Drilling Countersink Holes in 1/4" Hard Board

dusty · Post by **dusty** » Thu Feb 23, 2012 8:31 am

Are there any "not so obvious: tricks to drilling smooth counter sinks in 1/4" hard board or MDF.

I was experiencing a lot of chatter and a resulting rough counter sink so I bought a new bit. I am having the same problem with the new one.

My first thought was speed. I have been across the Shopsmith speed spectrum (almost) to no avail.

All of your suggestions will be greatly appreciated.

BTW I can drill really nice smooth counter sink holes using the hand drill. I just don't do so well at getting them centered on the through bore.

It frustrates me when ever I see one of reible's projects where he has done this. They look so perfect.

In aluminum, I have no problems at all.

garys · Post by **garys** » Thu Feb 23, 2012 9:17 am

MDF and hardboard are not the best product to work with. I refuse to buy any no matter how cheap they sell it. I like plywood with a wood core so much better.

I think the last time I cut MDF was 20-25 years ago, and when I saw sparks coming off my blade from the stray metal particles in the MDF, I decided to never use it again.

pennview · Post by **pennview** » Thu Feb 23, 2012 9:44 am

Dusty, could it be that the thin hard board need more support or control to prevent chatter. Another possibility is the design of the countersink itself. I've got a number of them and some clearly work better than others. My current favorite one has a single cutting edge and I use a diamond paddle every now and then to keep it sharp. Another possibility is a "V" shaped router bit in the drill press followed by the countersink in order to match the head of the screw.

charlese · Post by **charlese** » Thu Feb 23, 2012 12:59 pm

I have had the same situation when using one of those star shaped countersinks bits - designed for a hand held use - in the drill press. Solution for me is to make those countersinks by hand, or use the kind of bit like favored by pennview.

fjimp · Post by **fjimp** » Thu Feb 23, 2012 6:05 pm

I use many solutions for countersinking. These are one of my favorites.

http://www.woodcraft.com/Product/200553 ... l-Set.aspx

Jim

reible · Post by **reible** » Thu Feb 23, 2012 8:08 pm

Hi Dusty,

For the hard board I use what is called a shear-cutting countersink and depending on size and feel a speed of slow to D.

This a set of a 3/8" and 1/2" both showing where the chips are ejected and then in the next picture is the cutting face.

[ATTACH]16419[/ATTACH]

[ATTACH]16420[/ATTACH]

Ed

dusty · Post by **dusty** » Wed Aug 29, 2012 5:27 pm

reible wrote:Hi Dusty,

For the hard board I use what is called a shear-cutting countersink and depending on size and feel a speed of slow to D.

This a set of a 3/8" and 1/2" both showing where the chips are ejected and then in the next picture is the cutting face.

[ATTACH]16419[/ATTACH]

[ATTACH]16420[/ATTACH]

Ed

I ordered these from Lee Valley just a few minutes ago. The mail man had just delivered an order of stuffed animals to SWMBO. I thought the timing was just right.

dusty · Post by **dusty** » Tue Sep 11, 2012 10:59 am

reible wrote:Hi Dusty,

For the hard board I use what is called a shear-cutting countersink and depending on size and feel a speed of slow to D.

This a set of a 3/8" and 1/2" both showing where the chips are ejected and then in the next picture is the cutting face.

[ATTACH]16419[/ATTACH]

[ATTACH]16420[/ATTACH]

Ed

I received my order from Lee Valley and these bits do work well but I do not believe they are any better than the others I have used previously. After using a few different bits, I have concluded that most of my problems were "technique" and not hardware related.

If anyone cares, these bits were made in China. I would have looked elsewhere if I had known before I ordered.

My experimenting (wife calls it playing) has led me to wonder which hole (counter sink or through bore) should be drilled first or if it even makes a difference. That too is probably a matter of personal preference and individual technique.

terrydowning · Post by **terrydowning** » Tue Sep 11, 2012 12:00 pm

dusty wrote: My experimenting (wife calls it playing) has led me to wonder which hole (counter sink or through bore) should be drilled first or if it even makes a difference. That too is probably a matter of personal preference and individual technique.

Doesn't the answer to that question depend on the fastener and the project as well?

I have done plenty of rough 2 x 4, 2 X 6 joins without either, since It just didn't matter. Drive the screw in!!

I try to be cleaner than that in most scenarios though.

If the part of the fastener that contacts what you are joining is flat (like a carriage bolt), then counter bore only (gotta love forstner bits).

If the part of the fastener that contacts what you are joining is tapered, and you want the screw head flat with the top of what you are joining then counter sink only

If the part of the fastener that contacts what you are joining is tapered, and you want the screw head below the surface of what you are joining then counter sink and counter bore.

If using 2 separate tools, counter bore first to get close to desired depth, followed by an appropriate size counter sink to complete the depth.

Alternately and my preference is one of the combination pilot drill, countersink, counterbore tools on the market.

foxtrapper · Post by **foxtrapper** » Tue Sep 11, 2012 2:17 pm

Those cheapie B&D stamped countersink bits I mentioned on the other thread work very well in MDF, and partical board as I recall. Should work well in the likes of chipboard.