You’ve just taken delivery on your brand new CNC Mill. Shortly it will be up and running. What else will you need to be able to do some real work?
You’re going to need to be able to hold down your workpiece while milling.
1. Kurt-style vise (or a grinder vise if the mill is really small). Don’t skimp too much. If you want to save, you can buy a used Kurt off eBay (I Have 2) or you can try a Kurt clone from one of the better manufacturers. I have 2 Glacerns and can hardly tell the difference between them and the Kurts.
2. Parallels: To hold your work up high on the jaws for greater accuracy.
3. T-Slot Clamping Kit: To mount the vise and to hold things that won’t fit in the vise.
You’re going to need a way to stick an endmill in the spindle. I am assuming here your machine has an R8 taper. If not just substitute what you do have.
4. R8 ER Collet Chucks: Get 3 or 4 to start, and you’ll need to choose a size. I started with ER32 to accomodate the widest range of shank sizes. Eventually I also got an ER16 for tiny endmills and when I need to get into tight spots a big ole ER32 is too large for. ER Collet Chucks are one of the best types of holders you can use from an accuracy and rigidity standpoint. BTW, if you have a chance to pick some up with the ball bearing nuts, they are sweet. They tighten better and more easily. I bought a few from Arc Eurotrade and love them.
5. Set of ER Collets in the same size as the Collet Chucks. Eventually, you’ll buy more ER collets as you’ll find times when you want more than one tool holder set up for the same sized shank.
Things to Note:
You don’t need a drill chuck, keyless or otherwise. ER collets hold almost everything better and more accurately than a drill chuck. For a manual mill, the chuck makes sense. For a CNC, when you have to take the time to touch off and find tool length, they’re a lot less handy so it isn’t clear you gain as much. I’d rather have more ER collet chucks laying around.
Some prefer R8 collets, and they’re definitely cheaper and you can leave the same size R8 collet in the spindle and just loosen or tighten a little to grip the shank of bunch of same size toolholders, for example they might all be 3/4″ shank like the Tormach Tooling System. These systems can work well, but I prefer solid holders for a variety of reasons that I think are important for beginners to consider:
– You can have tool pullout problems if you don’t use the R8 system just right. That’ll definitely ruin your day and break some tooling.
– They’re just not as rigid as a solid holder system and they are more prone to chatter as a result.
Some things you can do to have the advantages of R8 collets with solid holders would be to get a powered drawbar going or even handhold a butterfly impact wrench like the one I use in my power drawbar. Tool changes will be fast. There is a speedbump down the road too. If you fancy a toolchanger, that’s tough with R8 because there is no ring to engage the carousel. With a toolchanger in mind, you really only have two choices–something like Tormach Tooling System or something other than R8.
Truth be told it is a shame beginners have to figure out this thorny problem. If you’re starting out from scratch and haven’t even got a mill, the best answer in retrospect is to get one with a 30 taper spindle. It’s a much beefier system that’s set up for toolchangers and doesn’t force all these tradeoffs. 30 tapers are available for RF45’s and from Tormach, so it is worth thinking about.
Meanwhile, R8 is common as dirt so you have to figure out what to do.
Measurement & Layout
You will definitely need some measurement and layout tools. Consider these a bare minimum!
6. Digital Calipers: A box of micrometers is more accurate, but less convenient. You won’t be all that accurate to start anyway.
7. Sharpies (Buy a box, they’re cheap and hugely handy!)
8. Calculator (Online like G-Wizard or handheld)
9. Dial test indicator. Don’t get a tenths indicator to start, though you could consider 0.0005″ indicators. You’ll use these constantly.
10. Some way to attach the DTI to your mill spindle for tramming. An Indicol or clone (available cheap!) would work great.
11. Z-Presetter. You need some way to set your tool heights.
12. Edge Finder: Everything from a Haimer 3D Taster (or clone) to the spinning kind and all points in between is possible. When things go haywire and you pull the piece out of the vise and you need to put it back and work on it some more, you will want an edge finder.
13. Spot drills / Center drills: I’ve written about this subject before. I prefer spot drills to center drills, but either is better than none.
14. Twist drills (I prefer screw machine length as they’re more rigid. I almost never use the jobbers, and most peeps will already have some of those anyway)
15. Endmills: 1/8, 1/4, 1/2 in 2 flute and 4 flute. At least 2 of each size.
What, no facemills or other indexable tooling? Start with just the endmills until you’ve got things working well with them. Facemills take a lot of horsepower, they’re expensive, they make a real mess if you crash one, and they’re mostly only used for making surfaces flat. You can do that, albeit less elegantly, with an endmill. Once you get endmills all figured out, spring for a 45-degree lead angle face mill and you can go to town. The other cutter that’ll be handy soon is a few corncob roughers in your larger sizes. I get by mostly with 1/2″ diameter corncobs. After that you’ve got chamfering and corner rounding cutters to consider, and so on.
16. We haven’t talked about how you will cut stock to size. Hopefully you have a bandsaw or chopsaw. Failing that, get a hacksaw. On second thought, better get the bandsaw or chopsaw!
17. A decent file or two
18. A deburring tool.
19. Kant-Twist clamps. You will use these little boogers constantly. I use mine as an impromptu vise stop a lot of times.
20. Safety Glasses and Chip Brushes. Okay, that’s 2, but don’t fool around. You will dodge broken cutter tips and other things whizzing around. Don’t wear gloves either, they can catch and get your hand sucked into the spindle. Use the chip brushes to move the chips.
That should be a pretty decent shopping list to get started with. Anyone else got any “must-have’s” I’ve missed?
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