Tool grinding persective

[Tin Falcon]

After reading the rant on the poor quality of a 115 pc drill bit set I got to thinking.
before I express those thoughts
I want to say this all respectful thoughtful input welcome.
I will not let this turn into another all Chinese tools are crap thread
or a American manufacturing is going down the tubes thread.
I have heard the complaints and the gripes and some are valid some use such threads to vent the same old stuff. I am looking for solutions to problems and a way to make the home shop productive and not pay top dollar for tooling .
I am not tying to solve a debate here if you can afford to pay full retail for new american made tooling god bless you if you only can afford the import stuff that is fine as well.
And i will remind you this is from the perspective of a home shop.

One of the points brought up in the other thread was getting new drill bits with less than a perfect grind. OK if you look at a machining manual or the machinery handbook you will see that different materials work best if the drill is ground for that material. Industry standard is pretty much 118 degrees for common use and a 135 degree for harder material and better performance. Brass and cast iron works best with zero rake at the edge .4/6 flute sharpeners are becoming more popular.
http://www.gadgetbuilder.com/DrillSharp.html
Info on the web is available. there was build article in home shop machinist and Tormek sells a very nice jig for drill sharpening. And of course there is the drill doctor. So IMHO there are many good reasons to have the tooling knowledge and experience to sharpen a drill bit in the home shop.

The first reason that comes to mind is better performance. Tools dull and drilling is likely the number one machining operation so you need to keep the edge. Then economy most HSM folks are more concerned about money than time so it makes sense to sharpen drill bits and get you moneys worth.

IF I pay 2-4 hundred dollars for a USA made drill bit set yes I want the cutting edge to be ground right. But if I pay say $ 50 for a HF set and some of the edges need work or the symmetry is off is that really a big deal ?
Like i said earlier sometimes you want a grind that is not factory standard.
If I purchased 100 lathe tool blanks for $50 I would expect to have to grind every one to my own specification and grind it to purpose. Is it that much different buying 115 drill bits for the same money and having to grind a few to make the do what I want?

This hobby is about creativity, understanding tools, geometry, metals etc. sometimes it is a matter of adapting to overcome even when it comes to a humble drill bit.
When I worked in the pro shop running CNC the first thing we would do when a new carbide boring bare came out of the pack was grind it the way we knew it would work best.

I am an advocate of getting the best you can afford and the best bang for the buck in the long run . We all have to choose our own tooling.

It should not be a big deal to sharpen a drill bit . And a $150 is a good bit of money to save.
I know many of you out there know what works best for you and have a strong opinion and that is fine . This is fa few thoughts for the open minded who love to machine but are on a budget.

TIn

 

[canadianhorsepower]

I have one of those titanium coating 115 drill set, It's about 8 years hold
and it serve me well. Sure when I'm doing carb work or precise drilling I take care to measure the drill, just to make sure it's dead on. Those that are off I simply take a marker and put a small line beside it's size, it's a ref for next time use. We all know that to much pressure on a small drill will get it to curve and have the wrong size hole anyway.

I have a drill doctor to sharpen my drill and would never get rid of it. I replace the cutter once a year 10.00 and it does miracle. I really endorse the product

 

[goldstar31]

I was having a think. So there are 115 drill sets- some expensive, some like mine- dirt cheap.
Look again at one contributor who has a lathe and the tailstock end is - not drilling properly- or so he says. So what use is a range of drills covering from nearly nothing to 1/2"? So far, the same problem arises if the tailstock is spot on but the drill chuck is one of those ****ty things that is either worn- or inaccurate- or both! Quite simply, it is a waste of time and effort and money - without having a drill chuck which is as near spot on as we can get- then get a set of fancy drill sizes------------eventually.

I've a set of drills- I've sets of more sets and different qualities and ranges from Imperial Sizes, Metric sizes, Letter drills and Number drills of varying qualities and a crate of drill chucks of various sizes and-- accuracies.

I have a confession because I have a set of Metric ones which are half a millimetre apart- and that's 20 thous total-- and they seem to cover my ordinary needs.

I expect that some comment will arise.

