Multipass Cut Through - Not Retracing in the same spot.

[Joe Porter]

From the looks of the pinion, I would take the table off and give the rack a real good cleaning and do a careful inspection. The pinion looks damaged, not just worn. That could mean damage to the rack also. Have you tried shaking the table while the power is on but stationary? The X motor has about 65lbs of holding power so there should be no movement...hope this helps...joe

[TNWALKINGHORSE]

When I try shaking the table back and forth with the power on, I just hear a click, but just a hair thickness of movement.

[Brady Watson]

Pinion is wiped. Order a set of 3. One for each axis, although Z is probably OK.

The racks MUST be greased. Axle grease is fine. There are other options as well. A little dab every 6" & machine worked in with pinion + wiped with cloth is where you need to be.

The little 'tick' you hear is 'normal'. Most likely in the motor gearbox itself. SG-3.6 motors do this when new. No biggie.

-B

[simon]

Are you certain that you have held the work down properly?
Just saying cos it really looks to me like the work is moving around.
The cuts are all over the place.
This is not just a case of missed steps, this is random movement.
Simon

[Joe Porter]

I would also suggest reading up on how to check and adjust the spring tension on the motors. I think your X motor is like my Buddy in that it the motor shaft is horizontal and has a single pivot bolt that allows the motor to be drawn into the rack by the spring. Make sure that there is enough looseness to allow the motor to swing, but no extra looseness. The motor shaft wants to be at right angles to the rack and not wobbly. It is good that you got a ShopBot, especially a bench top (forerunner of the Buddy), they are built like tanks and are very repairable and put right, and then you will have a really good machine that will last forever....joe

[Brady Watson]

The spring should be 3.5 turns from just opening up. This will be different for the table on the Benchtop. Emulate the tension on the Y car (which is the Benchtop's X; Y on BT32/48 IIRC).

The Benchtop tools can chew up the gears if the Z bar isn't aligned parallel to the rails. The gear rack can become disengaged from the motor/pinion if the horizontal V-roller bearings are not properly adjusted.

Nothing to mountain climb over, but the machine could probably use a keen eye and a tune up.

-B

[TNWALKINGHORSE]

I also might be onto something else. The router measure a little out of level and was not square to table. The previous owner used PVC pipe as a spacer to hold the router securely in the holder. When I removed the router, I found this:

I placed the small piece behind the larger and re-tightened. Now it was square to the table. I repeated the cut and no more steps. Also, the router that came with the Shopbot was a Makita RF1101. Does shopbot or another 3rd party make a holder for this router, so that I do not have to use that PVC pipe? Thanks!

P.s. Also going to order pinions. Would that also quiet down the noise when moving that axis?

[bleeth]

If you are hung up on continuing with a makita router then you can always design and mill your own mounting rig. Nice exercise in learning to mill aluminum.
SB's standard is porter cable.
The more square, level, plumb, and properly adjusted, as well as good pinions installed, the smoother it will run.

[Brady Watson]

P.s. Also going to order pinions. Would that also quiet down the noise when moving that axis?

Porter Cable is all that came from SB. Others have used the Makita because it was the quietest at the time. You're on your own to figure out mounting it. I am sure you could adapt something or fab something since you now have a CNC. Let's not forget that we have access to more information than anytime in history: Google search "Makita CNC Mount"

Fresh pinions will quiet it down some, but with a lot less vibration that can be transferred to the cut. Experiment with different speeds. For the heck of it, change the MS in SB3 to say 1 inches per second for the XY. Then using keypad mode (k or SK) move the tool around. Sounds like a diesel doesn't it? Now change the MS in SB3 to 2 inches per second. Repeat. Smoother, isn't it? This is called mid-band resonance. All steppers do this at some speed.

Those are like 1998 stepper motor driver technology running there...and they are 1/4 stepping. If you want to eliminate most of that horrid noise & be on par with a current BT tool, you'll want to do a 4G upgrade. It takes 15 minutes. Plug & play. You need a good computer. You'll get 2.5 times better step resolution and some faster speeds with this upgrade. It's exactly where you want the tool to be - you just don't know it yet.

-B

[MogulTx]

What kind of noise are you hearing in that axis? Is it a herky-jerky spasmic kind of thing? A grinding sound? What are you hearing? It should sound fairly smooth and rhythmic... should not sound rough or aggressive....