Topographic Map Advice

How To
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I’m working on a topographic map design. I’ve got the basics down, what I am looking for is advice on how to improve the result and/or performance.

Now this is going to get very nerdy, but the map I am working on is not from the real world, it is from a computer game, Skyrim. I’ve been thinking about this for some time now, and I already have a lot of time invested in the heightmap and landmark tweaks. Most of the work was done in Photoshop, then leveraged heavily on the 3D modeling in Carbide Create

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There is a lot of elevation change in this map, and my current plan is to stack two 3/4" boards to give a total height of 1.5". All of this is modeling okay, but I’m approaching the limits of what Carbide Create can handle, the application crashes pretty regularly, but I’ve learned to save frequently and to incrementing file names.

Now I am starting to work on the toolpaths, and this is where I am looking for advice. The 3D Roughing with 1/4 Downcut (251) will take 8hrs, 47 min. The material is Baltic Birch, 1/8 stepover, 1/16 depth of cut, 100in feed rate. There is a lot of material to remove, not sure if I can go more aggressive just wanting to see if I am missing something obvious.

Once the roughing is done (and most of the material is gone) then I am left with how to do the 3D Finishing, and I see different ways to do this.

Idea 1: Take multiple finishing passes, reducing the bit size each time. So the first finishing pass would be with a 1/4 ball. The 1/4 ball would reveal some of the larger features, but miss most of the smaller details like the boarders, roads and rivers.

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I was thinking that this would enable me to be more aggressive in terms of feedrate when making a 2nd finishing pass with 1/8 ball, but does making 2 finishing passes improve the end result?

Idea 2: But then maybe the time I saved (idea 1) was actually wasted. Would it be better to just make a single finishing pass with the 1/8 ball and go slower.

Other random thoughts/questions:

On the finishing pass, I see the option for “Angle”, the default is 0.0000. This has me wondering if I went with multiple finishing passes, do I change the angle of the 2nd pass, and if so at what angle?

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Would it be better to split the map into sections? Instead of doing an single-long finishing pass, should I divide the map into sections just to have better restart options?

I’m not looking to tune this for mass-production, but if I am going to invest a couple days baby-sitting this in the garage I don’t want to waste time because I didn’t know what I was doing.

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I can recommend you to get a tapered ballnose bit. They’re darn strong (compared to very fine bits) while having a small point. 1mm radius and feed it at 50ipm with a 10% or so stepover is what I normally do.

I have considered doing a “roughing before the fine bit” but haven’t needed it yet at all; the tapered bits are strong enough and the stepover at 10% is small enough that it just hasn’t been an issue

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https://smile.amazon.com/SpeTool-Tungsten-Carbide-Tapered-Woodworking/dp/B07B94SMG1/ seems to have a diameter close to your 1/8" idea but the 1/4 shank+taper will give it more strength so you can feed it a bit harder

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Just so I understand, these bits are technically “tapered” but when I enter them into the Carbide Create I just ignore the tapered part. This would just be a 1.5mm ball and unless I was down in a really deep (1 inch) 1.5mm slot it’s not going to make a difference… I can just push tapered bit harder/faster?

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yup

one note of caution: Unlike most bits, the tapered bits sometimes are sold based on RADIUS not DIAMETER. Easy to miss, and results are not nearly as nice if you get it wrong :wink:

so this would be a 3mm ball (hence close to the 1/8") they also have them much smaller if you want to go to much finer detail; I often use the 1mm version of these for maps like Red Pin Terrain carve and The three volcanoes of N Oregon and S Washington

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I missed your question on the angle; if you were to do a second pass, I’d do it at 90 degrees unless you have something in the design that is a natural angle like a large mountain ridge… in that case it is maybe interesting to do the 2nd pass at a 90 degree angle from that mountain ridge.

However it will make the cut take twice as long, and if you’re going to spend that time you can also make the stepover smaller or use a smaller bit… both will give you even better detail and will also reduce the ridges that are typical for a ball nose

(and if you half the stepover you likely can increase the feedrate a bit, so you could likely go even less than half, say a third, increase the feedrate and be at the same 2x longer time)

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Regarding feeds, speeds and multiple tools, I don’t have a whole lot of advise other than to do test cuts. Get some scrap stock and just crop a chunk of your height map and try it, that way you can easily validate the different settings without spending a whole lot of time and stock if it doesn’t work well.

That’s one way but you could also just manually edit the G-Code if you need to resume.