 

[Tinkerer58]

I agree with Tin, we all know Chinese product is not always A1, but you get what you pay for. I have some Chinese machines and I expect to pull them apart and set them up properly, it saves me lots of money and as far as I'm concerned it's half the fun of the hobby. Once you know the limitations of a tool you should allow for it and use it accordingly. If I need a tool that I would use on a daily basis and it's going to make me an income I will buy the best I can afford. If it is a tool to be used for hobby work or used rarely I buy what I can get away with for the job at hand.
I think it all boils down to your budget and your priority, so I don't rubbish Chinese product because it does the job acording to the budget. I have been involved in importing bearing and engineering components from China for 15 years and over that time the quality has improved dramatically, but if you buy the cheapest you can find that is what you will get out of a back shed in China somewhere. It all has to be kept in perspective, if I want cheap junk I can also buy out of a back shed in Germany, USA, UK and Australia or anywhere else you would like to mention, don't tarnish everything from China or elsewhere with the same brush.

 

[Hopper]

Not sure what all the drama about drill-sharpening is caused by. Every 16-year-old first-year apprentice used to be able to sharpen a drill bit on a pedestal grinder without jigs or guides or anything other than five minutes' rudimentary training and a little bit of practice.
It ain't rocket surgery.

 

[Tin Falcon]

Good points being made.

so why not pick up a cheap set to learn and practice grinding on ?

And an inexpensive set can be ground to use for plastic and brass.

Tin

 

[Tin Falcon]

Not sure what all the drama about drill-sharpening is caused by. Every 16-year-old first-year apprentice used to be able to sharpen a drill bit on a pedestal grinder without jigs or guides or anything other than five minutes' rudimentary training and a little bit of practice.
It ain't rocket surgery.

So true and every apprentice could use a file and chisel. Uses a hacksaw and knew how to grind a lathe and shaper tool for any application.IMHO all basic machinist skills. but in production shops Cutters are changed not sharpened and some shops send drills out for sharpening by machine because it is cheaper. or simply buy new drill bits.



Industry automation and cnc give us cheap goods and at the same time reduce the need for highly skilled machinists. This reduces the the need to machine operator.

IMHO the machinist, blacksmith and any other artisan will do well to learn to first draw with a pencil then shape metal with the hand eye and other tools.
The time to learn skill is never wasted. In the modern machine shop the skill of programming is just as important as filling . times force change and modern technology often accelerates change. It is called the Edison Effect an interesting read if you happen across the book.
In the home shop we machine because we want to and we have the opportunity to learn and preserve the skills and machines of years past and hopefully pass them on .
Turn off the power and see who can still make a part HMM. Maybe the Amish have an edge there.
Tin

Tin

 

[tornitore45]

I flunked a middle school entrance test and had to go to trade school.
At that time a felt very bad but it turned out to be the best thing in my life education.

In middle school we had wood shop and metal shop we learned to saw, plane, chisel and make joinery. In metal shop we learned to draw, read a vernier, file a flat and square surface, make a simple slide joint without light showing, in 8th grade I had an opportunity to work on a lathe, we also had metallurgy and machining theory plus physic the regular middle school did not have.

Instead of going to the high school that prepared toward law, literature, engineering and medicine, I opted for the Technical Institute to specialize in electronic but the first 3 years were the same for all specialization so I got to do more filing metal, lathe work, and foundry shop.

The manual skill, mechanical attitude and the practical sense acquired were very important in my future carreer.

All stuff you are not going to learn via computers. Computers are great tools but you have to have built something in your youth to be a real engineer.

 

[Tin Falcon]

Learning Recall Related to Type of Presentation

Presentation Ability to Recall
after 3 hours after 3 days
Spoken lecture 25% 10-20%
Written (reading) 72% 10%
Visual and verbal (illustrated lecture) 80% 65%
Participatory (role plays, case studies, practice) 90% 70%
Adapted from: Dale 1969.

Table 2. Transfer of Learning

Training Components
Skills Attained Transfer to Job
Theory
+ 10-20% 5-10%
Demonstration
+ 30-35% 5-10%
Practice
+ 60-70% 5-10%
Feedback
+ 70-80% 10-20%
Coaching
+ 80-90% 80-90%
Adapted from: Joyce and Showers 1981.

Discussion
“What I hear, I forget;
What I see, I remember;
What I do, I understand.”

– Old Chinese proverb, sometimes attributed to Confucius

A related comment from Bobbi DiPorter's 'Quantum Learning' is that we learn:
10% of what we read
20% of what we hear
30% of what we see
50% of what we see and hear
70% of what we say
90% of what we say and do
Active learning engages the whole person, not just the intellectual mind. When people try to do things and fail or succeed, emotions are triggered, and these have a significant effect on how we remember.
So when you are teaching or persuading someone, and particularly if you want them to remember things, get them actively involved.

from :http://changingminds.org/

One can clearly see the importance of hands on involvement in learning a task.


