3-Axis Machine tension cord

[freddean2006]

Hello,

Anyone know what tension cord and fittings are being used on this cnc machine, and where to get them.

The one on http://www.milinst.com/ under robotics.

Also how useful would it be, would I be able to cut wood?

Thanks

[rustamd]

Originally Posted by freddean2006 Hello, Anyone know what tension cord and fittings are being used on this cnc machine, and where to get them. The one on http://www.milinst.com/ under robotics. Also how useful would it be, would I be able to cut wood? Thanks

Not sure what you mean by tension cords and fittings...

[Al_The_Man]

If you are referring to this sentence [ driven by a powerful 200 steps/rev 12VDC stepper motor with tension cord for backlash free operation.]::
I don't think they are inferring anything special regards the cord, just poor wording.
Al.

[freddean2006]

If you look at the building pdf the use tension cord to drive each axis. I have not seen this before.

[X-29]

My guess is that it´s an ordinary steel wire, turned around the drive axis, and then preloaded.
Like the frequency adjustment in an old radio.

[freddean2006]

Would it slip?

[MrWild]

stepper motor shaft slop. Most stepper motors I have seen have play that allows the shaft to wobble in and out a little bit. This is not rotational wobble but in and out end play. When a lead screw is attached directly to the stepper, it has the same amountof pl[ay and becomes part of the machi-ne's backlash (the amount of play the table has and is the total accumuation of leadscrew and nut play, linear bearing play, and other factors that equate to loosness)

To reduce the play coming from the stepper motor/solid mounted leadscrew, springs have been used to force the stepper shaft to one end of itsend play travel. I believe their wire is realy a spring. This isn't all that great of a fix as the spring will still allow play when the machine is pushed hard. It could be the steppers are so weak that they don't have the power to displace the spring....

[freddean2006]

by looking at the plans it seems that they dont use a leadscrew. all motion is achieved by a cord which is wrapped around the shaft of the stepper an connected to the ends of each axis. The motor is on th x axis underneath the table with the shaft pointing up.

I wondered if this style would have much power given i would think the cable would slip.

[Fer1526]

look at this link; there are a lot of machines with "cable drive system" and you can find complete plans to build that kind of machine!
http://cnc25.free.fr/machinescnc25.htm
is a french site but you can found very usefull info anyway.