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karandex
03-29-2011, 02:54 AM
hi
i got this solid carbide bit from local store for $6, and dont know much about it.
Its 4 flute and as per my knowlege its some chip breker. Up cut.

I use a dremel clone, but its speed is stuck to max which it qoutes to be 35,000

specs
3 mm shank
2 mm cutting dia
oal 38 mm
cutting length approx 10 mm

my machine which dosent have acceleration ,can go up to 300mm/min only.
i tried the drill up to 2 mm depth with 250 speed, at 3.5 mm ( as my z axis wobbles, i will fix it) the cut started with curve. but all in all it can cut

the problem is inspite such speed its still smokes and heatup a bit. i am trying for acceleration.

but can anybody give info on this bit and its chipload and all?

I am using mdf by the way. what are problems with mdf? can u suggest any other materials for cutting and engraving ( i am going to mainly cut parts for new cnc out of some wood or plastics and bit of relief and engraving)

louieatienza
03-29-2011, 03:14 AM
I would say that given your feedrate speed, you might want to consider a 2 flute spiral bit. I've evevn had success with a single flute spiral cutting MDF. With 4 flutes, you really have to amp up the feedrate, and you machine and router may not be up to the task; you'll just smoke the bit...

loyedp
03-29-2011, 04:09 AM
I accept with what loutenzia explained four flute have smaller chip space so it is better to use 3 mm 2 flute tool(Ham tool) to cut mdf , when working with plastics single flute is better with both of them require higher feed rates,
Play with feed& speed until u get the best.Slight water coolant is good to be used while cutting plastic

karandex
03-29-2011, 07:04 AM
I can't decrease the speed of spindle.this is the lowest flute bit I can get.other was 6 flute.is it safe to use mdf or I need different material for this bit.I am going to Try parralel port so I can use mach3 and add acceration.

Phife
03-29-2011, 10:08 AM
acceleration is not your problem, your problem is that 4 flute bit, your routers speed and the slow feedrate.


There are plenty of suppliers of 2 flute bits, so I find it hard to believe 4 is the lowest you can get.

Going to a 2 flute bit should solve your problem, but if you cant get a 2 flute bit then get a new router or try a faster feedrate.

ger21
03-29-2011, 11:52 AM
Even if you could reduce your rpm to 20,000, you'd probably still want to cut at about 1500mm/min.

Even a 1 flute bit will probably burn with that slow feedrate and high rpm's.

karandex
03-29-2011, 11:59 AM
My cnc is 10 tpi with nema 23 11 kg torque with a3982.the 300 speed now is achived in single step.so I think adding acceration will increase my max speed.ca. You give me idea how much speed can increase by ramping.after all it's about increaseing feed rate right?

Phife
03-29-2011, 04:20 PM
acceleration is the speed at which the axis accelerates from 0 to max speed, adding acceleration will not increase your max speed.

karandex
03-29-2011, 10:39 PM
When motor was not connected I tried to see max rpm.it was not more than 200. Lbut other people can achive 1000 rpm with acceration.when we don't accerate the initial friction need to overcome.at that high speed the torque is low.with acceration slowly increase the speed.so the torque is decreased slowly.ao initail force required to start movment in provided by low speed

for ex.see zen toolworks machine.it is much higher tpi then me with weaker motors but it still actives joging speed of 300.

louieatienza
03-29-2011, 11:08 PM
When motor was not connected I tried to see max rpm.it was not more than 200. Lbut other people can achive 1000 rpm with acceration.when we don't accerate the initial friction need to overcome.at that high speed the torque is low.with acceration slowly increase the speed.so the torque is decreased slowly.ao initail force required to start movment in provided by low speed

for ex.see zen toolworks machine.it is much higher tpi then me with weaker motors but it still actives joging speed of 300.

I don't think acceleration has anything to do with your top speed. If you're only getting 200rpm, it only means you're getting there sooner, which would be an improvement for sure, but probably not what you're looking for.

Maybe it's your stepper drives or power supply? Unattached I easily get 1000rpm on my steppers, and I have rapids on my x at 350ipm and y at 375ipm, and my gantry weighs about 70 pounds and the carriage alone about 25 with the router...

leaveme
03-29-2011, 11:22 PM
I don't think (motor) fine tuning will add that much speed.
I would suggest adding a closed loop speed controller to your router. You can then adjust in asking RPM but without loosing torque.

michaelthomas
03-29-2011, 11:25 PM
I could barely get 350 rpm from my steppers with my Keling drivers on my last machine. I read an article on here somewhere about hockey puck stepper dampers which help to tame some mid range resonance and allow the motors to reach much higher speeds. I spent the whopping 1.50 per axis and was rewarded with almost 1500rpm and much smoother stepping.

Incidentally, I tried a Gecko 203v on my x axis and was able to get the 1500rpm without the damper......but the Kelings needed help.

It could be a million other things......but you may be having some resonance issues as well. If you have a hockey puck laying around, drill a hole in the middle slightly smaller than your stepper shaft and press it on. It won't hurt to try.

karandex
03-29-2011, 11:29 PM
i saw some chats on bit manufacturers, the graph was like the less federate for more depth. I have 2 mm bit, so should i try 2xD or 3xD (4mm or 6mm depth)?

louieatienza
03-30-2011, 12:00 AM
i saw some chats on bit manufacturers, the graph was like the less federate for more depth. I have 2 mm bit, so should i try 2xD or 3xD (4mm or 6mm depth)?

I think it's usually better with home-made machines especially to use less depth and more speed, in order to produce anything resembling chips. I would try 1xD and keep ramping up the feedrate till the quality goes down, or evevn 1/2xD...

karandex
03-30-2011, 12:10 AM
i have reached my limit of feedrate and it can go we beyond 1xd