It's pretty simple, I have learned 3 things already in building a delta "pick and place" robot arm...
1) There seems to be a lot of math involved in making these guys move properly. I didn't know that going into this project. Hmm..
2) Every joint must deflect quite a bit, both ways, and in BOTH THE X AND Y directions. More than 45 degrees each way seems to be a minimum.
3) What Gareth is to polymorph, I am to brass tubing. Yes, after cutting (24) perfect spacers in a row, I am now the Tubing God. --Modest too!
https://www.youtube.com/watch?v=2DGEL6mkoqI
Your joints are binding
Your joints are binding because on each servos link the bottom 2 ball joints are much closer to each other than the top 2 joints making your arms form a trapezoid. That way the top and bottom joints are “opposing” each other. Try making the bottom horizontal bars the same width as the top and you should see a lot more movement.
I saw that.
You are very correct. I need longer threaded rod for the bottom linkages (to widen them and make the main rods parallel). The problem is the only place I can get 4-40 threaded rod is almost an hour’s drive. The craft store (that is close) didn’t have any. At any rate, you are correct, it is making my problem worse but I can sorta “do the math” on how far it would go without the trapazoid problem and it still wouldn’t be enough.
I am going to wait to do any rebuilding until I can fix those lower joints, but I fear when I do, it is not going to get much better. Those model airplane ball joints were simply not designed to move that far. --Or at least not the ones I have… …the are Dubro’s --should be the “standard”. I guess not.
