4th axis - several questions

[hbruns]

Today I received and installed the rotary axis on my AR6

I followed the directions and it went smooth, except the mounting screws for the tail-stock are too short. These are the longest screws included, and they will not engage threads in the nuts when mounting on the bed... until you remove the washer.

I followed the directions for modifying the settings in the controller.

Jogging the rotation manually (using the controller) brings up my first question - 
The headstock will turn both ways, but will stop and stutter back & forth randomly. 
Helping it rotate a bit by hand helps it get past these stutters.
Why and is this normal?? It sure looks like this isn’t normal. 

Running the first project brings up another couple questions - 
I created a rounding tool path for a 2”x2”x31” piece of hard maple. (Vcarve Pro 10.5)
I used a 1/4” end mill and a 1/8” cut depth. 
The x & y axes set to centerline and mid-point y of workpiece, respectively... both in the software and machine setup.  
Z-zero set to material center. I used an eyeball to set it to the point of the tail stock. 
I chose the optimized rounding pattern that cuts the corners first. Well, it’s supposed to. See the third question below. 
The cut started ok, yet was not centered on one of the corners. 
SECOND QUESTION - 
Why does the workpiece rotate when the bit is on a climb cut?
Cannot the 4th axis hardware hold the workpiece in place?

THIRD QUESTION - 
How does one index and zero the workpiece so the system knows where the corners are on your piece of wood?

Thanks

[joeblow]

Hi Hbruns.

I'll try and answer your questions.

1.  That stuttering isn't normal.  Mechanically there are a couple things you can check.  Here is a pic of the rotary with the back plate off.  The stepper drives the rotary via a belt.  Perhaps loosen the 2 mounting screws and increase belt tension.  Also the small gear is attached to the stepper with a set screw that is hidden right next to the mounting plate.  Might want to make sure that is secure.  The chuck is attached to the 1"x8" taper and held in place with 2 small set screws that are accessed at the back of the taper.  This requires you install the chuck first to the taper and then insert that into the rotary housing and then use the draw bar to tighten. 

2. The above answer should help with that too.  I've not had any problems with the chuck moving while cutting except one time when I was overly aggressive with my toolpaths.

3.  To index and zero when utilizing the optimized raster rounding you need to have one of the flat sides of your material facing up not one of the corners.  Then set that as your A-0 origin.

As for setting Z zero you really don't need to "eyeball" it.  Zero Z to the machine bed and then raise to 75mm and reset your Z-0 at that height.  I use the rotary quite a bit and set the CAD Pickup to 50.  So now when I use the puck to zero Z on the machine bed it automatically raises to 75 and then I reset Z. 

Hope this helps.

[hbruns]

Thank you for answering

Belt tension is tight as received. No issue there.
The taper has no set screws to secure the chuck. I see the threaded holes for them, but no set screws. I double-checked the packaging - no joy there.
    EDIT - went to big orange store and got the set screws.

The stuttering still happens with the chuck and taper removed.

When it does stutter the controller keeps incrementing degrees rotation, so it just lost the A-zero.

 - This is a sure way to ruin the item you're trying to make. 

The set screw on the small gear attached to the stepper motor is snug as received.

I called Axiom support and left a message.
Looks like I wait until Monday for help from them.

[aluomala]

I had similar issues as you (too short of bolts) and issues with the corners not getting cut off properly (using rounding gadget). I also found that the A axis lost steps WAY too easily. I gave up on the whole attachment for about a year (life is too short to waste on useless junk).

I decided to re-visit the 4th axis after I had a few more projects that I wanted to make, and I was already about $1500CDN into the rotary attachment (original price plus replacing the POS chuck that came with it).

I bitched and moaned about the slippage issue in the past, without results, so I emailed Support again, and this time they told me how to adjust the stepper motor voltage. Apparently the factory setting is at about 60% (WHY!??!?!?!?! WHY!??!), and once I cranked it up to maximum (and backed off a touch) I had far less problems with slippage (ie I was able to use the rounding toolpath, and was actually able to create some cylinder shaped objects, but had an issue with Z-axis driving into the project, which may be have been due to having too aggressive of a plunge rate.

