Hole Drilling

[Rita B.]

So much to learn and when things crop up, this is my go to place for answers.  From time to time in a project or house hold repair, I have been required to drill a hole.   I am aware that there are hole saws, spade/butterfly bits and forstner bits.  How do you choose which type to use and what are the differences between them?

[Jay Boutwell]

Hi Rita I will answer this for you tomorrow as I  will need get some samples from the shop and it will take a while to write the post.  Look for it around noon

[Rita B.]

Jay, please do not go to a lot of trouble with this.   My next project will require holes to be built for installing some desk grommets and such.   Planning ahead for supplies and while browsing the store noticed the variety and realized that they each must play a different role.

[James P. Cottingham]

This is what I use the bits for:

Hole saws: I use these to drill holes all the way through a board but for holes that are larger that what the spade bits can do.  I don't see many spade bits larger that 1 1/2".

Spade/butterfly bits: Like the hole saw, I use these to drill all the way through a board but only for holes smaller than or equal to 1 1/2"

 Forstner bits: I use these to drill flat bottom holes in board. That is, holes that do not go all the way through the board.

[Jay Boutwell]

Rita I will explain the difference and also give you an idea of what I use them for. It will be sometime today or night when I finish it.  To drill holes for dest top grommets and such I usually use a hole saw and if possible I  drill part way through and then drill from the opposite side.  This prevents large tear out when the saw exits the hole.  I do this also if using any type of bit.  When talking about a butter fly bit there are the ones for horse bridles and then the boring bit of which is also knows as a spade bit, flat bit and even called a paddle bit.  These are the common flat bit that have a shank with a flat surface that  equal to the diameter of the hole that it will bore.  It will have a point (lead tip) to stabelize the bit as it bores into the surface.  Some will have two short pointed surfaces that have a cutting edge that precut the outside of the material that it is boring. This prepares the cut for the cutting done by the flat surface of bit.  the flat surface of the bit will have  an angles that is the cutting surface and actually scrapes the material from the material within the boring surface.  They are great for cheap bits to drill holes in rough carpentary but I would never drill finished material with them as the do a rough cut and dull rapidly ,  The will also drill a flat bottom hole but will have a deep impression made by the leading point that will be about 1/3 inch deeper than the bored hole.  If you want to use this type then the brand I use is" irwin."   Thes bits, as most all bits can be purchased individual and in sets.   More to follow later. 
Rita B. said:

Jay, please do not go to a lot of trouble with this.   My next project will require holes to be built for installing some desk grommets and such.   Planning ahead for supplies and while browsing the store noticed the variety and realized that they each must play a different role.

[Jay Boutwell]

Hi Rita, as promised here is the reply to your question about drilling holes and different type of bits.  You asked for some information on the types of bits and what they were used for.  I have not touched on the router bits that also bore holes and did not discuss the step drill that we are all familiar with and sometimes break off the points. It is the  the Kreg Jig bit.  There are also reamers of different type but most are not used in woodworking so I did not include them.
  There are actually several different types of bits that are made for boring holes in different types of materials.  The main difference in the classes are types made for drilling of metal and hard surfaces and those made for wood is the way they are built and material that they are made of.  There are bits of which is needed to cut different materials of which includes many different types such as plastics and other man made materials that are soft and easily cut.  Bits made for metal also include different types depending on the material they are made of.  Some have carbide or hard tool steel for drilling very hard types of materials and then there are the ones witch have diamond abrasive as well as carbide abrasive cutting surfaces.  In the abrassive bits there would be the ones for glass tile, ceramic and stone as well as the ones for drilling in concrete common in the construction trade.  Then come the specialized bit such as air craft drill bits that have long shanks to reaching into deep locations. 
In the drilling of wood materials such as in woodworking and including carpenter trades we find several of the same styles of bits built only having different concept of cutting and specialized bits for different applications.  In the normal wood working we find the need for drilling holes in such things as walls doors floors and then into cabinets and other installation of wood products.
When building cabinets and or furniture we find the need to drill into wood as we are building or altering some
something.  This  would not be so bad should the job be simple and easy to get to but in many situations it is not and in a difficult location.  Sometimes it requires a specialized hole in the project and therefore demands an assortment of different items to complete the job.
Available in this assortment of hole cutting items include specialized bits having long shanks like aircraft bits and others require just a flat bottom hole.  Others will require a hole drilled all the way through the item.
We have also the hole cutting saws of which are great for some operations that require a hole to be drilled all the way through the wood.  Some project being built or repaired may require a dowel to be installed of which now requires a bit that will bore a flat bottom hole an it must be the correct in size.
So we have special types of holes to do as well as the" all the way through hole" and how to do this will require some knowledge.
In starting to drill a hole you need a proper sized bit and the bit must be sharp.  On flat bottom holes the forstner bit is the one of most popular.   On occasions some will reach for the spade bit however this bit does a bad job on furniture and or cabinet unless the rough cut does not matter.  Both bits will require some method of drilling to a depth is it is being used to drill a flat bottom of which does not go all the way through the piece.  The most popular is a piece of tape set at a predetermined distance on the bit and the other is to just keep checking it with a gauge such as the multi- tool made by Kreg.  With the tape you continue until the tape hits the surface and with the depth gauge you keep checking the depth as you drill.  If used on the drill press set the stop for that depth and it will stop the bit when it reaches the set depth.  I do this when boring cabinet or furniture for European hinge installation.  depth is critical here or you set the hinge too deep or drill through the door front.
Other options of drilling a flat bottom hole is the use of a brad point bit which is an excellent choice as it usually has a center point of which does not drill as deep.
Another choice is a hole saw of which is use often to drill a hole all the way through the material.  This is the one of choice and used for cutting holes through the cabinet backs so that pipes and wired can be inserted into the cabinet. this can leave a lot of tear out on the exit of the saw unless a method is use to prevent this.
 
