eliminating tool marks on a pocket

This forum is for general discussion regarding VCarve Pro

eliminating tool marks on a pocket

Postby GervRich » Tue Mar 12, 2019 4:47 pm

Hi, I was wondering if there was any solution to eliminating or at least reducing tool marks when pocketing? Typically use a 1/8 or 1/4 End Mill. Any help would be greatly appreciated.

Thanks Ric
GervRich
 
Posts: 13
Joined: Sat May 26, 2018 7:44 pm
Model of CNC Machine: Shark HD 4 extended

Re: eliminating tool marks on a pocket

Postby adze_cnc » Tue Mar 12, 2019 4:52 pm

The flippant answer would be don't cut the pocket in the first place---no toolmarks.

The more serious answer is two questions: what kind(s) of toolmarks are you seeing that you don't want to be seen? Do you have a picture(s) so we can see too?
User avatar
adze_cnc
Vectric Apprentice
 
Posts: 674
Joined: Sat Jul 27, 2013 10:08 pm
Location: Vancouver, BC, Canada
Model of CNC Machine: AXYZ 4008

Re: eliminating tool marks on a pocket

Postby ger21 » Tue Mar 12, 2019 6:25 pm

Make sure your Z axis is trammed perfectly, and try an endmill with a small corner radius, so the tip doesn't dig in.
Gerry - http://www.thecncwoodworker.com
ger21
Vectric Wizard
 
Posts: 1416
Joined: Sun Sep 16, 2007 2:59 pm
Location: Shelby Township, MI, USA
Model of CNC Machine: Custom DIY

Re: eliminating tool marks on a pocket

Postby TReischl » Tue Mar 12, 2019 8:42 pm

I know this is heresy, but try doing finish cuts.

Most of us like to cut as fast as we can for all sorts of reasons. I was doing that this morning on a bunch of pockets with a 6mm end mill. After the pocket roughing the sidewalls were a bit rough and the bottom was not spectacular. A .005 finish cut fixed all of that.

I did the rough pocketing at 200 IPM, DOC was 6mm. Then I used an inside profile with a spiral and a pocketing at full depth to clean up the bottom. These cuts were done at 150IPM.

If you are pocketing and you set your feedrate to produce nice smooth cuts on the walls an bottom you are wasting a lot of time not to mention dulling your bit faster.

Edit: I just read your signature line and see you are running a shark. Not to berate your machine but it is not known for its superior rigidity. Taking finish cuts will improve the results a lot.
http://www.tedreischl.com

Low Profile CNC Router Vise
User avatar
TReischl
Vectric Wizard
 
Posts: 2489
Joined: Thu Jan 18, 2007 6:04 pm
Location: Leland NC
Model of CNC Machine: 8020 Build 48X36X10 RP 2010 Screenset

Re: eliminating tool marks on a pocket

Postby martin54 » Tue Mar 12, 2019 8:54 pm

I tend to use a finishing pass as Ted has already mentioned, hog out most of the material to almost full depth with a large(ish) DOC & a high stepover & then a seperate finish toolpath to ake a small DOC with a smaller stepover & slower feedrate. The 2 toolpaths can use the same bit & output together o there is only one file. Using a bottom cutting bit will also help give a cleaner finish on flat surfaces :lol: :lol:
User avatar
martin54
Vectric Wizard
 
Posts: 4411
Joined: Fri Nov 09, 2012 2:12 pm
Location: Crossgates, Scotland
Model of CNC Machine: Gerber System 48 (modified)

Re: eliminating tool marks on a pocket

Postby rscrawford » Wed Mar 13, 2019 1:30 pm

The way to have no tool marks is to have a perfectly trammed spindle, a substrate that is securely positioned and doesn't release tension and warp when cut, a heavy, solid machine, and a bit that doesn't flex (either a larger bit, or if you need to use a 1/8" or 1/4" bit then keep it as short as possible in the collet).

Unfortunately with a Shark cnc (extremely light duty machine), you will have a harder time getting perfect bottoms on your pockets. I can flex the router on those with very light hand pressure, so you know it is happening when the router is changing directions and cutting. Compare that to a welded steel gantry with a spindle that I couldn't deflect a thousandth of an inch with all my body weight. But both machines will leave marks if the wood moves or warps during cutting, or if the spindles aren't trammed perfectly.
Russell Crawford
http://www.cherryleaf-rustle.com
User avatar
rscrawford
Vectric Wizard
 
Posts: 931
Joined: Mon Jan 17, 2011 6:49 pm
Location: Wetaskiwin, Alberta
Model of CNC Machine: CAMaster Cobra 408 ATC with recoil

Re: eliminating tool marks on a pocket

Postby GervRich » Thu Mar 14, 2019 2:38 pm

Folks, Thank you for all the input as I will most definitely try the finishing pass. In regards to what tool marks I am getting, I am pocketing out letters and I am getting the tool path of the pocketing of letters if that makes sense. Hopefully one day I can beef up to a bigger and better machine.

Thanks again
Ric
GervRich
 
Posts: 13
Joined: Sat May 26, 2018 7:44 pm
Model of CNC Machine: Shark HD 4 extended

Re: eliminating tool marks on a pocket

Postby adze_cnc » Thu Mar 14, 2019 4:47 pm

GervRich wrote:I am pocketing out letters and I am getting the tool path of the pocketing of letters if that makes sense.


If I can intuit what you are implying does it look like a "zig-zag" / "back-and-forth" path?

If so remember that if this plywood / real wood that the grain has a direction. By cutting against that direction the fibres are "lifted". So you'll get the same effect that groundskeepers at baseball parks with grass fields get when mowing opposite stripes.

See also this table by Ontario (Canada) designer/maker Peter Fleming:

Image

Each square of beech veneer is rotated 180 degrees.
User avatar
adze_cnc
Vectric Apprentice
 
Posts: 674
Joined: Sat Jul 27, 2013 10:08 pm
Location: Vancouver, BC, Canada
Model of CNC Machine: AXYZ 4008

Re: eliminating tool marks on a pocket

Postby 4DThinker » Thu Mar 14, 2019 6:39 pm

Cut your pocket using raster with the grain direction, no last pass, and a small positive pocket allowance (.005" or so). Then follow up with a profile full depth in one pass that cleans up the pocket face.

4D
4DThinker
Vectric Wizard
 
Posts: 1199
Joined: Sun Sep 23, 2012 12:14 pm
Model of CNC Machine: CNC Shark Pro

Re: eliminating tool marks on a pocket

Postby Mikehell » Mon Mar 18, 2019 3:12 pm

Make sure to zero in the exact same spot and with the exact same part if the touch plate.
Mikehell
Vectric Apprentice
 
Posts: 87
Joined: Wed Mar 22, 2017 9:34 pm
Model of CNC Machine: eBay special China 3040

Re: eliminating tool marks on a pocket

Postby Rcnewcomb » Mon Mar 18, 2019 3:57 pm

Other contributors to toolmarks on the bottom of a pocket are:

Vibration: Check your holddown method. You may need to add more clamps, screws, adhesive, vacuum, etc.

Tool Geometry: For some materials a fishtail end mill gives superior results, but in other materials a fishtail end mill yields a poorer bottom finish.

Image
- Randall Newcomb
10 fingers in, 10 fingers out - another good day in the shop
User avatar
Rcnewcomb
Vectric Wizard
 
Posts: 3427
Joined: Fri Nov 04, 2005 5:54 am
Location: San Jose, California, USA
Model of CNC Machine: GCnC/WinCNC


Return to VCarve - General

Who is online

Users browsing this forum: Google [Bot] and 22 guests