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Author Topic: Bobcad feed and speeds are wrong when loading in mach3 Newbie  (Read 5937 times)

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Offline Rune

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Bobcad feed and speeds are wrong when loading in mach3 Newbie
« on: September 10, 2012, 01:47:31 PM »
I have maked a test part for the first time in bobcad and all seems to work but when i loaded it in the mach3 all looks great all about the feedrates that are WAY slower then it was calculated in bobcad... i attached pitchure of bobcads calculated feeds and speeds and the mach3 speed that are way slower. why? is my units calculated wrong? one unit in mach3 i have calculated to is 1mm each unit.

please help...

Offline Graham Waterworth

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Re: Bobcad feed and speeds are wrong when loading in mach3 Newbie
« Reply #1 on: September 14, 2012, 05:13:46 PM »
What is the maximum feed rate of your machine?

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Offline RICH

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Re: Bobcad feed and speeds are wrong when loading in mach3 Newbie
« Reply #2 on: September 15, 2012, 06:39:58 AM »
Can't have a feedrate which greater than your machines is capable of, same goes for a spindle rpm ( 24000 rpm used in calc).
RICH

Offline ger21

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Re: Bobcad feed and speeds are wrong when loading in mach3 Newbie
« Reply #3 on: September 15, 2012, 08:27:11 AM »
The g-code is displaying F499.999, so it's BobCAD that is setting the feedrate to 500, not Mach3
Gerry

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Offline Rune

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Re: Bobcad feed and speeds are wrong when loading in mach3 Newbie
« Reply #4 on: September 16, 2012, 06:58:41 AM »
thanks for all replys..  if i understand this right so if the feedrate is much higher than max it  will not work right`?

where do i adjust maximum feedrate in mach3?

I found out why it was so slow at first time.. the post prossessor was calculating in inches.

Offline Rune

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Re: Bobcad feed and speeds are wrong when loading in mach3 Newbie
« Reply #5 on: September 16, 2012, 07:31:15 AM »
I also want to ask if my native units can be in millimeters? example of meaning x and y on mach3 showing 4.0000 eaqual to 4 millimeters in x and y? is this the right setup?
and if so.. i have calibrated the motors for this machine as in the simple manual i got with it. and i see now that velocity stand on 2007 mm per min? isnt that wery much? again please help me as i dont understand this at all.. is there anyway or any website that displaying a chart for these things?

Offline RICH

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Re: Bobcad feed and speeds are wrong when loading in mach3 Newbie
« Reply #6 on: September 16, 2012, 09:50:17 AM »
Rune,
Have a look at the thread END MILL SPEEDS AND FEEDS in Members Doc's. It provides basic information and suggested rates for machining.
A program calculates based on some generic info ( actualy over time studies have been done to arrive at the info basis). Thus  if your system can't do what the calculated basis was ( ie; not many spindles turn at 24,000 rpm) then you need to modify the feedrate for the spindle speed you will be using. Additionaly, machining experience certainly can be the deciding factor. ie; If your machine has backlash,you can snap
a small end mill in a heartbeat.

RICH

Offline Rune

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Re: Bobcad feed and speeds are wrong when loading in mach3 Newbie
« Reply #7 on: September 16, 2012, 04:18:40 PM »
There is one thing.. i calculated max speed of my machine and it is about 3.6 meters per minute in speed on millingboard and as im considered is 3.6 SMM???
and for me that is VERY fast milling speed... an complex part milled and drilled finish in about one minute... so therfore i cant understand why bobcad is calculating 150 SMM on aluminum its imposebol to imagine that speed on a millingmachine... is it only becouse of my milling engine that can handle 24000 rpm? if so maby i need a diffrent mill engine for milling aluminum? my milling engine gets wery weak in a rpm of 400 rpm. so i cant mill at the best tool speeds. does this sounds right? i think this sounds ridicolus low rpm at so fast mill speeds,. but I am new to this hobby.