Z AXIS DEPTH VARIATION

Anything and everything CNC-Shark-related

Moderators: ddw, al wolford, sbk, Bob, Kayvon

Post Reply
GLEEPER
Posts: 3
Joined: Sat Feb 09, 2013 7:01 pm

Z AXIS DEPTH VARIATION

Post by GLEEPER »

I hope someone can help me.

Yesterday the depth on my carvings started to change. The right side, carved first, was the right depth but the left side was not carving the depth correctly, it was getting shallower.

Today, it seems to be the opposite. It does not appear to be what is carved first, since last night it was deep in the beginning, and today it deeper more toward the end. It does not appear to change all at once.

I have look at the the tap file and they appear to be correct.

I have change bushing and done some cleaning. The problem does appear to have lessoned but it is still very noticeable.

Your ideas would be appreciated.

Jim

jimily
Posts: 104
Joined: Mon Sep 14, 2015 9:06 pm
Location: Texas Hill Country

Re: Z AXIS DEPTH VARIATION

Post by jimily »

Check your router clamp. If you still have the plastic one make a mark on the router and kind of watch it while it is running. Mine was bobbing up and down ever so slightly when making cuts and I would never had been able to tell looking just at the wood.

If you do have the plastic one a replacement may be in order. The only other thing is if your table parts are loose and depending on how much clamp pressure you are putting it is making differences each time that might show up as shallow/deep cuts.

I'm new so that's all I would have to look at without knowing anything else.

Good luck!!
Another Jim
It is easier to destroy than it is to create, just look at my scrap pile.

2014 Shark Pro Plus HD
Bosch EVS1617 w/ PrecisionBits Collets
Dixie Billet Aluminum Router Clamp Upgrade
Vcarve 8.0, Inkscape on Windows 8; CP 2.1 on WinXP

Rando
Posts: 757
Joined: Tue Jan 06, 2015 3:24 pm
Location: Boise, ID
Contact:

Re: Z AXIS DEPTH VARIATION

Post by Rando »

I obviously can't say for sure, but someone local here was having a similar problem. We did "some things" that seem to have fixed it; he's been running about two weeks now without any problems. We believe the errors might be related to static electricity built up during carving. We don't really know for sure, but the things we did seem to have fixed the issue so far. What we did was add a 470K resistor from the cross-mounted aluminum angle (so it connects to all the extrusions) down to the control box. The idea is to give the system the ability to bleed off the static slowly. The static charge is split between the spindle shaft (and bit), and the bed. Well, actually the other part is the chips that come off the stock. Those carry the charges away, which is then transferred to the bed as the chips fall onto it. Connecting the bed (and wiping it down with some 3M anti-static mat cleaner) to the controller box completes the circuit only because the router spindle/bit is commonly grounded. But, just connecting them together with no resistance breaks the z-height touchoff when you're using metal (or something else conductive) for your stock.

Hope that helps with the problem. If you're not familiar with such things, I can make you an assembly (lugs + wire + resistor + heatshrink tubing) and send it by postal mail.

Regards,

Thom Randolph
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

GLEEPER
Posts: 3
Joined: Sat Feb 09, 2013 7:01 pm

Re: Z AXIS DEPTH VARIATION

Post by GLEEPER »

Thank you both.

I tried watching the router as you suggested but it was not moving.

The extreme problem has disappeared. It could have been static like was suggested. I don't know but what was happening but it has stopped. I had showed my wife and I am glad, otherwise I would start thinking I had lost my mine and it never really happened. The small part of the problem was the wood I was using was longer than usual and one extreme end of the spoil board was to low. The table itself was level but the spoil board was lower on the left.

Bottom line after I complete some one jobs I am going to redo the spoil board and hope the "other issue" does not reappear.

Once again thank to both of you.

jimily
Posts: 104
Joined: Mon Sep 14, 2015 9:06 pm
Location: Texas Hill Country

Re: Z AXIS DEPTH VARIATION

Post by jimily »

Static is indeed interesting. I was watching some sawdust dance on the gantry arm around my finger so there is quite a bit of built up static there especially on the remaining plastic parts. And winter is coming so it'll only get worse with reduced humidity and cold temps. Going to have to watch this concept closer.

Good luck finding the gremlin!
Jim
It is easier to destroy than it is to create, just look at my scrap pile.

2014 Shark Pro Plus HD
Bosch EVS1617 w/ PrecisionBits Collets
Dixie Billet Aluminum Router Clamp Upgrade
Vcarve 8.0, Inkscape on Windows 8; CP 2.1 on WinXP

GLEEPER
Posts: 3
Joined: Sat Feb 09, 2013 7:01 pm

Re: Z AXIS DEPTH VARIATION

Post by GLEEPER »

Well the gremlin is back!

The z axis does not maintain the .080 point.

It is late and I am going to bed!

What was said in Gone with the Wind, tomorrow..... is another day!

McBuster
Posts: 185
Joined: Sat Aug 31, 2013 8:02 am

Re: Z AXIS DEPTH VARIATION

Post by McBuster »

If, your router cord is running alongside the servo cords, that can cause some strange problems. Minimize that by running servos on one side of the gantry, router on the other.
Jon ...
Woodbury Mn

Post Reply