Cutting on a slope.

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Roly
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Location: Batlow Australia

Cutting on a slope.

Post by Roly »

Hi there to everyone,

I have developed a small but rather infuriating problem.

As my machine cuts the depth increases from left to right. That is , when my cut is finished, the left hand side is shallower than the right. This doesn't matter too much in some cases but when I am trying to do inlays or carvings with fine detail it becomes very noticeable.

The problem does not appear to be a loss of steps as the carving is almost ramp like. Nor does it appear to be associated with a lack of lubrication on the Z axis. I hjave reflattened to spoik board using a 22mm flat bit ant this has workde for me before. I haven't found as way to show it in a photograph or would post one here.

Would any of you learned gentlemen out there have any idea please.

Thanks in advance
Roly in Batlow

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RoutnAbout
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Model of CNC Machine: 24x18 Desktop
Location: North Manchester, Indiana

Re: Cutting on a slope.

Post by RoutnAbout »

Is the material flat?
Have you checked the thickness of the material around all edges?
Have a image of the finished piece so we can see.
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Don

Roly
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Joined: Thu Nov 16, 2006 12:17 am
Location: Batlow Australia

Re: Cutting on a slope.

Post by Roly »

Hi Don,

I checked the material and every piece I have tried has been flat and even thickness all round. I don't know how the photo will turn out but you can see the difference between the detail in the left and right side of the claws.

Roly
Attachments
P1010087.JPG

gravirozo
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Re: Cutting on a slope.

Post by gravirozo »

hello roly...

if you can post your gcode, on any way, that should help... to discover what went wrong in this case...
as i know you can post *.txt file

thanks
viktor

Fleming
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Re: Cutting on a slope.

Post by Fleming »

Roly,

Had that same problem. Found that my CNC table was not exactly parallel to the X axis. You might want to check that.

Fleming
Cobblewood Carver

Roly
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Location: Batlow Australia

Re: Cutting on a slope.

Post by Roly »

Viktor,

I have attached the G code but I do not hold much hope that this is a software problem. I thought that the Z axis may have been binding a bit and just gave it a fine coat of powdered graphite grease. May make some difference.

Fleming,

Before making my last cut I leveled my spoil board with a 22mm flat bottom bit by cutting a .25 pocket in the spoil board. I thought this would have given me a parallel surface to the X axis. Is this what you meant or am I missing something in relation to the X Axis. How did you check the parallel.

Thank in advance
Roly from Batlow
Attachments
LIAMSD~1.TXT
(300.33 KiB) Downloaded 245 times

kilrabit
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Location: Uvalde Texas

Re: Cutting on a slope.

Post by kilrabit »

Check the machine bed itself for a slight twist, maybe the machine has been moved or bumped and the four corners are no longer in alignment. If you have a slight twist, even though you route the spoil board, the bed which the spoil board is attached can be out of true. If you have a good level compare the bed in all four directions.

gravirozo
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Re: Cutting on a slope.

Post by gravirozo »

hello roly


i just run it trough on a g code editor, if anyway a missing part of the toolpath...

these pattern is so shallow that even it would be of solid metall it could cause difficulties to make it...
on several point the toolpath no more than 0.05 mm...
my suggestion would be, because of this drawing size, a cleaning pass on the surface can help.... nomore than 0.3-0.4 and your surface be same like as your machine goes...

to select the most outer contur, a 5-6 mm dia bit can works fine... not too much extra work and your picture will be perfect...
with mach this cleaning pass will takes minutes... , or need to set indicator on the z axis and check surface before milling... but same work to "clean"

the liam text already enough deep to working with some "bumpy" of wood...
also the grain is too "strong" for these fine details...

thanks
viktor

ps even your spoilboard is flat, this size of wood might not "straight" does mean a few tenth of mm enough to causing this... looks it's a 6-8 inch wide board... and that is already enough rigid to "resist" "clamping"
Attachments
tigertoolpath.jpg

Roly
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Joined: Thu Nov 16, 2006 12:17 am
Location: Batlow Australia

Re: Cutting on a slope.

Post by Roly »

Hi gents,

I have been out of action for a couple of days so havn't been able to reply.

Thank you all for your input, I will now go and try all suggestions and hopefully will come up trumps.

Thanks again,
Roly,
From Batlow

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