[rcheli]

I am looking at buying a Sieg X3 or the heavy duty dovetail and converting it to CNC. I am also looking at the HobbyCNC package which comes with 3
#23-200-DS, 200oz-in, 3v, 3A, 200 S/R,2.3mH, Size #23, Dual Shaft, 6 wire
stepper motors.

I am just starting to look at ball screws. Ground, if I can find some that are reasonable. If not, then rolled. I'm also open to using the stock screws if that makes any sense. At least until they wear out.

I have been spending and hour or two a night reading up on everything but still have some questions. Maybe I can get lucky and find someone that's already done this conversion.

Will the 200oz-in steppers be big enough or should I look for something with more torque?

How does the software know how much distance is covered with one step?
Is that a configuration parameter?

Any thoughts on the HobbyCNC vs other controllers etc like Geckos?

Before I start trying to shop ebay etc I want to know what I should be shopping for rather than just looking for "ball screws" and if the price is reasonable deciding if I can use it. I would hate to buy something and then find that I can't (or would want to) use it because I didn't understand what I was buying.

Thanks
John

[wisp]

John, you will deffinitly need larger stepper's, unless you want the machine to be painfully slow. I would look at Nema34 size, 440oz/in and higher.

I have never tried the hobbycnc controller, but you can not go wrong with Gecko drives.

If you want ground ballscrews, you will have to get them on eBay. Ground ballscews start at several hundred dollars each.

Yes there is a parameter to tell the software how many steps it takes to move one inch.

cheers. :cheers:

[rcheli]

Thanks Wisp.

I'm now setting my sights on some 640oz-in steppers from homeshopcnc.com to be driven by some Geckos. I just need to figure out which model. I think I'll give them a call

I have been shopping the ball screws and found some ground ones that look like a good deal but I am far from actually buying them because I don't have the mill yet and don't know what minimum length I will need.

Major parts list so far

Mill: Sieg X3
Steppers: Bipolar 640oz-in, Dual shaft
Drivers: Gecko G2??
Power supply: ?
Computer: AMD 1100 mhz
Software: ?
Ballscrews: ? Dia: ? Lead: ?

John

[Bird_E]

John,
I converted my X3 using servos, Are you considering servos over steppers?
Bob

[rcheli]

I thought about it but so far in all of my reading this is what I think I've heard.

Stepper Guy: Servos are more complicated and harder to tune.

Servo Guy: You have to watch out for missing steps.

From what I have read, on modern steppers losing steps is rare unless you are trying to run the motor too fast. From the pictures I've seen the steppers apear to be less complicated to mount. Straight shaft to shaft connection. Many of the servo install seem to use gear reduction timing belts which in one way kind of attractive because you mat be able to tuck the motor out of the way.

While I'm not looking to do the coversion on shoestring I don't tons of bucks to throw at it either (Two boys in college).

So, I am open to the idea. Do you have any pictures of your conversion? How does it perform? What are some of he specs for what you used?

I would like to benefit from someone else's experience. If someone has a good performing machine that can be built at a moderate price without having to spend many hours shopping ebay and getting real lucky picking up parts then I would like to just duplicate their conversion rather than engineer it all my self.

[rcheli]

Wow Bob,

That's a really nice installation you have. I really like the way the servos are tucked back out of the way. Do you have any part numbers for the motors, pulleys, belts, encoders, etc?

I also saw a post somewhere that said that you need a scope to tune the servo motors. Did you find that to be true? Anyone else?

I saw the R/C heli sitting on the bench. Did you go to IRCHA this year?

Thanks
John

[Bird_E]

Here is a BOM of the major components that I used:
Vendor Web Site Part Number Description Approximate Cost
Stock Drive Products http://www.sdp-si.com/ A 6A 3-20DF03708 Motor Pulley -.200 (XL) Pitch, 20 Teeth, Aluminum Alloy Timing Pulley $9.25
Stock Drive Products http://www.sdp-si.com/ A 6A 3-50NF03710 X & Y Pulleys .200 (XL) Pitch, 50 Teeth, Aluminum Alloy Timing Pulley 20
Stock Drive Products http://www.sdp-si.com/ A 6R 3-082037 X Belt - .200" (XL) Pitch, 82 Teeth, 3/8" Wide, Neoprene Belt $5.55
Stock Drive Products http://www.sdp-si.com/ A 6R 3-102037 Y Belt - .200" (XL) Pitch, 102 Teeth, 3/8" Wide, Neoprene Belt $6.01
Stock Drive Products http://www.sdp-si.com/ A 6A 3-17DF03708 Z - Motor Pulley - .200 (XL) Pitch, 17 Teeth, Aluminum Alloy Timing Pulley $9.21
Stock Drive Products http://www.sdp-si.com/ A 6A 3-50NF03710 Z Big Pulley.200 (XL) Pitch, 50 Teeth, Aluminum Alloy Timing Pulley $20.91
Stock Drive Products http://www.sdp-si.com/ A 6R 3-102037 Z Belt .200" (XL) Pitch, 102 Teeth, 3/8" Wide, Neoprene Belt $6.01

Industrial Hobbies http://www.industrialhobbies.com/ 5/8" Rockford Single Circuit Ballnut (2 Per Axis) $22.00
Industrial Hobbies http://www.industrialhobbies.com/ 5/8" 5 TPI Rockford Standard Grade Ballscrew (6 Feet!) $51.00
Industrial Hobbies http://www.industrialhobbies.com/ 3 Gecko 320 Combo (Servo Drives) $342.00
VXB Ball Bearings http://stores.ebay.com/VXB-Bearings-...rd-and-Slotcar 7201B 12x32x10 Angular Contact Bearings (2 Per Axis Back to Back) $15.00
ColdFusionX Ebay Digital and Analog Panel Meters
[email protected] Ebay Controller Box 75
Cabelldesigns www.cambelldesigns.com BreakOut Board Parrallell Break out board 137
US Digital www.usdigital.com E2-250-250 250 Count Encoders (For the servo motors) (3 Pcs) 120
Avel Lindberg http://avellindberg.com/index.html Y236951 30AMP Toroid Transformer (32Volt) 82
CNC Zone. http://www.cnczone.com/forums/showth...t=cheap+servos Surplus Clifton Precision Servo Motors $10.00 Ea! See Link for info $30.00
Jeff Davis http://www.homecnc.info/cnc-main.html Preloaded Ball Nut Plans - Also Sells Servo Motors that would be good for the X-3 7

[rcheli]

Great reply!

Thanks Bob