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router tips burning
« on: December 07, 2009, 06:25:55 AM »
help needed
I keep burning the router tip (tool)
using a dremel tryed 50% to 100% rpm ( slide control)
3.4mm 2 flute router
7mm (3ply)  ply wood
Z cut depth is set to 1.5mm pass
feed rate 450mm per min
if I try to go faster stepper motors just make a noise and sit still
motors are 1-1 drive to a 1.25mm per turn screw
have mirco steps set with controler  1/16  2560 step per mm
controler is TB4-axis  HY_TB4DV-N
down loaded  dinosaur  my software   is v carve pro
router table can only take 600x300mm so nested file and  v carve made 6 sheets to cut
 But I only get about 50% of 1st sheet cut when I can smell smoke  ( have a little computor fan blowing on tool)
and tool tip starts to look black
Help needed
what can I do to make tool last longer
thanks for any help
roly

Offline RICH

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Re: router tips burning
« Reply #1 on: December 07, 2009, 08:23:40 AM »
Carbide cutters. Vary the depth and feed rate to address the cutting. ie; cut thru the wood and then take a shallower cut thru the glue joint. Experiment some to find out how long the cutter remains sharp and correct feedrate for what your doing.

Rich

Offline ger21

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Re: router tips burning
« Reply #2 on: December 07, 2009, 08:35:24 AM »
AS I said on the Yahoo group, slow the spindle speed down. Run the machine as fast as possible, and lower the spindle speed as low as you can making sure it still has power to cut.

When you get burning, there are only two things that will stop it. Lower RPM and or higher feedrates.

You can try blowing compressed air on the tool, but I don't think it will help much
Gerry

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Offline lemo

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Re: router tips burning
« Reply #3 on: December 07, 2009, 09:33:32 AM »
I don't think you will be lucky with that setup. All you can do is what was mentioned before. But if you lower the rpm the Dremmel will have not enough torque and will stall and if you speed up the motors do not have enough torque. Only suggestion I have is to run as fast as you can with the Dremmel set as fast as possible and then take shallow passes.
Dremmel and it's bit's are garbage for cnc application. You will always end up with a compromise and once you have a setup you like you will figure that it's time to buy the next Dremmel as the bearings have gone to cheap china crap bearing heaven. Get at least a proxon or a rotozip. Not ideal either but leading to results. I bought a small water cooled spindle from ebay and together with a PC cooling radiator and a cheap VFD I paid less than $500. THAT rocks. As small as a Dremmel and 1HP at 24K RPM. Neat, and almost no noise. Scary little bugger. Again... with the Dremmel as spindle you will not go anywhere soon while having a lot of pain trying. The Dremmel is cheap hand tool for 'fudging' things. 10 dead Dremmels equal 1 correct setup. My dremmels when I was in my 'cheap out' phase lasted about a week till total and utter failure.
Best of luck!
Lemo
Cut five times and still to short...

Offline Katoh

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Re: router tips burning
« Reply #4 on: December 07, 2009, 10:34:11 AM »
I agree with Lemo, your best solution is if you can not lower your spindle speed to a point were you can run your feedrate at a comfortable speed without burning or stalling is to look into a VFD or even better get a little spindle motor.  As example I run a 3 flute cutters at a feed rate of 2to2500mm/min at 7000rpm or a 2flute cutter again from 2to2500mm/min at 9-10,000 rpm. Why 2 to 2500mm/min, thats were my router feels comfotable working, and then you have to adjust your cutting rpm to suite. Also i dont know what cutters your using but some of your standard router bits are just "CRAP" for CNC work, stick to good brands and spirel bits work best in my opinion.
Not adverising or sprooking for anyone homeshopcnc have nice little spindle motors, that will give yo an idea what to look for.
Cheers
katoh
Cheers
Katoh

Offline Tweakie.CNC

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Re: router tips burning
« Reply #5 on: December 08, 2009, 03:12:30 AM »
The problem here is heat which is generated by friction.
The low cost bits are made from tool steel (if you are lucky) and will not stand overheating whereas the more expensive carbide bits stand a much better chance of survival.
Cutting bits have side and face clearance which reduces the area in contact with the work and thus quite low friction (heat) is generated but if the cutter flutes become choked with the cuttings then the friction increases at an alarming rate and will ultimately lead to tool failure for all but perhaps the extremely expensive cobalt alloy tools (stellite) which will carry on and just burn their way through.
Using an air jet, aimed at the tip of the tool, will clear these cuttings from the cutter and kerf as well as providing a measure of tool cooling. Shop air, run through a pressure regulator, is just fine for this task.
I have found the single flute carbide cutters to be best for both for wood and plastics as the face and side clearance is much greater than with multi fluted tools. Cuttings don’t get trapped in these tools and so little frictional heating occurs but the low pressure air jet is still desirable. The cutter on the right of this picture is a single flute type and shows the exaggerated side and face clearance quite well.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline stirling

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Re: router tips burning
« Reply #6 on: December 08, 2009, 05:30:25 AM »
pretty much all been covered, but I'd just add this: Up your screws to (say) 10mm lead and cut your microsteps to 10 max (more than 10 microsteps is (generally speaking) not only pointless, it's counter productive). This will get your max feedrate waaaaaaay up at your motor's stall speed of 6 revs/sec without loosing any *real* resolution. There's no way you're going to get your current theoretical res of 0.000390625mm/microstep anyway with a dremmel's runout - not to mention your rig would need to be made of granite etc. etc. ;D

Ian
« Last Edit: December 08, 2009, 05:41:32 AM by stirling »
Re: router tips burning
« Reply #7 on: December 11, 2009, 03:45:15 AM »
An up date on my router bit/tip burning
I cannot seems to get my feeds up past 430 mm per min
computer is a 2.8gig   
2 gig ram
and a 8400 giga bite video card with 512 ram on that
steps set to 1-1  my motors are 1:1 to screw  1.25mm per turn
so this is 160 steps for 1 mil ,This I have set up
power supply is a x radio work shop power supply 12 24 volt at 30/40qmp max
I run on 24 volts
Have used  Aerospace Tb_axis HY-TB4DV-N controler
and the 3 axis micro stepper motor controler    by Mechatronics

stepper motors are 1.8Nm/2490zin
1.8 deg  /200  from cnc machinery
4 leads wiring
thanks for help roly

Offline stirling

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Re: router tips burning
« Reply #8 on: December 11, 2009, 05:02:16 AM »
rolyjm - Sorry - I may have misled you by wording my previous post poorly. Reducing your microsteps to full steps is not going to help with your speed problem - I shouldn't have mixed that with my comment about increasing lead. Put them back to 10 or 8 or whatever's near 10 on your setup. I was just saying that above 10 microsteps is pointless.

My suggestion above re: increasing lead would give you more linear speed for the same stall speed of your 6 revs/sec. Alternatively you can up your present stall speed by increasing your PS voltage. You don't say what your motor's rated V is but I'm guessing your PS to motor V ratio is not very high.
Re: router tips burning
« Reply #9 on: December 11, 2009, 05:09:55 AM »
Roly

The screw pitch should be at least 10mm per turn as others have suggested yours are 1.25 if you did do that alone you could run 8 times faster.

Your motor power is low at 1.8Nm so again you have another failing here.

Then there is the power supply voltage at 24volts you should run much higher i run 65volts

There is a saying you can't get a quart out of a pint pot

You on the other hand are trying to get a gallon out of a pint pot, there is nothing wrong with your computer speed.

Sorry
Phil
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