j_nigrelli Posted February 1, 2007 Posted February 1, 2007 is there a source of drill bits smaller than #80? if a 1/25th scale inch is 40 thousanths (.040), then a quarter inch is 10 thousanths (.010). a #80 drill measures about 12.5 thousanths (.0125) if i'm reading the dial caliper correctly. when i use the drill for .010 brass wire the hole yields a reall sloppy fit. help appreciated. j
bob paeth Posted February 1, 2007 Posted February 1, 2007 I wonder if just heating the wire and pushing it through the styrene would work. Naturally I would suggest using neddle nosed pliers in trying this method. Bob :shock:
Steve H. Posted February 1, 2007 Posted February 1, 2007 www.micromark.com Item #60362 bits from #60-#80
dptydawg Posted February 2, 2007 Posted February 2, 2007 According to the chart on this site http://www.madison.k12.wi.us/toki/teched/codrills.htm you need a #87 drill. Were you get one is a different story. I didn't know that they existed that small. they would be fragile little suckers Thanks Carl Avis edit: Here is an excerpt from that above site: Continuous Drill Bit Sizes Measurement Systems (Include: fractions, letters, wire gauge numbers and metric sizes Drill bits from zero to one half inch are sized in four ways; fractions, wire gauge numbers, letters, and metric in millimeters. You will see drill bits with a fraction, number, letter or metric number stamped on their shank indicating their size. The fractions range from 1/64 inch to 32/64 inch. The numbers range from 107, (smallest) to 1 (largest). Where the number 1 drill bit leaves off the letter A (smallest) begins and continues through the letter Z (largest). The metric sizes are dispursed throughout. All of these drill bits are different in size except for the 90 and .22mm which are both 0.0087 inches in diameter, the 85 and the .28mm which are both 0.0110 inches in diameter, the 13 and the 4.7mm which are both 0.1850 inches in diameter, the 4.8mm and the 12 which are both 0.1890 inches in diameter, and the 1/4 inch and letter E bits which are both 0.250 inches in diameter. All of the drill bits are listed below with their decimal equivalents. Drill Decimal Bit Dia. Equivalent 107 0.0019 106 0.0023 105 0.0027 104 0.0031 103 0.0035 102 0.0039 101 0.0043 100 0.0047 99 0.0051 98 0.0055 97 0.0059 96 0.0063 95 0.0067 94 0.0071 93 0.0075 92 0.0079 .2mm 0.0079 91 0.0083 90 0.0087 .22mm 0.0087 89 0.0091 88 0.0095 .25mm 0.0098 87 0.0100 86 0.0105 85 0.0110 .28mm 0.0110 84 0.0115 .3mm 0.0118 83 0.0120 82 0.0125 .32mm 0.0126 81 0.0130 80 0.0135 .35mm 0.0138 79 0.0145 1/64 0.0156 .4mm 0.0157 78 0.0160 .45mm 0.0177 77 0.0180 .5mm 0.0197 76 0.0200 75 0.0210
Guest zebm1 Posted February 3, 2007 Posted February 3, 2007 ahhh, a #80 drill bit is actually 0.0135, better get yur eyes checked for :shock: glasses man yu sound like me...farsighted. :wink: or perhaps yu should resize yur drill bit to fit tha 0.010 brass wire, tha number drill for that wire is #39, which is actually 0.0995. I mean, yur not using "1/25th scale" brass wire are yu j? :twisted:
Guest Anthony Oteri Posted February 3, 2007 Posted February 3, 2007 zebm1 said: ahhh, a #80 drill bit is actually 0.0135, better get yur eyes checked for :shock: glasses man yu sound like me...farsighted. :wink: or perhaps yu should resize yur drill bit to fit tha 0.010 brass wire, tha number drill for that wire is #39, which is actually 0.0995. I mean, yur not using "1/25th scale" brass wire are yu j? :twisted: Boy Zeb u sur r good wit numbrs! :wink: :wink:
j_nigrelli Posted February 3, 2007 Author Posted February 3, 2007 admittedly i am not using a journeyman's quality dial caliper [general fiberglass - $22 at the big box stores]. the wire i use is by Detail Associates [our friend in the model railroad section]. the wire was marked .010. i used the dial caliper as a "go - no go" guage and both the bit i used and wire made a snug fit. the best i could guess [the dial is divided in .010 increments] is an approximation of .0125 so maybe your .0135 measurement is more accurate than mine eyes can extrapolate. could the loose fit [of the wire in the hole - material = styrene] be attributed to radial thrust while drilling? i am using a pin vise. i don't understand where the #39 drill bit came from...? but my original question was: Where could I get drill bits smaller than #80?. it's okay; sometimes "I don't know" IS the correct answer!
