i've struggled to balance my lawnmower blade after sharpening it.
today, i tried drilling holes in the heavy end. I started with a small ~ 1/8 drill and tried working my way up.
these are my father's drills from a 1/64" drill set. He was a machinist, but these weren't his numbered/lettered drill sets. Some (small) ones were missing and there were different types, some all silver and some darker on the uncut surfaces.
i'm not sure what lawnmower blade is made of, but i'm guessing some type of steel, not just iron.
all the drills looked relatively sharp, none broken/ragged edges. Some cut easily through the blade. Others chattered and screached and i gave up on them, thinking they may shatter.
what is the likely reason that some drills cut so easily and others couldn't?
thanks
greg - Philadelphia & Reading / Reading
Greg,
The best way to check to see if a drill bit is still usable is to look at the angled cutting tip with a pair of optivisors or a magnifying glass:
Drill bits can be made from steel, high-speed steel (better), or carbide (best). They can also come with a variety of coatings applied to the surface to make them last longer - e.g. blackened oxide, cobalt, titanium, and titanium-nitride.
Chances are that the drill bits you used that chattered and screeched were just plain worn out. In instances like that a cutting oil (3-in-One or WD-40 can be used in a pinch) will help keep the drill bit take cool and could allow you to get a little more mileage out of a less sharp drill bit. However, if the bit just smokes but doesn't cut the material then it's time to resharpen it, or get another bit.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Most drill bits will cut through steel when they are new.
.
Spending the money on a good metal cutting bit is money well spent.
High Speed Steel (HSS) bits are commonly the type in sets, and these do not hold up well when used on steel.
-Kevin
Living the dream.
Everything Tom said +1
gregci'm not sure what lawnmower blade is made of, but i'm guessing some type of steel, not just iron.
A lawn mower blade is probably an example of some pretty carefully alloyed metals. Too hard or brittle and it will shatter, too soft or malleable and it won't hold an edge. So, the manufacturer will use a steel alloy that will have properties that will allow different degrees of "case" hardening, yet the bulk of the blade will remain "soft" so that if you hit a stone the blade won't shatter and send shrapnel flying into the neighbor's front window. Actually, a carbide-tipped mower blade would be ideal if it weren,t for the hazard of the carbide insert flying off and injuring the dog or neighbor kids.
Carbide-tipped machine tools have the best properties of both a very hard cutting edge but a relatively soft hub or shank that will resist breakage or shattering.
The drill bits themselves are similarly hardened so that the cutting face remains sharp but the shank remains relatively soft so the chuck can get a grip on it and not snap in two.
https://en.wikipedia.org/wiki/Case-hardening
If you see your drill smoking, you probably have already ruined it's temper and re-sharpening may not hold an edge any longer.
Lots of variables are involved in the types of steels that can be tempered, hardened, annealed, welded and machined.
Good Luck, Ed
In addition to what has already said, it can be as simple as different manufacturers quality control standards.
If you have access to a bench grinder, you can sharpen drill bits, though my eyesight now precludes me from successfully sharpening the small sizes.
Cheers, the Bear.
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
gregc i've struggled to balance my lawnmower blade after sharpening it. today, i tried drilling holes in the heavy end. I started with a small ~ 1/8 drill and tried working my way up.
Rich
Alton Junction
Lawnmower blades are not really meant to be resharpened.........Once you grind it down, it will loose it's temper and chips will develope in the cutting edge and will become duller than when you started. I don't waste My time. Throw it in the recyle bin and get a new one.
As far as drill bits go....look at the link for info:
https://toolandgo.com/best-drill-bits-for-hardened-steel/
I replace the two blades on My tractor every two season's, whether they are needed or not. It only costs 34.00.....I have a big yard, front & back and use a 24horse v-twin Tecumseh motor 46'' cut. Tractor is 15yrs. old still looks and runs brand new. When it comes to PM.......Why fool around to save pennies..........
Take Care!
Frank
Drill bits come in every grade of quality. An old mixed set probably has a variety of grades as well as degrees of wear.
I bought a set of Harbor Freight fractional / number / letter bits years ago. Cheap price = cheap quality. Smaller ones break off easily if they catch in the material being drilled.
Then I bought a fractional set of Norseman bits. WOW! They cut, not gum their way through steel. So then I found Norseman number sets on an Ebay store and bought them. What a difference good quality tools make. As a rule. Dan
Edited in: There are also different point types and different tip angles for different materials. I don't know all the facts on all that, but just getting good sets of general use bits pays.
SouthgateThen I bought a fractional set of Norseman bits. WOW!
that's what i thought with the bits that cut -- they cut smoothly through the blade with two spirals coming out -- beautiful.
I cut my lawn with a Murray standard mulching mower for over 20 years. After several years when I noticed the grass cut was becoming raggedy, I took the blade off and had it sharpened by a local lawnmower repair shop. No big cost but I was trying to save a buck. The resharpened blade lasted only one season and I was moved to just buy a new one at Home Depot and toss the old one to the scrap yard dealer. I ended up doing that several times over the years- the blades cost under $10. Some things you just can't recondition and must be disposable by definition.
By analogy on the layout if I replace wiring I use fresh wire, not that which has already been twisted or kinked from prior use.
Cedarwoodron
what do you think the lawn guys do?
on This Old House, years ago, they talked to one. He said he had to resharpen his blades every 2 weeks.
Grinding some metal off the end of the blade instead of drilling it may be an easier way to balance it.
gregc i've struggled to balance my lawnmower blade after sharpening it. today, i tried drilling holes in the heavy end. I started with a small ~ 1/8 drill and tried working my way up. these are my father's drills from a 1/64" drill set. He was a machinist, but these weren't his numbered/lettered drill sets. Some (small) ones were missing and there were different types, some all silver and some darker on the uncut surfaces. i'm not sure what lawnmower blade is made of, but i'm guessing some type of steel, not just iron. all the drills looked relatively sharp, none broken/ragged edges. Some cut easily through the blade. Others chattered and screached and i gave up on them, thinking they may shatter. what is the likely reason that some drills cut so easily and others couldn't? thanks
Being that your father was a machinist, the bits he owned were probably a lot better quality than the average. They do cost more, but they don't wobble as much in operation. Cost alone makes it worthwhile to resharpen them.
As to the type of bits, yes, there are different bits. The usual bits are more general purpose in nature, suited for wood or steel. There are more specialised bits, with a different cut, that are meant for brass. They work well in soft materials like brass, not so well in hard materials. It is possible they were mixed in with regular bits.
With hard materials, a cutting fluid is a good idea. In a pinch, kerosene will work. Many do use kerosene if they can get it at a good price.
My tractor has a 72" mower deck with 3 blades. I've always sharpened the blades with a file. It doesn't take that much longer to sharpen, you usually don't alter the balance, and it doesn't get hot enough to destroy the temper.
It's really not that hard, and I just use a screwdriver through the center hole to check the balance. If I do alter it slightly, just a couple strokes with the file will put it right back in balance.
Joe