So Close. . . Please Help!

Greetings all,

About six months ago I bought an Axis 2.1 printer from Botmill (I know now how crappy a company they are to work with, believe me) and I'm trying to get this thing running. The exact design is apparently a "Sells" Mendel, and its page on Botmill's site is here: (http://botmill.com/index.php/axiskit-106.html)

I've got everything assembled and all appears to be functional EXCEPT:

The X and Z axes appears to be too tight (somehow) for the stepper motor to be able to move them. If I push or pull with my hand in the direction I send the motor, I can get it to be able to move, but it cannot move on it's own.

Conversely, the Y-axis appears to be functioning quite nicely.

Do you have any suggestions on how to reduce the amount of friction present in the X and Z axes, or any ideas about what I might be doing wrong?

Any help would be vastly appreciated, because after all the hell Botmill has put me through, I just want to get this thing working.

Thanks,
MrBlack

Does it use bearings as the link doesn't work or bushes?

---

__________________________________________________________________________
Experimenting in 3D in New Zealand

is the carriage tight without the belts attached?

do your electronics have 4 adjustable pots on the board?

Hi Mr. Black,

If you remove the belts, you should be able to push the x axis with your finger back and forth (without moving the printer around on the table). It should slide smoothly with no more force than pushing a coffee cup around on a table top. If that's the case, your trouble isn't friction.

The Z axis screws should turn freely with the motors disconnected. Once connected they should turn freely but with the added motor resistance. There should be little to no binding. The steppers can overcome a bit of binding in the Z axis but the smoother the better.

If you disconnect the belts from the motors and then try to move the motors, do they turn? If you grab hold of the pulleys and then signal the motors to turn you should feel a good deal of torq from the motors... not enough that you can't stop them but it should take some effort to stop they movement.

Some motor control boards have adjustable torq (turn of a screw). It may be that you just need to turn the torq up a bit. Increased torq is also increased heat from the motors so if you increase the torq, do so gradually and stop when it is sufficient.

Let us know your results.

Regards,

Ross

---

You don't need a parachute to skydive. You only need a parachute to skydive twice.

Also make sure your end-stops are correctly wired. I've just completed my prusa build, and scratched my head over why the steppers would just give a wee buzz but not go anywhere.. ( in my case, the microswitches needed to be normally-closed, going open when the end-stop hit).
Unfortunately the botmill site is rather vague on details as to what is in its Axis/Sells Mendel kit.

As people have pointed out, X, Y & Z should move freely when the belts are moved. I had similar experiences with my Mendel. So you might want to check the following.

X-Carriage: Mine was badly formed and the top half rubbed on the bars. I had to grind away several mm's of material before it no longer rubbed. I think the carriage was built a few mm's too big as the bearings also don't ride on the bars in the right spot. I had to tweak this mounting to get them right.

Z-Screws: Make sure they are not bent and are as parallel as possible. Also make sure the X-axes is level and not canted on the screws. I also had problems with the captive M8 nut that runs up and down the screws. I just happened to pick one that wasn't well machined and was very stiff. When I changed it out it was much better.

Stepper Motors: The original motors I picked (directly from the Wiki) were not beefy enough to drive the Z-Axis once it was running smoothly. I had to buy more powerful ones in the end.

Good Luck

JB

---

--
Check out my blog: AdventuresIn3-DPrinting