OzVMX Forum
Clubroom => Tech Talk => Topic started by: mx250 on October 31, 2007, 10:07:32 pm
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Yeah, yeah I know; I'm the dullest tool in the shed and shoudn't be let loose with sharp objects or power tools, but do you guys have good results sharpening your drill bits?
I've never been shown or taught but I have very poor results; the new surface very quickly loses its effectiveness.
So what do you guys do? Just buy new ones or is there some trick or two that I'm missing.
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60 degrees, and make sure the cutting edge is the highest point. I 'natually' grind them so the bit that's digging into the material is behind the cutting edge - this doesn't work too well... :)
Don't put too much heat in - if you do, then slow cooling will soften the bit, making it blunten easily.
Beyond that, I'm interested to hear.
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STEP 1 Buy 2 drill bits and you well have a sharp one for Ron .
STEP 2 when the spare is F$#K
STEP 3 Repet step 1
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i have a sharping tool that fits on the side of my grinder that dose a great job keeps all the drills at the right angle , the right speed for diffrent size drills and cuting oil helps keep drills cooler
small drills high speed slow feed
large drills slow speed slow feed
hard metals slow speed slow feed
soft metals high speed high feed
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Drilling into what?
It depends on the material, drill size and if you go through or make a blind hole. Generally smaller dia drill require higher speeds larger slower speeds. Softer materials ali/steel can get away with 118deg point geometery harder materials stainless/Ti/ Inconel need slower speed 132deg point and flood coolant.
A good habit to get into is drilling pilot holes before going to final size.For drilling into thin materials I you can't go past step drills/cone cuts.
As for resharpening get a jig to get the right geometry, if you have overheated the drill it won't resharpen very well
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an easy way to set the angle is-
nuts have 6 sides right,
place two nuts together, {no, not those ones}
and the angle between them will be 120 degrees which is good enough for me,
all the tips as above but also, when grinding by hand, take care that both sides of the drill are even in every possible way.
a bit hard to explain without a picture or me nuts.
HTH
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Im still building my house and i for ever seem to be drilling in to the steel work, so far i have learned to slow down when i drive, but i have also got the recut down pat due to the number of times i have had to do it on these I beams. It dont seem to matter much on the angle ( some have been crazy) you cut at, but be sure your grinding from behind the cutting edge, so long as its higher than the back side your grinding in from, they always seem to work, infact i have been getting better result on the recut than when it was new, just hit it with the grinder "greek style" and if you can see a nice edge, its just gotta work.
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Modified a chain saw filling tool and adpted it to zee bench grinder , works for me
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i allso have a set of cobalt drills that are made for tougher drilling conditions cost a lot more but work a lot beter to
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http://www.woodcraft.com/articles.aspx?articleid=267
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If your of the average age of the VMXrider you have a lot to catch up,
you should have gone to Tech. for 4 years back in the late 60's to 70's then spent the next 30 years trying to teach apprentices how to sharpen drills before they invented the drill sharpener attachment,
A fine grinding wheel on a bench grinder is best but at pinch an angle grinder can be used
buy only High speed steel (HSS) drills they do not mind if they get hot while sharpening if you quench them in water before you use them,
Use a metal ruler with the end against a flat surface and hold the drill along the ruler then rotate to check that both side's of the drill are even then measure from each side to middle
and again get that measurement equal other wise drill will cut over size ,
if you look at the drill from the top it should have a "chisel edge" not a point across the smallest part of the undercut (middle )
the cutting edge should be the highest point when viewed from the side, but to much back rake (ie if the cutting edge is to high compared to the meat of the drill ) it will tend to make the drill bite in to much and jamb,
after you have sharpened the drill start a test hole and if it is not drilling to you liking take out and look at the top surfaces , you should be able to see where it is rubbing and where you need to grind a bit more of , if it is bouncing around a lot it probably has to much rake (ie too sharp)
Have a look at a new good Quality HSS drill before you use it (P&N Brand usually OK) to see how it is sharpened, both from the top and both sides
don;t bother with cheap drill bit's included free with your u beaut drill from Bunning's
use some sort of cutting oil when drilling ideally a specialised cutting lubricant like trefolex etc,but grease or oil with do (just)
aluminium likes WD40 or similiar,
(what do I do for a living drill Stainless Steel and teach apprentices)
Cheers
Noel
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First ever fitting job was a twist drill template.
Second one was sharpening every god damn twist drill in the factory.
Twist down and to the left .Other side twist down and to the left compare.
I really really wanted to be a chef.
some okay quality twist drills come with a handy cardboard template as part of the packaging . Must say that two hex nut template of Vandy's is a good handy hint
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Thanks guys, lots of good info and encouragement. I think it is the encouragement I needed - I was think drill sharpening was a waste of effort.
I think my mistake is not quenching the drill bit after sharpening. I think I get a fairly good shape (I compare to a new drill) and I use P&N's and lube the hole then drill( ;) ;D) mostly getting a satisfying results ( ;) ;D) . Generally I make my drills last well its just my sharpened drill that quickly deteriorate.
Back to the shed.... :) :) :)
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After 30 years of trying to get it right I asked the missus for a drill doctor for my birthday. Sharpened all my drill bits, called the old man over and did all his as well. I never have to deal with a blunt bit again, Great for us dummies that never went to tech.
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After 30 years of trying to get it right I asked the missus for a drill doctor for my birthday. Sharpened all my drill bits, called the old man over and did all his as well. I never have to deal with a blunt bit again, Great for us dummies that never went to tech.
Is this what you got crasher?
http://cgi.ebay.com.au/DD500X-Drill-Doctor-Diamond-Drill-Bit-Sharpener_W0QQitemZ170165101366QQihZ007QQcategoryZ3247QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
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Mines blue and looks a little different, but it's the same brand. Although I read in an english hobby machinist magazine where a reader wrote in saying he had one and wasn't happy with it. I don't know what the professional fitter and machinists think of them but for a laydummy like me who doesn't know better it seems good. I sharpened a bit and drilled through some 4mm stainless flat so that was good enough for me. They're expensive but I like to drill holes in things.