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medgalys
30-11-2016, 03:45 PM
Can someone guide me what drill bits do I need for cutting 2d items from sheet metals like brass, copper, bronze and stainless steel.

I've recently bought a router ant trying to cut some simple items but my drill bits just breaks almost instantly. Is it more likely that I'm using wrong bits or wrong settings?

magicniner
30-11-2016, 11:33 PM
So what bits are you using for what materials and with what rpm & feed speeds?

medgalys
17-12-2016, 12:31 PM
Ok, two weeks and lots of endmills I've finally get some work done with 2mm Carbide End Mills (uncoated). But the work process seems very slow, so I gues if I use 1mm endmill it will be extreme slow. Watching videos it seems other working way faster.

And I'm still not sure if these are good choice for what I need.

Can someone advise me where to buy good end mills for cutting and engraving 1mm sheets of brass, copper and silver in Europe?

Also what's the difference between carbide and 2 flute mills?

Maxakarudy
17-12-2016, 07:20 PM
You don't use end mills for engraving, as you've found out they break, you need to use single flute engraving bits, they are conical ground bits, with a flat on the bottom, the depth is important when using them, true engravers have floating heads to control depth of cut.
Something like these on ebay..302114685055
Martin

JAZZCNC
17-12-2016, 07:33 PM
Would you drive Car without learning to drive and expect not to crash.?? . . . . . Your wasting your time buying cutters until you learn more about the tool your using.
The question "what's the difference between Carbide and 2 flute cutters" says that you are not ready to cut anything. Certainly not soft metals like Copper ,brass.

The reason your breaking cutters isn't quality it will be mixture of user error and possibly machine strength. Probably 99% user error.!
Machine strength plays big part in cutting and becomes even more important when tool size gets small. Only with trial and error will you find what works for your machine. Unfortunatly this may mean breaking tools to learn.

So I suggest you go away and do some research about the difference in cutting tools so can select the correct type of tool for the job. Then invest speeds/feeds calculator which will give you base reference point to work from with different materials.
Take this base point and make decision based on your machines strength/weakness to how much need to reduce or can increase the cutting parameters.

But you at least need to learn the basic differences between cutting tools before getting into the CAR.!! . . . . . Else you'll always Crash.!

cropwell
17-12-2016, 11:22 PM
C'mon Jazz, where's the fun in doing things properly ?

Brass is the most fun for buggering up tools as it is a soft (ish) but brittle combination and sticks like sh*t on cutters. You need lots of air to clear chips and cool the workpiece and tool and some lube. Brass can be cut with normal 2 flute cutters, but feeds and speeds have to be right. Too slow and you get rubbing and heat and excess sticking on the cutter. Too fast and you can dig in and get a shite finish (before the tool breaks).

Go for it, but buy lots of cutters and acres of brass, you'll get a lot out of it, mainly scrap brass and broken cutters.:hysterical:

JAZZCNC
18-12-2016, 10:17 AM
C'mon Jazz, where's the fun in doing things properly ?

Ok was having bad day yesterday but same applies today.! . . . . I could easily tell him the where to buy quality tooling that cuts brass like butter but he'll only snap those as well.!!

We know because all been there that selecting the correct tool isn't always obvious but if user "like in this case" hasn't got clue then they need to at least learn differences between tools and what terms relating to tools mean before ever buying one let alone sticking one in machine.

I could easily ballpark speeds/feeds etc but this isn't really helping the OP. He'll still be clueless to why using HSS rather than Carbide, why 1 flute not 6 flutes. Why 1000rpm when his spindle can spin at 5000rpm. Etc etc.

Likewise it would be wrong of me to suggest absolute speeds/feeds to someone who clearly has Zero knowledge regards using cutting tools, manual or CNC.
Even with users that have good understanding in difference between tooling but limited experience I would only give ballpark figures and then suggest caution.

(Not having Go at you Cropwell with this comment.) But Comments like use "lots of Air" are useful at some point down the road but Air won't stop him breaking tools if using wrong tool at wrong speeds/feeds. For this people need to learn basics before Clicking buy or power to machine.!

Maxakarudy
18-12-2016, 10:18 AM
Cutting and engraving require completely different cutter requirements depending on the detail required, engraving is really what the OP is needing info on.
I would not engrave or cut with anything smaller a 3mm parallel cutter personally, as they have no lateral load strength and break, pls advise me if there are tools other than conical cutters that are used for engraving text bellow 12mm
Martin

magicniner
18-12-2016, 11:19 AM
What you use for engraving depends on the required results, to get sharp corners on small letters you will need conical D-bit cutters and V-Carve type cutting paths, interestingly some V-Carve implementations allow use of a slot drill/endmill to rough out areas between sections requiring the tapered cutter.
Conical cutters inevitably yield sloped sides, if the job requires vertical sides on the engraved features then small slot drills/endmills will be required.
I've done work in brass with endmills down to 0.6mm with spindle speeds at 28,800 rpm and above, a good feed & speed calculator becomes vital here as minimising tool deflection is as important as anything else in generating a working tool path and maximising tool life,

- Nick

cropwell
18-12-2016, 11:28 AM
How about a feeds/speeds/toolselection topic so members can share their experience (good or bad). I know that there are other factors, but a start point is always useful.

