Favorite cheapy ball nose bit?

Hey everyone! I’m making a 3D topographic map for a christmas gift this year and need an 1/8 inch ball nose bit. This will probably be a one off project so I don’t want to buy a $50 amana bit. Does anyone have a cheapy amazon brand that they like well enough to recommend it for a one off project?

I’ve used the ever loving hell out of the 1/4" spiral down cut bit and been very impressed with it. Haven’t tried this ball nose yet, but will when it comes time.

Thanks! It looks like that brand has a 5 pack of 1/8 ball nose bits. I’ll give them a try!

What material are you cutting into? How deep? Are you certain 1/8" ball will resolve all your features? For a topo, it probably will, but it depends on specifics of the job.

Simple answer though is just the 2-flute Chinesium, often sold in 10-packs. 2 flute is better than 4. They come in various lengths and you generally want the shortest one that meets your needs.

In most cases I recommend against doing an initial clearance pass. I’m pretty unusual saying that apparently, but I’ve found it’s not necessary in most cases and kind of a waste of time, esp in MDF.

Hey Danny!

It’s an 11x11 inch square with a 1.06 inch total cutting depth on soft maple.

I was going to do a clearance pass with a 1.125 inch bowl and tray bit and then a detail pass with the 1/8th ball nose. Do you think that will be worthwhile?

Depending on the finishing tool path strategy (raster or z level) when you’re removing that much material going with a mill ( even 1/4” straight mill) first to hog out material quickly would be to your advantage with respect to time.

Your Z depth on a 1/8” ball nose might be .125” but your x delta is only .065”.

My experience has been V carve will make multiple passes but only at EACH Z level in your toolpath which is 1/8”

I haven’t figured out how to eliminate that part of the g code that is removing minimal bits of material. It would traverse the entirety of your piece multiple times. Pain in the a**

A 1/4” ball bit would speed things up considerably as your Z might be the same but speed could be more aggressive and delta x or y pass is double the 1/8th bit. Adjust editing the bit selection part of your rough and finish tool paths.

A bowl and tray bit doesn’t make much sense to me here. Most don’t plunge but the CAM is going to do plunging for sure. It’s a complicated profile that doesn’t do anything helpful. You can just do a clearance pass with a 1/4" o-flute or 2 flute. But, clearance passes can be pretty complicated.

Have you done a simulation on vcarve to see that a 1/8" resolves the sharpest part of the valleys well? You will need to use the secret shift key to engage set Modeling Resolution to ludicrous (maximum). If you can go with a larger ball, do so.

I’ve had a lot of good work with this 1/16" one Sparktech has:

Personally, I’d use this one, and avoid clearance passing altogether:

The simulation looks pretty good. I did a 0.09 pass depth and a 3D raster so it looks like it will do 11 passes across the wood to rough it out. The time estimate is 20 minutes for the roughing. I know the estimates aren’t always correct, but hopefully it’s close to that.

Here’s what the piece looks like after the roughing.

As far as I can tell the 1/8 bit looks like it will give good detail. I think because the whole piece is 11 inches wide the details are more spread out. If it was a smaller piece I’m not sure the 1/8 bit would work. I don’t remember the secret shift key though! How do I do that?

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I thought I would share how this project turned out!

I did an initial 3D raster roughing pass with a 1.125 bowl and tray bit set at 630 feed rate, 20% stepover, and .09 inch pass depth. Run time was 23 minutes.

The finish pass was a .125 ball nose at 100 feed rate and 8% stepover. Vcarve estimated 4.5 hours but total run time for this pass, thankfully it ended up being just over 2 hours in real life.

Total run tine 2 hours 34 minutes!

It came out smooth and I didn’t do any sanding afterward.

In hindsight I wish I had done a v groove compass in the corner to indicate orientation and add some interest to the valley.


Oh, fabulous! Did you use 3d mode or 2d?

How did you hold down the workpiece? Painter’s tape and superglue method?

Yep, painters tape and super glue. I used 2D mode. I heard someone say that usually works better, even for 3D cuttings.

I haven’t used 3d mode in a long time. The retraction happened so quickly the z axis lost some steps. I know Danny tuned the z axis retraction speed down. I haven’t tried since then.