accurate center drill geometry is req'd.

[Mr. Dayshift]

Hello everyone,

 

I need to be able to define center drills #0-#5 more accurately for milling tool library.

 

Maybe I'm missing it in one of the mill libraries?

 

Can anyone confirm DRIILS.zip on FTP works?

 

Please, not comments regarding spot drills, it's off topic here.

 

Thanks.

[Guest]

The bottom line is if you "really" need it accurate then you need to draw it and define it as a custom tool.

 

The definition in the tool library does not take into consideration the tip length.

 

I'd use a spot drill instead

 

[Mr. Dayshift]

Thanks. I'll try drawing a custom tool.

[Matt Berube at Ferron Mold]

This should really be improved. I have been using custom tools for center drills for a long time. It's so nice to be able to see if the chamfer looks right during verify...

[kunfuzed]

This is a big gripe for me! I really wish MC would fix this so you don't have to draw up a custom tool for ever center drill you use! I personally would love to switch to spot drills, but I don't pay for the tools, and have been told we'll keep using center drills.

[Matt Berube at Ferron Mold]

quote:

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custom tool for ever center drill you use!

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Actually... If I remember correctly... I modified the original Mastercam Center Drill file and saved under a new name and now MC scales the geometry for each size as needed.

 

Since I replaced the original geometry with a more realistic shape I have been very satisfied with the accuracy in backplot & verify.

[kunfuzed]

I'll have to give that a shot. Thanks!

[#Rekd™]

__________________________________________________

"I'd use a spot drill instead"

__________________________________________________

 

+1000 for this!

[Guest CNC Apps Guy 1]

Ummmmm.... there IS a standard for Centerdrills, but every center drill manufacturer makes theird different. I've never been able to measure a centerdrill from two seperate companies and have the measurements be the same.

 

But, YES, being able to better define them instead of having to vreate a custome tool would be a better solution. I put in the request a number of years ago.

[TK-32™]

Off topic:

So spot drills are better then C'drills? Why?

[Matt Berube at Ferron Mold]

I think the only reason they're better is the ease of calculating depth/dia...

 

We have found better accuracy with center drilled holes in the mold steels we deal with.

[High Sierra Plastics]

I think center drills were created for lathes.

[Moldmaker74]

Center drills are for making a 60° cone with clearance for the tip for a center on a lathe tail stock (or cylindrical grinder centers).

 

When you drill a 118° drill into a 60° taper the drill squawks and dances around. A spot drill has a 118° included tip like your drill, so your drill will immediately cut on the same position as your spot drill. Way more accurate and less abusive on the corners of the cutting edge of the drill.

[Roger Peterson]

1. they have a thin web so you can cut faster without creating a lot of heat or worse breaking off that little tip on a center drill

 

2. the whole idea behind a spot drill is that your drill makes initial contact with the center of the drill on the workpiece. So if you are using a 118 degree drill use a 120 degree spot drill.

 

3. using a center drill will make the the drill contact the workpiece away from the center of rotation, since it is a 120 degree included angle it will contact at the small pilot diameter, causeing chatter which will be bad for accuracy as well as the drill.

 

4. Using the wrong angled spot drill is worse than using a center drill. If you use a 90 degree spot drill with a 118 degree drill, when the drill comes in it will contact the workpiece at the diameter of the drill which is as bad as it gets for chatter.

 

 

5. don't use a 90 degree spot drill just so it puts on a 45 degree chamfer, use the right sot drill for the drill being used. I assume because carbide drills are usually much more rigid, and shorter, I was always told not to spot drill when using them. I don't know if it matters?

 

 

HTH

[TK-32™]

Thanks for the information about spot drills VS C'drills.