4th-axis not holding torque

[scw]

Does anyone have experience using the 4th-axis? I'm noticing that the motor doesn't hold any torque. The spinning force of the bit will cause the wood to rotate off course. This happened when I was trying to reduce the diameter of a wooden dowel and also when was trying to route the flutes. Attached is was the attempt to make an evenly distributed 6-spiral wooden spindle. I'm not sure if you can see the detail but the flutes are all over the place. Some of them unintentionally started in the same spot but ended up diverging paths half way down the dowel. At one point when reducing the diameter of the wooden dowel, I grabbed the dowel and was able to rotate it either direction with no resistance. I then noticed that the hand-held controller was not detecting any of my rotational movements. Anyone have any ideas on what might be happening with my 4th-axis?



I'm not sure if this matters, but I probably received my 4th-axis kit out of the first batch that started shipping back in October 2017. I just haven't had the need to use the 4th-axis until now (May 2018).

[scw]

*crickets chirping softly*

Hello? Anyone here...?!?

[ricphoto]

Hey Dan...We're not ignoring you...really we're not

Problem is there are more than a few on here that are suffering after having purchased a 4th axis...I personally cancelled my order after the 3rd un-announced delay...Others have reported that there isn't any documentation available (why would there be? it's only a $1k add-on ;-)

Good luck...sorry you're having problems but you're not alone...keep after Axiom...call them and email them every day and document the process here...sometimes that will get a response when other methods don't...

[scw]

May 23, 2018 22:32:07 GMT -5 ricphoto said:

Others have reported that there isn't any documentation available (why would there be? it's only a $1k add-on ;-)

Hi Ricphoto,

I guess I'm glad that I've only recently tried to use my 4th axis after have received it back in October 2017. I too would have been livid if I'd been trying to get the 4th-axis to work for the past 6+ months. I guess I was overly optimistic seeing as how Axiom released the 4th-axis post processor and manual last week. Now I'm in the boat with everyone else on trying to figure out the 4th-axis, now that I'm on the hook to complete a customer's project. Thanks for the moral support. 

[joeblow]

1st post here and new to this forum. .....”Hi everybody”.

I just received my new AR6Pro with the rotary indexer (1st cnc purchase). I primarly bought this for the 4th axis capability.

Machine is set up and I have been running simple rounding tool paths with raster and optimized raster. I had the exact same problems you identified in your post and this is what I have found....

* the chuck is mid-level quality at best. I am used to a much nicer Nova chuck on my manual lathe and will probably purchase another one to replace the one provided. The self-centering action is very notchy and perhaps will smooth out.

* on a maual lathe that can operate in reverse, the chuck is secured to the headstock via a set screw so it won't back itself out while reversing. After I did the simple rounding too paths and had the exact same thing happen with the chuck slipping, I removed the chuck and headstock arbor to look for that set screw. What I found were 2 small set screws (allens) at the shoulder plate at the end of the 1x8tpi. Bingo!

Contrary to the 4th axis manual that states to insert the MT2 arbor into the head stock first and then attach the chuck, I attached the chuck to the arbor, then tightened those two set screws firmly, then inserted the arbor/chuck assembly into the head stock and then used the draw bar to secure everything. So far this has stopped the slipping that I, too, experienced.

I hope this solves the problem for you and I hope no one takes offense to me stating what could be interpretted as “stating the obvious”.

[scw]

May 27, 2018 12:12:41 GMT -5 joeblow said:

* on a maual lathe that can operate in reverse, the chuck is secured to the headstock via a set screw so it won't back itself out while reversing. After I did the simple rounding too paths and had the exact same thing happen with the chuck slipping, I removed the chuck and headstock arbor to look for that set screw. What I found were 2 small set screws (allens) at the shoulder plate at the end of the 1x8tpi. Bingo!

Contrary to the 4th axis manual that states to insert the MT2 arbor into the head stock first and then attach the chuck, I attached the chuck to the arbor, then tightened those two set screws firmly, then inserted the arbor/chuck assembly into the head stock and then used the draw bar to secure everything. So far this has stopped the slipping that I, too, experienced.

Hi Joeblow,

Thank you! I just ran a test cut after reading your reply and that was exactly my issue. I've never used a lathe or 4th-axis before, and so I didn't realize that the Aspire tool path was spinning my 4th-axis in reverse and backing out of the chuck.


