[CECILIO]

Hola! was making some 3mm puzzles with 2mm end mill. No problem everything fine.
changed the puzzle and the bit (2.5mm). The cut was very bad from the first track , like burning and brooke.
I cleaned the collet, the nut and the spindle. Put a new bit. Started again and the same happened, just passed a couple lines further and broke the new bit.
Put an other collet and nut and a new bit and started again and broke the bit again
So I cleaned again put a new bit and did it with a deep of cut of 0.5mm. I finally made it, but that took 6 time longer than normal
here is a pic of the cut. if any one has an idea of what is happening lease help me

[SignTorch]

need more info - like # of flutes on each bit and cutting speed and spindle rpm on each puzzle and if there is any major difference in the way the two puzzles are drawn - one may be smooth and clean and the other might be jagged and rough on a small scale leading to poor cut quality and or such reduced speed that the bit overheated from going too slow - which partly depends on if you have constant velocity on or not -

with all things being equal except for tool diameter - the larger bit would typically use somewhat lower rpm and somewhat greater feed rate than the smaller bit - but then it should be less likely to break - so - more info please-----

[CECILIO]

I have cut those same puzzles many times with no problem
I have made dozens of puzzles and brake a few bits before but never like that
no big diference between 2mm and 2.5mm so I cut same speed / same rpm
bits are fish tail from Tinker. normaly gives a clean cut until now
I made a shoe to prevent plywood from moving so no vibration
???
saludos

[ger21]

Are you sure the spindle is spinning the correct direction?
How many flutes on the tool?

[CECILIO]

the bit has 5 flutes
here is a pic
spindle working fine
I finished the job I started. it came out fine but I made 6 passes of 0.5mm instead of one
I never had this problem before

[ghyman]

> no big diference between 2mm and 2.5mm so I cut same speed / same rpm

>The cut was very bad from the first track , like burning and brooke.

Actually, the difference is 25%, which is not a trivial change - a larger diameter at the same rpm gives a significant increase in the surface speed, which undoubtedly explains the burning.

What feed/speed are you running?

[SignTorch]

yikes - looks like the wrong bit for wood - try their 2 flute fish-tail for wood/plastic

[CECILIO]

I have made hundreds of 3mm plywood puzzles with it
it works very fine and they last long

[ger21]

yikes - looks like the wrong bit for wood - try their 2 flute fish-tail for wood/plastic

That's not the same tool.

[SignTorch]

That's not the same tool.

oops - I couldn't find the same bit - so is that type of bit good for wood cutting ?

[CECILIO]

it works good for me with 3mm plywood

[alan_3301]

You still haven't said what rpm and feedrate you are using.
Are the 2.5mm bits the same number of flutes and style as the 2mm bits? You have a link to specs for both bits?
Are you sure you didn't get 3mm left hand bits?
You are leaving a lot of room for guessing on what your problem is.

[CECILIO]

rpm is 20000
i dont know the feedrate
here is the bit: Chip-breaker Routers

but I have been using those bits for long now, with this setting and made hundreds of puzzles and other jobs and it is the first time I get the cut like on the picture
so I try to guess what's wrong

saludos
cecilio

[alan_3301]

You have to figure out what the feedrate is. Also, I would try a bit that is made for cutting wood. What you are using is made for cutting fiberglass.

[ghyman]

I believe you said 5 flutes on this tool?

We really need to know the feedrate, whether in feed per minute, feed per rev, or feed per tooth.

You said it smells like it is burning - assuming it is not loaded up with chips down in the cut, then that is a sure sign the speed is too high. About 16,000 RPM at this diameter will give the same surface speed as the smaller tool; that would be a good place to start if it is actually heating up enough to burn the material.

Is the tip shearing off at the collet? Solid carbide will be prone to snapping much sooner than HSS / Cobalt, and as has been pointed out the supplier does not say this is good for wood.

What about the cutting edges? are they showing signs of burning / wearing / fracturing / heat damage?

[awerby]

Usually bits intended for wood have 2 flutes, or even one. It sounds like your 5-flute toothed bits are clogging up and breaking because they can't clear the chips they make. Maybe the wood that worked before has picked up some more moisture, and the material that used to fly away as dust is now compacting itself in the tool's recesses.

[bhurts]

You would be better off with something like this.

5 1 60mm 0630" 2 Flute Endmills Overstock Sale | eBay

Check out his store for other tools also. Almost any mini-micro sized tool you could ever need.

Ben

[CECILIO]

ok I have those bits also. they work fine on plastic and acrilic and also aluminium

[CECILIO]

I thought of that but the kerf is kept clean because there is a shoe with a vacuum

[SignTorch]

rpm is 20000
i dont know the feedrate
here is the bit: Chip-breaker Routers

but I have been using those bits for long now, with this setting and made hundreds of puzzles and other jobs and it is the first time I get the cut like on the picture
so I try to guess what's wrong

saludos
cecilio

just what I thought - that's not a wood cutting bit and it could be the worst possible choice for cutting wood - I don't know how you got this far

if you follow the links on that page it shows a feed and speed chart (40 ipm @ 27k rpm) and a description of how that bit is designed to cut fiberglass FR4 copper clad board

in wood, 6 flutes would have to be moving 100+ ipm (for .001" chip load) - it wouldn't cut good - finish would be horrible - go too slow and it will be smoking -

Attachment 303154

a good 2 (or 3) flute wood bit should give much better results

Attachment 303156