I know that for drilling brass, you need different geometry, I have a chart somewhere that shows it for different metals. This isn't strictly on topic, but the same rules apply for milling cutters.

As far as 'having a go at me' Jazz, you probably realised that the majority of my post was tongue-in-cheek. It was a bit of a flashback to when I was a kid and I wanted to do something my dad saw as stoopid. He used to say 'go on then - do it, but don't come back to me crying when you get hurt'.

Rob

cropwell
18-12-2016, 11:38 AM
What you use for engraving depends on the required results, to get sharp corners on small letters you will need conical D-bit cutters and V-Carve type cutting paths

The problem I get is chewed edges to the cut. This plate, for instance, 20024 had to be sanded and polished back to smooth. Is this ususal ?

magicniner
18-12-2016, 12:10 PM
How about a feeds/speeds/toolselection

That's not at all a bad idea! ;-)

- Nick

Boyan Silyavski
18-12-2016, 01:14 PM
I dont know what brass you are using? The brass i use is the best material ever i have used. I started to hate aluminum and mild steel . I dont know of a material thats easier to cut than brass.

Engraving with 1 and 2mm tools is very nice in certain cases and generally sth entirely different from V carving. I like it much.


Reasons for tools to break, not all but those that could concern us:

1. Lack of rigidity of setup, machine or spindle runout. Its all the same. Results in very high wear due to friction combined with bad chip removal , leads to heating and tool brakes prematurely. This is a no brainer.

2. Incorrect feeds and speeds that result in higher deflection than tool can accept. Tool stick out from collet also must be taken into an account.

3. Incorrect geometry of tool and typpe of tool-number and angle of flutes, etc.

4. all tools from <=2mm are in a different world where all should be carefully calculated and no rush.

5. machine acceleration too high.


I dont think we need to make a tool database. HSMAdviser or G-wisard are more than enough so no mistakes are made. I know i repeat my self but HSMAdviser is a Great program which is a must . i know via Exceoll sheet all can be calculated but using the program is such a breeze and flawless process. Believe it or not but 10 times more experienced than me people started to ask me on opinion on feeds and speeds with special and small cutters.




I dont know what machine and cutters are we talking here but that below is how i do it and it works 100%. Suffice to say that i have in that range tools that each is 50-60 euro and i could rush them 200% faster from that below.

Anyway, try always to use lower stickout if possible/ not so with the calc below as some clearance was needed due to deep channels. And have in mind i am using TiCn coated cutters so lower that a bit for uncoated carbide cutters.

20031

Now if you have a mill, thats what the same will look like:

20032


PS. Sorry above if you see its for edited ball nose cutters which i have the same size and type. But ball nose box is unchecked so its for straight flat end cutter. if Ball Nose are used, halve the depth of cut and double the feed

JAZZCNC
18-12-2016, 01:14 PM
The problem I get is chewed edges to the cut. This plate, for instance, 20024 had to be sanded and polished back to smooth. Is this ususal ?

Stiffness of machine plays big part to finish quality. So if you got spaggetti machine then yes this is usual.!!

cropwell
18-12-2016, 02:36 PM
Stiffness of machine plays big part to finish quality. So if you got spaggetti machine then yes this is usual.!! not spaghetti - worse MD :disillusionment: much wobblier, but I have to live with my mistakes until I get my own build done.

cropwell
18-12-2016, 04:33 PM
'I dont know what brass you are using?' No Boyan, nor do I. I just bought it as .7mm sheet. Few metal suppliers seem to know what grade material they are selling.
'I dont think we need to make a tool database' - I am not proposing that, just a place to discuss problems related to feed and speeds etc.

Rob

JAZZCNC
18-12-2016, 10:54 PM
not spaghetti - worse MD :disillusionment: much wobblier, but I have to live with my mistakes until I get my own build done.

Holy shite.!! . . You have MD and put brass in front of it.! . . .Are you crazy Man.:stupid:

cropwell
19-12-2016, 12:57 AM
Holy shite.!! . . You have MD and put brass in front of it.! . . .Are you crazy Man.:stupid:

Barking mate ! Woof woof, :dog::dog: mad as a box of frogs :frog::frog: