Strange X-Axis Motion & Inaccuracy (includes test files)

[wren]

I was hoping some of you might be able to lend me a hand by running a simple test using the attached mpc file.

Basically, I've been having trouble with random X-axis motion when drilling holes. Around the new year, the machine made a return trip to Texas to address this problem and another problem related to Z-Axis misbehavior. Unfortunately, the random X-axis motion appears to be unresolved. So, I am wondering if this is a problem specific to my machine or a problem for CarveWrights in general.

My machine has exhibited this behavior from the get go (I ordered it last summer), and unfortunately my projects are dependent upon resolving it.

Here are some more details. Using the attached mpc file, the machine should advance the X-Axis (sandpaper drive) and then drill a row of holes. It should advance the X-axis again and drill another row of holes, etc.

However, frequently on my machine after drilling a hole, the X-axis will jitter back and forth rapidly, generating a random X-offset. This causes the next hole in the row to be grossly malpositioned (see figure).

Note: I'm using autojigging and I've tried a variety of boards all of which were smooth, uniform, and square. Also, the regular hole pattern was made using the Copy Offset command. In addition, I've been through a number of software versions. The attached figure and mpc design file were made with version 1.115.

Chris Rawls of LHR Technologies suspected this might be due to a problem with the Aux Sensor. Unfortunately, the good folks at CarveWright appear to be swamped with support problems. Perhaps, someone here might be able to help.

Any thoughts? Would anyone be willing to try the attached design and report back?

My thanks for taking the time to investigate this.

[pkunk]

I had trouble with mine drilling oblong holes which was traced to slop in the x axis gear train. Can you feel any slop when you manually push the sandpaper back and forth?

[sundog2001]

My machine performed perfectly on your mpc file. I ran it both staying under the rollers and not. See the attached pictures.

[Digitalwoodshop]

If I were guessing about this problem I would look at the power supply stability. Either the power supply itself or your 115 VAC power stability.

Next I would look at the stepper motor drivers for a part failure.

Question? Does it reproduce the same way every time?

Does a freezer, water heater, or some other high power appliance kick on and cause a voltage drop at the Carve Machine?

Take the machine to a friend's place with different power.

Is a shop vac running causing static problems? while you cut?

Just some thoughts....

AL

[Digitalwoodshop]

What about selecting all the holes and doing a "group" all.

AL

[wren]

I had trouble with mine drilling oblong holes which was traced to slop in the x axis gear train. Can you feel any slop when you manually push the sandpaper back and forth?

I've had issues with oblong and oversized holes as well. Thanks for the suggestion. I checked for slop as you suggested and found none.

In my case, the problem was traced to flexing of the truck assembly. This issue was noticeably reduced by tightening some bearings and using shorter bits.

The holes are still slightly oversized, but they are more symmetrical.

[wren]

My machine performed perfectly on your mpc file.

Thank you for running the test!

It was good to see that the problem was not systemic. I was relieved to learn that I wouldn't need to return the machine for good.

[wren]

If I were guessing about this problem I would look at the power supply stability. Either the power supply itself or your 115 VAC power stability.

That was an excellent guess. Based on your suggestion, I tried running the machine with it attached to a recently installed 20A circuit from the house using a heavy duty extension cord, and the problems went away! Fantastic! I was previously using an outlet in the shed.

Question? Does it reproduce the same way every time?

Different X-axis errors were seen every time.

Does a freezer, water heater, or some other high power appliance kick on and cause a voltage drop at the Carve Machine?

Maybe, I did some tests, but was unable to detect a voltage drop. However, I was only using a volt meter. So, a short drop may have gone undetected.

Is a shop vac running causing static problems? while you cut?

No, a shop vac is not running while cutting.


Well, there seems to be some problem with the wiring in the shed. I'm guessing that it could be a ground problem. A poor ground might allow noise from the motor to confound the encoder signal from the X-axis Aux Sensor.


Thank You!

I'm delighted this problem is now solved.

[pkunk]

I've had issues with oblong and oversized holes as well.

The holes are still slightly oversized, but they are more symmetrical.

I couldn't deal with the oversized holes after I solved the oblong thing, and changed my shelf pin holes to .24 instead of .25. Pins fit tight now.

[Digitalwoodshop]

Wren,

Glad you found some help in my suggestions about power. The Shop power problem could be a loose connection, a fuse or circuit breaker screw, or a loose wire nut, or just 14 gage wire. The voltage meter might not show the dip. A 12 gage wire gives better voltage stability than a thinner 14 gage wire.

When working at the Sony Picture tube plant a guy would scan the power panels monthly looking for hot connections due to loose connections. He used a IR camera like firemen use in a smoke filled room. I repaired a few connections. The following month they would show you the results, a cool connection.

When I worked for Sony at a service center I would talk to customers often. A Sony phone that I repaired had 4 extra handsets. The AC wall adaptor for the base phone was big and the 4 extra handset adaptors were tiny. The tiny adaptors would fit the base phone too, but have just enough power to light the lights on the base but not enough to work properly. The complaint was dropped calls. My first question, what size is the AC adaptor plugged in the base?.... That fixed many a problem.

Happy Carving,

AL