Has anyone tried this?

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Wood Butcher

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I am not, nor have I been, a big fan of brad point drill bits. I do have a number of them but the points are, well, very pointy. I like to segment using metal along with some of the more boring wood species, acrylic and Corian and have had decent results. I've tried the glue ups with CA and with 5 min. epoxy with an overnight cure. The one issue I frequently have is that if the segmented metal/wood, etc. is on the bias, cut on an angle, I have a fair amount of failures at the glue joint. I have determined that the culprit is, as it always is, heat. When the drill bit gets to the metal it heats and the glue released. I caught this video on You Tube and wondered if anyone here can attest to its validity, does this work? If it does it could be an improvement. I'm gonna try it but wanted to check here in the meanwhile.
Note the point of the bits he grinds.
WB

https://www.youtube.com/watch?v=XA8L4L30TyI#t=331.2798664
 
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It is not heat. It is the angle you are fighting and any degree bit will have a tendency to grab the metal. 118degree is the common bit.
 
Those aren't the type of brad points used in woodworking, but they too look like the cutting edges would grab the metal. That's why the glue joints fail. The cutting edges grab the metal and try and pull the metal out, breaking the glue joint.

Ross
 
As stated by John & Ross, it will grab the metal. The metal basically becomes a plug at that point, and it's nearly impossible to drill any further. If you look at the video, once he cuts through the sheet metal, you can see a ring of metal at the tip of the bit. Now when the metal is segmented into the wood, that metal plug has nowhere to get out. I do know the time I had this happen, there was a lot of heat built up fast. But that may have been me pushing too hard, and not understanding what was happening. I don't know for sure if it was heat or the pressure I applied that made the joint fail, but it failed.

Now, I drill a pilot hole when drilling through segmented blanks. And I never use a brad point anymore.
 
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I suspect that for drilling mixed metal/other media blanks, pilot point bits are probably your best bet. If you have wood on the end, start with a brad point to keep the bit from wandering, and once you have the hole established, switch to a pilot point.

Perhaps we can find a graduate student in some engineering discipline who needs a thesis and would be interested in discovering/testing the best drill point geometry for mixed media?
 
I suspect that for drilling mixed metal/other media blanks, pilot point bits are probably your best bet. If you have wood on the end, start with a brad point to keep the bit from wandering, and once you have the hole established, switch to a pilot point.

Perhaps we can find a graduate student in some engineering discipline who needs a thesis and would be interested in discovering/testing the best drill point geometry for mixed media?


That info is out there already. The point there is not so much the angle of the bit but the amount of fascets on the bit for each material to gain the optimum. Now you combine wood metals and acrylics there is no cure all bit. Then top it off and put the blank on a bias and all bets are off. The true key is the adhesive that is used. Plus the speed at which is drilled and if at all possible extra support on the outside of the blank and that is why it has been sugested many times over that popsicle sticks or some sort of webing be applied to the outside for fragile segmenting. Can not get the blank hot or the adhesive will fail.

Thats segmenting. :)
 
Just throwing this out there, but would drilling with a smaller bit for a pilot hole first work?
Maybe half the size of the final bit.
Less of a contact point, and would give the final bit a chance to stay centered and not tear away inside so easy.
 
Just throwing this out there, but would drilling with a smaller bit for a pilot hole first work?
Maybe half the size of the final bit.
Less of a contact point, and would give the final bit a chance to stay centered and not tear away inside so easy.


Not really and in fact I have found it to be worse because now you are pulling at edges of metal. My suggestion is to use the correct bit right away. Now this is just my opinion and I give them out freely:)
 
The video is good for the purpose that it is used for. To drill straight round holes in sheet metal or wood at a 90 degree angle. Notice how much pressure it took to puncture the sheet metal and the washer that was formed on the end of the bit that would stop the drill from traveling any depth in metal. The wood clears the chips out , so there is no problem there. But you are not going to be able to drill the sheet metal at a 15 or 20 degree angle and produce the oval hole you need in segmenting!! The pilot point on the sheet metal drill will tend to slide down the angled metal in your blank causing heat to soften the glue or lateral pressure that will break your blanks. As John T says, there is no magic drill for mixed materials !! However there are solutions I have used to solve this problem. First, but not 100 % full proof, is to soak the outside of your blank with thin CA, hit it with accelerator, and wrap it tightly in duct tape or some other nylon reinforced packing tape. This may not keep it from coming loose, but it will keep all the pieces together and inline so you can glue it back together, most of the time. Resoak the inside after drilling and rerun the drill bit back through before untapeing. The second method I use is to drill my blanks before I assemble them. How do I do this ?? Drill the wooden or poly blanks before cutting into segments. I have made several jigs out of 1 inch square metal (whatever you have on hand) and short enough to fit the stroke of the drill press. Drill the size holes you will need to fit your pen tubes at least 3/4 of the way into the metal jig, or all the way if you want. Next cut 4 one inch by the length of your jig wood or metal strips about 1/4 inch thick. Stick these to the four sides of the jig with two sided tape. Drill 2 holes in each about 1" from the ends all the way through the slat and the 1" square metal. Tap the metal out for small machine screws. Take your slats and enlarge the holes on one end so you can slide the jig apart and have enough room to fit the thickness of the you intend to insert into your blank. Now cut the metal jig in half at the angle you want to insert the metal pieces at. When you go to drill your pieces you will only have to remove one side of the jig and loosen the screws where you have elongated the holes on the other three. I cut my metal pieces 1 inch by whatever the inside measurement of the jig is after you cut your angles. put the remaining side back on and tighten all your screws. Drill your perfectly angled holes in the pieces. I do my glue ups on the tubes I am going to use and coat the blanks again with Thin CA to fill any voids. If you don't use a metal lathe, or even if you do, take your blanks to the band saw, disk, or belt sander and round off the corners for smoother turning. Jim S
 
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