What angle to sharpen a drill bit
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Hey fella’s, got an odd question I need an answer to. Tommorow morning I am going to re-write my level one auto body tech test. Anyone not following my other threads I’ll bring up to speed. I want to get licensed and cant really afford the time off for school so am trying to challenge the tests instead. I have three tests and then the final license test to pass, so far I wrote the first one and failed it with a 66 or 67% i think it was, I need a 70 (and they make you wait 6 months if you fail to rewrite).
The test they gave me the last time was from the early 90’s and the questions were definately made up of things the majority of techs now probably have forgotten because its somewhat useless information but anyhow I need to know it for now..lol.. I’ve been studying from the course manual and after writing the first one have a better idea on what I need to know and feeling much more confident going in. What I need to know from some of you fine folks is “what angle do you hold your drill bit on when sharpening”, I believe the question was specific to a spot weld bit…..and buy a new one wasn’t an option on the test…lol..
I’ve looked threw my textbook several times looking for the technical answer on this but am drawing up a blank, wondering if someone can help me out in case they give me that same test again…(and considering the age of the one I got I’m willing to be they don’t have many to choose from). Anywho, thanks!
Generally around 15-20 degrees (depending on how you are measuring it). I do have the book somewhere (with the info that is used for the Red Seal exams) if I remember, I can try to check it for you
measure the angle of a new bit …. sorry best I can do :stoned
Screw the drill bit and get a plasma cutter :chair :chair :chair
lol, ya thx ben if you could I’d appreciate it.
[quote=”jimmo” post=17574]lol, ya thx ben if you could I’d appreciate it.[/quote]
Ok…just so you know, there are several exams. You probably won’t get the same exam next time. However, the exam you get could have the same question or one similar to it…or no drill bit question at all.
The question on the exam should give you the 4 options (a, b, c, d). Each should be a range. The correct answer should be 18-22 degrees (or something very close to that, depending on which exam you get). Do you recall what you answered on it last time?
:cheers
wait, wouldn’t it depend on the bit? some are 118 some are 135 etc.
[quote=”Ben” post=17577][quote=”jimmo” post=17574]lol, ya thx ben if you could I’d appreciate it.[/quote]
Ok…just so you know, there are several exams. You probably won’t get the same exam next time. However, the exam you get could have the same question or one similar to it…or no drill bit question at all.
The question on the exam should give you the 4 options (a, b, c, d). Each should be a range. The correct answer should be 18-22 degrees (or something very close to that, depending on which exam you get). Do you recall what you answered on it last time?
:cheers[/quote]
I dont recall what the choices were or even what i picked, they don’t let you see what you got wrong after either so that kinda sucks. I just took a wild guess. If I recall correctly the choices were all multiples of 5. I just tried to make a mental note of the questions that stumped me along the way. It was mostly these kinds of numerical questions…mig torch angles when doing a reverse weld or spot weld…HHS do not exceed temperatures, aluminum panel thickness, melting temps…ect….. a few questions on the electrical system got me too…
Another question they had was they give a VIN number and want you to identify the year, I counted it several times and it was a 16 digit VIN number and as far as I knew they were all 17.. I didn’t know to count 10 forward or 8 back….I was thinking it was a misprint but I wasn’t completely sure. For the estimating systems they were asking about removable storage including those bigass old black floppy discs and cdrw’s too, was interesting.
[quote=”jim c” post=17578]wait, wouldn’t it depend on the bit? some are 118 some are 135 etc.[/quote]
I believe spot weld bits are flatter than standard bits. They are about 150 degree…so if you divide the drill down the centre (at 90 degrees) and subtract the 1/2 of 150 you get 15 degrees (the angle that you hold the bit to sharpen it).
Ben is correct.
Most standard twist drills used for spot metal cutting are high to extra high clearance angle bits. meaning they are typically around 130-145 degree’s.
Compared to what is considered an average universal drill which is a low clearance angle bit containing a 118 degree clearance angle.High Clearance twist drills are typically used simply for the fact that they have a highly pronounced sharp chisel edge, and a very low profile cutting edge.
This basically means that the bit digs in fast, and cuts with as much surface as possible at once
This leads to more “Chipping” which means you’re taking more material out in less turns. Which equals less heat, which results in longer cutting life as well as a stronger bit, because more of the bit is doing the work at once.Unfortunately high clearance bits have virtually no self centering capability, as well as produce some of the least precise holes of many other angles and bit styles.
