Correct bit and feeds for 3D carve

Hey!
I am playing around with my machine and wanted to try some 3d carving.
Everyone is talking about ball nose bits, so I ordered one.
But now I am really confused, because most people talk about 1/8" ball nose bits.
Mine looks like this:


Is this a correct “ball nose”? It has a 1/8" shaft and .04" tip.

I am trying to carve the awesome 3d piece of @AK_Eric
Thingiverse Files

So my questions are:
Is this a suitable ballnose bit for this project?
I am trying to carve from a 2" x 2" pine piece of wood.
Does the finishing pass really take 15 minutes at 150 ipm @ 16.000 rpm?
Can I use the same bit for roughing pass as well? Just checked again. When I use a 1/8 bit roughing takes 5 minutes.

Thank you for your help!

If the cutting end of the bit is flat then it is an End Mill, if the cutting end is rounded then it is a ball nose, When someone refers to a 1/8 ball nose it is a tool with a 1/8 inch cutting diameter and a rounded end.

A 1/8 Endmill and a 1/8 ball nose both have a 1/8 inch cutting diameter.

Here is a good explanation of the different cutting tools

Seems to look like a ballnose from your pic. I use mainly .25" and .125" ballnose bits for most of my creative work, like you’ve shown above. if yours has a .04" width, that’s… really small, 1/25"? Looks bigger than that in the pic to me.

To answer your questions:

  • Is this a suitable ballnose bit for this project? : Yes
  • I am trying to carve from a 2" x 2" pine piece of wood. Sounds good.
  • Does the finishing pass really take 15 minutes at 150 ipm @ 16.000 rpm? : Maybe? Entirely depends on your stepover and bit size. To get a nice finish I usually set mine to a 10% bit width for stepover. For a .125" bit, that will take twice as long as a .25" bit.
  • Can I use the same bit for roughing pass as well? Just checked again. When I use a 1/8 bit roughing takes 5 minutes. : Yes, I often use the same bit for both passes. But I’ll also use a .25" endmill (flat tip) for the rough, then switch out to a .125" ballnose for the finish.
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Thank you for your replies!
Where I am still very unsure is the bit size.

For the beginning (because I break lots of stuff) I ordered some different bits from Aliexpress.
This is the one I got here:

https://de.aliexpress.com/item/R0-25-0-5-0-75-1-0mm-with-3-175mm-1-8-shank-Tungsten-solid/32785872951.html?spm=2114.13010608.0.0.1J3NyI

And it says 1mm tip radius, which should be equals to 0.04". Do you think I can just leave it to 0.125 and give it a try?

The link is pointing to a tapered bit. That will do a great job for your detail pass and a horrible job for the rough pass.

If you are using a tapered bit you need to be sure you have told the CAM software that you are using a tapered tool, it works much differently than an endmill or ball nose.

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Looks like a tapered bit. The tapered bit is preferred by some because you get a smaller tip but a stronger bit overall.

As Allen said, you need to tell your software you are using a tapered bit. In that link, there is a column in the table that says the taper degree per side. You’ll need that for your CAM software.

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Ah thank you so much. Think I slowly got it. I even ordered a ball nose before, but I cannot find it anymore :confused:
Just ordered 6 more. Even found the settings for the tapered bit now.

@AK_Eric why do you do the roughing pass slower than the finishing pass? In theory I would have thought it should be the other way around

The roughing pass is removing lots of material. Just how much is removed each pass depends on the roughing statedgy you choose.

The detail pass only removes small amounts of material.

nononono : You need to tell your CAM software the exact bit size, or chaos will ensue. that’s a super tiny bit, completely overkill for something like this, the cut would take forever.

Per what AsslenMassey said: Rough passes remove large quantities of wood, thus, you generally need to cut slower so as to not stress the machine\snap bits. Finish passes only remove a tiny amount per pass, so you can run it much faster.

Fore example, on my rough-passes, I used a .25" endmill (flat tip), with a .125" stepover (.5 bit width) and .125" cut depth (.5 bit width).
For finish, I’ll use a .125" ballnose (round tip) with a .0125" stepover (10% bit width) : I’m removing far less material, so I can run it a lot faster.

However, the values I’ve listed I’ve spent hours\days tuning per wood type, per bit-type, on my machine. The value you use could be very different.

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I should also note, I used a .25" ballnose for both rough and finish on the above cut, for comparison sake.

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Thank you for all your help.
By this few answers I already learned so much!

So although it didn’t come out correct…here is what I just did:
Roughing pass took around 10 minutes (1/8" end mill).
Finishing pass took around 7 minutes, but I stopped after 2 (1mm tapered ball nose ) :wink:

Unfortunately my finishing was moved a little bit (by around 1 cm).
But at the top right you can at least see that he made some really nice smooth edges.

I am really happy with the result. Unfortunately I cannot try it again right now, because its half past ten here and I have to cut in a small house where several people live :smiley:

Have to try it again tomorrow.
Thank you so much for all your help!

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Due to the default lower max speed rate for Z vs X/Y, and also acceleration value is less = any contouring Z-motion will take longer compared to pure X/Y.
Stepover is also set lower for finishing pass.

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I bought a set of ball nose bits from ebay
Like these. I didn’t buy these but they look like them.

Yep: I doubled my z to 40ipm in the firmware, really helped my times out. I tried going faster, but the stepper started skipping on the retracts, causing progressively deeper cuts. Need more power! :wink:

Just wanted to say thanks to all of you :wink:
Had to try it again and this is the result.
100 ipm at 24.000 rpm

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I know your ipm are higher because you suped up your machine but does that affect the step over or can i use 8% on my stock machine?

Hm usually I carved small stuff at 30 ipm and 16k rpm.
Thought this was so fast that I should turn the rpm a little bit higher.
I do not have an x-carve. I have an ooznest ox from openbuilds and use a Kress 1050 FM-E.
But I fell in love with the community and the easel software.
Please don’t ban me :wink:

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