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By gcude

March 3, 2013, 6:28 am

Manual Machines

ZD,
Should my manual mill with power feed on the x-axis be able to use HSMAdvisor to good use?
I broke a 3/8" cutter the other night and wanted to try your program and put in the parameters I know about my Bridgeport J-head mill (and was using when the endmill broke), but can't find the "Max Torque" value for the J-head Bridgeport anywhere.  I "Add"ed the Bridgeport as another machine under "Machine Limits" and played with the "Max Torque" by lowering it several times, but I'm getting what I feel is an unrealistic "DOC" value that never changes when I change the "Max Torque".
BTW, I am starting work on building my CNC mill.  So, if HSMAdvisor isn't the tool for me now with the manual mill, I look forward to using it when I get my CNC up and running.
Thanks for your efforts,
Gary

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Eldar Gerfanov

March 3, 2013, 10:07 am

hello gcude,
I very much doubt you could use it on manual machine.....
There are several problems with that: how do you specify feedrate? And also how dobyou set RPM? As far as i remember RPM is very inacurate on those variable drive machines.
Also i dont know a way to see the feedrate you are going at without a DRO. But power feed has varying torque depending on how much resistance you are getting....

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Eldar Gerfanov

March 3, 2013, 10:10 am

Also max torque is only warning you when machine is out of torque.
but in order to go easyer on the cutter in case of not ideal conditions you shoud reduce cutter performace slider.

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gcude

March 3, 2013, 1:50 pm

The Bridgeport mill I have is the older step-pulley model, not variable speed.  So, whatever belt position and/or backgear, that's the speed you get.  The power feed for the x-axis is a Servo brand and has a dial 1-9 to choose the speed of travel for the table.  I have taken a ruler and measured the travel at each numbered position as far as inches per minute.

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Eldar Gerfanov

March 3, 2013, 3:57 pm

Well, then yeah.
If you have ways of acurately controlling spidle speed and feedrare, it should work for you.
A word of caution though: calsulator assumes IDEAL conditions.
For starters you should set performance slider to the minimum position.
Also if machining aluminum, calculator assumes FLOOD coolant.
Said all that i know a guy who successfully uses my calc on his CNC knee mill with 70% on all overrides and it works for him.
If you tell me parameters of your cutter and how it broke, i could tell you why it happened and how to avoid it in the future.

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gcude

March 4, 2013, 2:02 am

Thanks for the tips.  It was a 3/8" 4-flut Cobalt cutter that I broke.  Milling unknown class of Cast Iron dry, no coolant.  After I looked a the IPM at each setting of the x-axis powerfeed and doing some calculating, I determined that I was advancing more than double the max for the cutter and deflection broke it.  I was squaring a couple of blocks and had finished the first and started the first side of the second block and decided to try a faster feed, since the motor was not groaning.  I will go back and change the sliders and see what HSMAdvisor recommends.  Lots to learn.
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Eldar Gerfanov

March 4, 2013, 6:19 am

Hah that explains it.
One last question though. Were you using online calculator, or standaline HSMAdvisor?
Because while online version will just inform you of deflection, the standalone will also try to fix it by reducing feed rate.
So, its really hard to break anything using standalone version.

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gcude

March 4, 2013, 2:41 pm

I am using the standalone HSMAdvisor.  Didn't try it before the breakage, so when I get a chance I will play with the sliders and numbers again.  Should work ...

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