First CNC Bit

[The J]

I hit the search up for as many different combination of words before I decided to post.

To you, what is the first and 2nd bits a person should invest in? I know it depends on what you are cutting, so I'll limit it to wood and plastics. If you think there are more than 2 main bits a person should invest in, then go ahead and post them. I'm just looking to see what others recommend or don't recommend.

J

[BobF]

For cutting out material I like solid carbide spiral upcut bits. These come in many sizes and you can match them to your router. I have 1/4", 1/2" and 3/8" of these. The larger ones are more expensive because of the amount of carbide required and I started with only the 1/4" . If you do V-carving, you will want a 90degree and a 60degree bit to start. For plastic I would either use the upcut above, or get an O-flute bit.
Look at:
https://www.onsrud.com/xdoc/FeedSpeeds

[stevespo]

You may start with 2 bits, but that collection will grow!

I use many 2 flute upcut (Whiteside generally) and downcut as well. Straight bits work well for some materials because they don't tend to lift. Single and double flutes for different plastics.

Sizes? On any given day, I'll use .023", 1/32", 1/16", 1/8", 1/4", 1/2", 3/4", possibly some bullnose or v-bits as well. It all depends on what you need to do.

Start with a 1/4" spiral upcut. That is definitely my workhorse. Maybe add an 1/8" as well, or possibly a single flute straight (or O-flute like Bob recommended) bit if you're cutting plastic.

The tooling really adds up fast.

Steve

[The J]

Thanks guys, I was hoping this would help all the new comers to the DIY world as well. The idea for the machine is the easy part, getting it to cut the way you want it too requires actual trail and error. That was the part I was hoping to help solve here.

[Jack000]

flute count is important too. Especially for plastics a 2 flute is better since it gives more room for the material to escape. (correct me if I'm wrong, I'm not an expert!)

Also, make sure the cutting length of the bit is long enough to fit all the way through the material you're cutting. I bought a 1/8 bit with 1/4 shank only to find that it can't 'poke' through the wood before the 'neck' of the bit hits the surface. I now use a 1/8 bit and 1/4 adapter bushing.

[cdndave]

Thanks for this thread. I was starting to wonder the same thing.

Dave

[stevespo]

You'll find there is an awful lot of trial and error to determine what the best bit, spindle speed, feed rate are for a given material and task. The available charts and calculators are very helpful, but it ultimately depends on your machine as well. How rigid is it, how accurate, how much runout, etc?

As Bob recommended, I would also stick with carbide for all your tooling. The HSS endmills are attractively priced, but you'll get much better results with carbide. There is an endless variety of tooling available, but you can get a lot of mileage out of a couple of spiral bits and a few straight bits as well. Bullnose and V-carving are useful for signs and 3d work.

I've had good luck with even the less expensive brands from Grizzly, Rockler, Woodcraft. Watch for sales. You'll drop a few bucks before you know it!

Steve

[BobF]

Originally Posted by Jack000 flute count is important too. Especially for plastics a 2 flute is better since it gives more room for the material to escape. (correct me if I'm wrong, I'm not an expert!) Also, make sure the cutting length of the bit is long enough to fit all the way through the material you're cutting. I bought a 1/8 bit with 1/4 shank only to find that it can't 'poke' through the wood before the 'neck' of the bit hits the surface. I now use a 1/8 bit and 1/4 adapter bushing.

Sorry Jack,
I disagree on the plastic. You want an O-flute which is a single flute for plastic. This increases chip load which helps with cooling and reduces the chance of melting all the swarf back into clumps and clogging everything up. Look at the feeds and speeds stuff on onsrudcutter.com. Lots of good info there. Run the router slow if you have variable speed and run the ipm of your cnc as high as you are comfortable with depending on part size and geometry.
A 2 flute spiral will also work, but if you buy a bit just for plastic, get the O-flute.

[Jack000]

yeah, I just know that the less flutes the better for melt-able materials. The problem I had was in the beginning, not knowing anything about endmills, I bought a bunch of 4 flutes, which I think aren't as good as 2/0 flutes for soft materials.