CNC Router from scratch

[Punk_Boy]

Tks for all your advice. I will come back to you soon with more questions

[Clackneil]

Just a little piggy back advice here, Jim and Ger seem to be the masterminds behind everything here lol.
If they have advice to give, it's worth more than their time typing it.
Oh, and thank god that measurement was a typo 😂
50' machine sounds incredibly insane for 99% of anyone in the world lol.

I myself have decided to build a steel frame, 4' x 4' router, using a rack and pinion system and N34 steppers, based off of a multicam that I have access to.
Goodluck with your build. And be sure to keep us updated!

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[MajorTendonitis]

Just a little piggy back advice here, Jim and Ger seem to be the masterminds behind everything here lol.
If they have advice to give, it's worth more than their time typing it.

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I joined fairly recently and certainly noticed that too . I'd like to stay on the good side of Ger if I can ,as these guys are just a plethora of information.

Question,
I watched the video on Servos and was quite impressed . There saying there cheaper , even without the conterparts needed for a stepper , but I'm not seeing that ?
I'm liking the part where there's less wiring and connections involved though .I see with Servos , that the driver is built in , so you don't need separate drivers like a stepper motor requires , but do you require external power supplies, or do you connect 120V ac directly to a stepper ? (I guess I could look that up)
I'm assuming the wiring from the breakout board connects directly to a servo also .

Are there any disadvantages to using Servos ,other than cost if they burn out ? I was also wondering if they work with UCCNC?

[louieatienza]

I joined fairly recently and certainly noticed that too . I'd like to stay on the good side of Ger if I can ,as these guys are just a plethora of information.

Question,
I watched the video on Servos and was quite impressed . There saying there cheaper , even without the conterparts needed for a stepper , but I'm not seeing that ?
I'm liking the part where there's less wiring and connections involved though .I see with Servos , that the driver is built in , so you don't need separate drivers like a stepper motor requires , but do you require external power supplies, or do you connect 120V ac directly to a stepper ? (I guess I could look that up)
I'm assuming the wiring from the breakout board connects directly to a servo also .

Are there any disadvantages to using Servos ,other than cost if they burn out ? I was also wondering if they work with UCCNC?

As far as Clearpath... compared to most industrial stepper drives/motors it's on par, and cheaper than branded servo/drive systems. You cannot wire 110VAC to Clearpath, it's max input is 90VDC and they rate them at 75VDC max.

[Clackneil]

I'm getting nearly double the cost of my steppers and drives, plus the power supply, just for equal clear path servos. Might be nice if I had the extra cash just laying around, but considering my first build is piece by piece, I'm sticking with steppers...

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[MajorTendonitis]

As far as Clearpath... compared to most industrial stepper drives/motors it's on par, and cheaper than branded servo/drive systems. You cannot wire 110VAC to Clearpath, it's max input is 90VDC and they rate them at 75VDC max.

Ok , as I thought nema34 steppers were quite cheap , even after you buy the stepper driver . I'll have to check again ,but I don't think a Nema34 and it's driver is 300 bucks ?

I wanted to either build s 4'x4' router Table , or buy a pro version from CNCrouterparts, and these were the stepper drivers and steppers I was going to use . Just over a $100 to do one , not including the PS

http://www.automationtechnologiesinc...k-is-included/

Nema 34 CNC Stepper Motor 4.5Nm(637oz.in) 5.5A 34HS31-5504S - US$

[Clackneil]

He was talking about namebrand ateppers and drivers, I believe.
I myself found chinese steppers that I will be using, still at a cost of $80/ea. And Gecko G214 (?) Drivers @169/ea.
Finding a decent power supply to actually provide ~70VDC and the amperage is proving QUITE challenging but it is only day one on the search for that.
I'm still looking at around $800 for my drive system (not including the one gearbox for my z axis) this way. With the clearpaths, to get nema34 sized servos at a close torque to these steppers, 4 of them would run me nearly $1700 alone.

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[MajorTendonitis]

Thanks guys . I think I'll be fine with Nema34 steppers

[Jim Dawson]

Ok , as I thought nema34 steppers were quite cheap , even after you buy the stepper driver . I'll have to check again ,but I don't think a Nema34 and it's driver is 300 bucks ?

