17+ hours to cut a strip of molding... any advice on bits?

[skintigh]

Ok I think I attached it.

[steve_g]

Well… I guess that’s that!
SG

[steve_g]

I don’t imagine that the trial version will let you export the vector as a DXF either… if you can, take a picture of the vector or a cross section of the actual molding, and I’ll redraw it!
SG

[skintigh]

Doh! It's the makerspace version so I thought I could share it, but maybe I can only share it with the same makerspace version. That would make sense...

Here is a screenshot of the molding profile (actually a pair, slightly altered as the original is thicker than a 2x8) and the settings. The path is a straight line 46" long. Onsrud taperd 1/8" bit 1.5" CL. With the current settings the molding pass takes 5:32:59 with rapid rate 100 scale factor 1. I have no idea what to set those last 2 to.

shape.jpgtool.jpg

[scottp55]

Aah, Just looking at some recent putzing of 3D's.
Lion's were done at 4% stepover, and then 6% stepover with a Chinese .25mmR TBN..and I CAN'T tell the difference.
Also a recent project with accurate multiplier for estimates with the same bit(but at 1.5,1.5, and 6% stepover..so multiplier should be close.
Maybe go at least 6% stepover, and use a multiplier of 2?
Not any experience with Moulding Toolpath Yet, but should be even higher multiplier I think?
scott

Listen to Steve though!
Oh Steve..Those little .25" depth and CA'd "Twig Butterflies" kept my Aunt's 5/4 Black Walnut cracks from spreading.. this pic was 2 years later, and the flatness of he board after 2 years curled almost .5".
I put that down though, to having those "Butterflies" on both faces, and almost the same spots. Just mentioning after 2 years.

[srwtlc]

Try a 8% to 10% stepover. 3% is way to small. If 10% leaves too much sanding to clean up, then drop it down further. Don't trust the calculated machine time. Run one with optimal settings and then tweak the scale factor to match the actual time that it took. After that, you can use that scale factor for similar toolpaths.

Try it without/with 'vary stepover' enabled.

Don't put your kerf line in there, as the bit will take more time to drop in at that spot and if it fits, it could drop all the way down and make a full depth pass.

[skintigh]

I set the speed to 4 IPS pretty much randomly. The ShopBot speed sheets recommend 1.8-3 IPS and cutting 1xD. But I'm cutting up to 12xD but with only a 6% step over, so can I go faster? Even full speed -- 6 IPS?

It's an $86 bit so I don't want to take any big risks... But if I start at the most shallow cut and maybe make that square trench in the middle super shallow it will be safe?

[steve_g]

I eliminated the down cut separator between the two moldings and would plan to separate them on the table saw, it would have to eventually be cut there anyway…

It’s my understanding that the reason you need a multiplier for the time is that the Z action time isn’t calculated into the mess. This tool path has VERY LITTLE Z action… just a slight step at the end of every 46” of travel. I have found that no correction factor is needed when cutting moldings.

I’m seeing 2:28 total time for both moldings.

SG

[skintigh]

That's great, thank you! So you think I should stick to 3 IPS? What step over percentage did you use?

I'm going to try running this today.

[steve_g]

My stepover of 4.5% will result in almost no sanding… at least in MDF, likely your SPF also. If some sanding is ok, move it up to 6% or so.

My machine would like to run this at 3 ips yours may be different! My machine is getting up in age and needs some TLC! If yours is new and tight, bump it up!

SG