Drill Doctor Question

[dimwittedmoose51]

Yeah, it's not old school, but it could be sharpening a bunch of my old drill bits soon.

I got the 750X model for Christmas and was curious as to the advantage of a 135 degree bevel on a bit vs. the standard 118 degree?.  Also, this machine gives you the option of "splitting the point'.  do I wont or need to do that on regualr bits??  Also if any of you have one of these units, any tips to make it work better.  I've done like 3 old bits I don't care about for practice, and the next round will be bits that need attention.

Thanks.

DM&FS



BTW, I did get a couple of old Hinsdale line wrenches under the tree from my son.  WINNING!!!!

[rusty]

The harder the thing you are drilling, the larger the point angle needs to be.

118 is typical for mild to semi-hard steel (what you are drilling holes in), if you are using the bits for alumnium, or wood, you can use even a smaller angle than that. The trade off is a flat (large) angle makes it harder to start the drill (assuming you don't bother with pilot holes) and the drill has to be feed more slowly. (use 135 if you drill high speed steel, assuming you can actually sharpen a HSS bit with that thing without lighting it up like a christmass tree and taking all the temper out of it)

If you generally use a pilot hole, you can use a smaller angle, which will increase drilling speed. If you are one of those folks who likes to start 1/2" holes in high speed steel without a pilot hole, and you hate watching the drill bit wander around all over the place, use the split point.  ...(split point drills were developed for deep drilling where chip buildup is an issue, but it also helps  you  to center the drill when starting a hole, and for keeping in the center of the hole when you are drilling without a pilot)

Once you get used top the idea of sharpening drill bits instead of throwing them away, learn how to do it with a stone, it wastes less of the bit, and you can do better than the machine ;P

[Ietech]

My experience with the drill doctor is one of the best when sharpening  --- if you actually got the model that will do 135 deg it will also do the split point for you. What a great gift for the "Workin' Man"

Yes Rusty you are correct -- most 135s (not all) are split point and require no need  for a pilot hole.

Hand drilling is best done (of course also depends on the material being drilled) with a 118 deg and a center punch to locate the accurate center and for larger holes a pilot is probably the best. For the drill press where you have properly located your center point the 135s are super - they require somewhat higher pressure and the larger the dia the slower rpm for the press. The great thing about 135s is that once accurately located, center, the drill will not wander and will toss the chips better. 

 BTW Happy New Year early.
Rich

[dimwittedmoose51]

Thanks gentlemen.  So if I retain the 118 angle, then I don't need to cut the split point in then???

DM&FS

[scottg]

Thanks gentlemen.  So if I retain the 118 angle, then I don't need to cut the split point in then???

DM&FS

Not at first.
 Drill bits taper over their length. When they are new only the largest bits or higher angle bits benefit much from a split point. It doesn't hurt any of them really, but certainly not necessary
 
 But the more you use and sharpen them, they get thicker and thicker at the web.
 The spine that runs up the middle.
  Pretty soon you practically have to split the point, or at least thin the web one way or another.

 I would be interested to hear how long the drill doctor takes, and how satisfactory the results are. I've been sharpening bits freehand most of my life.  Something that really did work well and quickly, I'd like to hear about.  Especially the little ones under 1/8" that are getting harder to see.
  yours Scott 
   

[dimwittedmoose51]

Drill Doctor says their units will sharpen bits down to 3/32" in diameter.  My experimenting tells me that once you watch the DVD that comes with the unit, it takes less than a minute to sharpen the average bit.  the 750X will do bits up to 3/4" in a\diameter....bigger the bit, the longer it takes to sharpen it.  I'm not an expert on this skill, so I don't know what to expect from the initial results.  I do know that there's some sort of a cam action during the grinding process that's spozed to simulate how the bit was original9y ground.  someone better informed might be able to answer your question more informatively.

DM&FS