View Full Version : X Axis rumble/stutter/clunk

01-08-2015, 10:35 PM
My Stinger I has performed flawlessly since I got it about four years ago. I love it and have recommended it to several others. It is a real workhorse and has cut no telling how many thousands of pistol grips, 3D plaques and craft project for my wife.

PROBLEM: When moving to the right, there is a rumbling sound accompanied by a stuttering movement with an occasional clunk that vibrates the entire machine. This occurs while cutting as well as when jogging. At some point, it causes an apparent loss of steps, always in the same direction, causing the cut to move approximately 1/8" to the left. It may cut like that for 5-10 minutes, then take another step to the left. It does not appear to happen in the same place but the occurrence is frequent enough that it is difficult to determine. Very small differences are possible, but un-observable.

When first starting to use (after initialization and warm up) with the rack and gear cleaned and lubricated, it will run fine for about 10 minutes before the noise/vibration starts. There is no play anywhere. The rack is .5 degree off level, but so is the entire machine. The rack is parallel to the table. No difference with a new bit.

The machine went down yesterday and I called support today but thought I would seek help on the forum while waiting on a call back. Any help would be appreciated.

Mick Martin
01-09-2015, 12:19 AM
Clamp a large piece of MDF on the spoilboard then draw a large square in Aspire, use a V-Bit and do a profile cut on the line about .1 deep. Measure corner to corner to see how square your machine is cutting .... let us know the results.

01-09-2015, 01:33 AM
I will try that tomorrow (Friday)



01-09-2015, 08:53 AM
Hey Joe! Good to see you're still out there working hard! Sorry to hear you are having issues with the Stinger though...

Are you clear under the machine? Almost sounds like something is getting caught in the rack underneath. I had similar sounds before my shaft broke on the x-axis stepper. I replaced the motor (I had the 1/4" shaft which they have since upsized) and then I cut a big hole in my tabletop so I have access to that area to check my tension and blow out junk, etc. If something is getting caught you might slip teeth or maybe the belt tension is loose?

Hope you get it all worked out!

Mike [stinger]

01-09-2015, 09:04 AM
Thanks for the reply! Everything under the machine is solid and clean.
I have easy access to the underside of the machine due to my table construction, so it is well maintained. The noise is only when the machine is moved to the left or right...more so when moving to the right.


01-11-2015, 03:19 PM
Leverage a piece of wood or a wrench handle between the back plate of the car and the edge of the slider plate that carries the pinion gear. You should be able to move it away from the rack about 1/4", and it should spring back smoothly to re-engage the pinion in the rack.

Check the drive belt for tension and missing teeth.

Also look to see that the linear bearings are running smooth. The easiest way to check would be pulling off the rack gear and sliding the car throughout its travel.

While you have the rack gear off, with the machine powered down, turn the pinion gear by hand and make sure it moves smoothly. It doesn't seem likely but one of the sealed bearings could be fried.

Check electrical connections at the stepper motor.

01-13-2015, 10:23 AM
Thanks, Evan, for the tips. I am somewhat unfamiliar with the proper nomenclature for the parts of the machine. When I bought mine I think I got two or three pages worth of setup instructions and a manual for the WINcnc. Basically, it said, "Plug in machine...have happy life."

Is the pinion gear what is spring loaded to engage the rack? On my machine, the pinion lacks about 3/16 of an inch of fully engaging the rack. See picture.

01-13-2015, 10:54 AM
I may be making up the names for these parts...

Yes, that is the pinion gear that engages with the rack gear. You should see a spring sticking out of the back of the gearbox, held in place with a machine screw. It pushes on the slider plate which carries the big pulley and the pinion. This suspension system allows the pinion to absorb some misalignment in the rack, like a tire follows the road.

If the slider plate doesn't move for some reason (lack of lube between the slider and the bottom plate of the gearbox; or the 2 bolts that hold it down are too tight; or the screw that holds the spring is pushing on the slider), the pinion may be binding with the rack.

01-13-2015, 11:12 AM
I can find no spring anywhere on, in or around the gearbox. I am convinced it is binding between the pinion gear and the rack. With the controller turned off, I can move the head a few inches before it binds up and won't move anymore. Is the pinion gear supposed to fully engage the rack?

01-13-2015, 11:58 AM
I don't know the Stinger I, so the spring may have been a feature that was added after your machine was built.

If it's not buildup of gunk in the teeth, then the pinion engagement might be too tight. That's a question for Luke or Gary.

Even with the machine turned off, there will be changes in the resistance if you push/pull the carriage. The stepper motor acts as a generator when you push it and the voltage that is being created meets varying resistance in the controller circuitry.

Gary Campbell
01-13-2015, 12:47 PM
In that generation of Stinger 1, the rack must be adjusted to the pinion gear. This is accomplished by loosening the socket head cap screws located in the slotted adjustment holes in the rack, shifting the rack to be in contact with the pinion in 4-5 places along its length and tightening the screw at that point. Once the interval points are adjusted and checked, tighten the balance of the rack screw.

Note: The pinion and rack should be checked for wear, clean and free from debris, be lubricated with paraffin or candle wax and exhibit no lateral "play" when moved back and forth. Same goes for the Y and Z. Also, when checking and adjusting the rack clearance, one should move the axis by hand to ensure there are no binds in the linear bearings. Regular cleaning and lubrication is required for all of these motion components.

01-14-2015, 04:15 PM
In the years since I bought my machine, has there been any documentation published for it. Is there any parts breakdown or dis assembly instructions?

01-27-2015, 09:04 AM
Thanks to all who replied and thanks to Gary and Luke. The little fella is up and running perfectly again. Gotta love that Stinger!

01-27-2015, 09:12 AM
Joe, glad you're up and running . What was wrong with it , if you don't mind my asking ?

01-27-2015, 09:32 AM
I spent a lot of time adjusting the rack and got it perfectly aligned. I also got some of the recommended grease and a grease gun and lubed the bearings. Way back when I bought the machine, someone told me to use light machine oil. Obviously, that was bogus, but there was no published information on the machine at the time. Mine is a very early machine.