Countersink bits with depth stops

[Cheese]

Well that's not good Jonathan...Sure you're not running those at too high a RPM?

Here's an example of a #4 (55331), #6 (55228), #8 (55240) and a #10 (55242) in maple strip flooring at 540 RPM. I also tried the #10 in Baltic birch ply and a piece of cedar. No marks.

[attachimg=1]

I increased the speed to 1150 RPM on the maple and it left 2 short marks across from each other. Increasing the speed to 2220 RPM left a single mark about 1/3 around the c'sink.

I then tried the #10 on a primed cedar shingle reducing the speed to 540 RPM and it did not make a mark.

You want to countersink it until the outer ring just stops and then immediately lift the drill press handle.

[attachimg=2]

 

[semenza]

Could the problem be that they work well on hard wood but not on ply or coated surfaces? I am thinking that a really smooth or coated surface might not have enough grab to prevent the spinning / slipping.

Although I have never been able to completely trust any depth stop that contacts the surface. No matter what they are made of or how good the design, they always look like trouble to me.

Seth

 

[elfick]

There are people way more knowledgable about this topic than I am already in the conversion, but couldn't you just hold onto the depth stop to keep it from spinning?

 

[Cheese]

I tried several holes on Baltic ply @ 540 RPM and they didn't mark the material. Next I tried the #10 in some cedar pieces, primed siding and white painted trim. Again, using 540 RPM these are the results.

[attachimg=1]

Only on the one countersink on the painted trim did I get a small mark.

These c'sinks have a series of bearings internally so they are real sensitive and when the collar just touches the wood, it stops almost immediately. However if it's spinning at a fast rate of speed there will be some lag time because of the high RPM. So slower is better.

[attachimg=2]

[attachimg=3]

 

[JonathanJung]

Thanks guys, I ran them again at 450rpm and it's much much better. Not 100%, but satisfactory. Shame, because that slow RPM makes the drilling slower...

Surely they should have made them out of something other than aluminum? Alu and wood don't go well together.

 

[Cheese]

Ya, I would have thought they’d use Delrin.