81 (someone else recommended this one)

Power Supply
Decide on motors first, but links?
Antec?
Others?
or make (rather not)


Is anyone using a similar configuration that works well, and wants to share their $.02?

If i cant decide tonight on the drives, oh well, but I could save $50! Ok, so I did decide on the G201 drives, I hope I made a good choice!

Ok enough info for now, brain overload!!

Mods - If my post should be moved, please do and rename if you like, I am bad about category and title selection when I am stumped, aggravated or in a hurry!!! LOL

[Wolfesmetalfab]

Anyone? I would like to make sure I know what I am talking about, and get the right motors before ordering.

[TOTALLYRC]

Hi wolfesmetallab,

Your math is a little off. The g201s micro step so that 600 steps per inch is actually 6000. 200 steps per rev x 10 micro steps = 2000 per rev x 3tpi = 6000steps per inch. 300 ipm = 5 ips. x 6000 = 30,000steps per sec.
Make sure your computer can run that fast or use a smooth stepper or other motion control card to move the step generation off of the computer.

The other big kicker is that the torque charts are at differing voltages. The chart for the 425 is at 30 volts and you are going to be running at near 80v A better than doubling of the voltage. The chart for the nema 34 is at 100v if I read it correctly, but it comes up distorted on my computer.
Also note that the nema 34 is wired in series, not in parallel as with the 425 chart, so basically the torque speed charts can't be compared, at least the way I see it.

I would recomend the g203v since they morph from micro to full step on the fly and will give max motor torque at speed compared to the g201. Use near 80 volts and the nema 23 425's over the other motor options.

I prefer 4 wire motors if I am going to use them in parallel as the wiring is a little neater.

Kepp the gantry weight to a minimum as there are no real cutting forces involved in a plasma cutter.

I have the candcnc breakout boards and like them. Ask Tom what he recomends in the way of motors and power supplies as he does a lot with plasma machines.

Antec makes a nice power supply. I have several copley's that I have picked up on ebay and they work well also.

Just my $.02

Mike

[Wolfesmetalfab]

Mike, thanks alot, I didn't realize that! Ill call them in the morning, as they haven't shipped yet, and see if I can change to the 203s. Its more money than I originally wanted to spend, but oh well, Ill have good drives!

So with the 203s, you suggest the 23 425s....is this because the 34s are more than enough, or because the 23s are better for speed? Im learning alot, but have so much to learn. I just want to make sure, so that I dont get too small of motors when I could have bigger ones for $10-$30 more.

I really appreciate the information, it is very helpfull,

[TOTALLYRC]

Mike, thanks alot, I didn't realize that! Ill call them in the morning, as they haven't shipped yet, and see if I can change to the 203s. Its more money than I originally wanted to spend, but oh well, Ill have good drives!

So with the 203s, you suggest the 23 425s....is this because the 34s are more than enough, or because the 23s are better for speed? Im learning alot, but have so much to learn. I just want to make sure, so that I dont get too small of motors when I could have bigger ones for $10-$30 more.

I really appreciate the information, it is very helpfull,

As far as the motor selection it depends on exactly what you need/want to do.I went with the 425's as the tendancy is to put too much motor on thinking it will work better. I think the 425's will work but looking at you 3tpi specs however, I would feel better if someone with more experience gave some advice as I would hate to steer you wrong.

See this thread for more info.
need help with 4x8 table!!

Mike

[Wolfesmetalfab]

I called gecko this morning, and talked to mariss or marice, I cant rember exactly his name. He was very, very, nice and informative. he said by using mach and the 201s, it was possible to get that speed, as mach can run 45khz i think he said. But I talked to him about the 201 and 203s differences, and I decided I would bite the bullet and get the 203s. (the only way this was possible, was my internet order didn't go through for some reason, and my ordered had not been shipped) Gecko being as good of people as they are, they still offered them to me at the sale price, which I was really happy!

He gave me lots of information (I thought I knew alot from all this browsing, but I guess not!), and had also mentioned that they have tested kelings 906oz nema 34 stepper, actually pulls 700oz, and runs very nicely and smoothly with the drives, so I might think about them, although I think they may be way more than I need.

If I did get them, I would wire the x and y parallel and the z in series. And he highly suggested using a 24volt supply and 1 motor on the x axis as the best way to determine the needed power for my wanted ipm. That way I am not heating the motors with uneeded voltage.

