Drill (carving) bits usage (what they are used for), size and density

[Nazar]

The 3 bits that came with the machine (or in the shop) - are the same as the 5 bits in the shop (you just get 2 extra)

When you get delivery - don’t assume it is correct, bought the 5 bit set and got 2 ball (instead of 1), and missing single flute 3.175

I am using digital feeler gauges - these are the measurements I get.

There is no post about this and I would have found it really useful - I am using Luban to conduct this experiment. and i am a beginner, so please like this if it is useful. (so others find it)

The reason for this thread, is to get an idea of what the different bits (drill carving bits) are used for - I broke my flat end mill that came with the machine and I tried to flatten a piece of wood with the V bit - yep, you guessed it, it made a mess of the board - the flattening part was full of fur (pulled bits of wood strands out of the wood), was told I need to use a flat end mill (now it is perfectly smooth)

Personally - I can see why the 3 bits came with the machine and the reason for different bits with a bigger CNC, but with Luban I am struggling to find a reason to purchase the 5 bits from the shop. Unless fusion and easel give more functionality - please tell me if i am wrong?

With density - I am finding the minimum density before I get individual lines for each run.

The 3 (carving) drill bits that came with the machine)

V bit - length 29.14mm width 3.52mm density - usage : carving wood, acrylic, PCB - at a 3mm depth (just before this depth) it was making a horrible noise because it was hitting the edge of what it was carving (3mm is too deep with straight walls - had to stop the job)
Flat end mill - length 37.93mm width 1.5mm density - usage : cutting thin wood, carbon fibre sheet, plastic - also good for smoothing off your wood (getting it level)
Ball end - length 38.47mm width 3.19mm density - usage : cutting thin wood, carbon fibre sheet, plastic

The 5 bits that are available in the shop

Flat end mill, double flute (cutting diameter 3.175mm) - length 38.81mm width 3.20mm density - usage : cutting thin wood, carbon fibre sheet, plastic - also good for smoothing off your wood (getting it level)
Flat end mill, single flute (cutting diameter 3.175mm) - length 37.96mm width 3.20mm density - usage : cutting thin wood, carbon fibre sheet, plastic - also good for smoothing off your wood (getting it level)
Flat end mill, single flute (cutting diameter 1.5mm) - (same as came with the machine)
Ball end mill (same as came with the machine)
V bit (same as came with the machine)

Update : the V bit is no longer included with the machine

for speed and work depth - this is a good guideline (thanks sdj544)

@sdj544

For harder woods (oak,maple) I use a .5mm step down. For softer woods I can sometimes get away with 1mm. 340mm/m work speed and 240mm/m plunge speed seems to be best combo of speed and smoothness and not straining the motor. Listen as it’s cutting and you’ll get a feel for it but it’s pretty obvious when the motor is straining and working too hard.

Any help appreciated (to fill in the blanks) will keep the thread updated, especially other uses for the bits, at this point I don’t know density (have to do a job before I can do experiment with density)

Contributions : @sdj544

[ITmaze]

A cutting tool is designed for specific behaviour using specific feeds and speeds for particular materials. There are literally thousands of them, whole companies, libraries and careers devoted to this field.

Additionally, they’re considered a consumable item.

I’d recommend finding a tool library that has the tools you’re attempting to document and linking to that here.

[Nazar]

hi ITmaze - been thinking about what you posted over the last few days, and i just can’t see how it works.

with big CNC bits, you make one pass and get the desired shape you want.
with these small bits - there are only 2 cutting faces - the base and the sides (and the cutter needs to move up, down and sideways) and make multiple passes.

so the 3 bits (being V, mill and ball) should be all you need.
granted, the bigger mill would do it much faster (setting the density lower) to make a smooth board to start your work - and that might be a reason to buy it.

but the 3 main bits should be all you need.

[ElloryJaye]

(Please keep in mind as you read this that I’ve done a lot of background reading, but not experimented with CNC yet. What follows is elementary information not suited for individuals already familiar with CNC, who will know more than I do about this stuff. I expect someone will jump out and contradict me if I’m wrong. In fact, please do.)

The flat-end bits are for general use (cutting, flattening, etc.) The difference between the single and double-flute bits is that the double flute can probably remove more material more quickly.

The ball-end bit is mostly for carving. It should produce better curved surfaces than the flat-ends. This is the one you would want to use for elaborate bas-relief dragons.

The V bit is for fine carving (smaller details) and things you want a slanted edge on. Among the available bits, this may be the best choice for milling something like a PCB, which is all shallow, fine details.

