Forstner bit sharpening jig

For these 2 forstner drills I payed the same money   as for a complete set of  15 drills from 10 to 50mm. Today we will sharpen one of the cheap drills  to perform as well as the expensive ones. The cheap drill is not cutting very  well. It is creating dust but not chips.   The more expensive one in contrast is  creating curly shavings. Let me show   you how to sharpen a drill with this jig and  then show you how to build this jig yourself. Let's put the drill in the jig and tighten it. We will first sharpen the outer  rim. After removing the lockpin   from the jig the chuck is locked in place and we  can tighten it to hold the drill bit in place. For the outer rim we use either a cheap diamond  or a abrasive grinder with a cylindrical shape.   The grinder is put in a drill press. We put the lockpin back in the jig  so that the chuck can rotate freely. After loosening the knobs on  the sides we adjust the angle   so that the edge of the outer rim  is in full contact with the grinder. As a quick test you can  color the edge with a sharpie   and control that at least the upper  half of the coloring is removed. Next we push the base very  much to the front of the track   and fix the plywood base to the drill press table  so that the edge is just touching the grinder. After starting the drill at slow speed  we can carefully grind the cutting edge. With the same setup we can touch  up the tip of the drill bit. Let's remove the lockpin, loosen the chuck, then  adjust the tip so that the side of the tip is   parallel to the edge of the jig  and then tighten the chuck again. Again the angle is adjusted so that the entire  side of the tip is touching the grinder. When locking the plywood to the table the tip  should only lightly touch the grinder. Now   we move the jig forward within the  tracks and grind the first side. After the first side is  refreshed we move the jig back,   turn the drill 90 degree and  continue with the next side. The last edge we have to grind is the  inner cutter. For the inner cutter   we have to switch from the cylindrical  grinder to a grinding or a diamond disc.   Fix the grinder in the drill press and  put the jig on the drill press table. The lockpin is not in the jig and the cutting edge  is aligned parallel to the front side of the jig. The angle is adjusted so that the  entire cutting edge touches the disk. Move the jig forward to grind one edge. Stabilize  the jig with your hand while moving it forward. Then move it back, turn the drill  180 degree and grind the other side. The freshly sharpened drill performs really  well. It is creating chips and drills super fast. Let's now have a look how to build  this jig. All the STL files and a   very detailed assembly instruction  will be for sale on my website. The first thing to assemble is the  chuck. Here we have to options. Either   a fully 3d printed chuck or an adapter for  this cheap Chinese quick release chuck. For the quick release chuck we just print  the adapter and press fit it to the chuck.   When you are sure that it works it is a good  idea to secure the chuck with a drop of glue. For the 3d printed chuck we need  to pick the right diameter of the   forstner bit shaft. I created versions of  the chuck in 0.5 mm increments - just pick   the one that corresponds to the  diameter of your forstner bits.   The shaft of my set is 9.5mm and the 3d  printed version works for the entire set. Next are the knobs. For the larger knobs  we press fit an M8 nut into one part.   The other part gets a 100 mm long  M8 machine screw tapped in place. The Square base holder is secured with  a 70 mm long M6 screw to the trackbase. The next step is optional  and not strictly necessary.   When grinding several drills in a row I found  it more convenient to mark the right position   and lock the base in a certain position  in place rather than clamping down the   entire base. For this feature we install an  excentric lever with a 50mm M6 machine screw.   When pushing the lever forward the  base is locked securely in place. After connecting the two M8 knobs through  the base we can lock it at a certain angle. The first track is positioned on the plywood   and aligned parallel to the border. The holes are  predrilled and the track is secured with screws. With a paper shim between the track and the  base the other track is screwed in place.  After removing the shim the base should  slide freely between the two tracks. The last thing to assemble is  the lockpin. Glueing the two   parts of the cap together is only for the  look. And with that the jig is finished. I sharpened now all my forstner bits with this jig  and it performs really well. The drills work fine   and in contrast to an expensive set for 300  Euro I can resharpen them whenever they get   dull again. I will leave a link to the  plan and the STL files in the description.

Channel: WayofWood

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Id: g84EHTufaes

Length: 7min 17sec (437 seconds)

Published: Sat Mar 20 2021