I wanted to either build s 4'x4' router Table , or buy a pro version from CNCrouterparts, and these were the stepper drivers and steppers I was going to use . Just over a $100 to do one , not including the PS

http://www.automationtechnologiesinc...k-is-included/

Nema 34 CNC Stepper Motor 4.5Nm(637oz.in) 5.5A 34HS31-5504S - US$

You can pay a little or a lot for steppers and drives. Here is a Wantai 1232 oz/in kit, motor, drive, power supply, for $155. USA free ship!CNC Wantai 1 Axis Nema 34 Stepper Motor 1232oz-in 5.6A +Driver 80V | eBay

The Automation Direct equivalent system is $620. But they are not really equivalent. The specs just read kinda the same, but the AD motor is higher quality, the drives aren't even in the same universe, and the power supply is a transformer brute force supply rather than a linear and capable of high short period overloads and high back EMF adsorption.

A comparison like that is probably what ClearPath is using in their statements. Like everyone else, their marketing department is prone to hype Nothing wrong with their systems, but you can buy cheaper steppers. On the other hand, their torque curve is much flatter than any stepper and thus is capable of much higher performance, in addition to internally closing the loop.

[Clackneil]

I agree, and this is what I was trying to get at. I will probably buy a set of servos from them one day to use and test on a personal machine. Jim you and I have discussed what I intend to do and unfortunately I think that these are out of the question for now for those plans. Lol, would be unbelievably nice though.

Now, a question I do have, however.
Because of the torque curves, and the muddied chinese specs, as well as manufacturer's hype. Would it even be possible to directly compare say a 1300oz/in stepper from china to a 1300oz/in servo from clearpath? Or would a more realistic comparison be sometging like 1300oz/in chinese stepper vs say, for this example an 800oz/in clearpath servo.
I guess what I'm asking is, does it make sense to be able to compare specs and to buy servos based on the knowlesge one has of steppers? Because of the flatter torque curve I would imagine a more sensible torque range (or lower I should say) would make sense when upgrading to good servos from low quality steppers.
It's late, I couls go on jabbering this over and over again so I hope my question makes sense

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[louieatienza]

He was talking about namebrand ateppers and drivers, I believe.
I myself found chinese steppers that I will be using, still at a cost of $80/ea. And Gecko G214 (?) Drivers @169/ea.
Finding a decent power supply to actually provide ~70VDC and the amperage is proving QUITE challenging but it is only day one on the search for that.
I'm still looking at around $800 for my drive system (not including the one gearbox for my z axis) this way. With the clearpaths, to get nema34 sized servos at a close torque to these steppers, 4 of them would run me nearly $1700 alone.

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I think it would be a bit unfair to compare the NEMA34 steppers' torque to those of the ClearPath. You have to make a comparison of the torque curves for both. You also have to consider with open loop steppers you have to factor in at least 20-50% more torque than you need because they are open loop, so you cannot afford to miss steps because neither the drive nor controller would detect it. I also think the Teknic motor build quality far superior to that of Wantai or even Leadshine. That's not to say that the garden variety steppers won't work fine. They likely will, and the ClearPaths may be a bit overkill for your application.

[Clackneil]

I think it would be a bit unfair to compare the NEMA34 steppers' torque to those of the ClearPath. You have to make a comparison of the torque curves for both. You also have to consider with open loop steppers you have to factor in at least 20-50% more torque than you need because they are open loop, so you cannot afford to miss steps because neither the drive nor controller would detect it. I also think the Teknic motor build quality far superior to that of Wantai or even Leadshine. That's not to say that the garden variety steppers won't work fine. They likely will, and the ClearPaths may be a bit overkill for your application.

If I were to use the clearpaths in my situation, a 4' x 4' steel frame and gantry router (gantry being 4" x 6" 1/4 wall and a 3KW spindle) would you, in my shoes, build it using clearpaths of a smaller or larger torque than the 1300ozin range?

