Are "split point" and "four facet" drill bits exactly the same thing?
- Thread starter Kev
- Start date
Hi. Just read your post, and it brought back vague memories.
I didn't think they were the same, but that was as far as it went - lol.
So, googled "split point" and "four facet". All will be revealed - interesting, but, I found some of the info' heavy going.
A couple of quotes:
"A split point can have four facets."
"A four facet doesn't have to have a split point."
Must admit, it made me think about what bits I'll use for metal in the future (have lots of bits to use first though.)
Basically, it seems, can drill cleaner, quicker (with less effort) than with 'conventional' bits.
Just curious - what's your interest?
Richard.
I didn't think they were the same, but that was as far as it went - lol.
So, googled "split point" and "four facet". All will be revealed - interesting, but, I found some of the info' heavy going.
A couple of quotes:
"A split point can have four facets."
"A four facet doesn't have to have a split point."
Must admit, it made me think about what bits I'll use for metal in the future (have lots of bits to use first though.)
Basically, it seems, can drill cleaner, quicker (with less effort) than with 'conventional' bits.
Just curious - what's your interest?
Richard.
Four facets are one way of getting a split point. In the metalworking industry there are many variations on this theme. The end goal is to have a thin point that is still robust enough to withstand the pressure of penetration. The actual center of the drill is at a speed of zero. Pretty hard to cut at that speed. [smile] you are basically pushing the point into the material, hence the need to keep it thin.
Every drill maker on the planet has his own name for the manner by which they do this.
Every drill maker on the planet has his own name for the manner by which they do this.
You are correct that they aren't synonymous there is a great discussion at http://bbs.homeshopmachinist.net/showthread.php?t=51865 that will explain much better than I can.Kev said:
Kev
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fuzzy logic said:
I'm looking at two different sharpening systems for drills.
The Drill Doctor DD750X talks of sharpening split point drills and has a sharpening method that sharpens the primary cutting surfaces (the drill is fitted in a specialised chuck and you rotate the chuck in a cam socket against a cylindrical diamond cutting wheel). Applying the "split point" involves sticking the chuck containing the drill in a side socket of the Drill Doctor, but I haven't found a good technical description of the result achieved.
The Tormek drill sharpening jig is a bit of a beast, but videos explaining it's use show a solid procedure for producing a four facet sharpened drill bit - it seems to be a plodding, structured, methodical procedure. None of the Tormek procedures refer to "split point".
So the question is probably about the effective resulting drill geometry.
I'm also on the fence about the Drill Doctor because of the "air cooled" method of sharpening ... various schools of thought consider both the Drill Doctor and Worksharp methods of "air cooled" sharpening to be a bit misleading in that they both heat the sharpened metal tip and introduce a degree of brittleness to the metal, where a slow moving whetstone does not (e.g. Tormek).
... The fear hear is that the Drill Doctor is quick and easy, but produces a edge that blunts quickly v's the Tormek that "could" be creating a more lasting edge.
In the past I've only ever used a contraption that sharpens a drill bit against the side of my grindstone - very poor results. As you'd expect - I have a lot of drills now!
A further part of the conundrum is that the various sharpening systems are only good for common types of drill bits. Also, go under 3mm or over ~23mm are you need a different sharpening tool (and who sharpens under 3mm anyway?)
...
If there was a "cash for blunt drill bits" service I wouldn't even be considering a sharpening system!
Kev
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Jerome said:
Oh dear [eek]
This goes into materials, intended purposes and more point styles than I knew existed.
This is a great example of the third type of knowledge ...
1 is the stuff you know
2 is the stuff you know you don't know
3 is the stuff you don't know you don't know
I'm getting cold feet ... forget the cost of the sharpening system ... the time to do it, the time to get the technique right initially ... then the quality (the limit of my skill) as a result.
I just hate throwing drill bits away ... at least I don't keep old hacksaw blades like my father did [smile]
greg mann: thanks greg. I understand a little better now.
Jerome: Your link was one of the many I looked at. My eyes were already glazing over. Good stuff all - but struggled to take all in.
Kev: Thanks for the post. Will be researching, and then trying one or two of these bits. But re-sharpen them - gulp!
I also use my bench grinder to re-sharpen my bits - with similar results [unsure].
Richard
Jerome: Your link was one of the many I looked at. My eyes were already glazing over. Good stuff all - but struggled to take all in.
Kev: Thanks for the post. Will be researching, and then trying one or two of these bits. But re-sharpen them - gulp!
I also use my bench grinder to re-sharpen my bits - with similar results [unsure].
Richard
Kev,
I don't know the answer to your question but I can say this. I got rid of my drill doctor after I started using the Tormek. There really is no comparison in my experience. The Tormek is easier and cuts better and lasts longer. the Tormek really does as it advertises in my opinion. I resharpen brand new bits!
I don't know the answer to your question but I can say this. I got rid of my drill doctor after I started using the Tormek. There really is no comparison in my experience. The Tormek is easier and cuts better and lasts longer. the Tormek really does as it advertises in my opinion. I resharpen brand new bits!
waho6o9
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http://www.tormek.com/en/jigs/dbs22/index.php
Here ya go [big grin]
Tormek DBS-22 Drill Bit Sharpening Attachment
Here ya go [big grin]
Tormek DBS-22 Drill Bit Sharpening Attachment
greg mann said:
I would only add to Greg's usual great insight that the more a twist drill is sharpened (as the drill gets shorter), the thicker the web becomes. After sharpening the drill a few times it is also necessary to thin the web otherwise more and more thrust (and horsepower) is required to drill the hole. Probably not as pronounced in wood as in harder steels.
More than you wanted to know about twist drills:
http://www.mmsonline.com/articles/widening-interest-in-twist-drills
http://www.icscuttingtools.com/the-champ/drill_point_geometry.pdf
RonWen said:
We used to blank parts for a guy that had his own business making highly sophisticated cams and eccentric gears, and he did this before the advent of CNC. He was an old Ford Trade School graduate from a time when that meant you were amongst the elite of all toolmakers in the country. He used to complain that we did great turning work but had "the worst drilled holes in town." I wish he was around today to see how we drill. A normal day here is around 80,000 holes in ductile iron and forged steel. In DI a drill might last for 6 months before it needs to be sharpened. Not so in the forgings but even there they last an order of magnitude longer than they did in 1980, and they look like they were reamed. Quite often they look better than a reamed hole. How things have changed.
To do this, the factory grind needs to be duplicated precisely, the edge needs to be honed (usually with an abrasive brush) to a radius of from one to maybe three thousands of an inch depending on the material drilled. It is both an art and a science these days.
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