Killer tip for using a hole saw bit for control panel

[dkubarek]

I had a bear of a time with a hole saw until I saw this tip online. What makes a hole saw slow is that the glue and wood particles jam into the teeth and quickly slow the bit to a near standstill. Here's how to drill a hole in a matter of seconds:

Have the centers of your holes marked and use the saw and mandrel center bit to score the top of the wood. Just enough for it to mark the wood on top. Then use a spade bit about half the size. (ie for a 1 1/8-inch hole, use a 1/2-inch spade bit) Drill a hole with this bit so that it just overlaps the edge of the circle you want to drill. A 1/16-inch overlap is fine. Good spade bits should tear through two pieces of wood in about 20 seconds. Then switch back to the hole saw and complete the drill. Should go through 3/4-inch MDF in about 10 seconds. You should be able to go much faster with the bit without overheating it, too. It helps if you have a quick attach on your drill or, better yet, two drills.

It's also a very good idea to clamp a piece of wood you want to sacrifice to the bottom of the control panel. This prevents blowouts on the bottoms of the holes. If you do this, you'll need to spade drill both pieces, of course, but only need to hole saw the top piece. You'll be able to guess how far in you are and you can feel the bit want to stop when it hits that second piece of wood. Also, a shop vac to suck out the saw dust will greatly speed things up.

Here's how it works: The spade bit hole allows saw dust to escape the cutting area and allows the bit teeth an open area so it can cool.

[Lecithin]

It's also a very good idea to clamp a piece of wood you want to sacrifice to the bottom of the control panel. This prevents blowouts on the bottoms of the holes.

  Definitely a good way to avoid blowout!

I've drilled a good amount of MDF with various sized hole saws, perhaps its because I work at a shop but I haven't had that big of a problem with it. Then again I'm working with some expensive and fancy equipment! I guess when I do this CP I'm about to start we'll see if my luck continues....

[richms]

A similar trick I have heard is to drill the pilot hole and then use a jigsaw to cut from it to the edge of the hole so that there is a gap for the gunk to escape thru.

[Blanka]

Why not drill everything with the spade bit? They drill cleaner holes too!

[dkubarek]

If the spade bit works for you then keep using it. I have never tried to do a whole CP with a spade bit, but it stands to reason that the hole saw was made for something. I think a hole saw gives a cleaner hole, but for a CP it wouldn't really matter. I think spade bits tend to chip more, but again I haven't done a lot of holes with one in MDF.

[Blanka]

A hole saw is more for bigger holes (4cm and up).
The problem with it, is that the teeth-to-centre distance is not very constant. It tends to wiggle a bit. A spade bit is high-precision CNC'ed and it only has two sharp edges, so as long as it's in a stable vertical drill platform, it cuts very precise holes. With MDF you won't have chips as you have with particle board or plywood. The only thing to take care of is to keep a slow speed for the last mm of drilling. So I'm no big fan of hole saws. Perfect for making an outlet-hole in gypsum board,
If you want very nice big circles, even a router is better than a hole-saw for precision.

[richms]

I have a holesaw for wallboards that is 2 blades on an adjustable spinning thing. Never tried it on wood but it does a great job cutting downlight holes.

[erictrumpet]

A forstner bit makes perfect buttons holes - and I do mean perfect. Quick, easy, clean - and a sacrificial board underneath to avoid tearout is less necessary (but still recommended).

Eric.

[opt2not]

A forstner bit makes perfect buttons holes - and I do mean perfect. Quick, easy, clean - and a sacrificial board underneath to avoid tearout is less necessary (but still recommended).

Eric.

Eric is right, I just bought a forstner bit this weekend, and I got to say it is AMAZING. The cutting was clean and fast, for both my wood panel and plexiglass.
Sure, this bit cost more than your average spade bit, but it's totally worth the $18 for the peace-of-mind of knowing your holes will be done right.
I will never go back to Spade/Holesaw bits again! 

[MrMojoZ]

I just ordered some forstner bits, looking forward to trying them out. Anything I should know about them for first time use?

[cmoses]

Any hints on using a forstner bit to drill plexi?

