The start of something new ...I Hope...

[bgolash]

Hi Group

I’ve been visiting the cnc zone website for a few months. During that time I’ve been reading many of the threads. There are so many talented people that visit the site I have learned allot here. It’s a certainty that I will have many questions for the members of the site.
So now,for better or worst the construction begins. I visited my favorite junk yard. I managed to find aluminum extrusions, Thomson block assemblies and the best find... A 36 X 80 I-beam base. eBay as usual seems to be place to find the expensive components. I found lead screw assemblies with the bearing blocks and purchased two sets. One complete set will be used for the Z axis. The other will be cannibalized for the bearing blocks which will be used on the X axis.
Note: ¾ dia .2 lead In addition, I procured four thk linear sets with 4 bearing blocks. I plan to butt these end to end for the Y axis. For the bearing assemblies I turned two blocks on my old south-bend lathe.
I’ve been working on the electronics for the project. I have one gecko 201 and an Automation Direct stepper. Since I am not an electronics expert to get started I purchased their 40 volt power supply. I haven’t had much success with the electronics part of this project. I did manage to get the stepper up and running. The problem is the motors spins at about 2 to 3 rps. I’ve played with the mach 2 tuning selection to no avail. Hope someone here can help me with this frustrating problem.
So frustrated with the electronics, I started to mount my Thomson 1.25 dia linear motion rails to the bottom of my frame. This required 48 bolt holes to be drilled in the aluminum frame. I got one rail mounted and then setup a measuring system to check the other x rail for parallel. I mounted a dial-indicator attached to an extrusion and linked it to two Thomson bearing blocks. I adjusted the blocks as tight as possible to eliminate any clearances. After about 5 hours I managed to get the two x rails within .001. As a test I mounted a 13 x 36 piece of MDF to the four bearing blocks .. clamped four wood clamps to secure the MDF and pushed the new assembly to test for any binding. It seemed OK but I did push on one side and the MDF did twist a bit. I hope that the machine will not see any offset loads because it did move .010.
In a few days I’ll receive another eBay purchase …more extrusions so I can finish the base. I do have the gantry ends roughed out. I think I`ll send them out to a machinist to square them up. I thought it might be a good idea to have the ends machined so I would have reliable references to mount the other components. Its getting late. I hope you`ll visit this thread again. I`m certain I`ll have endless questions.

Best Wishes, Barry

[ViperTX]

Do you have any other information on the stepper....I'll chase down the Gecko 201 drawing. Can you describe how you have it hooked up....it is stepping in one direction and not just stuttering??

[bgolash]

Hi ViperTX
I have one gecko 201 and stepper with a 40 volt power supply.
The motor I have is STP-MTR-34066.The motor and the power supply
are from Automation Direct. Motor specs 5 volt, 2.8 amp 410 oz*in
http://web3.automationdirect.com/sta...stepmotors.pdf
I am using Mach2 but even with endless combinations with velocity
etc. The stepper only seems to move 2 to 3 revs per second.
I am using bob campbell`s breakout board. I tried the motor as XYZ
on the breakout board..all axes run but very slowly.
The wiring off the top of my head is step to step , direction
to direction and a com to and from the breakout broad to the gecko.
It seems to me the LED`s are working on the breakout. Someone mentioned
in another group that my old 450megahertz PC maybe too slow. I haven`t
tried using my 2.4 PC but will tomorrow.
Note: Mach2 has sample code and sometimes the motor just makes noise no
movement. I have run the stepper in manual mode with the joy stick and then
it will move at about 2 to 3 rps.

Thanks for the help..Barry

[bgolash]

Hi all

I need to purchase a rolled ball screw. The length
is approximately 72 inches. Is a 5/8 diameter
large enough to minimize sagging or whip of the screw.

Regards Barry

[ger21]

Hi ViperTX
I have one gecko 201 and stepper with a 40 volt power supply.
The motor I have is STP-MTR-34066.The motor and the power supply
are from Automation Direct. Motor specs 5 volt, 2.8 amp 410 oz*in
http://web3.automationdirect.com/sta...stepmotors.pdf
I am using Mach2 but even with endless combinations with velocity
etc. The stepper only seems to move 2 to 3 revs per second.
I am using bob campbell`s breakout board. I tried the motor as XYZ
on the breakout board..all axes run but very slowly.
The wiring off the top of my head is step to step , direction
to direction and a com to and from the breakout broad to the gecko.
It seems to me the LED`s are working on the breakout. Someone mentioned
in another group that my old 450megahertz PC maybe too slow. I haven`t
tried using my 2.4 PC but will tomorrow.
Note: Mach2 has sample code and sometimes the motor just makes noise no
movement. I have run the stepper in manual mode with the joy stick and then
it will move at about 2 to 3 rps.

Thanks for the help..Barry

If it just makes noise and doesn't move, your acceleration may be set too high. Also, If your manually jogging the machine, it may not be able to go any faster. Try running some g-code and use the F word to set the speed you want.

