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General Category => Tutorials, Techniques and Tips => Topic started by: Len on August 06, 2011, 06:28:37 am

Title: tear out
Post by: Len on August 06, 2011, 06:28:37 am

Hi everyone hope you are all in good health.I would like to know how to prevent tear out on back side of my work after I drill the starter holes.Some of them are pretty deep for sanding,and I don't know what my planer would do to the work piece after it is cut out. Any help would be most welcome.

Thanks
Len

Title: Re: tear out
Post by: julief on August 06, 2011, 07:27:35 am

Len, To prevent tear out on your drilled holes, use a board under your workpiece to keep the bit from tearing out the bottom of the hole.  A scrap piece of anything will do.

Title: Re: tear out
Post by: Len on August 06, 2011, 07:32:07 am

I have been using a board and still get the  same thing mostly in pine,but also in oak.

Title: Re: tear out
Post by: newfie on August 06, 2011, 08:08:25 am

try taping the back side up before drilling and see what happens

Title: Re: tear out
Post by: Len on August 06, 2011, 08:17:36 am

I never tried the tape idea will try it  ;)Thanks

Title: Re: tear out
Post by: mrsn on August 06, 2011, 10:56:15 am

you will also get more tear out if you have a dull drill bit. You might get better results if you try a new bit.

Title: Re: tear out
Post by: dgman on August 06, 2011, 11:43:16 am

Hey Len, There are three important steps to help prevent tear out when drilling holes.
One, You must use a sharp bit.
Two, Use a back up board.
Three, Use the correct speed for the wood and size of bit you are using.
For a speed chart click here: http://images.meredith.com/wood/pdf/drill-press-speed-chart.pdf

Title: Re: tear out
Post by: TripleB on August 06, 2011, 04:09:12 pm

I just wanted to add about backer boards, it's important that they are flat to the back of the work piece. A warped or un-flat board will leave a gap between the work piece and the backer, that gap will allow for tear out as the bit passes through the gap. For the same reasons, you can't drill a smaller hole into a larger hole that has been made in the backer. Anytime the bit leaves the hole being drilled tear out will occur. I use a couple pieces of good, flat 3/4" plywood glued together as  backer and replace it once there is no more room for new holes.

Dan that's a great chart.

Title: Re: tear out
Post by: Len on August 06, 2011, 06:16:28 pm

Thanks to all of you for your help, I did all that was suggested and it worked ;D. One of my many new bits made a big difference,my wife said she was wondering when I'd use them :-[ .Got them on sale and forgot I had them ::) .
Again thanks ,
Len

Title: Re: tear out
Post by: dgman on August 06, 2011, 08:01:47 pm

Another happy customer!!! ;D

Title: Re: tear out
Post by: oohlookitsarabbit on August 09, 2011, 11:07:16 pm

Thanks for the chart! I have a variable speed drill press and no clue how to use it properly!

Title: Re: tear out
Post by: GrayBeard on August 09, 2011, 11:34:52 pm

Higher drill speed will decrease the 'tear out' problem as will using a  good flat backer under the piece being drilled.

~~~GB~~~

Title: Re: tear out
Post by: spiderman on August 10, 2011, 07:35:04 pm

use an good old fashioned hand crank drill when using one of these you'll get in to really good shape and lose a few pounds...