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Thread: Using the 3D Finishing Toolpath for ROUGHING vs using the 3D Roughing Toolpath

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  1. #1
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    Default Using the 3D Finishing Toolpath for ROUGHING vs using the 3D Roughing Toolpath

    After searching the forums I am going to start a long overdue project, a 3D model ~ 8x20 on old growth redwood (Praying Cowboys from Design & Make).

    I was intrigued by the idea (if I understood correctly) of using the Finishing Toolpath for Roughing vs using the 3D roughing Toolpath.

    I ran both simulations, using for this stage, a 1/4" bnb with 30% stepover. The Roughing Toolpath showed over 2 hours time with 5 passes across the grain, and the Finishing toolpath, using the same bit and SO showed 25 minutes and one pass.

    Is this truly more efficient, or am I missing something?

    I think the difference in time is that, using the 3D Roughing Toolpath, I had chosen a depth of 0.125 for a max depth 0.6779, thus all the passes.
    In the Finishing Toolpath, if used for roughing strategy, there is no option to do incremental depths, so it does the max depth (0.6779) in one pass, so to speak. Is that too much for one pass?

    I realize the purpose of roughing is to hog out material and make it 'easier' for the final bit.

    My strategy is: A) run a profile pass first (1/4 bnb, SO 30)
    B) Run a roughing strategy crossing the grain ( 1/4 bnb, SO 30)
    C) Run a 1st Finish with the grain ( 1/4 bnb, SO 30)
    D) Run a 2nd Finish with the grain (1/16 bnb, SO 5)

    Comments appreciated.
    Last edited by carolinasmith; 05-18-2019 at 11:08 PM.
    ShopBot Desktop MAX, spindle, 3" Indexer, Aspire 9.5, and a big learning curve...

  2. #2
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    Too much wasted time, just use the 3D roughing toolpath and use a 0.25" downcut end mill (not a ballnose) at 48-50% stepover with a machining allowance of 0.04" and up to 0.375 per pass depending on the quality of your end mill. Run it as 3D raster across the grain (keeps long slivers from plugging the dust foot). Then run the 3D finish toolpath across the grain as well with an 8% stepover. Done. You may think that a final finish pass across the grain will leave scoring, but with the proper tool and stepover, it will be fine and have a lot less fuzzies to clean up.

    All of these have been done that way. https://drive.google.com/drive/folde...jQ?usp=sharing

    Depending on the level of detail in your design, determine if you need to do a finish pass with a 0.0625" ballnose or can you get away with a 0.125" ballnose. Do this by generating a toolpath for both and preview the 0.125 one first followed by the 0.0625 one to see if the detail gets better.

    With proper ramp settings and feedrates (try to match feed and plunge speeds or get close as your machine can handle), your roughing pass should be around 20-30 minutes or so for that size and the finish pass probably around 8-10 hours, but that depends on your layout, dished or framed recess. Be sure to limit the toolpaths with boundaries as needed, that will save travel time. Another thing you can do to some models or parts of your model, is to put a slight draft on any vertical walls. This helps to keep the flow going instead of abrupt stops to raise up and over.
    Scott

    If guns kill people, I guess pencils misspell words, cars drive drunk and spoons make people fat.

    "Those who hammer their guns into plows, will plow for those who do not" - Thomas Jefferson




  3. #3
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    Thanks Scott, for your suggestions. I had already progressed through the roughing. I really like your tip of previewing the toolpaths for different bits. I didn't realize one can view a toolpath over another one, and after comparing several times, find I don't need the 1/16 bit, but can use the 1/8 bit... you just saved me about 8 hours

    I started to run the 'roughing' toolpath using the Finishing Toolpath, but quickly aborted that as the plunge depth was too much (bit chattered and redwood chipped alot). I like doing incremental layers that using the 3D Roughing toolpath affords.

    Thanks also for sharing your expert and beautiful works.
    ShopBot Desktop MAX, spindle, 3" Indexer, Aspire 9.5, and a big learning curve...

  4. #4
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    Yup, forgot to say that the finish toolpath always goes full depth. You could trick it by setting the Z higher, but that's what the roughing pass is there for.
    Scott

    If guns kill people, I guess pencils misspell words, cars drive drunk and spoons make people fat.

    "Those who hammer their guns into plows, will plow for those who do not" - Thomas Jefferson




  5. #5
    Join Date
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    What a GORGEOUS selection of slabs....AND you done them Proud Scott!!!
    What's your Exterior finish?
    scott

    Carolina..there ARE sometimes when you like to use a Finishing toolpath to Rough(such as going down through Bark to good wood...trying to incorporate a Heart/Sapwood line into a carving,etc)...
    BUT it will Always go to Finish depth! You have to Cheat the Z up(M ove N udge) the same amount you'd use as an allowance BEFORE carving.
    Make SURE by looking at Preview, that the Toolpath does NOT jump around, and give you any full depth plunges!!!
    IF none, then initially cheating Z-Zero up, and then incrementally down to original, should give you only stepover width cuts...which if you have the CEL are usually fine.
    The Owl/Squirrel/Hippie are an example;
    Attached Images Attached Images
    Last edited by scottp55; 05-19-2019 at 06:31 PM.
    Scott Plaisted
    2013 Desktop/spindle/VCP 9
    Maine

  6. #6
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    Hey Scott,

    I just spray a coat of precat lacquer to seal them (maybe a little extra on the relief), then some Van Dyke Brown glaze in the relief and black spray ink in the letters after masking off around them. Work the glaze to desired look, sand off ink over spray and then do the final coats with the same precat lacquer (Fine 3M pad between coats). I don't have patience for multi coats and days of drying in between coats.

    Love that owl, gonna have to try something like that some time. Great work, as always!
    Scott

    If guns kill people, I guess pencils misspell words, cars drive drunk and spoons make people fat.

    "Those who hammer their guns into plows, will plow for those who do not" - Thomas Jefferson




  7. #7
    Join Date
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    Thanks Scott!
    Now that I see it, I realize you've answered that before...difference being, THIS time I'm saving it
    Thanks!!!

    Yep, Just finished a Burl Slab for Dad's ashes with his favorite Mountain on top.....Talk about SLOW, but it's one-of..and no do overs.
    A little nerve making ready to getting everything to fit!
    https://forum.vectric.com/viewtopic.php?f=2&t=32122


    Doing this the multi-day(week?) old fashioned way
    scott
    5.20.19 CANYON FINAL 1.61 DEEP WITH INLAY LIP.jpg5.20.19 KATAHDIN IN PLACE9.jpg5.20.19 KATAHDIN IN PLACE0.jpg5.20.19 KATAHDIN IN PLACE 1.jpg
    Scott Plaisted
    2013 Desktop/spindle/VCP 9
    Maine

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