» Topic: Feedrates
- July 12, 2014 at 10:14 am #18918
On a mill program, is there a way to have BobCAD output reduced feed rates when the cutter enters a smaller inside radius. Currently I have been modifying the G code output manually. Very time consuming.July 14, 2014 at 10:11 am #18921
It is possible to output a reduced feedrate when going around an arc. On the tool selection page of a feature, there is an option for Arc Slowdown%. This number can be modified to reduce or increase the feedrate that outputs around arcs based on a percentage of the cutting feedrate.July 14, 2014 at 11:26 am #18926
Thank you for the fast reply. I have have experimented with the Arc Slowdown % but that only reduces the feedrate to a predetermined feed on all inside contours. I have a part that has .187″ radius inside cuts and other arcs that are 2.00″ radius. Using a .250″ diameter end mill, I have to reduce the feedrate by a high percentage but do not need this much reduction in other areas. I have used other types of software that looks at the diameter of the cutter and the diameter of the arc and reduces the feed accordingly. Can this be done with BobCAD without manually changing the feeds of the G code output?
TomJuly 14, 2014 at 1:16 pm #18929
It can by adjusting the feedrate output in the post processor itself. It would require a script that checks the size of the arc and then you can create a scale factor off of that.July 14, 2014 at 3:44 pm #18930
How is this done?July 14, 2014 at 11:50 pm #18933
Tom,I think BoB will want $$$
Over at the Zone there are a few people who understand scripts.There have been threads on scripts before over there.Can be pretty powerful to tweak your code in different ways.This particular question has never came up,but this would be doable pretty easily I reckon.
Actually,I encourage you to post over there as this is something that would be pretty nice to have.
A future feature request maybe Sean ?July 15, 2014 at 10:17 am #18934
I will submit a feature request to development to have radius specific slowdown, basically, if smaller than a certain radius size, reduce feedrate.
For us to do the scripting JR is correct. There are ways in which scripting can be done, but they would vary based on the specific conditions. If you wish to limit the feedrate feature by feature basis, rather than a general rule of thumb, you would have to create a page inside the feature that would allow input. If you want a general rule of thumb, here is an example of that style of script. This would go into one of the open program blocks in the 2001 + area of the post processor. You would then change the feed_rate value on block 64-66 to the specific program block used, i.e. program block 1 would be program_blocK_1.
feedValue = Mill_GetFeedRate() ‘Grab feed value using built in API
feedValue = round(feedValue,4) ‘Round feed value to 4 decimal places
rValue = MILL_GetArcRadius() ‘Grab radius value using built in API
rValue = round(rValue,4) ‘Round rValue to 4 decimal places
‘Conditional Statement to check value of radius and reduce feed
feedValue = round((feedValue*.2),4)
July 15, 2014 at 8:27 pm #18985
- This reply was modified 2 years, 2 months ago by Sean.
To do this correctly, the radius must be compared to the tool diameter and the feed slowed accordingly to maintain a constant chip load.
Is there any data or documentation available for writing scripts?July 21, 2014 at 11:11 am #19009
We do not have any documentation available in regards to scripting. You can review tutorials online that cover vbscript, which is what we use for our scripting engine. The argument you need to make needs to grab tool diameter and the radius value of the arc and do a comparison between the two. There are many ways this can be done, but it is a more complicated script then the one that I showed.
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