CNC End Mill / Drill Advice

[mike324]

Just getting into CNCing

I'm drilling 14mm holes (94 to be exact) on a wood board with a CNC machine.

What type of drill bits are the correct types for drilling holes on a 15mm plywood board?

At the moment I'm using a normal drill bit, which is most likely not the most suitable.

I know if I run the spindle too fast, it will burn and smoke and cause the drill bit to become damaged and not sharp only after less than 50 boards. Whats the best way / fastest way to finish drilling a board with 94 holes. At the moment it takes me around 8 minutes per board which is causing a short life span of the normal drill bit.

Any help would be appreciated in regards to the correct type of drill bit and speed.

[h90]

there are special bits for wood, but I don't know how easily they are available in shops.

But buying on ebay in Europe or USA is usually no problem at all and no import tax if small package per post.

[sickwaterbuffalo2]

Maybe your spindle speed is not the problem but what feed rate are you using for the tool and are u using the correct programming code or G code for drilling,Normally modern cnc machines can calculate the correct spindle speeds and feed rates or certain knowledge of maths and tooling and material is needed but can be found online.

[mike324]

Maybe your spindle speed is not the problem but what feed rate are you using for the tool and are u using the correct programming code or G code for drilling,Normally modern cnc machines can calculate the correct spindle speeds and feed rates or certain knowledge of maths and tooling and material is needed but can be found online.

I think my problem is a combination of spindle speed and feed rate, still in the learning phase and I did read some programs that can calculate all that for you. I'm kind of learning by trial and error at the moment as I go along as well. Thanks

[sickwaterbuffalo2]

Maybe your spindle speed is not the problem but what feed rate are you using for the tool and are u using the correct programming code or G code for drilling,Normally modern cnc machines can calculate the correct spindle speeds and feed rates or certain knowledge of maths and tooling and material is needed but can be found online.

I think my problem is a combination of spindle speed and feed rate, still in the learning phase and I did read some programs that can calculate all that for you. I'm kind of learning by trial and error at the moment as I go along as well. Thanks

Most cnc brands have theyre own kind of programming siemens,fanuc,mazak,...but normaly al brands can be programmed with ISO programming and there are certain pc based programs wich have ISO CNC programming CAD CAM OR CADIA or you can get pc software from whatever machine u are using but they cost a lot of money.

[h90]

Maybe your spindle speed is not the problem but what feed rate are you using for the tool and are u using the correct programming code or G code for drilling,Normally modern cnc machines can calculate the correct spindle speeds and feed rates or certain knowledge of maths and tooling and material is needed but can be found online.

I think my problem is a combination of spindle speed and feed rate, still in the learning phase and I did read some programs that can calculate all that for you. I'm kind of learning by trial and error at the moment as I go along as well. Thanks

Most cnc brands have theyre own kind of programming siemens,fanuc,mazak,...but normaly al brands can be programmed with ISO programming and there are certain pc based programs wich have ISO CNC programming CAD CAM OR CADIA or you can get pc software from whatever machine u are using but they cost a lot of money.

There are also some forum on the internet. Always good to get hands on some finished programs and analyze what they did. Also lots of things on Youtube. But the milling is a more complex thing than the CNC turning I do, lathe is really easy to program, just having X and Z

[sdanielmcev]

Regular carbide bits are fine. You should not get any burning on wood until the bits get dull, regardless of speed. Might want to invest in a drill bit sharpener.

Forgot to ask, what is the size of the hole you are drilling? Forstner bits, hole saws or paddle bits will be different. As a rule of thumb, for those 3 types the wider the hole, the slower the drill speed and feed.

Edited July 3, 2015 by sdanielmcev

[NeverSure]

I agree, it sounds like the bit is dull. If it can sit there and spin and generate enough heat to burn it probably isn't cutting.

I'd experiment until a sharp bit would go in at normal speed. Remember a good bit is cutting out shavings even if they aren't recognized as such, and isn't supposed to wear the hole out, LOL.

Once I got that dialed in and if I wanted the cleanest holes I'd try Forstner bits.

[RasiMike]

Ply can or will burn depending on the direction and speed of the cut. Try altering feed rate to minimize it, however the Homag at a factory I where I worked would burn ply (>6mm) no matter what we did. New spiral cutters would machine everything from MDF and HMR particle board to compact laminate with no problem but the ply and solid timber always burned at some point of the cut.

[sdanielmcev]

Ply can or will burn depending on the direction and speed of the cut. Try altering feed rate to minimize it, however the Homag at a factory I where I worked would burn ply (>6mm) no matter what we did. New spiral cutters would machine everything from MDF and HMR particle board to compact laminate with no problem but the ply and solid timber always burned at some point of the cut.