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[louieatienza]

Ok , as I thought nema34 steppers were quite cheap , even after you buy the stepper driver . I'll have to check again ,but I don't think a Nema34 and it's driver is 300 bucks ?

I wanted to either build s 4'x4' router Table , or buy a pro version from CNCrouterparts, and these were the stepper drivers and steppers I was going to use . Just over a $100 to do one , not including the PS

http://www.automationtechnologiesinc...k-is-included/

Nema 34 CNC Stepper Motor 4.5Nm(637oz.in) 5.5A 34HS31-5504S - US$

I have a Parker E-AC high-voltage stepper drive and their HV-342 NEMA34 stepper, that puts out over 1000in-oz stall torque and over 300in-oz at 3000rpm. Last I checked the drive was over $450 and the motor somewhere under $400. I use three E-AC drives and HV-233 steppers on my mini-mill, and they do run powerfully and smoothly; well at least as far as steppers go they're relatively not too noisy...

But before you dive into what steppers you want, you may want to figure out what you'll need based on your drive system, and speed requirements...

[Jim Dawson]

I couldn't readily find the torque curve of any Chinese steppers, not that I would trust them anyway.

But here is a comparison of an Automation Direct 1200 oz/in Nema 34 stepper and a ClearPath 700 oz/in SD servo. I would have to say that in most applications they would be functionally equivalent. Normally I try to size steppers with at least 3x the holding torque of the nominal torque of a servo just because it helps eliminate lost steps due to momentary overloads.


Automation Direct


ClearPath

[louieatienza]

If I were to use the clearpaths in my situation, a 4' x 4' steel frame and gantry router (gantry being 4" x 6" 1/4 wall and a 3KW spindle) would you, in my shoes, build it using clearpaths of a smaller or larger torque than the 1300ozin range?

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A lot depends on what type of drive mechanism you're using to move that gantry (rack and pinion, ballscrew) and the speed you want to drive it. If I were in your shoes, I'd probably wait until I had the machine built or at least have components in hand, to get a sense of how much power you'll need to get your axes going. That 1300in-oz stepper has a relatively low speed range, and would probably work best direct-driving a screw with a relatively large lead.

[louieatienza]

I couldn't readily find the torque curve of any Chinese steppers, not that I would trust them anyway.

But here is a comparison of an Automation Direct 1200 oz/in Nema 34 stepper and a ClearPath 700 oz/in SD servo. I would have to say that in most applications they would be functionally equivalent. Normally I try to size steppers with at least 3x the holding torque of the nominal torque of a servo just because it helps eliminate lost steps due to momentary overloads.


Automation Direct


ClearPath

Actually the ClearPath has about 33% more torque at 1500rpm than the AD stepper, and closed loop...

[Jim Dawson]

A lot depends on what type of drive mechanism you're using to move that gantry (rack and pinion, ballscrew) and the speed you want to drive it. If I were in your shoes, I'd probably wait until I had the machine built or at least have components in hand, to get a sense of how much power you'll need to get your axes going. That 1300in-oz stepper has a relatively low speed range, and would probably work best direct-driving a screw with a relatively large lead.

Good advice.

As louieatienza said 1300 oz/in stepper would have enough power to move a pretty heavy gantry at reasonable acceleration as long as you keep the RPM down in the lower range. Even with a large lead, you can get good accuracy if you microstep.

For instance I have a moving table 4x8 machine with ball screws, 40 mm lead on the table screw and a 2:1 reduction so 20mm/motor revolution. 1280 oz/in stepper. 763 RPM = 600 IPM for the rapids. The table weighs about 700 lbs. The drive is set to microstep at 20,000 steps/ revolution, this gives a theoretical resolution (not to be confused with actual accuracy) of 0.001mm. For rapids it accelerates reliably at 5 RPS^2, cutting acceleration is set at 10 RPS^2, which works fine for cutting under 300 IPM (and normally much slower). The bottom line that steppers will do the job, but you have to do the calculations to get it right. I was able to cheat a bit on mine, the original servos were 500 oz/in DC servos so I knew what would run the machine. When I installed the steppers, I just more than doubled the torque, then through trial & error figured out the max accelerations the system would take.