Where do I go now!

[The Wizard]

Hi Folks,

I am currently building a modified version of JGRO's machine (build log is here... http://cnczone.com/forums/showthread.php?t=6244) and I have hit a major stumbling block!

I originally bought a Stepperworld SP-3/HT card and three Nema 23 steppers rated at 5V, 1A, 53 oz./in. torque which I am running from a regular computer power supply. When I bought the card I was undecided between the above and the Hobby CNC kit and finally went for the SP-3/HT based on it's alleged 'high torque' output. Unfortunately due to a combination of the card, power supply and the TPI of my leadscrews (1/4"-20 all-thread) I find that my machine speed is woefully below what I expected or need as I will mostly be cutting wood and plastics. Using Turbo CNC as the control software the best I can get is 3.75" IPM in rapid before the motors start to lose steps big time! The motors just stall once you hit the 3.75" limit. I have tried the card in both 'high torque' and 'half-step' modes with very little difference in performance. I have checked and re-checked the rails/slides to make sure they are not binding and they run nice and smooth in all directions with very little effort.

I obviously need to upgrade the control/motor/powersupply set up but the big question is just which way do I go now? I am medically disabled and on a very fixed income so every cent counts when it comes to expenses but having come this far I really need to get this machine working.....lol.

The Hobby CNC package has been recommended to me by Balsaman (from here) and others on the TCNC Yahoo group and as I said it was on the top of my list before (along with the SP-3/HT package). The problem I now face is just what do I do? Buy just the board and hope the motors and power supply I have are up to the job? Buy the board and the power supply and hope my motors can cope with the increase in voltage/speed? Go the whole hog and buy the complete package with the larger motors and power supply and sell what I have?

The only other solution I can think of is to change out the 1/4"-20 all-thread for something with a coarser pitch but that would be a major re-engineering challenge at this stage as the machine parts are glued and screwed together and would have to be re-machined to accept larger diameter leadscrews. I would also have to re-make my A-B nuts from scratch too.

Do you guys/gals have any suggestions as to my best options from here?

Thanks for your time.

Larry

[ger21]

The 53oz motors are a big part of your speed problem. And so is the 12V. But, as Eric said somewhere else, the best you'll be able to get with even 100 oz motors is ~12 ipm.

What speed are you trying to attain? You probably want at least 30ipm, I'm guessing. I'd try to sell the Stepperworld board on Ebay, and get the HobbyCNC. Then, try to find a 24V supply on Ebay. If you wait long enough, you should be able to get one for around $10-$20. And you really need bigger motors, preferably at least 200 oz-in. HobbyCNC has these as well.

And if you still can't get enough speed, you need to switch to something like 1/2-10 acme.

Unfortunately, I don't see any cheaper way to go about it. You could try running 24V through the Stepperworld board, but I doubt it will give you much better performance based on what I've read.

[The Wizard]

Thanks for replying Gerry,

Originally Posted by ger21 What speed are you trying to attain? You probably want at least 30ipm, I'm guessing.

That would be a good figure to aim for I guess, at least for rapid traverse/homing situations. I will only be cutting wood and plastics (with maybe some PCB material) and will need a 'reasonable' feed rate to prevent burning of the parts/cutters. I will be using a laminate router (20,000 RPM) with 1/4" and 1/8" collets and the largest cutter I have with a 1/4" shank is 1/2" diameter. The smallest cutters will be tiny carbide PCB type drills/mills and engraving bits. The router is being wired through a speed control too so that I can adjust spindle speed as well as feedrate.

Originally Posted by ger21 I'd try to sell the Stepperworld board on Ebay, and get either the HobbyCNC or the Xylotex. Then, try to find a 24V supply on Ebay. If you wait long enough, you should be able to get one for around $10-$20. And you really need bigger motors, preferably at least 200 oz-in. You can get these 166oz-in for $29 from http://web6.automationdirect.com/adc.../STP-MTR-23055 And if you still can't get enough speed, you need to switch to something like 1/2-10 acme.

Yup that's what I thought I was going to have to do but I thought I would ask first before making another costly mistake :frown: . The really frustrating part is the hours I spent researching all the different options in terms of motors, drivers, power supplies etc. and I still messed up!

Originally Posted by ger21 Unfortunately, I don't see any cheaper way to go about it. You could try running 24V through the Stepperworld board, but I doubt it will give you much better performance based on what I've read.

Neither do I. Ho hum, time to make some changes I guess.

Larry

[HobbyCNC]

HobbyCNC has 200oz-in steppers at a very good price..even better when purchased with a package or driver board kit.

Dave Rigotti

[The Wizard]

Originally Posted by hobbycnc HobbyCNC has 200oz-in steppers at a very good price..even better when purchased woth a package or driver board kit that GER21 failed to mention. Dave Rigotti

Thanks Dave, I did see that on your page. While I have your ear what would the shipping be to ship a 'major 3 axis package' with the 200 oz-in steppers across the lake as I am in SW Ontario, Canada (if I was on a tall enough building I could probably see you.....lol). I would prefer USPS rather than UPS or FedEx as we get nailed for brokerage charges with those outfits.

Thanks,

Larry Green

[HobbyCNC]

Originally Posted by The Wizard Thanks Dave, I did see that on your page. While I have your ear what would the shipping be to ship a 'major 3 axis package' with the 200 oz-in steppers across the lake as I am in SW Ontario, Canada (if I was on a tall enough building I could probably see you.....lol). I would prefer USPS rather than UPS or FedEx as we get nailed for brokerage charges with those outfits. Thanks, Larry Green

Larry,
Email your request to dave@hobbycnc.com. This is a support forum.

Dave Rigotti

[The Wizard]

Originally Posted by hobbycnc Larry, Email your request to dave@hobbycnc.com. This is a support forum. Dave Rigotti

Oooops sorry, my goof!

Direct email to follow.

Larry