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The Newbies Arena Are you new to knife making? Here is all the help you will need. |
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#1
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2 Questions to help me understand
Hi guys, I need help. First, I am making a hunting knife and drilling my holes. 4 - 1/8" and 2-1/4". I got all 6 drilled and wanted to check
and make sure that my pins all fitted correctly. I mic'd my rods and they are all dead on, .125 and .250. The pins will not fit. I was told once that drill bits are NOT to true sizing. Since they didn't fit, I mic'd the bits; .121 and .245 ... really ??? So the pins don't fit and I am drilling one size up. Here is my issue, I use DeWalt Cobalt bits and have never had a problem drilling through anything until tonight. From the .25 I went up to 5/16"(.312) and burned up 2 bits. I easily got the smaller bits through the steel with NO problem. I should mention that I am using 1080 soft and not HT. I always use either type of cutting oil when drilling. I even tried a step down bit and burned it up. Can anyone help me and tell me what I am doing wrong or what I am missing? I am using a drill press and tried speeds from 390 up to 1100, no difference. Second question ... why do manufactures make bits that are not true to size ?? I went through all my bits of different companies and steel, I could NOT find a 1/4" bit that was .250 ... I included some pixs to show the blade and the bits being used. The .312 looks like a countersink (looks the same on both side as I tried 3 different ways and bits) [IMG][/IMG] [/URL][/IMG] [/URL][/IMG] Thanks for your education and sorry for the rant Troy |
#2
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Are you measuring the bits on the shank? Drills are tapered from the tip to the shank. Measuring across the cutting adges is the way to get a size.
The rules for drilling steel with HSS drills are: use dry to cut waay oversize. To cut undersize, use oil. to cut oversize use water. To make the hole to size, use a reamer. |
#3
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Quote:
bit cool while drilling. Seems like I need to go buy a couple new bits and a reamer. Since I believe the got the steel hot and hardened, where should I go from here? Troy |
#4
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i use a size #30 for 1/8 " hole and size #12 for 3/16 "and size f for 1/4 " hole . these are just a bit over sized . get a drill bit chart off the web to get all your drill bit sizes .
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#5
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A little cheat for trouble work is a concrete drill bit. It has a carbide bit. They are not pretty to use but will get through. More than likely your bits are just dull and wont go through. You can learn to sharpen your bits. Yesterday I purchased some cheap bits, the 1/4" bit didn't even make the first hole. I sharpened it and it did much better.
Also, a pilot hole can be used and you can step up. I've used a 3/16 concrete bit and finished with a file. |
#6
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It's really difficult to cut a slightly larger hole when you are using only a small portion of the bit's cutting edge. I've tried this with a cobalt bit and it burn up on hardened steel. In your case, you are going from 1/4" to 5/16" and that's 1/32" of cutting edge on each side. Things get hot and dull pretty fast. Ideally you want all of the cutting edge in contact with the steel.
My workaround is to use a diamond coated die grinder bit in the drill press. They make them in Dremel sizes as well. I simply evenly "walk" around the inside of the hole. Once I had some mosaic pin that didn't fit after heat treating the knife. I know most guys will sand the pin to fit, but instead of sanding the thin walls of the mosaic, I opted to enlarge the holes. Dan Last edited by DanCom; 07-06-2014 at 09:49 AM. Reason: Added image |
#7
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Could using the dull bits, and/or higher speeds have work hardened the materiel around the hole you are trying to remove? If the steel around the hole hardened; then nothing short of a cobalt bit would cut it. Maybe some machinists or more experienced metal workers could chime in here. I suppose if you try a round file and still have trouble cutting, you could carefully anneal that area of the tang and then use your drill bits.
I may be looking too much into this, but it stands to reason in my mind. As far as the variations in bit sizes , I haven't had that problem. I use 3/32" size pin stock and 3/16 for thong hole tubing. I plan on increasing the size of the thong hole tubing to 1/4" soon and I'm sure I will run into the issue of what you described here. Thanks for posting those questions! __________________ AT "We shall walk with a walk that is measured and slow, And watch where the chalk-white arrows go To the place where the sidewalk ends." Shel Silverstein Last edited by ATalley; 07-06-2014 at 10:00 AM. |
#8
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When trying to go with the next size or two up on a hole that is already drilled you have to slow the drill press way down. Actually less than yours is rated for. Also it is even more important to have it clamped down to the table because the drill bit is very likely to grab. Learning to sharpen bits is an asset especially when you have to open holes up to the next size. I avoid pilot drilling unless I am drilling a hole 1.00" or bigger which is usually not a concern with knifemaking. The holes are likely work hardened but may only be the surface where the bit contacted so a sharp hss drill bit running slow enough shoild still get you thru or what Dan said about the dremel bit or even a mounted stone wheel would work great also. Hope it works out for you without too much frustration.
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#9
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You probably work hardened the steel by using too high an RPM.
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#10
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I keep a few carbide bits for my pin hole sizes.
they are not cheap, but they do cut |
#11
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Quote:
__________________ R Rogers Knives |
#12
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Wanted to thank EVERYONE for their help and insight !!!!
I am going to try all your recommendations and get my drilling correct with the correct bits. I thought to drill bigger holes that I was supposed to step up my holes to achieve the bigger one. I now know NOT to do that again. Colbalt bits into the wood only pile Troy |
#13
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I use carbide bits for drilling pin holes and then a carbide bur to carefully enlarge them. I get the closet fit that way.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
Tags |
blade, dewalt, diamond, drill, edge, education, file, help., hot, hunting, hunting knife, knife, make, making, o-1, pins, press, problem, sand, sharp, steel, tang, thong hole tubing, tips, wood |
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