V-Carve flat depth problem

V-Carve flat depth problem

Postby darkclown » Wed Apr 04, 2018 4:06 am

I've been having this problem for awhile now and I can't figure out why this is happening. I don't know if it's human error or machine error. I have included some pictures of the problem I'm having.

I'm using Aspire 8.5. The problem I'm having is when I'm V-carving and I need to put in a flat depth I use a 1/4" or 1/8" endmill to hog out the majority of the material then I use a 45-degree vbit to clean up the areas where the endmill can't reach. I raster with an endmill with a 10% stepover and it's perfect, but when the endmill does its profile pass at the end it seems to dig into the material just a fraction too deep and you can see an outline in the wood of the endmills profile pass. If you look at my pics I circled a couple spots in red where it really showed up but you can see the outline of the profile pass all the way around everything. I have no clue why it does this as the rastering pass is perfect but the profile pass is messed up.

The other problem I'm having is that after the endmill is done hogging out the material I switch to the vbit to get into the areas that the endmill couldn't, but what happens is that when the vbit is clearing out the leftover material it's cutting a fraction too deep in comparison with how deep the endmill cut. If you take a look at the 3rd pic you can see I highlighted how deep the endmill cut in purple and how deep the vbit cut in green. As you can see the vbit cut down deeper than the endmill did. I use an aluminum touch plate to zero out the x,y, and z-axis on top of the workpiece. When I do a tool change I re-zero the Z axis again. I measured the aluminum touch plate with digital calipers to be as accurate as I could.

I don't know if it's me that's getting the Z-axis measurement wrong or something else. I have noticed that when I zero out the x,y, and z-axis then run a program. After it's all done and returns to the starting position everything in Mach 3 looks good except the X-axis reads 0.0006 off. Y reads 0.0 and Z reads 0.4 exactly what I put in Aspire. I don't know if that would make any difference or not.

Any help would be greatly appreciated.

Additional info:

I have Aspire 8.5
My machine is a Romaxx HS-1
I'm using a 2 flute 1/4" upcut or 1/8" 2 flute downcut endmill
45 degree 1/8" 2 flute vbit
My wasteboard has been machined level
I run the 1/4" endmill at 75 ipm
Router speed #3 or around 18950 rpm
Attachments
custom sign 11.jpg
custom sign 22.jpg
custom sign 3.jpg
darkclown
Vectric Apprentice
 
Posts: 3
Joined: Thu May 25, 2017 9:08 am
Model of CNC Machine: Romaxx HS-1

Re: V-Carve flat depth problem

Postby LittleGreyMan » Wed Apr 04, 2018 9:09 am

Hi,

As you get the issue only in some parts of the job, you probably do not have Z issues with the code or the machine.

Wood moves when you remove a lot of material, and you can just try compensating this in order lo limit manual finishing.

How do you hold your material?

A vacuum table is probably the best solution.

You may get better advice from people used to carve wood reliefs, which is generally not my case.
Best regards

LGM

W7 - Aspire 8.517
LittleGreyMan
Vectric Wizard
 
Posts: 630
Joined: Fri May 15, 2015 1:10 pm
Location: France
Model of CNC Machine: 3 axis Charlyrobot & Mecanumeric

Re: V-Carve flat depth problem

Postby rapidskate » Wed Apr 04, 2018 5:11 pm

Are you using dust collection “fringes”? I had a much worse problem at first using “fringes” that were too stiff to allow an accurate z plunge. I took it off and problem was solved. I since got more flexible horse hair fringes. Just a thought.
rapidskate
 
Posts: 2
Joined: Wed Feb 08, 2017 3:41 pm
Model of CNC Machine: Shark HD4

Re: V-Carve flat depth problem

Postby darkclown » Thu Apr 05, 2018 3:27 am

rapidskate wrote:Are you using dust collection “fringes”? I had a much worse problem at first using “fringes” that were too stiff to allow an accurate z plunge. I took it off and problem was solved. I since got more flexible horse hair fringes. Just a thought.


My "fringes" are pretty stiff but my dust boot isn't connected to my router in any way.

LittleGreyMan wrote:Hi,

As you get the issue only in some parts of the job, you probably do not have Z issues with the code or the machine.

Wood moves when you remove a lot of material, and you can just try compensating this in order lo limit manual finishing.

How do you hold your material?

A vacuum table is probably the best solution.

You may get better advice from people used to carve wood reliefs, which is generally not my case.


I was kinda thinking that same thing but it even happens when I flat carve out a little area. Right now I use 6 wooden clamps to hold my pieces down. I thought that would be enough to hold it flat.
darkclown
Vectric Apprentice
 
Posts: 3
Joined: Thu May 25, 2017 9:08 am
Model of CNC Machine: Romaxx HS-1

Re: V-Carve flat depth problem

Postby LittleGreyMan » Thu Apr 05, 2018 8:23 am

darkclown wrote:Right now I use 6 wooden clamps to hold my pieces down. I thought that would be enough to hold it flat.


Wood will twist if you remove a lot of material and you can't hold it in the center.

Try the same project with a cheap synthetic material (light or board or insulating foam) and see if the problem still occurs.
Best regards

LGM

W7 - Aspire 8.517
LittleGreyMan
Vectric Wizard
 
Posts: 630
Joined: Fri May 15, 2015 1:10 pm
Location: France
Model of CNC Machine: 3 axis Charlyrobot & Mecanumeric

Re: V-Carve flat depth problem

Postby LittleGreyMan » Sat Apr 07, 2018 12:41 pm

See this topic:
http://forum.vectric.com/viewtopic.php?f=2&t=29658

ElevationCreations gave an excellent explanation I couldn't write in English.
Best regards

LGM

W7 - Aspire 8.517
LittleGreyMan
Vectric Wizard
 
Posts: 630
Joined: Fri May 15, 2015 1:10 pm
Location: France
Model of CNC Machine: 3 axis Charlyrobot & Mecanumeric

Re: V-Carve flat depth problem

Postby darkclown » Sun Apr 08, 2018 8:42 am

LittleGreyMan wrote:See this topic:
http://forum.vectric.com/viewtopic.php?f=2&t=29658

ElevationCreations gave an excellent explanation I couldn't write in English.


Thank you, I'll have to check it out.
darkclown
Vectric Apprentice
 
Posts: 3
Joined: Thu May 25, 2017 9:08 am
Model of CNC Machine: Romaxx HS-1

Re: V-Carve flat depth problem

Postby Rcnewcomb » Sun Apr 08, 2018 7:44 pm

Since wood moves when a lot of material is removed it is sometimes better to use the V-bit toolpath first (assuming that it is removing less material) and then run the end mill toolpath.
- Randall Newcomb
10 fingers in, 10 fingers out - another good day in the shop
User avatar
Rcnewcomb
Vectric Wizard
 
Posts: 2888
Joined: Fri Nov 04, 2005 5:54 am
Location: San Jose, California, USA
Model of CNC Machine: Shopbot, CAMaster


Return to Hardware related questions

Who is online

Users browsing this forum: No registered users and 5 guests