Trouble with a rectangle

Trouble with a rectangle

Postby howeclan » Tue Nov 08, 2016 12:48 am

Did a search but could not locate anything that explains what I may be missing while programing a rectangle and have it cut correct in a squared off fashion

When I draw a rectangle like for a camper window it looks correct.
I then build the tool path and preview it. it looks correct in aspire.

When I send the code to Mach 3 to cut, it will make the windows with large curves in the corners and will not completely close the rectangle. It is like the V-bit comes out early. This also happens when the doors are done also

I am using a profile tool path and have also tried a v-carve, but the v-carve tries to clean out the complete inside of the window.
Small windows have come out correct, but when I have to make them larger they mess up.

I also have straight lines wrong also V-bit looks like it ramps out early.

I just know it is something simple, but I am at a loss

can anyone help??
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Re: Trouble with a rectangle

Postby FixitMike » Tue Nov 08, 2016 1:05 am

Check that you have selected the correct post processor. The wrong one can have weird effects.
Good judgement comes from experience.
Experience comes from bad judgement.
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Re: Trouble with a rectangle

Postby howeclan » Tue Nov 08, 2016 1:08 am

I am using the same one I always use.

Mach 2/3 Arcs (inch) (*.txt)
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Re: Trouble with a rectangle

Postby howeclan » Tue Nov 08, 2016 1:54 am

This is the issue.
One good rectangle and the rest are bad.
They are all programed the same. Just different sizes.
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IMG_20161107_191942414 (2).jpg
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Re: Trouble with a rectangle

Postby Rcnewcomb » Tue Nov 08, 2016 1:59 am

Increase your acceleration or lower your feedrate.

See this thread on CNCzone.com: HELP Mach3 strange corner radius issue happening
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Re: Trouble with a rectangle

Postby howeclan » Tue Nov 08, 2016 2:16 am

I will give that a shot. The Thread did make sense.
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Re: Trouble with a rectangle

Postby 4DThinker » Tue Nov 08, 2016 3:37 pm

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Re: Trouble with a rectangle

Postby ger21 » Tue Nov 08, 2016 3:41 pm

In General Config, check "Exact Stop on Angles >" and set it to 89.
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Re: Trouble with a rectangle

Postby martin54 » Tue Nov 08, 2016 4:22 pm

ger21 wrote:In General Config, check "Exact Stop on Angles >" and set it to 89.


Gerry I know you are an expert with mach3 so is that recommendation something that has changed over the years? Can't remember what figure it is set at but pretty sure my machine is set a lot lower than angles less than 89 degrees which was something I read on the mach support forum a few years ago :lol: :lol:
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Re: Trouble with a rectangle

Postby ger21 » Tue Nov 08, 2016 4:57 pm

It really depends on what you are doing. There is no "one size fits all" setting.

But if you're cutting mostly 90° corners, than the 89° settings works well.
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Re: Trouble with a rectangle

Postby howeclan » Tue Nov 08, 2016 6:03 pm

Thanks for all the Help.

I will try all suggestions tonight after work.
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Re: Trouble with a rectangle

Postby howeclan » Wed Nov 09, 2016 7:59 pm

Slowing down the feed rate corrected it all.
Never thought that would make that big of a difference.

Thanks everyone for the help
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Re: Trouble with a rectangle

Postby ger21 » Thu Nov 10, 2016 2:40 pm

Slowing down is probably the least desirable fix.
Increasing acceleration is the better option, if your machine is capable of it.
Second best option is adjusting the CV controls.

Slowing down results in shorter tool life, and longer cut times.
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