I don’t know if this is available in Carbide Create (maybe @WillAdams can comment, he knows it a lot better) but in Fusion 360 there’s a feature called “rest machining”, which allows you to configure a smaller tool to skip over all the parts you’ve already milled with a larger tool.

Everything the 1/4" endmill can get at on its own would be handled by the “1/4” pass and then all the smaller details would be handled by the “1/8” pass. This means you don’t have to cover the same area twice (which I think is what you’re asking), the 1/8 endmill would be used only for those small detailed spaces the 1/4 endmill can’t fit into.

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Carbide Create does not offer rest machining at this time — it’s a frequently requested feature though.

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with ball endmills, that is likely complicated and the “ridges” of the ball means you likely rest machine EVERYTHING

I still think the 2 pass makes no sense; I would rather pick a stronger bit (tapered end mill) and just do it once instead… (there seem to be people who don’t even do roughing once they use a strong enough tapered endmill… I’m not that brave yet)

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Thank you for the advice on test cuts, I ended up with a 3D roughing pass at 1/8 stepover, 1/16 depth of cut, 200in feed rate. WAY faster than what I was going to originally use.

I’m pretty sure it could have gone even faster, but it was at this rate the sweepy started having problems. I was getting a series of one to two inch long sticks that were collectively getting stuck within the sweepy. It was only happening when there were long X axis passes, and the alternating plywood grain was also running the same direction.

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Thank you for the advice. Today I finished the roughing pass, and the first finishing pass with the 1/4 ball. After watching it run today I agree that multiple finishing passes is probably not needed. I could have jumped right to the 1/16 ball finishing pass.

However this has turned into an interesting experiment. This weekend I am going to do another finishing pass, but skip straight to the 1/16 ball and I am going to run that with the 90 angle option.

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What stepover are you planning for?

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@ColdCoffee, this project screams for lasering things onto it, @ClayJar style?

[nerdy sidetrack: to this day Skyrim is the only video game where I remember doing contemplative walks in the wild for hours, amazed at what those developers had accomplished. I read somewhere that the next one is still years away, and a few days ago Microsoft bought Bethesda, and that felt like taking an arrow in the knee]

Regarding how to finish this piece, I’m on team tapered endmill. You can run them crazy fast (relative to their size) in a situation like this.

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For the 1/16 ball I am using a 10% stepover so .00625 which means it will take awhile. However since this is the second finishing pass there won’t be much material removed so I am going to leave the dust collection off, and probably be brave enough to not remain in the garage the entire time.

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I am going to get some tapered endmills, but I want to finish this project this weekend so I am going to continue with the standard 1/16 ball.

So far everyone that has seen the two maps in person has suggested another project for me. So it looks like I have several topographic maps on my to-do list, the tapered endmills will get a workout.

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Sadly, I had to pull the plug on this attempt. Had multiple problems, the final blow appeared to be a bit slipping or some other z axis problem. The 1/16 ball started milling about 1mm lower than it should have right down the center of the map.

I’m going to start over, reduce some of the detail (roads between towns) and try again with the tapered 1/4 inch shaft bits. At this point I’m going to try and avoid 1/8 shaft bits in the Shapeoko. I have not owned the Shapeoko long enough to draw any definite conclusions other than I’m having bad luck with 1/8 bits slipping.

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you shouldn’t need to reduce detail at all…

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also may I suggest starting with something a little smaller in size, maybe 4"x4" or so… just to get to the end of it and ensure all your settings are sound/working/etc

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Looks like you have got a lot of great advise on cutting. My one suggestion is to consider using a different material. Baltic Birch can be from great to not so great in quality. There can still be voids in the subsurface of the plys. Even in Baltic Birch or Finnish Birch there can be knots in the middle plys. If you hit a void it could ruin all your work. MDF could work but solid wood might be better even if it is just clear pine with glued up boards.

With all this work you dont wont to find out you got a bad batch of baltic birch plus the glue on the plys can fail when getting to fine detail like the top of a mountain.

Also check out HDU Material at https://www.curbellplastics.com/Shop-Materials/Specialty-Products/Prototyping-and-Tooling/High-Density-Urethane-(HDU)-Boards/High-Density-Urethane-(HDU)-Boards#?Shape=CRBL.SkuToolingBoard

and check out https://precisionboard.com/tooling/topographical-map-time-study/ for reference.

FYI

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I got my Baltic-Birch from WoodCraft, and (so far) that is the only option I found to locally source “good” plywood. I paid $50 for a 48in x 30in x .7in board, and yes it has roughly 4 to 5 knots on every inside layer :rage:

I need to find a local source, like what John Clark found near him.