I would guess that the single-flute flat-end 3.175mm bit is less useful than the similar double-flute unless it has some other special characteristics. The bigger flat-end bits should be faster than the little one for work that doesn’t have any features smaller than the size of the bit (and maybe they’re less likely to break?), but aren’t really essential.

Beyond that, there are, as ITmaze said, a whole bunch of additional variables: fine details of the shape of the bits, the material they’re made from, any coatings that might be applied, number of flutes, capacity of flutes, etc. There are also at least a couple of specialized bit types not included among Snapmaker’s offerings, but that may be useful under specific circumstances (there’s one that’s specifically for levelling surfaces, for example).

[brent113]

For fine detail, like the dragons mentioned, you’ll need a fine point, likely even finer than the provided v-bit, like this:

[sdj544]

Maybe this will help:

CNC Router Bits – A Simple Guide | All3DP

-S

[Nazar]

thanks guys for explaining - i need to modify the op post to portray the correct info - but also leave it there so the comments don’t look unusual Thanks again…
can’t see how to edit the op - so i will put further info here

THE RESULTS OF TESTING

All I can say is WOW, using soft pine, max stepdown 0.5, work speed 340, plunge speed 240

D = density, SD = stepdown

As per the photo, top left going down using mill that came with the machine using soft pine.

Mill
D 1 SD 0.5
D 2 SD 0.5
D 3 SD 0.5
D 4 SD 0.5
D 5 SD 0.5

The winner D 3 - D 1 you can to feel the roughness, D 5 is ultra smooth - D 3 I think is the best results for time (and there is not much difference in the smoothness of D 5 to D 3)

2nd run
V bit
D 1 SD 0.5
D 2 SD 0.5
D 3 SD 0.5
D 4 SD 0.5
D 5 SD 0.5

Honestly - they are all terrible, ripping bits out of the wood. Thought it might be a problem with SD, so did another try.

3rd run
V bit
D 5 SD 0.1
D 5 SD 0.2
D 5 SD 0.3
D 5 SD 0.4
D 6 SD 0.5

All terrible, ripping bits out of the wood. The V bit is probably designed for hard wood (like jarrah)

4th run
Ball
D 1 SD 0.5
D 2 SD 0.5
D 3 SD 0.5
D 4 SD 0.5
D 5 SD 0.5

Apart from making a really bad/loud noise (I believe the noise was made by the bit going through the wood, not the machine) - clear winner is D 3 - you can definitely feel the high points of the ball run (at the sides) with D 1, D 5 is very smooth but little or no difference between D 5 and D 3.

Conclusion :
Mill (that came with the machine) - D 3
V bit - test didn’t work (don’t use on soft pine)
Ball - D 3

My favourite bit for going forward with soft pine is the Mill

My son tested (with his finger) not telling each other, we both came to the same conclusion.

hope you find this useful i sure do

[sdj544]

Could’ve told you before your test that a flat end mill would do the best at milling something flat. (But I like doing those types of tests too and helps me to see and understand and make sure it’s working how I think it is)
The v-bit is used for fine engraving and details.
The ball end mill is best for smoothing and contours.

The density setting on Luban really doesn’t make any sense. No other CNC or CAM program uses this terminology. It should be step-over by either a specific measurement or %.

Pine can be really hard to mill cleanly.
You also should try a test going cross grain. The way the bits respond and cut is completely different especially with a stringy wood like pine. Unfortunately in Luban you can’t choose that. You have to rotate the work piece. With Easel and Fusion you can choose direction of travel.

-S

[Nazar]

thanks again @sdj544, the info you give just above is excellent and complete.

and yes, the plan is to change to fusion and easel shortly - thanks again, i can really see the short comings with Luban - but most beginners will be using luban, and i wanted to give them an idea (as well as me )

[jgb]

Let’s keep in mind there is one very major difference between a Snapmaker CNC and any other CNC specific machine.

RIGIDITY

A purpose built CNC machine is quite rigid and will not allow the tool bit to move while milling. That allows deeper and wider cuts into harder materials. And a good speed of cut. The amount of flex allowed at the bit end is measured in 10’s of microns

A Snapmaker CNC is too flexible and as a result you are very limited on depth of cut, width of cut, speed of cut and material hardness. The amount of flex is probably in 10th’s of a mm. That level of flex creates bit chatter (vibration) which gives rough surface finishes, tear outs and will even break bits.

There is nothing you can do to sufficiently stiffen a Snapmaker. At best, a reduction on feed depth, cut thickness and feed rate is all you can do to get a better cut. That also means adding hours to the job time. And make sure you use sharp bits, and keep dust and cuttings away from the cutter.