Delta ORD Bot

[kbob]

I can't imagine doing this with without CAD tools and digital fabrication.

That's probably why nobody was doing it in 1960. (-:

[bdring]

I got the thing calibrated. I started by using a caliper to measure the height of the carriages off the bed. That was probably a waste of time because when I used the gauge, I was way off.

Here was my process.

• Zero the machine
• Run it down to the bed
• move it in a line perpendicular to one of the axes
• adjust an end stop trigger (thumb screw)
• Repeat until it is level across the bed
• Repeat on another axis

I got it to within about 0.12mm across the whole bed. I probably could have done better, but I might be doing some tweaks soon that would spoil the calibration. I did not have any humps or troughs so my geometry must be right (go CAD!)

I also drew a little shape. It was manually entered GCode one line at a time so there are some bleeds in the corners as it waited for me to think and type.

[macona]

I can't imaging doing this with without CAD tools and digital fabrication.

Why is that? Looks simple enough to me.

Much more complex and difficult things have been designed and built by hand in home shops all around the world. We are lucky to get to play with the toys we do.

What is controlling this? I see something there on the base. Does the control handle a delta natively or do you have to program for it in software? I didnt see anything earlier in the thread.

[SystemsGuy]

Looks great Bart, and yeah - if you don't have convex / concave deviation of the effector when moving to the x/y extremes, you've done stunningly!

[bdring]

built by hand in home shops all around the world

Sure, but I can't imagine myself taking on a project like this with such a small time budget without CAD tools, spreadsheets, etc. It was really nice to just pop the dimensions into the firmware and have them work.

It is a complicated project. Every location in the working envelope has a different step/mm resolution. It is all simple triangle math, but it is nice be able to play with values and see it graphed in real time on a spreadsheet.

What is controlling this?

It runs standard 3 axis G-Code using modified versions of standard Arduino firmware (Marlin, Repetier). The 3 linear actuators are labeled in firmware as X,Y,Z, but the GCode is translated on the fly into the moves required to get the motion you want. It is sort of like the way an arc move is broken down into line segment moves on some systems.

[macona]

Dosnt LinuxCNC have the kinematics built in for a delta? Maybe make a mod for lCNC to pass through the non-movment g-codes to the arduino for extruder and temp control.

I know, sounds complicated but leaves the hard stuff for linuxcnc to handle and then the g-code is more universal.

[bdring]

LinuxCNC does have that. There is a whole inverse kinematics layer. I think there is a default kinematics that most of us use that basically says x=x, y=y, z=z. I have seen setups for 6 axis delta bots in EMC2.

It is amazing what the Arduino can do, but I am sure Rapsi and 32 bit controllers will be taking over very soon. The Arduinos just can't look far enough ahead.

[SystemsGuy]

Bart - what are you going to do for an extruder / hotend on your delta?

[bdring]

Right now the plan is to use parts I have on hand. That will be a QU-BD hot end. The hot end bolts through a small CPU heatsink and is cooled by a 30mm fan.

The drive will be a bowden system using QU-BD motor, MK7 drive gear and a idler bearing similar to my modification. I will start by mounting the drive end to the top of my spool cartridge and see how that works and looks. I printed most of the parts last night.

I have some teflon tubing and delrin quick release tube fittings that are super light and easy to use.

The hot bed is a big 6061 plate with power resistors. It will take a while to heat up, but should do until my final hot bed shows up. I kept the wattage low so I don't have to worry about blowing fuses or FETs. I threw it in a friend's batch of aluminum getting hard coated, so it will have an awesome black finish.

[SystemsGuy]

Sounds interesting - can't wait to see what you come up with. I've still not got enough offcut extrusion to build one of your spool holders, but they look too sexy to pass up!!