[Gatsu]

What I usually do for plexi is drill a small pilot hole in the center of the button hole, then take a (I think its a 3/8's) spade bit and make a small hole from that.

Then....use a flush trim bit on the router and just route out the rest. Easy breezy.

For drilling the initial holes into the control panel wood....I use a spade bit the whole way through. I dill about 3/4's of the way down on one side (making sure the center of the bit has fully punctured the wood. Flip it over, place the bit back in that center hole and finish drilling.
Zero blowout.

[erictrumpet]

The forstner bit works pretty well on lexan too - use the cp wood top as a "template" of sorts - cut your button holes in the wood cp top panel, then sandwich the lexan between the pre-cut cp and a sacrificial board underneath, then place the forstner bit in the already-cut holes of the cp and drill through the lexan into the sacrificial board beneath.

Eric.

[opt2not]

Any hints on using a forstner bit to drill plexi?

Try to retain your joy and happiness resulting from the awesomeness that is the Fostner bit.   

Besides that, a good tip is to make sure you're drilling at a high speed, so that the fostner bit heats up a bit to melt the plexi as it cuts through. You don't need to apply too much drilling pressure when the bit is hot.

Have fun and let us know how it goes!
 

[Chadwick]

A forstner bit makes perfect buttons holes - and I do mean perfect. Quick, easy, clean - and a sacrificial board underneath to avoid tearout is less necessary (but still recommended).

Eric.

What he said!  Can't go wrong with a good Forstner bit.

[R0UNDEYEZ]

What I did when I drilled holes in my control panel was use a holesaw about half way,flip it over and then do the rest. no blow out, no need for scrap wood under. I still started all my holes from the botom side, "just in case" but I had no issues.

[ZEN]

I have had little problems ever with a spade bit and a power drill (not cordless), for both the mdf and the plexi.  Make sure that when you do the plexi you go in reverse to essentially melt through it, assuring no cracks.

[SavannahLion]

Make sure that when you do the plexi you go in reverse to essentially melt through it, assuring no cracks.

Just to point this out. Melting the plexi in this fashion isn't that big of a deal. The plexi isn't critical and if it breaks... oh well, right?

Anyhow, I digress. According to acrylic specifications, melting the plexi in that matter introduces a stressed edge which can lead to cracks. Not a problem with CP's, a huge deal if you're building say... a fish tank.

Just something to keep in mind.

[Xiaou2]

Actually, Ive tried reverse plexi drilling,  and cracked it.

 This backwards crap is a myth.

 The point is to melt the material as you remove it.  To remove it best.. you want
to scoop it away properly thus the holesaw or drill running FORWARDS.
 
 The biggest reason plexi cracks is due to people pressing downwards too fast.
One has to barely press down at all.  Each hole should probably take like 60 seconds.

 If the plexi is cold... its brittle.  Thus if trying to remove too much material when
cold... it cracks easily.   When plexi is at melting point.. its flexible and does not
transmit energy and vibrations to the entire sheet - which is usually what breaks
them.

 
 The Stress Edge to which they are talking about... is more to do with something
like bending plexi at a 45 to 90  degree angle with a heat gun or hot-blanket.
This will make the edge more seseptible to be broken, as the plexi loses its
flex in the heating process.

 HOWEVER.. because you are limiting the plexi to a hole shape, and removing the
material altogether.. you do not really have to worry about this.

[SavannahLion]

The Stress Edge to which they are talking about... is more to do with something
like bending plexi at a 45 to 90  degree angle with a heat gun or hot-blanket.
This will make the edge more seseptible to be broken, as the plexi loses its
flex in the heating process.

Or something.... A stress edge is caused by excessive polishing of an edge or melting of an edge from routing, carving or drilling.

In any case, when shaping acrylics, the story is always the same. You want to "scrape" the plastic away, not melt it out. A hole with a stress edge is not necessarily any less susceptible to cracking than a stress edge around the outside. You're probably compounding potential issues with so many holes drilled so closely together as typical in a CP.

But like I said, a cracked CP is a lot less worrisome than a cracked fish tank. So do with it what you will.