[abferm]

Hello, I'm designing/building my first CNC router. I have no idea how t choose a stepper motor. I want the machine to work well, but cost as little as possible. Please provide me with some guidelines as far as torque, etc. are concerned.

[arizonavideo]

You will need to give us a bit more info.

What size router and material you wish to work with.

Low cost is a relative term.

[Jesse B]

Machine size, approximate weight of the gantry/moving table, depending on your design, and your budget are all needed, as well as which materials you're using and what kind of cutting speeds you'd like to achieve.

[abferm]

I'm going to guess my gantry will weigh between 50 and 75 lbs(very rough estimate). My major material will most likely be wood. Everything will move on rails and will be propelled by screws. Cut time is not my top priority. I'm not sure what type of router I will use. It may end up being just a Dremel or a flex shaft tool.

[jsheerin]

For that size of machine, I'd go with a Nema 23 380oz*in size from either cncrouterparts.com or Keling and drive them with a Gecko G540 with a 48V power supply. Use the rack and pinion components from cncrouterparts.com for high speed or longer than 4' of travel or a 1/2-10 5 start acme screw with antibacklash nuts. Don't use single start screws - you'll want to go faster than those screws will let you for wood.

[CarveOne]

You may be patient enough to watch a one start lead screw machine run at 30 ipm initially, but we guarantee that your patience won't last very long. I'm with jsheerin, pay the price now and have the option to run faster as a simple keyboard command. I went the cheap 1 start screw route for the same reasons and paid for screws and nuts twice. Cutting wood cleanly needs around 100 to 300 ipm speeds. I had to change to 5 start screws to get into that range.

CarveOne

[TheDon92]

Hey guys I have the same prob. Lol im brand new to this and I'm building a 4x4 cnc with a 1.5 horse router. I have no clue what size motors to get. Amy suggestions on kits? Id rather get a kit for now so I can learn the basics. Then replace motors/ drivers as needed. I also plan on cutting this aluminum and mainly wood.

[TheDon92]

You will need to give us a bit more info.

Anything in particular?

[TheDon92]

I also plan on cutting this aluminum and mainly wood.

Haha I never did good in English class.

[ssutton]

cnc router parts nema 23 kit with gecko drive G540. Tried and tested for 90% of all non production machines needs.

[TheDon92]

Thankyou. I appreciate the help. But will this have enough juice to carry my carriage that 4' or do you think that the nema 34 would be ideal? Thanks again for the help tho

[ssutton]

My machine is 4' X 4' and my gantry weighs 75 pounds. I rapid at 400 ipm and cut at 150-175 ipm all day long. CNC router parts nema 23 kit will push most any home machine fine.

[louieatienza]

This has to be one of, if not, the most asked question concerning CNC building, and the answer is not always straighforward.

As the others have mentioned, while cut time is not your priority, wood in general machines best with at least 60-70ipm and up to 200+ipm with really no speed limit depending on your machine.

Before you figure out what steppers you need, you need to sort out exactly what spindle you'll be using, and what exactly lead of screw. You'd also need to figure out approximately how much force would be needed to push each axis around.

Note that while finer lead screws havev a higher mechanical advantage, they do so at the cost of efficiency, and the manufacturer's charts will have those percentages, which should be factored in. Also you should allow for at least 10% and possibly more headroom.

I would check out the documents in the GeckoDrive.com website that discuss exactly this, as well as other topics.

[TheDon92]

This has to be one of, if not, the most asked question concerning CNC building, and the answer is not always straighforward.

As the others have mentioned, while cut time is not your priority, wood in general machines best with at least 60-70ipm and up to 200+ipm with really no speed limit depending on your machine.

Before you figure out what steppers you need, you need to sort out exactly what spindle you'll be using, and what exactly lead of screw. You'd also need to figure out approximately how much force would be needed to push each axis around.

Note that while finer lead screws havev a higher mechanical advantage, they do so at the cost of efficiency, and the manufacturer's charts will have those percentages, which should be factored in. Also you should allow for at least 10% and possibly more headroom.

I would check out the documents in the GeckoDrive.com website that discuss exactly this, as well as other topics.

I went out and bought 5/8ths in. -11 threaded rod. So that means that if i get a nema 23 motor that maxes out at 400rpm then my gantry will only move at 36 ipm right? Or is there a way to spin those motors faster than 400rpm?

[TheDon92]

My machine is 4' X 4' and my gantry weighs 75 pounds. I rapid at 400 ipm and cut at 150-175 ipm all day long. CNC router parts nema 23 kit will push most any home machine fine.

Aliexpress.com : Buy Best Selling! Wantai 3 Axis Nema 23 Stepper Motor 57BYGH115 003 425oz in+Driver DQ542MA 50V 4.2A 128Micro CNC Router Plasma Cut from Reliable stepper motor single shaft dual shaft 30kg.cm lowest price suppliers on Changzhou Wantm
Is this the kit you are suggesting? Again I really appreciate the help guys

[louieatienza]

I went out and bought 5/8ths in. 7/11 threaded rod. So that means that if i get a nema 23 motor that maxes out at 400rpm then my gantry will only move at 36 ipm right? Or is there a way to spin those motors faster than 400rpm?

A stepper can spin over 3000rpm, but it depends on the drive, the stepper itself, the voltage applied to it, and the load it's spinning. With my 425in-oz steppers and 48v and G540 drive, I can achieve over 750rpm before stalling, which translates to 750ipm with my 8-start leadscrews. The more voltage you can apply to the stepper the faster it can go before the torque stops dropping, but at the cost of heat. Steppers can withstand relatively high heat continuously. The speed of your controller can also determine how fast you can ultimately spin the motors since it determines the maximum amount of pulses per second that can be sent to the drives.

The issue you'll face is that the efficiency of the 5/8"-11 screws not too great (maybe a bronze or plastic nut will help) so most of the torque you DO generate will be wated overcoming friction in you leadnut before it even starts pushing your axis or overcoming stiction in your linear bearings.

[ssutton]

Is this the kit you are suggesting? Again I really appreciate the help guys

This is the kit that I was making a reference to;
4 Axis Electronics Kit | CNCRouterParts

[TheDon92]

Thanks so much guys. I really appreciate it. Good news. The kit is ORDERED!! Now I'm scrapping the threaded rod and getting acme rod. Any suggestions on what start thread I should get for half inch?