Some info on cnc tool changes and combo cnc/laser projects

It sounds like you just line up the origin for Laser passes manually? Have you tried finding an offset between the laser module and CNC modules so you can just compute the laser origin from the CNC origin? I haven’t tried that yet, but it seems like it should be the ideal solution.

Considered it but never ended up doing it.
Main reason is that file dimensions and shapes usually end up being different than cnc. By the time I figure out and adjust everything in whatever program I’m creating my artwork for engraving or laser paths it’s just easier to do it manually.

Great thread! I’m just starting out with CNC (already managed to break two bits this weekend), but I like the idea of being able to do multiple tool passes. A couple of questions:

-I’m assuming this means that the z offset is independent of the work origin (x,y)? I didn’t realize that it was separate coordinates-neat!
-I gather that small irregularities in the surface (I was just using bits of scrap to test) are going to be an issue, so are you guys doing a first “facing” pass on any pieces you mill?
-It looks like you’ve got some larger bits in there for toolpaths and roughing out the bigger sections. Are you able to use something bigger with the A350? It looks like it’ll take anything with a 3.75mm shank, but I wasn’t able to find anything on Amazon with a larger head and smaller shank.

New bits are on the way, so hopefully I can try some of this out in the next week or so.

1 Like

It’s all tied but you can set each individually before running the job. This works out nicely with the laser sometimes. Like if you’re doing a cutting board and want the graphic to be a certain distance from the corner you can line up the dot on the bottom edge then move up a specific amount and set the y. Repeat from the side for x.

All depends. If everything is going to be cut away anyway, than why bother. But sometimes. I have a few .5mm milling passes of various sizes saved as gcode.

You can get a set of er11 collets that will allow you to use up to 1/4"/6.35mm shank.


Thanks! That really helps. Started looking at the ER11 collets on Amazon. When I was looking for bits, I got the impression from other posts here that looking for something marked HSS (High speed) was all you really needed to worry about. Any pointers on what to look for otherwise? Any suggestions for something good to check out for a larger “first clear pass” bit to use with an A350?

HSS is a type of tool steel, as opposed to carbide or other metals cutters are made from. HSS and carbide will both work.

HSS supercedes high carbon cutters, there’s some interesting history there from 1940s machining technology.

As far as types, this kit (which you don’t need) has a nice selection of shapes and sizes you can reference off of:

It’s the kit I use, but you definitely don’t need to spend that much. A variety of straight and V cutters, some tapered ‘pointy’ bits for fine detail, whatever you need really.

Edit: Thanks SDJ, I also use Whiteside bits on my router, they are very high quality. Also Rockler makes (relatively) inexpensive good quality router bits, likely would work for the SM also. These guys.

Carbide is harder than HSS and will stay sharp longer. HSS tends to be cheaper. For the type of use they’re going to see on an SM it probably won’t matter.

There are a lot of choices and price ranges. Amana is widely regarded as the best but with a price that matches the reputation. For larger bits and final passes I really care about I’ll spend a little more. I really like Whiteside and CMT for value. They perform great and don’t break the bank.
For smaller bits, since they break easily and there is less to stay balanced I go with cheap. I’ve really liked the HQMaster that you can find on amazon and ebay. But they’re all probably made in the same one or two factories.
For flattening most stuff and first clearing passes I use a 1/4" downcut bit.
If you want to surface a large surface (like your bed) you’ll want a spoil board cutter I went with a Whiteside:
You can find cheaper but with the diameter it’s spinning I wanted one that I could trust to be balanced. Need to use small step-down - .2mm to start.
As far as other things to look for there’s a whole world of choices as far as number of flutes, profiles, upcut & and downcut etc. This will help get you started:
CNC Router Bits – A Simple Guide | All3DP


@brent113 and @sdj544 already mentioned all the important stuff.

It all depends a bit on what you want to be doing. What I did for myself was just order a bunch really cheap bits from the well know chinese websites. the SM2 is my first cnc type of device and I knew I would want to get some practice first and learn what type of bits (and sizes) would be most useful.

