Chatter please help!

[Initial Sound, LLC]

hello everyone,

I've been having customer comment on chatter in parts, both corian and hardwood.

It seems to be happening during x travel.

I have an older prt 96.

I've regularly maintain the unit for I cut at least 40 hours a week.

I've recently replaced the pinions and it really didn't help. I think the rack is maybe worn so I ordered new .25x.25 rack. I'm using 25tooth pinions with 7.2 gear boxes.

I think my z mounting may have something to do with it.

I have a 5hp Colombo but the previous owner got more z travel by remounting on the plate. In the process one of the mounting holes must have stripped which I found and tapped larger to tighten.

So now I'm kicking around buying the z retro fit not knowing if that cost will help.

I thought at first I had an interference problem because my av spindle leads were close to the DC motor lead around X1 motor. X1 motor makes a clicking sound which I've always contributed to the internal backlash etc. funny thing is no matter if I switch the motor, cable, driver, or output channel the noise still comes from the X1 area. The only common denominator is the proximity to the ac line.

I removed all the estop leads prox switch leads zero plate and prone to try to isolate the issue. The noise is still there even when the pinions are not engaged.

I have videos of this I sent to frank and tom. They can't seem to figure it out. We've tried everything.

So I'm getting new racks and pinions to eliminate the chance of a physical issue.

The weird thing is I only hooked my z plate back up to the terminal strip pin 1. I disconnected the ground from spindle to side rail to control box and somehow z plate is getting ground to function.
I went as far as disconnect motor leads still ground. Also disconnected spindle ground in breaker panel 250v circuit, still z plate is getting a path back to the control box. The table is on isolated .125 rubber mat material for vibration isolation. I don't know how it is grounding but it may be a clue to some ground loop interference.


I just need the chatter to stop.

By the way I've had Waco connection come loose which cause violent chatter which is not what's happening.

I'll try to get a vid up here or s link to Dropbox

Thanks in advance everyone.

My control box is v4 gecko 202s.

[Brady Watson]

You should call SB and have production support come out and get you sorted.

-B

[David Iannone]

Years ago I removed the plugs and soldered the motors right to the cables because I was chasing down com errors and trying to eliminate things. I have a older PRT with 4g upgrade. Good luck chasing it down. Like Brady said production support would be a good idea. My cuts improved dramatically when I went to 4g. My machine doesn't see a lot of high production work though. Mostly smaller cuts and carves 2 hrs long or less a couple times a week. My original rails from 2001 still are in good shape.

Dave

[Initial Sound, LLC]

Can someone elaborate on third party hardened X rails please? What and where to source. I'm thinking of drawing some up and getting them made by Lapham Hickey locally. The stock structural steel is not hardened. Does anyone know the material spec for a hardened rail application?

Also thinking of re grinding the profile on the rails as an option.

Thanks in advance.

Also how do you measure the backlash on the x motors? I have dial indicator. Guessing just mount to the side rail and grab the pinion and move it to extreme limits by grabbing it physically.

[Initial Sound, LLC]

You should call SB and have production support come out and get you sorted.

-B

Yeah I hear ya. Thanks, Gary contacted me. Im 99% sure my rails are shot man. I'm ok with getting new ones made or grinding. Sounds like you've been down this road personally.

[Brady Watson]

You need to determine the problem before you throw money at it. PRT rails can be dressed with a file & scotch pad.

The only replacement for the Z axis T-rail is the RetroZ. This is MOST LIKELY your problem, although there can be several other factors.

With the machine powered up, take the bit out of the router. Move the Z all the way down. Now wiggle it front, back, left & right. Move the Z up 1". repeat. Now up 2" repeat. 3"...until you top it out.

Did you feel any movement? Hear any noise? SEE where the t-rail is coming off of the v-roller?

How many v-rollers are on the Z? 4 or 8? If there is only 4, the t-rail is most likely wiped out. If you can't get any more adjustment out of it and the t-rail is roll forged where the wheels made contact, it's cooked.

...but you gotta find out where the problem is. The X&Y rails should be dressed anyway...I've instructed how to do this many times. Example (http://www.talkshopbot.com/forum/showthread.php?22054-Loose-Y)

EDIT: If you linked up with Gary, you're in good hands. Both of us were SB road techs for years...

-B

[Initial Sound, LLC]

4 roller Z can no longer adjust. Rails are 2.5 x 1.5 angle, resurfacing. Motors have .01-.015 backlash. Z has .02-.025 backlash.

It all adds up.

I'm buying cut angle iron and tube to make new z and y carts. Also building new z to adjust rack pinion engagement vs v roller setup.

Probably going to replace control side once I get another prt modified.

New rack and pinions.

Oh and the z plate is getting a ground through the spindle neutral that is bonded on the main panel. That explains why when I just disconnected ground on spindle circuit in the sub panel the z plate worked. The neutral lead is bonded to ground in the main panel.

When all is adjusted and replaced if I can't get good cut quality out of corian, I'll let you all know.