And BOB he said ones that they see ok are Bob Campbell, PMDX, CandCNC
I like the PMDX-122, and the bob campbell, are there any notable differences?

So the 203s are actually on their way this time! I will post again later.

[Wolfesmetalfab]

Ok, I think its all decided.

Drives - 3 Gecko G203 - $114 each (on the way)

BOB - Bob Campbell - $130 (it was tough decision over PMDX-122) any reason PMDX would be better?

Motors - 3 Keling 3A:KL34H295-43-8A (Single Shaft) Price: $99 each 6.1A, 2.1V (in Bipolar Parallel) (Mariss at Gecko said they have tested and had good results with these motors, they actually are closer to 700oz which is fine)

PSU - 24volt to determine best supply voltage -$10 ebay

Running Total w/o shipping = $779

Still need to purchase proper power supply and we will see about the THC300, but will do without it for now.

Im spending more than I wanted to, but I should have a great system. I would rather spend a couple hundred more and have less worries and better performance.

[TOTALLYRC]

Ok, I think its all decided.

Drives - 3 Gecko G203 - $114 each (on the way)

BOB - Bob Campbell - $130 (it was tough decision over PMDX-122) any reason PMDX would be better?

Motors - 3 Keling 3A:KL34H295-43-8A (Single Shaft) Price: $99 each 6.1A, 2.1V (in Bipolar Parallel) (Mariss at Gecko said they have tested and had good results with these motors, they actually are closer to 700oz which is fine)

PSU - 24volt to determine best supply voltage -$10 ebay

Running Total w/o shipping = $779

Still need to purchase proper power supply and we will see about the THC300, but will do without it for now.

Im spending more than I wanted to, but I should have a great system. I would rather spend a couple hundred more and have less worries and better performance.

When was the last time that you spent less than you wanted to and were happy with the results??????

Looks to be shaping up nicely.

Mike

[Wolfesmetalfab]

Thanks for the reply rc, if it wasn't for you, this thread would be dead! Your right, I dont think I will regret my choices.

[TOTALLYRC]

Thanks for the reply rc, if it wasn't for you, this thread would be dead! Your right, I dont think I will regret my choices.

I have been helping, but with 198 hits on this thread others are watching, ready to correct me or offer additional advice. I do the same thing, I look at a lot of threads and jump in when needed, or if I have a differing opinion of what is being said. Just because it is you and me going back and forth, don't think that there isn't a bunch of others watching.

I have learned a lot in the last few years and not only do I come to the zone to learn more, I like to give back some of the knowledge that I have picked up. It can be tiring to answer the same old question time and time again, but I consider myself in the early stages of my cnc journey, not a newbie, but definitely not a seasoned pro either, so I help out with the newbie questions when I can.

Mike

[Torchhead]

Timing is everything. We just announced the BladeRunner Dragon-Cut system. It's 4 Gecko 250 drives in a case, our G250-5 motherboard and 4 Blades, 12A power supply in a case, 4 600 oz-in 3.5A Hybrid steppers (not a misprint) and an integrated Digital Torch Height control (plug-in card) that fits in the BladeRunner case. Nothing else to buy. Has an Expanded IO BOB (UBOB) and only needs one parallel port for all of the normal signals AND all of the DTHC inputs. We priced this one aggressively. It's more than you spent so far but less than you will end up spending if you buy a THC (and you will quickly decide you need one) that will work with what you bought. The 203 Drives are great but you have a lot of hand wiring to get done. We have cards to make that easier too.

TOM CAUDLE
www.CandCNC.com

[Wolfesmetalfab]

I got 3 G203v at $123 each = $369
3 906 oz keling steppers $99 each = $297
Sound Logic BOB = $130
Power Supply make for $60 with free capacitor or buy for $120

Total with made supply = $856
Total with bought PSU = $916

Add $370 if needed (i may make my own with mach 2 manual schematic)

It was cheaper than the $1500 price tag without any of your upgrades, and I dont mind doing the wiring and etc.

I scrounged alot of free stuff like case, switches, lights, fans, heatsinks, capacitors, etc even a transformer unless I go with the torodial ($60), and I have a more powerful, customized machine that I learned alot more doing.

Thanks for the info, (most of your replies I see, focus on trying to sell your product) but I kind of dont like how you speak, like since I didn't wait and buy from you, I LOSE!! Thats not how I see it.