- Joined
- Jun 23, 2011
- Messages
- 786
Hi folks, Long time no post. My machinist hobby goes in spurts and I'll go through a period of months where I have no desire to play in the shop. Then an idea for a project hits and I'm off and running. This time is no different.
I had a hankering to see what the hype was surrounding 4-facet drill sharpening and thought you guys would enjoy the results and the process.
Being fortunate to have a surface grinder and an old flaring cup wheel, I figured the hard part was already done. So, I just had to figure out how to use stuff around the shop to pull the rest of it off... Seeing my spin indexer and 5C collet set made me think, there's just the thing I need to hold a drill bit and be able to accurately index the bit 180 degrees so I could sharpen both lips. After that, I needed a way to angle the spin indexer to the primary and secondary relief angles. I chewed on that one for a while and tried a few things: angle vise (tilts the wrong way and the tightening handle is in the way if I turn it around), tilt table (too hard to set and tighten down), and a few other ideas that weren't fruitful.
In any case, my grinder's magnetic chuck wasn't deep enough to hold the spin indexer and still leave me enough fore and aft movement while securely holding the spin indexer with the bit protruding. I figured a steel plate on the magnetic chuck overhanging the front of the grinder would solve that. I started to price ground steel and CI plate and got sticker shock! Big $$$. So, knowing I had an old 3/4 steel plate kicking around, I cut it up and welded it back together shaped like a T then ground it flat on the surface grinder.
Getting back to being able to tilt the spin indexer, finally the idea of using a sine plate hit me... Problem was, I didn't have one. I asked around at work and a few of the older employees remembered we had one kicking around someplace. After about 1/2 hour of searching, I found it and was able to borrow it for the weekend. I have a set of gauge blocks, but I was curious what primary and secondary angles I'd get using a 123 block instead: 11.5 degrees and 23.5 degrees. Sounded reasonable enough to me...
I now had everything I needed and spent nothing.
Here's a picture of the setup:
![IMG_0042[1].JPG](https://www.hobby-machinist.com/data/attachments/35/35525-e3153728ff2afeb8857c9b90ec80fded.jpg "IMG_0042[1].JPG")
Here's a closeup view:
![IMG_0040[1].JPG](https://www.hobby-machinist.com/data/attachments/35/35526-1c6732f7e3f7fd201453ba3f183a4604.jpg "IMG_0040[1].JPG")
and a close-up of the first drill off the setup, a monster 1-1/16 silver and deming:
I chucked it up in the tailstock of the lathe, put a junk piece of aluminum in the chuck and drilled right through it. No pilot hole, no center drill, no nothing. Just as I'd head about 4-facet grinds, they take much less axial force to drill and walk a lot less. All true... It did seem to chatter a bit more, but that was in my opinion due to the aggressive 11.5 primary angle I used.
A successful experiment and it cost me nothing! If it's free - it's for me!
Cheers,
John
I had a hankering to see what the hype was surrounding 4-facet drill sharpening and thought you guys would enjoy the results and the process.
Being fortunate to have a surface grinder and an old flaring cup wheel, I figured the hard part was already done. So, I just had to figure out how to use stuff around the shop to pull the rest of it off... Seeing my spin indexer and 5C collet set made me think, there's just the thing I need to hold a drill bit and be able to accurately index the bit 180 degrees so I could sharpen both lips. After that, I needed a way to angle the spin indexer to the primary and secondary relief angles. I chewed on that one for a while and tried a few things: angle vise (tilts the wrong way and the tightening handle is in the way if I turn it around), tilt table (too hard to set and tighten down), and a few other ideas that weren't fruitful.
In any case, my grinder's magnetic chuck wasn't deep enough to hold the spin indexer and still leave me enough fore and aft movement while securely holding the spin indexer with the bit protruding. I figured a steel plate on the magnetic chuck overhanging the front of the grinder would solve that. I started to price ground steel and CI plate and got sticker shock! Big $$$. So, knowing I had an old 3/4 steel plate kicking around, I cut it up and welded it back together shaped like a T then ground it flat on the surface grinder.
Getting back to being able to tilt the spin indexer, finally the idea of using a sine plate hit me... Problem was, I didn't have one. I asked around at work and a few of the older employees remembered we had one kicking around someplace. After about 1/2 hour of searching, I found it and was able to borrow it for the weekend. I have a set of gauge blocks, but I was curious what primary and secondary angles I'd get using a 123 block instead: 11.5 degrees and 23.5 degrees. Sounded reasonable enough to me...
I now had everything I needed and spent nothing.
Here's a picture of the setup:
Here's a closeup view:
and a close-up of the first drill off the setup, a monster 1-1/16 silver and deming:
I chucked it up in the tailstock of the lathe, put a junk piece of aluminum in the chuck and drilled right through it. No pilot hole, no center drill, no nothing. Just as I'd head about 4-facet grinds, they take much less axial force to drill and walk a lot less. All true... It did seem to chatter a bit more, but that was in my opinion due to the aggressive 11.5 primary angle I used.
A successful experiment and it cost me nothing! If it's free - it's for me!
Cheers,
John
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