He's drilling, not routing. I think. In that case, a regular drill bit would be more cost effective, don't you think? I don't like those spiral bits in a hand router.

[Ace of Pop]

Long or Short run.?. What's the CNC. SANDVIC have a helpline

[RasiMike]

Ply can or will burn depending on the direction and speed of the cut. Try altering feed rate to minimize it, however the Homag at a factory I where I worked would burn ply (>6mm) no matter what we did. New spiral cutters would machine everything from MDF and HMR particle board to compact laminate with no problem but the ply and solid timber always burned at some point of the cut.

He's drilling, not routing. I think. In that case, a regular drill bit would be more cost effective, don't you think? I don't like those spiral bits in a hand router.

He is indeed. Typing and making the kids breakfast at the same time...my error.

[sipi]

When I did my trade as a machinist (back in the '70s) a book called ''Technology of Machine Tools'' was considered the bible for hand machining. Some good info about tool tip speeds etc obviously. The formulas would still be relevant to automated machining.

It can possibly be downloaded for free from

http://www.download-genius.com/download-k:Technology%20of%20Machine%20Tools.html?aff.id=6253

Otherwise just google a free download. Very good info directed at apprentice machinists and new tradesmen.

[mike324]

thanks for the advice, my drill bit is indeed dull

I'm using a regular spiral drill was wondering if another one knows an endmill bit would be better for drilling holes?

[h90]

thanks for the advice, my drill bit is indeed dull

I'm using a regular spiral drill was wondering if another one knows an endmill bit would be better for drilling holes?

A drill for wood would be most probably better for weed that a regular spiral drill

[sipi]

thanks for the advice, my drill bit is indeed dull

I'm using a regular spiral drill was wondering if another one knows an endmill bit would be better for drilling holes?

No. An end mill is primarily for milling. As mentioned you really need an auger timber drill. Not only the drill speed and feed are important, but also other things like rake angles etc. For example to drill rubber you need a negative rake angle (deliberately blunt) to stop the bit from digging in. Remember the drill does the work not the machine. There is no point in messing with machine settings if the wrong cutting tool is used.

[sipi]

The other thing Mike. You are possibly expecting a bit out of these drills. 4700 holes in 6 1/2 hours of continuous drilling through plyboard without dulling the drill bit?

[h90]

thanks for the advice, my drill bit is indeed dull

I'm using a regular spiral drill was wondering if another one knows an endmill bit would be better for drilling holes?

No. An end mill is primarily for milling. As mentioned you really need an auger timber drill. Not only the drill speed and feed are important, but also other things like rake angles etc. For example to drill rubber you need a negative rake angle (deliberately blunt) to stop the bit from digging in. Remember the drill does the work not the machine. There is no point in messing with machine settings if the wrong cutting tool is used.

We machine all the rubber on the lathe with high positive tools, else the surface is getting bad (unless cryocutting we don't do)

[mike324]

My drill bit become dull after 1000 or so holes. Hole diameter 14mm, dept of hole 15mm. Would this be consider as normal?

I did play around with the spindle speed and feed rate, still can't keep the drill cool enough so the wood board won't smoke.

[Crossy]

Let's try this in DIY.

[sipi]

When I did my trade as a machinist (back in the '70s) a book called ''Technology of Machine Tools'' was considered the bible for hand machining. Some good info about tool tip speeds etc obviously. The formulas would still be relevant to automated machining.

It can possibly be downloaded for free from

http://www.download-genius.com/download-k:Technology%20of%20Machine%20Tools.html?aff.id=6253

Otherwise just google a free download. Very good info directed at apprentice machinists and new tradesmen.

Nowadays cutting speed is much higher as in the 1970's was moving speed (I am sorry, I do not know the correct English term, but moving the tool from A to B to start a new cut) Cutting wood depends a lot of the wood. When it is solid wood HSS will do. When it is wood with glue in it, Particle wood for example, you need other cutting tools.

I did my apprenticeship in the 70's but still machine. Yes the resin in plyboard is tough but I don't have much experience with machining it.

Do you suggest tungsten carbide tip instead of HSS?

[sickwaterbuffalo2]

Yes for wood with resin you need tungsten,.carbide, or widia, (I am not German, but I thought "Widia" is a German term)

Widia is a brand name for certain machining tools.

[dench]

If you are drilling hardwood, use a carbide-tipped brad point drill, 1750 RPM at 1800/2000 mm Per Min Peck drilling will dull the bit. Anytime the bit is rotating in the hole and not cutting, it is getting dull. Faster RMP and peck drilling equals dulling

Edited July 10, 2015 by dench