2 rail sweep not behaving like I thought it would

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DLWOODWORKS
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2 rail sweep not behaving like I thought it would

Post by DLWOODWORKS »

I'm trying to create a 2 rail sweep with the attached file. Each time I go through the process of selecting the rails and the profile, the results are backward, upside down or inside out. I know it's my problem but I've tried flipping the profile around in different directions, changing the rails orders, and every other thing I can think of. I've also attached a jpg of what the profile edge is supposed to look like.

Any help would be appreciated in helping me get my head around what I'm doing wrong. THANK YOU!!

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Re: 2 rail sweep not behaving like I thought it would

Post by DLWOODWORKS »

Sorry, I went to add pictures and files and accidentally hit the submit button. Couldn't find a way to edit the post..

Anyway, here are the pictures and the file. Aspire 8.5
Attachments
Table edge profile I'd like to achieve
Table edge profile I'd like to achieve
Table edge profile.crv3d
Aspire file
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dealguy11
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Re: 2 rail sweep not behaving like I thought it would

Post by dealguy11 »

You need to put a leg on your profile like this:
Attachments
Capture.JPG
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DLWOODWORKS
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Re: 2 rail sweep not behaving like I thought it would

Post by DLWOODWORKS »

Thank you Steve.

The model is looking good now. I went to toolpath it with a 3/8" ballnose bit and the results are a little less then what I expected.

Unititled 1.jpg is the preview of the model
Unititled 2.jpg is the preview after toolpaths applied

Not sure what is happening with this but the toolpath preview looks pretty ragged. Any thoughts on how to clean this up? I've carved a lot a 3D models over the years and never had it do this. :?
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Model preview
Model preview
Toolpath preview
Toolpath preview

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Re: 2 rail sweep not behaving like I thought it would

Post by IslaWW »

Don..
Have you tried the Molding toolpath?
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Re: 2 rail sweep not behaving like I thought it would

Post by joeporter »

Your material size is very large with standard resolution. Your model is only 1.25" x 16.75". I would increase model resolution and decrease material size to just big enough and make your toolpath from that and then lay your full size sheet on the machine and just cut the model out of the edge and not worry about CNC'ing the full sheet...joe

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Re: 2 rail sweep not behaving like I thought it would

Post by DLWOODWORKS »

IslaWW wrote:Don..
Have you tried the Molding toolpath?
Gary,

I'm trying your idea and it's getting me much closer to what I'm trying to achieve. I'm so close - picture attached. I'm getting a little hook at the left end (edge of the board) and can't seem to get it to disappear.

I've checked to make sure my rail line is exactly the same distance from the edge as the length of my profile - 1.245". Also check that the depth of my profile is the same thickness of my material - .84". Tried moving the rail line, no luck. Not sure how to achieve the results that are in the help file of matching the profile exactly. :?
Attachments
Untitled.jpg

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Re: 2 rail sweep not behaving like I thought it would

Post by mezalick »

Don,
That "hook" is from the ball end bit...You'll need to over cut the profile more that the diameter of the bit...

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DLWOODWORKS
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Re: 2 rail sweep not behaving like I thought it would

Post by DLWOODWORKS »

Thank you Michael.

Since this profile exactly matches the profile of the existing table, what would I have to do in the moulding toolpath (cutting past the edge of the material) to get it to over cut the profile more than the diameter of the bit? I'm using a 3/8" ballnose. I've tried a 1/4" and a 1/8" ballnose and I still get the little hook in the preview. I don't want the CNC machine to cut into the edge of the board changing its current dimension. What I'm trying to do is cut a profile on the edge of a leaf for a table that will match the existing profile. If the CNC cuts any material off the end of the leaf, it will no longer be the same size as the table it is going in to.

If I can get the CNC to make most of the profile, I can complete the rest with the router table and a round over bit. I'm beginning to think that's what I will do because I can't get the CNC to cut my profile as I have it set up. The rounded end of my profile is the edge of the leaf board. If I can get the CNC to cut that profile, I will round the underside of the leaf with the router table.

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Re: 2 rail sweep not behaving like I thought it would

Post by mezalick »

Don,
Add an extra "leg" to the end of the profile...
A you should be able to do the undercuts on the router table..
Worst case is to move your vectors over a bit to leave more material before you cut on the router table..
You would need, i think, to make a profile cut before the router cutting...

Just some ideas,
Michael
Attachments
edge 1.JPG
edge 2.JPG
edge 3.JPG
edge 4.JPG
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Re: 2 rail sweep not behaving like I thought it would

Post by DLWOODWORKS »

Thank you so much Michael!!! :)

Out of curiosity, how did you know to add the little line and that would solve the problem (other than your incredible experience)? That would have never dawned on me to do something like that. I'm not even clear on how that made the profile be complete? Could you explain the theory behind why that would do what it did versus just using the profile as it was? Very curious about this.

Thank you again, SIR!!!

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Re: 2 rail sweep not behaving like I thought it would

Post by dealguy11 »

To follow up on Michael's excellent response, you might be wondering why the hook is there in the first place and why the little leg gets rid of it.

Here is what your original moulding path was doing. Remember that Aspire calculates this toolpath to the center of the bit, so you can see that the bit is stopping at the end of the profile and leaving the hook:
Hook 1.JPG
If you add a leg, it forces the bit down the front of the profile. In this version, I put the leg right at the bottom of the profile. Note that there is still a little hook at the bottom.
Hook 2.JPG
By adding a vertical to the profile equal to the radius of the bit, it forces the bit down past the ball nose and eliminates the hook entirely:
Hook 3.JPG
Note that in the third example, if the thickness under the profile is less than the radius of the bit you will cut into your spoilboard
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Re: 2 rail sweep not behaving like I thought it would

Post by mezalick »

Excellent Steve !!!
Well Done..
This should be in it's own tutorial.

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Re: 2 rail sweep not behaving like I thought it would

Post by DLWOODWORKS »

Thank you Steve!! That makes a lot of sense. Very valuable lesson learned on this.

I was able to get my profile cut and it is exactly like the original table profile. I think the customer is going to be very happy.

Thank you to all that helped with this!! :D :D

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Re: 2 rail sweep not behaving like I thought it would

Post by adze_cnc »

DLWOODWORKS wrote: Since this profile exactly matches the profile of the existing table, what would I have to do in the moulding toolpath (cutting past the edge of the material) to get it to over cut the profile more than the diameter of the bit? I'm using a 3/8" ballnose. I've tried a 1/4" and a 1/8" ballnose and I still get the little hook in the preview.
There should be a "Boundary Offset" field at the bottom of the Moulding Profile panel. Set that to your bit radius and all should be well with the world.

Steven

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