Drill bit web thinning.

[tonyfoale]

Prompted by Bob's excellent video on split point drill bit sharpening at http://www.homemadetools.net/forum/s...arpening-70940 I present my own simple tool modification for the same purpose.
Bob talked about drill point geometry and split point sharpening so I won't repeat that although I use the 4 or 6 facet geometry explained in my earlier post at http://www.homemadetools.net/forum/h...6205#post83247 .

Web thinning at the point of the drill enables a more accurate start to a hole and reduces wander, it also removes or reduces the need to drill a pilot hole with a smaller bit because the point of the drill is in effect the same as a smaller drill.

I had a little grinder designed for sharpening chainsaws which I used sometimes for web thinning but the blade was at an angle and was movable, this made it less than ideal for drill bit work. This is pictured below.

Click thumbnails for full size images.

To improve its utility I made this simple holding support from some bits out of the scrap bin.



The next pix show the grinder mounted on the support. It is now very convenient to use.



The wheel that came with the grinder is 3 mm wide which is fine for larger bits but too thick for smaller ones. Fortunately the hole diameter in 1 mm angle grinder cutoff blades is the same and so I change over to those for smaller bits.


Showing a 3 mm blade mounted with a 1 mm cutoff blade below.

[Frank S]

I have the Oregon brand chain saw grinder once ZI somehow odored a new grinding disk for it that had the RPM miss labeled I turned it on and was just getting started to make sure it was running true when it exploded even with the guard in place a large chunk was embedded between my 2nd and 3rd fingers, Hurt like all heck I pulled the piece of disk out of my hand only to find it had penetrated over 1/2" between the knuckles. so that caused me to decide to go to the emergency room to make sure there was no more debris inside. There wasn't and the doc said that he didn't want to stitch it up just pack the wound and let it heal on its own. I could have done that after all I had already done the clean out and disinfecting with a hydrogen peroxide betadine solution the only thing I didn't have was the ability to x-ray
I rarely use my saw grinder and only for sharpening the chains but I can see how they could work for what you mentioned, They just seem a little dangerous to me now even with the 10,000 RPM disk that I bought for it.
just gun shy I guess.

[tonyfoale]

I rarely use my saw grinder and only for sharpening the chains but I can see how they could work for what you mentioned, They just seem a little dangerous to me now even with the 10,000 RPM disk that I bought for it.
just gun shy I guess.

Gun shy matches well with 10,000 rpm. My grinder spins at closer to half that.

[suther51]

Thanks Tony for the post,
I bought a similar grinder off the internet that was so off from one side of the chain to the other I have started to make a small sort of all purpose grinder from it. I bought it to true up old chains to ring every last drop out of them but I can do better by eye than it could do and what is the point of trying to reset for each side I figure. Seems I will be able to use it as a sort of tool post grinder on the lathe also. Have found the narrow grinding wheel is helpful for some tasks as you clearly show in your post.
Eric

[Frank S]

I find that the fixed attitude of the grinder angle does not match well to the factory grind of many chains.
Like preciously stated by suther51 good for pulling the last little bit of use out of an old chain.
I won't use mine on a fresh chain that has had less than 2 dozen hand filings done to it. My grinder spins at 6500 RPM hence is why I use only the 10,00 RPM or better disks

[tonyfoale]

Thanks Tony for the post,
I bought a similar grinder off the internet that was so off from one side of the chain to the other I have started to make a small sort of all purpose grinder from it. ........ Seems I will be able to use it as a sort of tool post grinder on the lathe also. Have found the narrow grinding wheel is helpful for some tasks as you clearly show in your post.
Eric

Eric,

Using the narrow wheels is very useful and for drill points it works great, however if yours is like mine then it will not have anywhere near enough power to use as even a small TP grinder.

[tonyfoale]

I find that the fixed attitude of the grinder angle does not match well to the factory grind of many chains.
........ My grinder spins at 6500 RPM hence is why I use only the 10,00 RPM or better disks

I had no trouble with the angles nor sharpening the chains, but I do find it faster to do with a file. My needs are minimal, if I have to do a chain once a year that would be a lot.
I misunderstood your previous post. I read it as if your grinder spun at 10,000 rpm, now I see that you buy only buy 10,000 rated disks.

[DIYer]

Thanks tonyfoale! We've added your Drill Bit Web Thinner to our Grinding category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

Drill Bit Web Thinner by tonyfoale

tags: drill bit, grinding

[Frank S]

Tony my bad , I didn't include the 6500 RPM grinder speed for my reasoning for the 10,000 RPM disks These thin 3mm disks are not reinforced