Need Help!- Double x axis drive

[mrfreon]

Hi all. I am at the planning stage for my cnc router and was planning on having 2 x axis steppers. Do I drive these in paralell or do I need a seperate driver for each motor. Sorry if it's obvious but I've looked and can't find the answer yet. Thanks

[monte55]

You need a driver for each stepper

[mrfreon]

Thanks for the response monte55. Looking over the site it's all a bit confusing at the moment and I can see a lot more planning before I actually do something, never realised there was so many ways to achieve the same thing. Was planning a small'ish one about 1000 x 600mm. If I need any more help I'll post knowing I'll get a response. Great forum.

[Mr.Chips]

Originally Posted by monte55 You need a driver for each stepper

What about lost steps, and what would you do, it seems to be a common occurance?

[ger21]

Originally Posted by Mr.Chips What about lost steps, and what would you do, it seems to be a common occurance?

Don't try to run your machine faster than it's capable of. That's what causes lost steps. If you want to cut at 100ipm, build a machine that will cut at 150ipm and have more power than you need.

[Mr.Chips]

Originally Posted by ger21 Don't try to run your machine faster than it's capable of. That's what causes lost steps. If you want to cut at 100ipm, build a machine that will cut at 150ipm and have more power than you need.

For us newbies:
What are the things that enable a machine to be built to the 150ipm lever? And please don't just say bigger.

For cutting MDF:
PS Volts?
PS Amps?
Example of Min driver board (Manuf/Model)?
Stepper size?
Screw type?
Screw size?

For Aluminum:
PS Volts?
PS Amps?
Example of Min driver board (Manuf/Model)?
Stepper size?
Screw type?
Screw size?

[ger21]

Material doesn't really matter, but different materials may need different spindle HP.

Size and weight of machine makes a huge difference, so what works for one may not work for another. Volts and amps are dictated by the motors you use, so there is no general rule.

What you need to do, is decide how much force you want to have at a given speed. Then using the leadscrew you plan to use, calculate how much torque the motor needs to have at the rpm it's running at your target velocity. Then choose a motor that will provide that torque at that rpm. You'll need to see a motors torque curve to figure this out.

[Mr.Chips]

Originally Posted by ger21 Material doesn't really matter, but different materials may need different spindle HP. Size and weight of machine makes a huge difference, so what works for one may not work for another. Volts and amps are dictated by the motors you use, so there is no general rule. What you need to do, is decide how much force you want to have at a given speed. Then using the leadscrew you plan to use, calculate how much torque the motor needs to have at the rpm it's running at your target velocity. Then choose a motor that will provide that torque at that rpm. You'll need to see a motors torque curve to figure this out.

"For us newbies:
What are the things that enable a machine to be built to the 150ipm lever? And please don't just say bigger."

Well you didn't say bigger.

Let me ask it this way.

What IPM would you say this machine would calculate out to?

116 OzIn Steppers. (From Xylotex) configured as Unipolar.
Drive board set to full step.
1/2" 1 start acme thread.
1 3/4 HP single speed Porter Cable router.
1/4" 2 flute HS bit.

Is that enough information?

[ger21]

Originally Posted by Mr.Chips "For us newbies: What are the things that enable a machine to be built to the 150ipm lever? And please don't just say bigger." Well you didn't say bigger. Let me ask it this way. What IPM would you say this machine would calculate out to? 116 OzIn Steppers. (From Xylotex) configured as Unipolar. Drive board set to full step. 1/2" 1 start acme thread. 1 3/4 HP single speed Porter Cable router. 1/4" 2 flute HS bit. Is that enough information?

Sorry, I didn't have much time to elaborate earlier.

That's really not enough info to go buy. As I said, You need to have a torque curve chart for your motor to know how much torque it has at any given rpm. A stepper motors torque falls off as rpm's increase, and without a chart, you really don't know how much torque it will have at any given rpm. Taking a shot in the dark, I'd guess you're looking at 30- 50ipm out of that, but it depends on a lot of things.


Assuming a machine similar in size to Joes 2006, You can get 100ipm with 300 oz motors and 1/2-8 2 start acme running at 36V with a HobbyCNC board. Want to go faster? Get some 5-6amp motors and Gecko Drives, and run them at 15-20x their rated voltage. Faster still? Move up to 400 oz-in 6 amp motors, get some 1/2-10 5 start screws, and a 36V-48V power supply. You can probably get 300ipm from that.

[mrfreon]

I did say I was a newbie didn't I. I see there's a lot more to it than I first thought, I was planning a smallish fairly basic machine to do a bit of cnc work for fun and interest. I feel a bit inferior now hearing about 400oz/in motors and 300in/min. Does this mean I have to set my sights higher, or can I stay, dare I say it, Small-ish. Thanks

[Mr.Chips]

Originally Posted by mrfreon I did say I was a newbie didn't I. I see there's a lot more to it than I first thought, I was planning a smallish fairly basic machine to do a bit of cnc work for fun and interest. I feel a bit inferior now hearing about 400oz/in motors and 300in/min. Does this mean I have to set my sights higher, or can I stay, dare I say it, Small-ish. Thanks

Sorry MrFreon,
I didn't mean to Hyjack your thread.
Mr.Chips

[Eurisko]

Originally Posted by ger21 Move up to 400 oz-in 6 amp motors, get some 1/2-10 5 start screws, and a 36V-48V power supply. You can probably get 300ipm from that.

Gerry,

Did I read that correctly? 1/2-10 5 start ?

That would be, um, 1/2 in. per revolution?

Smokin!

Might be hard to find leadnuts, though.