Some of the more specialty sheet metal cutters with the centering point on them rather than a chisel can go all the way up to a negative angle 182 Degree’s. (Although quite precise, These lose their initial cutting edge fast. thus are less common, making them more expensive.)
So the answer to your question, is that this test is straight up dinosaur age questions, and they ain’t got a clue what they’re talking about.
Hey jimmo. I remember many years ago i learned to sharpen a dril bit at a trade school and i also believe it was 15-20 degree’s. do like the other techs do jimmo, just go on the snap on truck and buy drill bits:rofl
Hey fella’s, So I called it right and got the exact same test as before. I am pretty sure I at least passed it this time. Definately have some issues with the test but whatever, I guess as long as I’m over 70 whats the point of compaining. AS for the drill bit question it was asking how to sharpen for use on high strength steel, my options were 60,65,70 and 75 degrees…forget what i picked now… i know I elected multiple of 10. so wish me luck on that. I got the exact same 16 digit VIN question and the one that kinda grinds my gears is what the safe temperature to heat HSS to, the options I had were all 900 degrees and under, my textbook says it 1200 degrees and some manufacturers recommend 1000…. needless to say its a bit frustrating trying to give the answers that nobody seems to agree on.
A few that stumped me still:
What is a cross action grinder used for
How much of the grinding disc should come in contact with the panel (guessed at 1 1/2 – 2 1/2 inches)
How many layers of steel is an oxygen tank made up of
What angle should a da sander be held at (I thought flat but apparently not)
Angle a Plasma torche should be held at
How much stonger HSS is over regular body panels in %
The PSI Tensile strength of HSS
A panel comprised of more then 0.50% is (low/med/high strenght or allow metal) I picked alloy
When sanding for filler use a (open or closed paper,wet or dry, carbide) carbide sounded the coolest so I went with it.
The condition name for when a mig wire sticks to the side of the tip and starts to curl
The period of time manufacturers are obligated to provide warranty for parts (picked 30 days)
Oxygen is this type of gas in oxyacetaline welding (chose active) options were passive, inert and something else
There were a few that asked for the terms refering to damage conditions….etc..direct, indirect, primary, secondary.. a bit iffy.
A few questions asking about names for metal durability conditions, I know i got tensile & yeild stength right, theres a few that were harder to answer.
I’m tired though, getting late if more come to me I’ll post em .
[quote=”jimmo” post=17667]Hey fella’s, So I called it right and got the exact same test as before. I am pretty sure I at least passed it this time. Definately have some issues with the test but whatever, I guess as long as I’m over 70 whats the point of compaining. AS for the drill bit question it was asking how to sharpen for use on high strength steel, my options were 60,65,70 and 75 degrees…forget what i picked now… i know I elected multiple of 10. so wish me luck on that. I got the exact same 16 digit VIN question and the one that kinda grinds my gears is what the safe temperature to heat HSS to, the options I had were all 900 degrees and under, my textbook says it 1200 degrees and some manufacturers recommend 1000…. needless to say its a bit frustrating trying to give the answers that nobody seems to agree on.
A few that stumped me still:
What is a cross action grinder used for
How much of the grinding disc should come in contact with the panel (guessed at 1 1/2 – 2 1/2 inches)
How many layers of steel is an oxygen tank made up of
What angle should a da sander be held at (I thought flat but apparently not)
Angle a Plasma torche should be held at
How much stonger HSS is over regular body panels in %
The PSI Tensile strength of HSS
A panel comprised of more then 0.50% is (low/med/high strenght or allow metal) I picked alloy
When sanding for filler use a (open or closed paper,wet or dry, carbide) carbide sounded the coolest so I went with it.
The condition name for when a mig wire sticks to the side of the tip and starts to curl
The period of time manufacturers are obligated to provide warranty for parts (picked 30 days)
Oxygen is this type of gas in oxyacetaline welding (chose active) options were passive, inert and something else
There were a few that asked for the terms refering to damage conditions….etc..direct, indirect, primary, secondary.. a bit iffy.
A few questions asking about names for metal durability conditions, I know i got tensile & yeild stength right, theres a few that were harder to answer.
