Clean up pass

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leigh mills
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Clean up pass

Postby leigh mills » Wed, Apr 14 2010, 10:34AM

Hi,

Is there an option in control nesting to change the 2nd finish cut on the board so that it moves in say 1mm to give a cleaner cut. I know there is a pocket cleanup operation which cleans up a pocket but this is not what I am after, but it would work the same for the perimeter finish cut.

I have noticed on my parts that when performing the first cut the board is slightly curved, but when performing the second cut the wobble is removed as the cut has moved in and it is only removing the skin thickness. It moves in about 1mm but I can’t see where to set this and I have also looked at the code and this isn’t even visible in the code. The first pass is identical to the second pass. Take a look at small sample I created.

Also something else that is frustrating me is that when cutting Climb we get the wobble but the tool then moves in to perform the 2nd finish cut to clean this up, but when cutting in Conventional we get the wobble but when the tool moves in to perform the 2nd finish cut moves away which leaves us with the wobble and a step in the board.

Both G42 and G41 are both visible when changing the code from Climb to Conventional.

Does anybody have any suggestions.

Thanks
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Josh Rayburn
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Re: Clean up pass

Postby Josh Rayburn » Wed, Apr 14 2010, 10:57AM

Leigh,
What you're witnessing is tooling deflection, not a compensation.
Climb cutting deflects the bit away from the finished part as you described, but conventional cutting deflects toward the part, so if you're feeding too fast or using a dull tool, you'll notice it even more.
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Josh Rayburn
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Ryan Hochgesang

Re: Clean up pass

Postby Ryan Hochgesang » Wed, Apr 14 2010, 12:26PM

Leigh,

Currently there is no option to create perimeter finish pass in Control Nesting, only the depth cuts can be modified through MAX Penetration for given tool. As Josh has mentioned, it is tool deflection that is causing your issues.

barry gill
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Re: Clean up pass

Postby barry gill » Wed, Apr 14 2010, 4:29PM

Nearly all other routers / software controllers on the market compensate for this pheonomenun by using what is called lead in. This is a technique where the tool enters into the edge of the part in an arc motion from a distance of approx 1mm away from the perimeter of the part (that means that the adjacent part would need to be spaced a little further away and of course produce slightly less efficient nests). With the bitchy sensativity of most edge banders these days, it sure would make the cutting of parts more condusive to edging.

The other thing that would be eliminated if the thermwood did a lead in, is the costly and annoying breakout of the back edge of the part when the tool finally descends to full depth. Carcase parts are rarely a problem with this regard becuse that breakout is rarely seen in the finished product, being covered by another cabinet or panel etc. However, on doors, drawer fronts where hinge holes and drafwe front fixing holes are being cut in the nest, the face of the part is downward and experiences the breakout.

Of course this breakout is worse when the tool is blunt or the sacrificial sheet is well used. One might proclaim that keeping sharp tools and clean sacrificial will prevent this, but I'm sure that we are not the only ones that have experienced this issue even when keeping our eyes on the quality of these two items.

One problem with this breakout is that we have experienced better results (reduced breakout) when running conventional direction, however as Leigh mentioned, the wobble/ tool deflection is worse when running in that direction.

Unfortunately the thermwood only uses a ramp down technique which is excellent for tool life but entirely inadequate in the elimination of tool deflection issues.

Is it possible that thermwood can implement a lead in option within the control nest software.

Ryan Hochgesang

Re: Clean up pass

Postby Ryan Hochgesang » Thu, Apr 15 2010, 8:34AM

Barry,

I will certainly submit this request to our software engineering group for future consideration.

Thanks!


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