Now looking through the 4th-axis instructions, you're right, Axiom doesn't mention anything about the set screws!
I've just emailed Axiom (Chad) to let them know they should update their 4th-axis user manual.



As you've mentioned, the solution is to:

• First, attach the chuck to the arbor.
• Firmly tighten the two set screws on the arbor.
• Then insert the drawbar through the head stock and tighten using the drawbar.

[joeblow]

Hi Daniel. Really happy this solved the torque problem you were having and I was able to help

[scw]

Joeblow,

Now that the set screw issue is resolved, I'm noticing that my 4th-axis chuck still has a little bit of play in it (the handheld controller does not pick up this movement). I'm assuming that there's some mechanical reduction in the head stock and that there's some play between the gears or whatnot (the draw-bar rotates the same as the chuck so I know that the set screws are holding);if I had to guess, I'd say there's about 5-10 degrees of movement. Have you noticed this on any of your previous setups? Any tips or tricks for this issue? I would run a sample to see if this will cause me trouble under power but unfortunately, I've been having troubles running an optimized raster rounding toolpath since upgrading to Aspire 9.

Thanks,
-Dan

[scw]

I was able to figure out the wrapped job setup and the rounding toolpath last night... As I suspected, the wood stock does shift by a few degrees depending on which direction that the bit is moving along the wooden dowel (i.e. depending on climbing or conventional cutting). The arbor set screws are definitely holding and this movement is for sure within the head stock. Any Ideas on how to eliminate the play within my head stock?

[Gary Campbell]

If the play in the headstock for sure? What type of reduction is used? If belts are they tight?

If not mechanical, then you may be loosing steps. Reduce feeds and repeat

[joeblow]

Hi Dan. Because I'm a curious cat and have to know how everything works.....I removed the back panel to the rotary indexer this morning and here is what I found:

* the reduction is indeed belt driven which I suspected
* the stepper motor is attached with 2 allen screws in a slot which will allow you to control how much tension is placed on the belt

I would suggest you open the panel and see how much tension you have on the belt and possibly slide the stepper over a tad to put just a little more tension on the belt. 5-10 degrees of free movement on the chuck is rather substantial.

I have to admit I am a complete cnc noob and have a long learning curve ahead of me . I have recently retired from any field work (30yr career carpenter/woodworker) and am devoting all my time to shop work and decided to buy a cnc to torture myself haha.

BTW, I don't believe I will ever run an optimized raster operation. Takes way too long! I have a router table setup with a round over bit to knock down my edges before proceeding with any cylindrical work (takes 30seconds).

[Axiom Tool Group]

Having just looked further into this, I've discovered that the chuck that we are using in house for demos, videos and the manual does not have these set screws on the 1-8 Morse Taper that some of you are seeing.

It appears that the initial chuck provided, had 4 set screws that could only be accessed by removing the backing plate on the chuck itself...then threading on the MT2 and tightening the set screws before reinstalling that backing plate.

At some point this was noted and the chucks were switched so the set screws can be found on the MT2.

This does mean that this will need to be threaded onto the chuck before inserting into the assembly. Then the draw bar can be installed to pull it all tight.

Changes will need to be made to the manual, including some photos to show the location of the set screws.

[scw]

Jun 2, 2018 8:52:32 GMT -5 joeblow said:

I would suggest you open the panel and see how much tension you have on the belt and possibly slide the stepper over a tad to put just a little more tension on the belt. 5-10 degrees of free movement on the chuck is rather substantial.

Hi Joeblow,

I opened the cover on the back of my headstock. I loosened the two screws that secure the stepper motor so that I could remove the belt from the gears. I started to rotate the small stepper gear back and forth which confirmed that the stepper gear in fact had substantial play. Then I instinctively pulled on the stepper gear which slid off from the motor shaft without resistance. Alas, The set screw on the small stepper gear had never been tightened down at the factory!



Once I tightened up the single set screw on the small stepper gear, reattached the belt, applied tention to the belt by pulling back on the stepper motor and then tightening the two screws, and fastened the cover back onto the head stock, then the 4th axis finally had both the torque and accuracy that I expected from the 4th axis. Thanks for all of the suggestions that helped me fix this issue on my CNC machine.

[joeblow]

Fantastic! 

We may actually get this down someday.  Now if my brain can get the software to get the machine to do what my brain wants .