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I make a very useful tool in this video. We all use Countersink Drill Bit. It is possible to buy for cheap, but can not we do it ourselves? I wanted to try it and decided to do it. For 4mm drill bit, I started by cutting a 12mm bolt. Then I used a file and gave it the shape I wanted. In the end, something good appeared. I even did the second one, I made for a 3mm drill bit from an 8mm steel bar.
If you want the screw heads to fit properly, you should drill a pilot hole with a Countersink Drill Bit. Whether you buy it or do it yourself, use Countersink Drill Bit. If you want to make it yourself, just watch this video.


Making Video :
Go to this video's Youtube page and make a comment.
This is the page that contains the desktop jointer's videos. You can view the 3D model video. You can download the PDF plan.

After watching this video, you can download the free PDF document and make it easily. There are many 90 degree corner clamp videos on youtube. But this is a little differ