[PEU]

Finished the test bed https://www.dropbox.com/gallery/3624...otion?h=1faeff

2xthk guides, chinese ballscrew, Sino glass scale, usdigital differential encoder and OPB917 slotted sensor for homing

Next week I start with the electronics and then software, hopefully you guys can help me along the way.


Pablo
PS: is the yahoo list dead?

[TomKerekes]

Pablo,

What was the hammer used for? :}

It should be interesting to see how well it performs.

I'm not a mechanical Engineer but I've worked on a number of such systems. I can't see clearly but this seems to be an overly constrained system (constraining a rigid body in more than 6 ways). Basically if everything is not perfect the axis will bind. Nothing is ever perfect. The rails and screw will not be perfectly straight or parallel. The better and stiffer the system is built the more this becomes an issue. Normally flexures are used so that one of the rails or nut is allowed some amount of controlled "float" or compliance in one direction but still be highly rigid in the other direction where it is needed. Sometimes by luck there is enough compliance in the system so it works ok. Have you considered this?

Regards

[PEU]

The hammer? to adjust the glass scales

Adjustment was the most difficult part, but having the right tools and patience is the key to make everything go smooth, and it goes smooth.

Since this is a test bed for big machine we are designing I don't want to have flex, you start by aligning the rails, then the screw to them, then the glass and finally the encoder you know the drill... a royal PITA but obviously doable.

Let me fire a simple question: can I use the glass scale standalone reader in parallel with the inputs of kanalog, so I can check interactivelly if the commanded movement is accurate?


Pablo


Pablo

[TomKerekes]

Hi Pablo,

can I use the glass scale standalone reader in parallel with the inputs of kanalog, so I can check interactivelly if the commanded movement is accurate?

I don't really understand what you mean. But yes you have two encoders: one rotary and one linear. So connect them both to Kanalog to different encoder inputs so we can compare the measuremnts.

What type of motor is that? How do you intend to drive it?

Regards

[PEU]

I mean, split the each output of the glass scale into two wires, one goes to the kanalog and the other to the glass scale display unit


So I can check if the mach3 controlled kflop moves exactly the same as the display unit, this is obviously for testing purposes.

the motor is a nema 34 stepper, I have gecko 203v drives for it, still need to build the power supply.

[TomKerekes]

Oh I get it now, yes you should be able to just parallel the signals. Kanalog has a moderate termination of 470ohms across the + to - inputs for exactly this purpose. Normally it is best to terminate with about 120 ohms but then two devices in parallel might be too much of a load for the drive circuit.

Regards

[ej_on_line]

Hello,

Your experiment looks very interesting. I know it is a while a go you've posted in this thread but I was wondering if you ever concluded your tests?

Kind regards,