Need help diagnosing Desktop noise

[awalt1250]

We are running a 1.5 year old Desktop unit that sees use for about 3-4 hours a week. Today I noticed a noise when running the gantry across the X axis. The noise is repeatable and happens at the same locations. When a slight pressure is applied to the lead/drive screw, the noise is gone. I'm thinking it might be bearing related.

[scottp55]

Andy, Just guessing here, but have you checked tightness of every bolt you can reach/blown,wiped and inspected the screw and rails? Did you change move or jog speeds recently--noticed some speeds have more harmonics than others.
Hopefully others have better suggestions.
Can you vid and link to a Youtube?
I'd call Tech after checking the above:(
Good luck!
scott

[awalt1250]

video here:

http://youtu.be/3b2Pwh-Th-c

[scottp55]

Ok, NOT harmonics.
Are those Rub marks(not the best at terminology) between your 2 X-Rails on the gantry?
Just checked clearance on mine and at no place does the Z-Assembly have less than 3 business cards (.031") clearance. I've done the Z-Mod and never measured it before, but pretty sure it was similar before.
Sound like a larger surface rubbing- Can you get a good look in there?
Wouldn't use it like that!
Call Shopbot and post vid link for them--Somebody at Tech will be on call.
Double check all bolts first though-Just my first thought.

[awalt1250]

I think the rub mark you may be referring to is overspray from dry moly lube

[genek]

to me it sounds like the bit is hitting a high spot. do a video with out the spindle on.

[scottp55]

Andy, used to use dry moly when I started, Then Brady posted the specs. which pointed out that NO additional lubrication was needed, and maybe even deleterious to some parts.
Eugene, never even considered.
Andy, is noise the same at all Z heights? Same at all Move/Jog speeds.
How did you apply "slight pressure"? and in which direction to make it disappear?

[genek]

Andy, used to use dry moly when I started, Then Brady posted the specs. which pointed out that NO additional lubrication was needed, and maybe even deleterious to some parts.
Eugene, never even considered.
Andy, is noise the same at all Z heights? Same at all Move/Jog speeds.
How did you apply "slight pressure"? and in which direction to make it disappear?
Watch the video. it sounds like the bit is spinning and hit's a high spot, the sound, sounds like it is coming through the dust tube. Bit could be barely touching at that point, even a drop of water could cause the bed to have a high spot just in one place.

[awalt1250]

Spindle was off during the video..you are hearing only the stepper motors working.

Slight pressure was applied with the wooden end of a brush on the lead screw threads at either end.

Will try other z heights in the morning.

[Brady Watson]

Squirt a few drops of 3-in-1 oil on the bearing all the way to the left of the screw. See if that eats up some of that noise. That bearing is sloppy on purpose - so don't be alarmed if you can move it around + in & out.

-B

[scottp55]

Brady, is that just for diagnosing if it's the bearing?

[awalt1250]

Scott- the noise is there regardless of the z position.

I have isolated the noise to somewhere on the screw itself (could still be bearings). I have not tried to re-align the x axis yet at the bearing and motor ends.

The noise almost disappears if the 3 screws holding the black triangular plate are loosened so there is some play in the plate. See the attached picture.

[scottp55]

Andy, You're getting above my pay-grade here:)
Did you put 3-in-1 oil on left bearing like Brady mentioned?
Tighten X-rail bolts?
Tighten 2 bolts on X-Axis nut block(that silver plate that holds the the black triangle part you pointed to)?
Time to call Tech Support!!
Going to look for .pdf for Z-Mod kit document Shopbot wrote as lots of pics and terminology.
Good job isolating, but wouldn't go further until I talked to someone at Tech.
Hey, you've had machine longer than me:)
Is spindle still Plumb-Just wondering- chucking 1/8"X12" brass rod at hardware store with 2 90's bent into ends will give you a down and dirty trammel for $2-3.
Good luck-Don't forget to tell us what it was like some people do.:)
http://www.shopbottools.com/ShopBotDocs/files/SBG%2000197%205.5%20Inch%20Z-Axis%20Retrofit%202014%2009%2004.pdf