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What bits for a cnc rounter cutting hardwood?

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julianf

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I need to run some hardwood. Various recesses cut in the surface, and then the part cut out from the sheet.

Sheet will be around 18mm (3/4")

Some of the radiuses (spelling?) on the recessed parts need to be small.

I route non ferrous all the time, but, when ive tried to bodge it with my single flute carbide cutters in the past, they go blunt much quicker than when im cutting alloy, so im guessing i need to make some sort of adjustment.


In a possible conflict of interest, id find it difficult buying £50 cutters before i know they work, so, realistically, any high price suggestions will probably not work for me, just as id need to have more confidence.

As an indication, for the non ferrous, my 2mm cutters cost me about GBP 5 ea, and the 5mm about GBP 25 ea. (but, again, whilst they are great for my normal work, they dont seem the best for hardwood)
 

sunnybob

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Define hardwood? Normally wood is easier to cut than metals.
BIG question... What RPM is your cnc running at? I suspect its a lot more than a cheap wood bit is rated for. Is the wood burning? if so. reduce speed.
 

Alpha-Dave

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I generally save carbide for aluminium or occasional steel. For wood I pretty much always use HSS.

Also consider the rotation and movement speeds: you want it to cut and throw the chips (like a circular saw), too fast will generate dust and powder that will pack the flutes, rub, get hot and if you are lucky just smoke, but potentially can catch fire
 

SkinnyB

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I recently purchased some CMT insert router bits for my cnc. The ones where you unscrew the blade and can replace it. Has two edges so you flip the blade around and have another cutting edge.

9.5mm is the smallest diameter they do with a 30mm depth of cut. Got one and very happy. Also got a v bit with disposable blade. Very nice to!
They make multiple versions with either 1,2,3 blades and some designed for bottom clearing.

Supposedly the non brazed carbide is tougher and lasts longer than typical brazed router bits.

if you look on the CMT website it shows them all. Then purchased through Scott Sargent.
 

julianf

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Define hardwood? Normally wood is easier to cut than metals.
BIG question... What RPM is your cnc running at? I suspect its a lot more than a cheap wood bit is rated for. Is the wood burning? if so. reduce speed.
Last wood i cut on the machine was some reclaimed mahogony.

No load spindle speed 5-25k rpm.
 

julianf

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The first one i looked at, a 6mm cutter, was about 60 euros...
 

julianf

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I recently purchased some CMT insert router bits for my cnc. The ones where you unscrew the blade and can replace it. Has two edges so you flip the blade around and have another cutting edge.

9.5mm is the smallest diameter they do with a 30mm depth of cut. Got one and very happy. Also got a v bit with disposable blade. Very nice to!
They make multiple versions with either 1,2,3 blades and some designed for bottom clearing.

Supposedly the non brazed carbide is tougher and lasts longer than typical brazed router bits.

if you look on the CMT website it shows them all. Then purchased through Scott Sargent.
It looks like this one is 7mm dia, but...

...theyre still about £70 a hit. Which if its earning its keep, is fair enough, but theres the catch 22, that i dont feel confident enough to throw £70 at something that im not too sure about.
 

julianf

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APT are also good, I generally use 6mm 2 of 4 flutes HSS, ideally with a coating but not critical if not coated.
Could maybe use them, but the flute length is only 13mm. The shank is supposedly the same dia as the cutting end, so that kind of doable, with some bodgery, but its also not ideal.
 

julianf

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Im sorry, it seems like im being overly negative! I certainly like the look of the CMT bits, but, again, £70 is a fair bit to throw at an unknown. It may be one of those transformative tools, or it could be like the last special cutter i purchased - just didnt work as expected at all, and has never been touched since. That one as only £25, but still irritating, as i managed to write off the job with it also...

The closest CMT dealer to me is bristol. Maybe ill have a chat with them and see what they say.

Thanks to all.
 

scammell

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I use these guys for all my CNC cutters, wood and Alloy.
They have some good buy 2 get one free offers on at the moment. Worth a look
 

julianf

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To follow up this...

I purchased one of the single flute axcaliber 1/4 shank , 1/4 cutting dia, 1" cutting length tools.

I got pretty much the whole way though the job with it (various different cut, all on a CNC machine, none by hand) and then the cutter snapped doing a cut that had been preformed previously.

Probably human error (as in federates or hold down or somthing) but could have just been bad luck.

Anyway, apart from snapping it preformed nicely.

I've just purchased the twin flute trend equivalent, and will see how that performs. Supposedly a cleaner cut but slower feed.

I don't think the feed was really the issue as to why my cutter snapped today. It was down to about 18mm depth taking out the last 2mm, and it just went "click". It was close to the edge of the work so I wonder if some sort of reverberation / vibration did for it. Or maybe just bad luck. As I say, id done the exact same cut earlier with it and it survived.

I'm used to carbide snapping like this, but I assumed this one was a steel shank with carbide cutting edge, but it certainly snapped with a grain like a cast material.

Anyway, will see how the trend one works out.
 
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