AR3 in Florida

Hi,

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

Hey man,

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:

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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

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J2 motion is good

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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.

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J5 works fine but I think my alignment is off

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J6 works good

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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.

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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

Really amazing work done! Are you able to fix up above errors? I'm just starting to build... 😊

Before

After

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...

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:

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check the orientation of your part when you flip it for OP2...

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Drill the big holes first on a curves surface

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check that your chuck is tight when facing a part or it will go flying

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Sometimes you just need a 4th axis !

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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 !

Last but not least I'm taking some liberties with the design of the covers - the J2 cover will keep the AR3 logo but I added a shark to the J5 cover

The J2 spindle was a bit more complex that I thought initial;y. I had to alternate lathe, CNC OP1, lathe again and CNC OP2 and 3

But the result is great - neat little part. I still have to file the key way square and tap the holes but 90% done

And finally I was able to do some assembly - J1 mechanically completed !

Moving on to the second join, the J2 tension ring was a bit tricky to machine due to the thin thickness, I used the CA glue work holding method and it worked great

I didn't have a 5mm broach so I opted for machining the bulk and cleaning the corners with a file - this is no Clickspring quality but it worked

And now J2 ARM - very close the to limit of my CNC envelope, this is OP1

And the finish part (3 ops)

I went the broaching way for the first pulley (let's see if I can keep it up for the 5mm...) - first time broaching and it went surprisingly well

Next was J2 turret housing and this part really challenged me. I did offered a fresh end mill as a sacrifice to the gods of CNCs but that wasn't enough. I had the part fly off because the superglue work holding wasn't strong enough (or not enough surface in contact) for OP2.

I had to become creative with the setups and the tool path containment.

Overall it turned out all right, I blew the side of the part when I drilled for the countersink bolts but that's a small price to pay for 6 setups and over 2 hrs of machining time due to less than rigid setups.

While this was machining I was able to press the bearings into J1 with the help of my new shop oven. In retrospect I should have machined a die for my hydraulic press rather.

And the parts fit together

Quick update, today I was able to work on the J1 turret platform, pretty straightforward setups with OP1 doing most of the features

And the other 3 ops are for removing the hat and drilling the holes on each sides

Today motor mounts for J1 and J3

Op1

and final parts, I was perhaps a bit heavy on the chamfers

Tomorrow I hope to get the turret platform

This is coming along great. Really looking forward to seeing how this goes for you!

CNC machining of J1 spindle is now done, both the timing gear and the bearings fit. Also the lathe partJ1 housing is done as well.

Here is a sneak peak of the creative workholding necessary - chuck-in-a-vise

Tomorrow I hope to finish J1 housing and perhaps start on the J1 turret platform.

The lathe part of the J1 spindle is done

Now I need to drill the holes for the timing gear and the spindle on each face.

Another good news is that the tube I ordered for J1 housing arrived yesterday so more lathe time !

You know tings are getting serous when the 4 jaw chuck is out !

Hi Pierre,

I had a quick question. Is it possible to machine all the parts on the CNC machine or did you have to make some parts using another method?

Thanks!

And one J1 base is done - 3 setups/OPS only

The base is starting to look the part

Tomorrow I'll try to get the J1 spindle done and with some luck the stock for the J1 turret housing should arrive.

First part first modification, the J1 base is too large for my 3D printer (I'm using a flashforge creator pro). I contemplated modifying the base and cut it in 3 pieces to make it fit my printer envelope but i decided instead to make the base in aluminum.

You can see here OP1 what I cleared most of the material for the base, I now need to make a jig to be able to hold the part for OP2.

As the saying goes, machining is 80% work holding !

The enclosure is printed in ABS @230degC, I use a fine height resolution of 0.2mm because my extruder is 0.4mm.

The base is now finished, I opted to leave the floor of the base, this way no dirt can sneak but I'm sure I'm going to pay for this decision when assembling, tuning and calibrating the robot because I no longer have access to the belt. Time will tell.

I then drilled and taped 4 M4 holes to connect the base to the enclosure

Moving on the J1 Base now on the CNC, I'm hoping I can now run the program while working on the lather for J1 spindle...

If you are wondering the aluminum stock for the robot is fairly inexpensive, I'm working mostly with scraps and pieces I bought in the remnant section of my local steel shop. I only had to order the special tubing for J1 Turret Housing and J4 main shaft tube.

In today's remnant price I would say the stock for the ARM is around $250 (including the special tubes) - so hats off to Chris again for providing the complete kit for $489 !

Not to mention you need a lot of tools to machine these parts and a lot of setups if you are using 3 Axis