I’m tired though, getting late if more come to me I’ll post em .[/quote]
Glad to hear you did better! :clappy
I know, there are always stupid questions. Many would be much easier to do as a short answer so you can justify what you put on. As for the drill bit, if you take 90 degrees and subtract the 20 (the angle I measure) than your answer is 70 degrees.
I’ve got the answers to those, when I have time later I will post them up…
Best of luck on your results there Jimmo.
I hate how much bull filler they have in those tests. You’re stuck thinking “what is the answer they want” rather than what is the correct answer.
like they’re probably asking about standard twist drills rather than actual spot weld drills. Because the people that wrote it don’t know a difference, or because the questions to this test are older than what is standardized today.[quote=”jimmo” post=17667]
What is a cross action grinder used for
[color=#ff0000]to remove metal (buffing action is milder and used to remove things like paint)[/color]How much of the grinding disc should come in contact with the panel (guessed at 1 1/2 – 2 1/2 inches)
[color=#ff0000]my book says the top 1 1/2 to 2 ” so you are correct[/color]How many layers of steel is an oxygen tank made up of
[color=#ff0000]the tank is made up of 1 seamless piece of steel (no layers) to safely withstand the high tank pressure[/color]What angle should a da sander be held at (I thought flat but apparently not)
[color=#ff0000]never heard that one. I was always taught flat. They might be getting at somethng else here. Just another stupid outdated question…[/color]Angle a Plasma torche should be held at
[color=#ff0000]start off perpendicular to the panel (with the tip lightly touching) then proceed to slightly raise the tip off the panel and hold at a 15-30 degree angle once the arc is established. This is to avoid tip damage.[/color]How much stonger HSS is over regular body panels in %
[color=#ff0000]200% (about twice as strong)[/color]The PSI Tensile strength of HSS
[color=#ff0000]HSS is about 70,000 PSI tensile strength (just like regular mig welding wire). Mild carbon steel is about 35,000 PSI[/color]A panel comprised of more then 0.50% is (low/med/high strenght or allow metal) I picked alloy
[color=#ff0000]compromised of more than 0.5% what? Sounds like alloy is correct here…whatever that are asking[/color]When sanding for filler use a (open or closed paper,wet or dry, carbide) carbide sounded the coolest so I went with it.
[color=#ff0000]Open coat (regular dry paper). Open coat means the abbrasive is designed not to clog (generally placed further apart). Closed coat is what wet paper is (grit is typically closer together and clogs easy…the water in wet sanding acts as a lubricant and cleans the paper out). This is why wet paper with the same grit as dry often acts coarser[/color]The condition name for when a mig wire sticks to the side of the tip and starts to curl
[color=#ff0000]The wire cannot move out of the tip, but the rollers keep trying to push it out so it bunches up inside the machine and makes a mess. This is called a rats nest.[/color]The period of time manufacturers are obligated to provide warranty for parts (picked 30 days)
[color=#ff0000]I would assume that new parts are required to have at least a 1 year warranty. I don’t have anything about this. Again, another stupid question…[/color]Oxygen is this type of gas in oxyacetaline welding (chose active) options were passive, inert and something else
[color=#ff0000]I believe active is correct[/color]There were a few that asked for the terms refering to damage conditions….etc..direct, indirect, primary, secondary.. a bit iffy.
[color=#ff0000]Direct damage is the area that was actually hit (like the centre of a dent or the corner of the car that physically hit the telephone pole). Indirect damage is the damage around this and throughout the car as it travels (the buckles around a dent, the edge of a fender that is smushed into the door, buckled rocker panel roof and 1/4 panel etc). Primary and secondary are similar. Primary is the damage caused by the vehicles collision (change in direction/stopping the car). Secondary is travelling in the direction of momentum. A car hit hard in the front pushes the primary damage back (in) such as pushing the rad support in. Secondary is the opposite direction. The buckles caused by the back of the car still moving forward while the front has come to a halt (buckled 1/4 panel, dash panel as the drives forward momentum makes him slam into the dash…the junk in the trunk slamming into the back seat etc). [/color]A few questions asking about names for metal durability conditions, I know i got tensile & yeild stength right, theres a few that were [color=#ff0000]harder to answer. If you can be more specific on terms it would help. There are a lot of terms related to metallurgy [/color]
[/quote]I hope this helps and that I have everyone correct. Let me know if you have more questions! :rock
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