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Controling Z depth in Coons Patch


motor-vater
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Man I'm having a day. So anyway I got a part I'm making where there is a port that fillets over the top with a .7 radius if you follow me. I know, but I left work already so no file share tell Monday. But after fiddling with flow line for far to long I just gave up and went to a coons patch. Looked really good in verify compared to the flowline. The flow line was just choppy and I could not seem to get it smooth, even remade all the surfaces several times. Making sure to use arc's and a net surface. It was smooth as silk, but no mater what i did with the tolerance and smoothing I could not get a smooth consistent flowline going. It was like micro linerized if you follow me. Back to the Coons. When I ran the part the Z was making all these tiny hops of like .0001 to .003 along the path. So obviously the surface finish looked like chit! My settings were .020 across and along, with circle and parametric if that helps. I opened the NC and low and behold friggen Z moves all over the place. I started to manually remove them but Its just to much code to play with... Errr. Now I sit here feeling defeated wondering if Monday will be another wasted day staring at my computer screen vs. making chips.... I'm thinking blend might be my next greatest waste of time? Some days your the dog, some days your the hydrant, and today I am soaking wet!

 

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Blend is like Flowline, but on Steroids! You must have 2 blend chains that "guide" the toolpath. These are always "centerline" chains. So, on the "interior" of your Port, you need a chain that is offset "inwards", the radius of your tool. Plus, I like to give a couple extra thousands, just to give the Toolpath algorithm some "wiggle room". So for a .500 ball, I'd offset .255. On a .062 diameter, I'd offset .035, and a 1.000, I'd offset. 510. Just some examples that might help.

Do you know how to "synchronize" chains in the Chain Options menu? Chain Syncing will help the Blend Path to make a more "well formed" mesh grid. It helps especially in areas where you have "upper and lower" radii in you chains, with different radius values.

The Blend Toolpath works by creating a network of "meshed curves" across and along the blend curves. Without "syncing" enabled, we simply move from the start of each chain, to the "stepover distance". At each of these 'cut points' along the Blend Chains, we create 'perpendicular curves' that connects each of these 'cut points'. The motion between the Blend Chains is a smooth 'morph' from the shape of one chain, to the other.

We can also use Blend in a couple different ways. There are three Cut Pattern Types: Zig-Zag, One Way, and Spiral.

Using these different patterns, we can also get creative with the Chaining methods. Normally, your two Blend Chains are roughly parallel with each other. This type works well with Zig-Zag and One Way. For "spiral", you can use the "Chain Point" method to select 'a single point entity' as one entire "blend chain". This works really sweet for spiralling in or out from a center point, to an outer chain. This outer chain can be rectangular, circular, or any complex contoured shape.

Always make sure your chains do not self-intersect.

Dude, when you can, post up a file with just the geometry you're having issues with. I'll lay down some gorgeous tool motion samples for you, to show you the true beauty and power of Blend. The Blend path is a game-changer.

 

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Ill try to run into the shop today and do that. Not every day you get an offer like that. Do I post here or to an FTP server? How does it work? ZIP to go?

 

Also I have been using blend for years, mainly for combustion chambers on cylinder heads, so I do understand a bit of what you are saying, not giving it the wiggle room it needs might be part of the problem I have had when trying to use it on parts like this. Because the fillet rolls over to a vertical surface I always see some very weird stuff at the transition... But it makes since giving it the room it needs to actually do the work vs. slamming it against the wall and holding it there. Kinda makes me feel like a school yard bully, no that I think of it. lol

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Yes, Zip 2 Go works best. You can reach me at:

[email protected]

Depending on how big the file is, you can either email it to me, or I can setup a DropBox shared folder so we can share files.

Another trick to Blend is adjusting the "Blend Resolution". This can be used to smooth out the blend motion, and avoid the "jumping" around that the Toolpath sometimes does.

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Awesome Ill get that to you in the afternoon. Not sure how you find the time, but I appreciate the intervention! I know people have been saying for years flowline is not the goto anymore. I just know sometimes it the only thing I can use to get the motion I want. Most of the toolpaths will do it if you get the settings right, but I get frustrated after hours of tinkering and cussing at my screen. I guess my reading comprehension sucks because half the time when I try to use the help menu, it gets worse... lol I swear the older I get, the stupider I become.

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Just an update on this, I was messing around all weekend. So I went to a blend and still had alot of faceting, seemed like no mater what I did with filtering and tolerances it was jenky at best. So I found that by laying off Mcam filter and activating the smoothing in the machine has given me pretty acceptable results. Lucky this is not a part that needs any kind of surface tolerance.

Fabteck SBF V3.jpg

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