I'll have to look at the set-screws that you mentioned, since I was wondering how I could better seat the chuck and have it NOT spin (the chuck has a fair amount of mass, so I could see it slipping and causing issues.

I really like the idea of the rotary axis, but the execution, in my opinion, wasn't done that well. Considering how cheap a 4th axis can be had nowadays, $1000US seems pretty steep, considering the QC issues a lot of us have experienced, and having to replace the chuck right out of the gate didn't make me too happy. I plan on swapping my pieces back and forth from a floor mounted lathe, and that chuck is sketchy just on the 4th axis (not rotating at 1000+RPM) let alone at full speed on a lathe.

I haven't seen a lot of "outside of the box" things done on the rotary axis (on the Axiom) so I'm hoping to see what people come up with that have that "Whoa!" factor, and not just look like you used a regular lathe and added on some text or engravings. I am in the early stages of making wooden tank round "heads" (think of a bullet, and the projectile at the end) with unit crests 3D carved into them, and maybe some funky designs as well.

Allan

[hbruns]

I did get an E-mail pointing out a few issues.
The A-Home position never synchronized. This was due to the sensor being too close to the wheel inside the head stock. After a careful adjustment, the A-HOME position is now found.

I have been trying a roughing tool-path for a chess piece. The Software (Vcarve Pro 10.5) shows the tool paths as expected, yet the actual execution does not follow those shown tool paths when running the machine. I have tried re-downloading the post-processor and recalculating tool paths... no joy. When the file finishes, the result is completely FUBAR. This is not related to the A-axis stuttering or getting stuck as described below. The tool path the machine follows has little relation to the software tool path.

Also.... the rotation sometimes gets STUCK and does not move when it should be rotating during a cut. The system still thinks its rotating though. This will absolutely RUIN anything you're making, so this issue MUST be fixed.
I will bump up the drive strength and see if that eliminates this problem.

[aluomala]

I really wish Axiom had a better video showing the rotary axis in action. So far, the best videos I've seen come from SouthernGinger (Zach Manring). If Axiom isn't paying him, they should be.

Here are 2 videos that one should watch prior to ordering the rotary axis, and/or after purchase because he addresses the same issues that I see coming up, again and again, with the rotary axis (garbage chuck, short bolts, wiring connector that doesn't work (threads too short).





It would also be nice to see a video, using one of the Vectric apps at a minimum, showing how to set up a project on the 4th axis from start to finish. There is little to no info available, and the potential for disaster with having a spindle coming into contact with an accessory that is mostly metal, so having a video showing "best practices" would be appreciated before committing to using the Axiom in conjunction with this accessory.

It would be nice if someone from Axiom showed how much force is reasonable to move the rotary manually (with ones hands) so the end-user can determine if their rotary axis is set-up correctly (the sensor inside the housing, the belt tightness, the setting on the board controller and how to adjust it (to increase resistance/torque(?)). My rotary sat idle for way too long because I couldn't determine if the issue was on my end (having too high of expectations for how beefy the attachment is) or if something got dropped en route (the sensor and/or belt) or just poor/questionable quality overall. I have a ton of ideas in my head, but I can't proceed until I have more confidence in the equipment, and the thought of destroying any more wood and/or equipment (bits, spindle, rotary axis) whilst troubleshooting doesn't give me the warm/fuzzies. And phoning support every time I have a minor issue is kind of weird (aka stovepiping) because it doesn't help out any community members, whereas if there was a video (videos?) showing the basics would save a lot of aggravation for all concerned (end-users that don't want to call every 5 minutes, support staff can focus on unique issues, etc).