[bgolash]

Hi All

I believe all my problems are solved with the slow motor problem.
It seems as soon as I tried the motor with Mach2 on my 2.4 megahertz
PC everything seemed to work as I hoped it would. No luck with a old
450.
Regards Barry

[ViperTX]

Barry, Check the wiring to the Gecko. The red motor wire should go to Phase A and the while mtr wire should go to Phase B. The green motr wire should go to Phase C and the black motor wire should go to Phase D.

Also since you have a 40VDC motor supply you should have a resistor of about 2500 ohms (pick a 3.3 K or so resistor....don't remember what is between 2.2 K and 4.7K0 in series with the step and direction inputs. Check that Term 10 (+5VDC) is connected to a 5VDC power supply....I'm not familiar with the breakout board, but it will most likely have a 5 volt source. Let me know what happens.
Paul

[bgolash]

I checked over all the wiring. It seems fine.
Thanks for taking the time to help.

Barry, Check the wiring to the Gecko. The red motor wire should go to Phase A and the while mtr wire should go to Phase B. The green motr wire should go to Phase C and the black motor wire should go to Phase D.

Also since you have a 40VDC motor supply you should have a resistor of about 2500 ohms (pick a 3.3 K or so resistor....don't remember what is between 2.2 K and 4.7K0 in series with the step and direction inputs. Check that Term 10 (+5VDC) is connected to a 5VDC power supply....I'm not familiar with the breakout board, but it will most likely have a 5 volt source. Let me know what happens.
Paul

[bgolash]

Hi Group

The machine base is comprised of aluminum extrusions and welded I -beams. The current view of the frame is upside down.
The Thomson 1.25 diameter rails are mounted underneath the frame. It seems this orientation to load is the worst from a design | load standpoint. The frame to a degree only allowed easy mounting with the current placement. The load of each block is 2000 pounds. The specs on the blocks indicate that when they are in an inverted orientation they must be de-rated by 50%. So I think I`ll be safe at 1000 pounds per block. The next step is to mount a Thomson 5/8 diameter ball screw with a length of 68 inches to the
frame. The machining I hope to do myself. I`m a bit concerned because the screw is case-hardened to a Rockwell 57. I was thinking about annealing the ends with a mapp torch while the part was spinning in the lathe. I`m a bit concerned that it might be possible with the heat to distort the screw. I purchased a ball screw assembly on eBay just to use the bearing blocks for the x axis lead screw. At 30 dollars for the assembly that definitely saved a lot of time to fab something in-house.
Once the machine has its x lead screw attached I`ll flip the machine over
and start on the gantry.

[bgolash]

Hi Group

Here are a few more of the parts. I plan to use the lead screw pictured here for the Z axis. I have another lead screw that`s a carbon copy of the first. The second one I`ll use the bearing blocks for the X axis. The two aluminum turnings are bearing housing I turned for the Y axis. The IKO rails will be butted end to end for the gantry Y axis. It looks like making the machine
base was the easy part. Now for the detail work.

[bgolash]

Hi Group

I machined the ball screw and did a mock up of the x axis.
At the moment all the parts are secured by clamps. I tried
the steppers with Mach 2 software and a Gecko 210 driver.
The power supply is from Automation Direct as is the stepper.
The stepper is the largest they sell 410 oz*in. The power supply
is 32 volts.
I have to admit, I thought I would be moving the x a bit faster.
The current speed is 60 ipm. The ball screw is a Thomson
5/8 diameter with a .2 lead. I did try to run the steppers faster
but the motor stalled. I did check the alignment of the gantry
and the ball screw and there was no bidding. I`m wondering
if the motor is just sized too small.


Best Wishes, Barry

[ger21]

I don't have first hand experience, but I've heard that if you double your voltage you should roughly double your top speed. Maybe not what you wanted to hear. Is this the $99 motor they sell? #34066? There short description says it's 310oz-in, but the specs say 434oz-in. If you look at the torque curve chart on the website, you'll see that with 1/10 microstepping (What setting are you using?) this motor only has about 60oz-in of torque at 300rpm (60ipm). And at 375RPM, it only has about 25oz-in. It also has only just over 300oz-in holding torque, according to the chart. So it's looks like its really a 310 oz-in motor. They don't list the motors rated voltage (or the specs needed to determine it), so it's a bit hard to determine the Max voltage you could safely supply. You could measure the resistance of one of the coils, and the voltage rating should be 2.8a x resistance. More voltage should give you more speed, though. You might want to try something like this.
http://cgi.ebay.com/ws/eBayISAPI.dll...858922482&rd=1

Compare this Vexta motor's torque curve compared to yours.
http://www.orientalmotor.co.jp/cgi-b...K&frameSize=85
When wired bipolar parallel, there is quite a difference in useable torque for motors with similar ratings.

Lastly, make sure you have absolutely no binding and everything moves freely.
Can you turn the leadscrew easily with your fingers without the motor? How hard is it to move the X without the leadscrew attached?