DRILL DOCTOR ANGLES

[escavader]

Been experiimenting with my new drill doctor 500.Im trying to ge the bits to cut good through steel[mild]up to 1/2 thick for my projects.experimenting with 1/2 bit,and 1/2 battery operated drill:
Tryed at 135 degrees didnt cut good
tryed at 119 degrees didnt cut good
set bit up all the way to plus side /sharpened at 119 again still not that great
SPlit the point-cut great!!Now im confused might the 135 have cut good if i had split the point?

My question is for those who sharpen with theirs,
Should i be doing all my bits from 3/32 to 3/4 with the same angle,or should SIZE MATTER?119 for all or??
How much to the plus side should i be leaning it?Im assuming this determines how much comes off the back?
Ijust dont want to find out when trying to use them ,they aint working good
Iknow some one onTBN has been in this spot ,and have figured it out.Thanks
ALAN

 

[kenmac]

Try drilling a small ( pilot hole ) 1 st. this is the method I use. Can't remember the angle I use

 

[Wayne County Hose]

I absolutely love my drill dr. Instead of trying to go through with a 1/2" bit, why not start with a 1/4" bit then step up to the 1/2" bit? Maybe there's some formula for figuring what size to start with, but I don't know it. For me, I've found split point is a must. When I got mine, I did a little research and found that 135 degree was best all around for my application. I did have to do some fiddling with the bit depth in the drill dr chuck, but that's about it. I had to set the bit a little deeper in the chuck or it wouldn't cut enough. Wish I remembered more, but fortunately, it's been a couple years since I've needed it. I probably have at least 500 cobalt bits.

 

[scott_vt]

Good Evenin Alan,
I really dont think that your going to notice a huge difference in drilling chacteristics when changing your included by 15 degs IMO. Especially for the homeowner using a small drill press or hand drill ! What you will find helpfull is a pilot hole 1/8" to 3/16" being drilled prior to drilling a larger hole ! Also on your larger drills, you may need to thin out the web of the drill at the tip, this will enable you to drill easier with less pressure applied for the desired results. I have been in the trade all my life and I always sharpened or I should say touched up the larger drills myself. Now that my eyesight isnt as good as it used to be, the Drill Doc would really be great for those small hard to see drills. I think anything right around 125 degs included should work great for you. The secret to drill sharpening is making sure that your taking off equal amounts off of both flutes ! Also remember that when sharpening by hand that you have a primary cutting angle on each flute and then you need sufficient clearance beyond that. And of course dont forget your cutting oil !

 

[DieselPower]

135 deg is getting much more popular these day's with good quality bits. The 135 deg. split point is self centering for reduced thrust and easier penetration and less work hardening. Note, not all bits take having their tip spit very well. It really depends on the flute design and thickness.

 

[framer]

High Alan. I have drill dr. find it use less on bit that size 3/8 and smaller its
ok sharpening is slow.1/2 holes in 1/2 steel drill press or annular cutters
works best cutting lubricant a must..I have larger bits profesional
done last longer and better. Framer

 

[escavader]

Thanks for the replys guys.Itoo always sharpened myself,had a technique of cutting edge then turning while rotating [for clearance similar to the motion the drill doctor cam does.Except the drill doctor does the motion perfect each time.The problem i always have is not getting the cutting edges in the correct spot,in relationship with the flutes.
Dad brought his doctor to the house to show it to me,and i was so impressed had the wife get me one.Ireally like it.
I found by experimenting the 119 angle with the split point is the best ,also when setting up the bit ,going all the way to the plus side.Ithink this is the amount of clearance on the bit.They seem to cut the best for me this way.Ido agree using the small bit first,but with the split point ,they cut so good it wasnt needed.
Ihavent tryed to split a smaller one yet myself .Imay decide not to on 1/4 down,not sure yet.Ithink once ive got the angles perfected on all my bits ,touching up should be a breeze
What is the difference between the drill doctors and them exspensive units that are in NORTHERNS CATALOG?They look the same in the pictures.
ALAN

 

[scott_vt]

Good Evenin Alan,
For the heck of it I checked my machinists manual today at work, its a bit old, nineteenth edition that I got in 72 or 73 while serving my apprenticeship Yikes that along time ago !

Anyways the common point included angle then was 118 deg generally accepted. That angle increased for the higher tensile strength steels from 118 up to 135 degs. Various aluminum alloys 90 deg to 140. Magnesium 70 to 118.

As far as the relief angle that generally was from 10 to 15 degs. It was less on tougher alloy steels 7 to 12 degs, and when you got into the larger drills it was even less ! There is nothing worse that a large drill taking too much of a bite even while under power feed on a large machine tool, they can and will shatter !

On 1/4" drill bits and smaller that relief can increase with no adverse effects ! Soft metals 12 to 18 degs, and that relief will increase to 20 to 26 degs on 1/4" and smaller bits.

In conclusion, the average Joe homeowner really doesnt need to get involved in all this baloney. As I stated last night 125 or there abouts on the included angle should work fine for most drilling operations!

Hope this helps !

BTW like I said its more important that the cutting edges are of equal length, small bits the drill doctor does it, I did it by hand for many years before there was a Drill doctor, and on the smaller bits we would just go get another drill and throw the old one away !

 

[J_J]

Here is some good reading.

http://www.newmantools.com/machines/drillpoint.html

 

[escavader]

As far as the relief angle that generally was from 10 to 15 degs. It was less on tougher alloy steels 7 to 12 degs, and when you got into the larger drills it was even less ! There is nothing worse that a large drill taking too much of a bite even while under power feed on a large machine tool, they can and will shatter !
Evening SCOTTY,
Thanks for the info and looking it up.Iguess first it sounds like the better the quality bit,the less angle it needs. A big thanks on this info on the relief angle.Iwas wondering if there were any thing wrong with too much relief.Iguess id better back off a bit[no pun intended]
ALAN