I love the line from Apollo 13." I need solutions people......... Failure is not an option." Gene Frantz Mission Director.



Tin

 

[Beachside_Hank]

Just bought a drill bit grab bag from H.F. Checked for quality, and all were surprisingly good, then I noticed about half of them were ground opposite normal rotation. I pulled out the books and was going to go about resharpening for standard drill press rotation when it occurred to me that I could still use them in my lathe for boring, just run the head in reverse. Hope this little missive is in keeping with the thread.

 

[mu38&Bg#]

My problem is that if you're going to take the time to do something why not just do it right? If the vendor cared to make sure they were getting decent drills they would get them. But if HF or whoever doesn't check and doesn't care and the customer doesn't care because it's cheap that's what everyone gets.

I have a 250$ USA HSCo split point set and it is excellent except somebody filled two adjacent holes with the same drill and I needed the missing drill. I buy USA made drills when I need them. I do have a bunch of drills from toolbox purchases and I sharpen them by hand when needed. I don't always get it right the first time, but have some very good split points I made.

Greg

 

[Tin Falcon]

Were they left handed drill bits? Yes they do make them great for drilling out broken fasteners and other times where counter rotation is desired.

I have heard of using broken mill cutters as boring bars


Tin

 

[dnalot]

I can grind a decent point on a larger bit , but the smaller ones are difficult. So i bought a drill sharpener and i have never used a dull bit sense. 20 years ago i bought a 150 pound lot of drill bits from Boeing Surplus. Highest quality and they have served me very well over the years.

My pet peeve is the crappy key-less chucks on cordless drills. So i bought a set of bits with a hex end for chucking. Now the bits turns in the hex base instead of the chuck.

Mark T

 

[robcas631]

Mark,

When I was 14, my father taught me to sharpen bits on a grinder. It's good to know! Call me lazy but I like the drill doctor.

 

[goldstar31]

I have heard of using broken mill cutters as boring bars


Tin

Actually keeping centre drills ( usually Number 1's) with broken points for boring bars is standard practice over here( UK) Usually they are high quality HSS and are 'the right size' to replace the previous one fitted with a grub screw in the array of boring bars which are made up from what is laughingly called 'Silver steel' I must have smashed a few because I have a set of internal screwcutting tools as well:wall:

On the subject of sharpening them instead, I confess to being unable to re-point them( satisfactorily) hence the above notes.

On the subject of reconditioning worn twist drills, I conclude that there are two schools. One is those who can and those who can't. I fit neatly into the latter category

I'm not going into the endless ****-ing match but hark back to my earlier remarks about cheap and not too nasty Chinese collets. They are admirable for lots of reasons and are ideal to 'do' twist drills using the four facet method. If you think carefully, this four facet method is how endmills and slotdrills are re-sharpened. Apart from the different angles on the points, there are surprisingly few problems.

Having said all that, there is the two facet method of grinding lathe tools for lathe tools are only half twist drills etc. Ooops:hDe:

Enough for one day, eh? Time to be cook, slut, butler and duty driver for my poorly wife.

Bye

Norman

 

[Swifty]

Hi Norman, like you I always kept worn out centre drills and broken cutters, mainly 1/4", to use as bits in boring bars. Bored many diesets to take guide pins and bushes with these boring bars.

Paul.

 

[Gordon]

Sort of on the same theme of learning the basics: I learned "drafting" using pencil and a straight edge etc. Today's "designers" learn CAD and never actually learn the basics. I have found that many of today's designers treat the production of drawings as a computer game instead of a way to transmit information. When I was working as a machine builder I had to make drawings for approval and graduated to CAD. Many times I found the recipient was more interested in their CAD standards on colors, layers etc and really had no idea what the drawings were actually trying to show.

Learning to draw using a pencil and learning things like orthographic projection should be required before letting the student loose on a computer.

 

[gerritv]

Learning to draw using a pencil and learning things like orthographic projection should be required before letting the student loose on a computer.

Learning to dimension would be even more useful. Some of the hobby-produced CAD drawings are useless.

Gerrit

 

[toolznthings]

I would be more interested in the quality of the drill bit material and worry about the grinding later if needed. Better material will allow for longer life and more sharpening. It's not hard to learn to grind drills by hand and the compromise of price and quality will always be there.

 

[BaronJ]

I've just bought a cheap metric set of taps, dies and tapping drills from Aldi. Imagine my surprise to find that the drills are HSS and all split point.

Not had chance to use them yet so I don't know how good or bad they are. But for £17 who knows.