 It my practice to use the hole saw on both sides of the material  watching for the tip of the bit to exit the material if on 3/4 or thicker material and then cut from the opposite side by aligning the saw using the pilot bit as a reference.  I will do this when using any type of bit when I am drill all the way through regardless of how sharp the bit is.  It is not the sharpness of the bit it is the sudden breaking through the surface and the material that is not cut causes tears of the wood.  Plywood is the worse however all wood is prone to tear out in any board if it bored from only one side.   So if it is going to be visible then start the drilling from the visible side.  Tear out is a nasty problem to solve
 
 The link is to a slide show of which shows many of the bits of which I use in the cabinet business. and building trade  as well as installations of cabinets and also many of the bits while building them.

 

To play the slide show click on the link and it will load and open.  On the bottom left there is a icon to play in full screen and your ESC button of your keyboard to escape back to the small screen.  The show is musical so adjust your speakers to suit.  Enjoy and hopefully this will give you a better understanding ot the bit types and uses.
  Link:  http://www.smilebox.com/playBlog/4e4445774d6a41784e54553d0d0a&b...

[David Dean]

Nice smilebox Jay that was cool.

[Rita B.]

Wow Jay!  No wonder one can get confused over various bits.   Enjoyed the video and it was quite in depth.   Your smile box videos puts pictures in the mind for better understanding.  Do you do videos for u-tube as well?

Thanks to both Jay and James for your input.   Another couple of questions,   a hole saw labeled as Bi Metal, it is designed to cut both metal and wood?   Also, yesterday I was building some right angle jigs and it required a hole cut in.  I thought what better way to practice but as I was drilling,  I could tell there was a lot of burning going on.   Is that just the normal case or was I applying to much pressure to the drill?   It was a new hole saw cutter so the issue should not have been a dull blade.

[Jay Boutwell]

Hi Rita the hole saws that are marked bi-metal are one's of which will cut both wood and metal however the are not the best thing to use when cutting thick metal.  You could expect to find your self there a long time cutting and also dulling the saw.  They work well when cutting thin metal such as cutting a hole in a metal door for a lock set since the doors are only skinned with a thin sheet of metal.  You could cut fairly well through a 1/4" piece of aluminum reasonably well but a 1/4 inch thick piece of steel would be a little much for a hole saw. The selling point of these blades is that in the sheet metal trace holes saws are used quite a bit and also in remodeling trade they do not worry about nails and screws when boring a hole.

The burning you experienced is most likely the trapped saw dust that is in the saw kerf that gets hot and smokes.  That is one of the problems with hole saws as the sawdust gets trapped in the kerf.  When drilling a hole once you get the hole established with a kerf it works best is you pull the running blade out of the kerf to aid is getting rid of the saw dust.  You will find that you will get a faster and better cut this way.  you do need to be careful of the spinning saw and make sure you do not touch the metal as it will be hot and burn you.  The brands of the bimetal saws make a difference as they, like most other things have good brands and good brands.  Lenox are my favorite but there are several that are good blades.

Speaking of bimetal the next area of which you will see of which uses a lot of bi-metal blades are the reciprocating saws(sawzalls),  band saws, jigsaws and the popular plunge cut saws.

In answer to  your question about video for you tube, no I do not as I do not have the time anymore.  I do have a couple on there. 

I am glad you enjoyed the reply and glad it gave you a better understanding of bits.  Enjoy your work and work safe!  
 
Rita B. said:

Wow Jay!  No wonder one can get confused over various bits.   Enjoyed the video and it was quite in depth.   Your smile box videos puts pictures in the mind for better understanding.  Do you do videos for u-tube as well?

Thanks to both Jay and James for your input.   Another couple of questions,   a hole saw labeled as Bi Metal, it is designed to cut both metal and wood?   Also, yesterday I was building some right angle jigs and it required a hole cut in.  I thought what better way to practice but as I was drilling,  I could tell there was a lot of burning going on.   Is that just the normal case or was I applying to much pressure to the drill?   It was a new hole saw cutter so the issue should not have been a dull blade.

[Jay Boutwell]

Thanks David, it did take some time but did not know how to explain the topic without photos and the slide show is he best solution.  Have a good day in the shop and work safely,
 
David Dean said:

Nice smilebox Jay that was cool.

[james wilhelm]

Jay, very good write up for Rita, learned  a few thing,s for my self, and lot,s of good info.!!! Remember the old saying , a picture is worth a thousand words, really like the smile box, well done , well done and thanks for sharing with the community , JIM !!

[Jay Boutwell]

Thanks Jim, It was a hard one to explain without some photos, as drills cover a big spectrum of tools that we forget about at times.  I wished I would have had better photography conditions and time to do a better job.  I did this during my coffee breaks and finished it last night. Have a good day in the shop and work safely.
 
james wilhelm said:

Jay, very good write up for Rita, learned  a few thing,s for my self, and lot,s of good info.!!! Remember the old saying , a picture is worth a thousand words, really like the smile box, well done , well done and thanks for sharing with the community , JIM !!

[Rita B.]

Thanks again Jay!   The accumulating sawdust to burn makes a lot of sense now.   I was amazed at the amount of dust that one hole did accumulate.   I will practice a few more holes with the hole saw tomorrow before attempting one in my new project.   I hear you on the heat of the blades.   I have learned that the hard way a few times.  Near miss yesterday as well when the hole saw grabbed hold of my t-shirt.   Don't ask how it happened, it was just that quick.   Lucky for me that it did not touch skin but gave me pause to think how quickly a careless act can happen.