Hi everyone, I am starting an AR3 build in Aluminum. I purchased from Chris the hardware kit and the 3D models. I was able to import them in F360 and have spent the last week CAMing. I am planning to machine most parts on my PCNC1100 - wish me luck
Here are all the stock parts
I just received today the hardware kit, the motors and drivers kit. I just started sorting thru all the parts. This is a very exciting project with a lot of learning in sight. Many thanks to Chris for sharing his work and detailed instructions.
In order to machine these parts all you need are the STEP files that Chris is selling on this site. I converted these files to Fusion 360 and added the CAM operations. I can't share that with you since Chris sells the 3D model I used to generate the CAM but I will be happy to share the F360 files with anyone that purchase Chris's model. To answer your other question, with the right tooling I'm sure you could do most of the robot on the CNC 3 axis mill (like I did). I had to 3D print 1 part ( J4 timing hub) and I found that 3 parts are much easier to do on the lather (J1 turret, J1 spindle, J2 spindle) and you have to buy precision stock for J4 timing tube.
If you need these 3 parts don't hesitate to contact me and I'll help you with the lathe work
I had a question I was hoping you could help me with. I'm a complete noob when it comes to CAM but I have access to a CNC machine (and know someone who can operate it). I was wondering what files would I need to machine the parts and would a CNC machine be sufficient (no lathe)? Really appreciate the help!
I was able to complete the wiring, the programing and the first tests, there are good and bad news:
J1 skips, I have about +/- 10 degrees of joint movement before the motor skips. I need the check the set screws and the pulley tension
J2 motion is good
J3 only goes in one direction (-) or down - can't manage to have it go up. I also have a lot of slop in J3 when I move the joint manually - I'm going to try to tighten the chain a bit.
J5 works fine but I think my alignment is off
J6 works good
I have tried to home the joints that move correctly individually but I get an error every time saying the joint is out of calibration. I guess the encoder response doesn't match the motor target position.
I have tried the limit switches manually but they do not seem to response. Is there a way to troubleshoot the inputs (Limit switch and encoder data ?)
Any help or suggestion welcomed
Now I just need to teach AR3 how to clean ... :)
Today I received the gripper so I proceeded the mill the LAST part of the build: the gripper holder
And with the final wire soldered this is the time to close the box...
Which is honestly very similar to this
With this (and the missing gripper) the arm portion is now complete - I was able to focus on the controller assembly
This WE I was able to work on the assembly with all mechanical joints completed
Soldering of motors is also completed, along with limit switches and encoders 1,2,3
I hope to be able to complete the arm wiring tonight and start focusing on the controller next
Just for fun - here are the parts that didn't made the cut....
From left right:
check the orientation of your part when you flip it for OP2...
Drill the big holes first on a curves surface
check that your chuck is tight when facing a part or it will go flying
Sometimes you just need a 4th axis !
Remember to check the clearance of your tool holder/length of your cutter in CAM....
But overall 5 bad parts and 28 good ones in just 21 days - not too shabby
And here are 2 more parts :
J6 housing - I machined it on the CNC exclusively (6 ops) and no lathe - a bit unconventional but it sort of worked
And finally J6 bearing cup - another part that required a second take....remember to tighten your vise/chuck folks...
I plan to machine the gripper mount later as I haven't received he gripper yet and I want to make sure it will fit.
Now I'm going to focus on assembly and wiring
And one more part (J6 Main bearing arm) and a bit of assembly for tonight
With this done I'm left with 3 parts to machine and about 86% completion rate of the machining
And now 2 parts for J5: the belt carrier and the tension block
Only 6 parts left to machine !
Today J5 housing - pretty intensive machining (7 operations total) but result looks all right
And finally a lot of assembly to get to this stage where the ARM, J2 and J3 are pretty much done
I wasn't sure I could machine the J4 timing hub but I gave it a shot anyway. The timing belt does engage but seems to slip because the teeth are too shallow (my smaller endmill that can go this deep is 1/8"). So I resorted to 3D Printing the part for now (until I get a 4th axis :))
And this is J4 Motor mount limit arm - 3 OPS and routine toolpath with good ol' rectangular parts you can hold in a vise.
And while the CNC was busy I was able to progress a bit the assembly, motor for J2 and arm in place.
This part - the J3 tension ring gave me a hard time - final thickness is 2mm so work-holding and order of operations are critical.
I ended up using both CA glue and tabs
It worked great but I failed a few times before this result :)
It took 6 ops for the J4 turret housing but I am very pleased with the result - one of the cutest parts I machined
I'm now machining a busing in order to broach the 5mm key on the J2 spindle.
Next I'm going to focus a bit on the assembly and try to put J2 together this WE.
While the CNC was busy with J3 spindle I could run the lathe and create most of the features for J3 bearing cup. Then run a final op on the CNC for the hole pattern
Last but not least I have been trying to machine J3 tension ring but the part is so thin (2mm) that the CA glue work holding is not working and sent the part flying twice in the mill - I am going to find an alternative method - stay tuned
On the right is the first attempt at J3 spindle - this is what happens when you don't verify your tool stickout in CAM Vs real life....
After the necessary correction and 3 ops + 1 broaching later here is the finished part
Here is J2 Motor Support, the part was 90% done and the last drilling operation was very tricky and the bit wandered and ended up breaking. Had to scrap the part and restart !