Sorry to hijack your thread, but I think that either Axiom needs to step up their game (not holding my breath....) or we can at least have some record here (a dedicated sub-forum (if it doesn't already exist) for rotary axis, of the issues (and hopefully solutions) and people can search here rather than phone support (ie weekends, evenings, holidays, etc).

Allan

[joeblow]

Mar 8, 2021 16:26:24 GMT -5 hbruns said:

I did get an E-mail pointing out a few issues.
The A-Home position never synchronized. This was due to the sensor being too close to the wheel inside the head stock. After a careful adjustment, the A-HOME position is now found.

Thanks for the update regarding the initial problem. 

[gerry]

It show there is still a very big lack of quality control.

[hbruns]

Short update -

Increasing the A-axis drive strength has greatly reduced the stutter/stop condition.
I have yet to see it do that during a cut, though I have noticed it once or twice when rotating manually.

I did finally get a finish cut to complete as expected.
Details here -
forum.vectric.com/viewtopic.php?f=38&t=37088

The tool paths that crapped out were 3D Finishing cuts with a RASTER pattern and a raster angle left at the default 0-degrees.
Set a raster angle of 45 degrees and the problem does not manifest.

[joeblow]

I modeled a pawn chess piece and used a finishing raster strategy with an angle of 0 degrees and it cut just fine on my machine.  Rotated a full 360 degrees and then Y moved relative to my stepover followed by the next full 360 degree rotation and continued this way until completion.

Did you change the RT Type parameter in the controller?

axiomprecision.proboards.com/thread/856/rotary-attachment

[aluomala]

Re the set screw on the taper: I never thought to put one in there, and after searching through my nuts and bolts collection, I found 2 to fit. I had never been able to get the taper and plate to fit snugly together (it would back off and loosen), and now I don't have that issue. Tight as a drum!

Another possible solution might be to use a rubber washer or gasket so that there is a friction fit. It doesn't have to be much, just enough to stop it from backing off.

I'm going to adjust the sensor as well (I took the mechanism apart whilst troubleshooting, and I may have messed up the gap/spacing). Once that gets sorted out, I think I'll be able to start production runs on some of the things I have been prototyping (using pine and cedar while figuring things out, since I don't want to waste good hardwood).

Allan

[hbruns]

Issue updated in the Vectric forum referenced above.
With G-code file

My in-experienced eyes with G-code tell me it is OK, but the machine does not follow it.
As soon as the section with dimples on top of the crown finishes (correctly), the machine does step the Y&Z axes but there is no rotation anymore.
This results in a just line down the rest of the piece that follows the profile.

G-code:
hbruns.com/images/TMP/3DFinish0DegreeRaster425.mmg
Image of "Finished" piece:
hbruns.com/images/TMP/unnamed_01.jpg

[khuffman]

Does anyone have the directions to increase the A-axis drive strength? I started playing with my 4th axis last weekend and the motor doesn't seem to have the holding force I would expect.

[aluomala]

Jul 30, 2021 21:08:59 GMT -5 khuffman said:

Does anyone have the directions to increase the A-axis drive strength? I started playing with my 4th axis last weekend and the motor doesn't seem to have the holding force I would expect.

You will need to open your case, find the A-axis controller on the board (in the picture below, there is a "C" axis controller, which I believe is the A-axis (not near my machine right now), and adjust the small screw clockwise. Apparently they are set at 60% at the factory (why? WHY? WHY?!?). It is honestly that simple to adjust the settings. Obviously, do this at your own risk, but this is the advice I received from Chad when I emailed them about it.

In the first image, it illustrates how to figure out which axis controller you look for (at the bottom, they are labeled) and follow the wiring up to the proper controller, and that is the one you would adjust (this is the picture that was sent to me, and I was confused initially until I figured it out). I left the machine on while I adjusted it (I presume that it isn't overly dangerous/wrong) so I could make sure I was adjusting it. At 100% it is still pretty weak, but is a far sight better than the factory setting is.

Allan

[khuffman]

Thank-you for the information. My C-axis was set down around 40% so turning it up to 90% made a huge difference.