very basic cad cam software

[Clive S]

Because you need to use a drill operation for the holes.

Ok I have just tried this with Aspire and a 3.01 circle and a 3mm end mill with an inside profile and in simulation it's fine ..Clive

[GEOFFREY]

I have been routing all my holes this way for years. I wonder if Charlie is putting his cutter paths on the circle centre with no offset to the inside of circle? To my mind the problem will be in that direction. G.

[JAZZCNC]

USE A PECK DRILL like Eddy suggested. Can't interpolate 3mm hole with a 3mm cutter simple as that.!

[GEOFFREY]

USE A PECK DRILL like Eddy suggested. Can't interpolate 3mm hole with a 3mm cutter simple as that.!

That is why I suggested making the hole diameter slightly bigger and routing it out - this has worked for me for years!!! Of course if you have a drill cycle option that works fine as well. G.

[EddyCurrent]

That is why I suggested making the hole diameter slightly bigger and routing it out - this has worked for me for years!!! Of course if you have a drill cycle option that works fine as well. G.

This is the bit I don't understand, why make the hole bigger if a 3mm hole is required ? Sometimes this will be fine but I'm sure there are more instances where the measurement has to be right.

[Clive S]

This is the bit I don't understand, why make the hole bigger if a 3mm hole is required ? Sometimes this will be fine but I'm sure there are more instances where the measurement has to be right.

The way I see it is If you want the hole to be 3mm and you also want to profile it out then you have to use a smaller end mill say 2.5mm BUT if you have a job like Charlie is doing and he is wanting to use a 3mm end mill to do the total job and the 3mm hole size does not have to be 3mm then make it say 3.01 and use the same cutter to save changing bits (his holes are only for mounting holes anyway).
I did a very similar job for a quadcoptor all with one size bit and did the same just made the 3mm holes to 3.01.
.
Or like has already been suggested peck drill it

[JAZZCNC]

That is why I suggested making the hole diameter slightly bigger and routing it out - this has worked for me for years!!! Of course if you have a drill cycle option that works fine as well. G.

So what if there are say 166 holes.? Do you change ever piece of geometry.? how longs that going to take.! (Answer In this case would actually be to tell Cam tool is 2.99mm but hole will still be wrong size)
What if the holes are for dowl pins and need to be exactly 3mm.? In this case a 3mm endmill won't work so again more time wasted swapping out endmills.

Maybe I'm being a bit Pedantic here but Better to get into a habbit of using the easiest and less disruptive option which in this case would have been a Peck drill than changing geometry or using fudges like under sizing tools in Cam.

[charlieuk]

i guess then i should probably ether get some smaller cutter or go for the drill method. I have been looking at videos on cam bam and how to do the drilling and it mentions something about adding points list centers, im guessing this is just telling the drill were to go rather than to find the center of the hole one its own? Im assuming buy dreating the drill tool path and g code i then run this file with a 3mm drill bit instead after the profile code that does the rest of the cutting with the same start point?
I have found the peck setting but there is also a drilling method option with canned, spiral and custom im assuming i want canned as i wouldn't want spiral but cant find out what that means?

[EddyCurrent]

watch this
https://www.youtube.com/watch?v=2QpYclg6Ah0

read this;
http://www.cambam.co.uk/forum/index.php?topic=4620.0
http://www.cambam.info/doc/plus/tutorials/Drilling.htm
http://www.cambam.info/doc/plus/cam/Drill.htm