On Monday, March 28, 2016 at 7:24:38 PM UTC-4, Electric Comet wrote:
It's not true. I would guess that most Forstner bits are *not* flat
bottomed, as shown here. The center brad is used to get the bit started
I have heard of (but never seen) the technique of using 2 Forstner bits
to get a flat bottom hole. Grind the center brad off of one bit. Start the
hole with the center brad of the "full" bit and when the hole gets deep
enough to hold the other one centered, switch bits and finish the hole.
But the emphasis (as I read it) was why a TOTALLY flat bottomed hole? I
understand what you're saying, Leon, but if I'm using ANY Forstner bit
to drill say, a 1" hole in a board so I can insert a small fender washer
and a bolt or screw what difference will that slight pip in the dead
center make? If it's a screw the pilot hole will be there, if it's a
bolt, there will be a hole rather than the pip.
On 3/29/16 9:56 AM, Unquestionably Confused wrote:
I'm trying to find some pictures for one project I did.
It's more for looks than purpose. I needed semi-cylindrical shapes,
think: round mortise.
Except these would show. I could think of no easier or accurate way to
cut the shapes I needed. I experiment with a hole saw, first. But they
don't exactly cut clean holes, then there's the task of removing the
core that's still attached on a non-through bore. That means having
chisel out a clean, flat bottom inside a semi-circle. Not easy.
So that gets us to the subject of this thread. :-)
"Playing is not something I do at night, it's my function in life"
On 3/29/2016 9:56 AM, Unquestionably Confused wrote:
Totally flat does not mean every spot on the bottom is solid, it simply
means that the bottom is flat. Even though pegboard has holes in it, it
If there is any portion that is not flat the washer will not make full
contact, if the bottom funnels toward the center the fastener head can
deflect the washer and then only the edge/perimeter of the fastener head
is making contact. Why is this a problem? The fastener can loosen over
time. Now this is all being picky but flat bottom for these type flat
washers and fasteners need to be flat for the same reasons that you use
a tapered type countersink with flat head screws. It simply distributes
the load of the fastener more evenly.
And just to add a touch for the benefit if a flat bottom hole is when
you are drilling 35mm/1-3/8" diameter holes for Euro hinges. These
style hinges require a 1/2" deep hole. If you drill a 1/2" deep hole in
a 3/4" thick cabinet door with a spade bit or a huge twist type bit you
will certainly drill through the opposite surface of the stile.
No one but yerself is positing that it even IS a problem.
You say, "if". What "if" it is NOT a problem? I suspect good
forstner bits are jes as flat as those pricey pointless bits, with
only the "point" extending beyond the flat cutter arms. In fact,
if one has a drill press and good HSS bits, what's to prevent one from
grinding down the "point".
According to Wiki, the main advantage to forstner bits was not the
"Originally the Forstner bit was very successful with gunsmiths
because of its ability to drill an exceedingly smooth-sided hole."
Yes, I saw the comment about the flat bottom:
"(and incidentally spoils the otherwise flat bottom of the hole)".
Again, I say, who cares? Some anal purist, no doubt, but what with
all those power tools in the mix, it's pretty silly. Besides, don't
washers have a hole in the middle?
I'm rapidly beginning to suspect woodworking is merely yet another
reason for men to buy/hoard a whole buncha specialized tools. I've
got a 1/4" socket paring chisel coming tomorrow, which is amazing only
due to the fact that I have no clue how I'm gonna use it w/o that
necessary wooden mallet.
Yeah, I know. I'm already hooked. ;)
I am talking about a Forstner bit vs. a regular twist bit, or brad point
bit which do not leave flat bottoms.
Well leave it to Wiki to be the end all answer site. ;~)
Shickingly I can't say that I have ever had issue with a non smooth side
unless using a spade type bit. Standard twist and brad point bits leave
very smooth sides. Forstner bits mostly do exceptionally well at
drilling into a surface at an angle and or cutting non full circle arc's
indention or half circles.
Hummmmmmmmm. One poster asked and the question was answered. Now you
are becoming all anal about your point of view.
On Tuesday, March 29, 2016 at 10:40:57 AM UTC-4, Leon wrote:
...or a thrust bearing. BTDT
There's one at the bottom of the steering shaft for this
Soap Box Derby car:
However, I think we have a slight disconnect here. Doug used the word
"totally" in his post. Your flat washer (and my bearing) will both work
in the hole created by a Fortsner bit with a center point, which does not
create a totally flat hole. (I believe that that is what EC is actually
The only reason I can think of for a totally flat bottomed hole would be
for decorative purposes.
Actually I believe Mike mentioned totally flat. And I thought Doug was
just wondering about a flat bottom hole, NOT necessarily devoid of a
perimeter indention or center point.
My mistake if I misunderstood Doug.
I'm letting some coffee work on my brain to fire up the correct synapses
in order to recollect the past projects I've needed them.
However, on a recent cabinet rehab, the client wanted cup hinges on her
existing doors which were abnormally thin. Not only did I have to scour
the globe/google to find euro-hinges with the shallowest cups, but I had
to grind off the pilot point on my 35mm forstner to keep it from
piercing the outer edge of the cabinet.
Yes, it was a butt-pucker job as there was less than 1/16" outer veneer
left after the cup holes were drilled. Client wants, client gets. :-)
"Playing is not something I do at night, it's my function in life"
Actually a true Forster bit has no saw teeth and does not require a
center brad point to guide it. I have drilled numerous quarter circle
holes with only 1/4 of the bit cutting into the wood. The perimeter of
the bit does the guiding. This is all done however with a DP, not a
hand held drill.
On Tue, 29 Mar 2016 07:13:30 -0700, DerbyDad03 wrote:
On Tuesday, March 29, 2016 at 12:09:23 AM UTC-4, Leon wrote:
You're right, Leon. But I would add one caution. If you're drilling a
full round hole, the force of the bit is equal in all directions. If
you're drilling half a hole, the force is all in one direction. If you
don't have the work secured, the bit can pull the work (and your hand)
into it - DAMHIKT!
They're really fond of those bits aren't they? Four times or more the
price of a Freud or Bosch with a center point!
....and to what advantage!?
So, a center point leaves a little dimple at the bottom of the cut.
How is this detrimental to the flat bottom? I could see the added
expense of pointless bits if the bit point left a protruding dimple on
the bottom, but it does not. A flat washer will lay jes as flat with
a negative dimple under it as without. Or am I missing something? ;)
Unlike other bits, a Forstner can easily be used to drill multiple
overlapping holes. If a router won't work for some reason, you can make
pockets with a Forstner and a chisel. The little divots left by the
Forstner bit would be very unappealing in that case.
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