bob paeth Posted February 5, 2007 Posted February 5, 2007 For very small drill bits, check out what Dremel has to offer. I am not sure the dinensions of these bits but the smallest is very SMALL. I picked mine up at the Home Depot. they come in a metal case for easy storage. Bob :shock:
j_nigrelli Posted February 5, 2007 Author Posted February 5, 2007 thank you; i'll give them a shot. j
Guest zebm1 Posted February 7, 2007 Posted February 7, 2007 J....according to my drill bit lists, there is no actual 0.010 thousandths drill. The closest is a number drill - #39, which is 0.0995 thousandths dia. As to yur loosy-goosy fit, I'd say that yu are correct J, radial (side-ways) thrust is always a problem when using a pin-vise drill holder. Tha only way I can think of to make sure that yur hole has no radial thrust wuld be to chuck tha drill in a minature lathe and use a clamp mount on yur tail stock. But that would only work on small pieces. As to a drill bit smaller than a #80, I've never seen nor heard of one. Yu'd probably need an electron microscope to see tha lands on tha cutting edges of a drill that small. Zeb
j_nigrelli Posted February 7, 2007 Author Posted February 7, 2007 oh Lordy; now i have to go out an' buy a lathe, too???? i should have stuck with military models...... Carl, thanks for the good technical supplement; i printed it for reference. j
j_nigrelli Posted February 7, 2007 Author Posted February 7, 2007 .010 vs .099 isn't one of these numbers 9 times greater than the other...??? i guess this is why i was a carpenter rather than a machinist!
j_nigrelli Posted February 7, 2007 Author Posted February 7, 2007 okay: "Where could someone purchase a #87 drill bit?" that's all; this is becoming obsessive. lemme see, needle, match, pliers. okay, here goes...... Ouch!
crashalot2 Posted August 8, 2007 Posted August 8, 2007 Look in the train area of your hobby shops , they have drill bits so small that if you drop one you will never find it
Modelmartin Posted August 9, 2007 Posted August 9, 2007 Sorry I am responding 6 months after you asked. The Hobby shop stuff stops at #80. I would suggest machine tool supply places. There may be some online places too. I found a #87 drill bit for $13.00 !!!!!!!!!! I would use that #80. All you need is some sort of drill press to drill straight holes. You don't need a lathe! Can't recommend the heated poker thing. I can't imagine the wire retaining enough heat to sink through the plastic.
James W Posted August 10, 2007 Posted August 10, 2007 Modelmartin said: Sorry I am responding 6 months after you asked. The Hobby shop stuff stops at #80. I would suggest machine tool supply places. There may be some online places too. I found a #87 drill bit for $13.00 !!!!!!!!!! I would use that #80. All you need is some sort of drill press to drill straight holes. You don't need a lathe! Can't recommend the heated poker thing. I can't imagine the wire retaining enough heat to sink through the plastic. Don't worry Andy, a hundred years from now when people look at this site, six months won't seem like much. To answer the original question, when I need a hole to match a specific rod, I use the rod to make a drill bit. Use a short piece of the rod and grind half the length to half it's diameter. Then grind the half round end to a point using two different angles. The shallow angle will scrape the bottom of the hole. The chips will exit the hole through the hollowed part of the rod. If using this bit in a motor tool it will be important to get the two angles on the correct sides. If using a pin vise, just turn the other direction.
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