Now that I had some practice I’m getting a feeling of which types of bits I’ll be using for most of my projects and what’s most convenient. For example, there are often a lot of sets out there that have for example every size between 2 and 3mm with 0.1 increments. You usually won’t be using all of those.
Why not? Let’s say you’ve got one of those sets, in the middle of a job your bit breaks (or most likely at the start :), anyway, your bit broke and/or isn’t sharp anymore). What will you do? Just insert another one, maybe adjust your working speed and continue.
If you insert another size, you’ll have to regenerate your entire toolpath for the new bit size vs just insert the new bit and restart the job.

So you end up standardizing on the more common sizes anyway. And in the end that often means the biggest sizes you can use at the highest speeds (i.e. what results in the shortest time to finish the job) or what requires the least amount of tool changes.

As you go you’ll build up your list of favorite sizes and then you can spend a bit more on better quality bits that you’ll use more often.
On my list so far:

  • a surfacing bit
  • a 6mm bit (with larger collet) for larger clearing passes
  • a 3.175mm bit (which fits in the standard collet)
  • a number of 0.4 or 0.5mm bits for making pcb’s and 0.8mm for through holes

So far in my experience my cuts are not deep at all, so I tend to prefer downcutting bits as they result in the best looking edges from the top.

But in general it mostly depends on what you’ll be using it for. Do you intend to be making v-varved inlays or are you doing really fine detailed carvings etc you’ll need v-bits etc.

I’ve been using them for at least a decade for woodworking. Absolutely love their chamfer bits. U.S. made too if that’s important to you.

Should’ve included my source for good bits. Great service & prices and best of all fast and free shipping: Cutting solutions tailored to your particular needs!


Hope you guys don’t mind me adding to the thread with a question but I’m completely new to CNC and wanting to attempt to set up multiple passes for a design I’m working on that’s 240mm x 240mm x 26mm. I started cutting it with a carving V bit but realised it was going to literally take days so wanting to attempt to cut the rough larger depth out before going over and finishing up with the carving bit.

I’m trying to wrap my head around how you would set up the second pass to not have to spend ages going through the same depth so it can get straight to cutting the remaining material. Any tips would be super useful!

Edit: To add to the bit discussion, after snapping the flat end mill bit that came with the SM I invested in some Tungsten Carbide ones and they seem to be doing well!

I’m sure this applies to CNC as well. I followed some advice regarding router bits when I just started: buy a set of cheap bits, I got a 15 piece MLCS bit set. They don’t last very long, but when they get dull or wear out then you replace them with a Freud, Amana, Whiteside, etc. Then you only spend the bucks on bits you actually use.

I have a Whiteside 1-1/4" spiral compression bit that was a splurge, but good lord I use it for everything now. It’s incredible.

1 Like

What software are you using? In Fusion 360 it’s a standard feature to have multiple toolpaths that follow each other. So you have a first roughing pass that leaves 0.5mm for example and then you go in with the best bit (ball end, v-carve, smaller diameter) that you need to clear out remaining parts. So the software that generates the toolpaths takes into account what’s already milled away.

Luban does not support that.

Ah, yes. Well, I was using Luban, though I was thinking it might not support it! I’ll have to give Fusion 360 a go! Assuming you guys are generating the G-Code with other software then loading onto the Snapmaker directly and running?

have a first roughing pass that leaves 0.5mm for example and then you go in with the best bit (ball end, v-carve, smaller diameter) that you need to clear out remaining parts

That sounds like exactly what I’m looking for, thanks for the info! How do you know to change the tool with SM? Do you load multiple g-codes and the additional ones already know where/what to cut already using the same work origin and you just swap the tool between passes?

You should read this whole thread.

1 Like

Ahh I missed it, you’re right. Multiple files, one file per pass. Got it!

Thanks everyone for the suggestions-lots to look into! I ended up ordering a bunch of replacement 1.5 and 3.75mm bits. Bought cheap multipacks of each because they break easily, and I can see them wearing out as well. See how those last. Next might be a couple of larger ones assuming that I want to be able to do things faster.

Do I need a different sized collet for a 0.25 inch surfacing cutter, other than the one that comes with the machine?

Depends on the size of the shank. If it’s not 3.175mm you will need a different sized er11 collet.

I’m confused…

I read this:
and ordered a wasteboard mill with 1/4 inch shaft. I assumed that “it” in the second sentence referred to the collet.

I believe that the 1/4 inch shaft will work if I remember from what I’ve tried. It might be a snug fit as it is the upper limit that the included collet can hold, but definitely give us an update when it arrives to expand the knowledge of the community!