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Drilling
Apr 1, 2015 18:30:17 GMT -8
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Post by rocktechxj on Apr 1, 2015 18:30:17 GMT -8
Ive seen some mention of drilling on this forum that caught my attention. I won't get into crazy detail here but I'll say that drill bits should last a VERY long time. When used properly.
Since this is a forum/shop designed around learning I suggest a drill speed chart be clearly posted somewhere. Even better would be a Thursday night devoted to proper drilling techniques. Of course I'd be willing to bet there's YouTube videos on the subject. Maybe someone with machining/tooling background could host it.
At the shop we do a ton of drilling, both by hand and on a very nice press. Sheet metal, Toyota frames, 5/8 bar stock, tube notching etc. Yet we get an entire year from even our most used bits (1/4,3/8,1/2).
Choosing the right tool and technique is paramount.
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Drilling
Apr 1, 2015 18:37:26 GMT -8
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Post by rocktechxj on Apr 1, 2015 18:37:26 GMT -8
Things to discuss once a chart of surface speeds is acquired...
Formula to convert to rpm
General rules for different materials
(Double speed for aluminum)
Cooling fluid
Tool vibration/chattering
Reading removed material to adjust speed
(Chips are smoking or turning brown)
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Post by TacoProBro on Apr 1, 2015 21:06:18 GMT -8
About a 100 years ago in another life I was a machinest. You are correct in that speed vs. feed vs. material is vital for tool lifespan. However, it's much easier to get it right on a drill press, lathe, Davenport or whatever, than it is with a hand held drill motor. With a hand held, it's more of a general guidline.
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Post by CheapCherokee on Apr 1, 2015 21:28:07 GMT -8
Excellent subject. While I worked for a machinist I learned a very small bit about proper drilling, would like to know more. Some situations though I've been stuck using a right angle drill that is either on or off (no variable speed) which is how I've killed bits before.
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Drilling
Apr 1, 2015 22:21:34 GMT -8
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Post by rocktechxj on Apr 1, 2015 22:21:34 GMT -8
About a 100 years ago in another life I was a machinest. You are correct in that speed vs. feed vs. material is vital for tool lifespan. However, it's much easier to get it right on a drill press, lathe, Davenport or whatever, than it is with a hand held drill motor. With a hand held, it's more of a general guidline. Your right, but knowing the details and knowing your hand drill is xxxx rpm max, you can get pretty close with said guidelines, then you just watch the materials reaction. |
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Drilling
Apr 1, 2015 22:23:18 GMT -8
via mobile
Post by rocktechxj on Apr 1, 2015 22:23:18 GMT -8
About a 100 years ago in another life I was a machinest. You are correct in that speed vs. feed vs. material is vital for tool lifespan. However, it's much easier to get it right on a drill press, lathe, Davenport or whatever, than it is with a hand held drill motor. With a hand held, it's more of a general guidline. Your right, but knowing the details and knowing your hand drill is xxxx rpm max, you can get pretty close with said guidelines, then you just watch the materials reaction. Non variable drills should be tossed in the trash. Same goes for grinders with an on off switch rather then a paddle switch of sorts. You won't find any in our shop. |
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Post by EL GRANDE on Apr 2, 2015 7:22:31 GMT -8
Thanks to the top. Fred has covered the subject in person, but it's good to have it on the forum so us armatures can learn how to take better care of our tools.
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Post by lostpinky on May 31, 2015 8:10:39 GMT -8
The first thing I catch new people doing wrong in the shop is running drill bits too fast in hard metals like steel. Go slow and use a moderate amount of pressure. Keep the bit moving through the material. When you get to the back side of the material reduce the pressure. Drilling holes in sheet metal is dangerous. Clamp two pieces of wood to the sheet metal (one on each side). When you are using a drill press always use a vise or clamp the work piece to the table. Do I have to mention safety glasses? Most people do not have coolants around their garage, buy some, it's cheap. If you ask nice and give me a squirt bottle I will give you some (I buy 35 gallons at a time). The reason coolant is so important has to do with metallurgy. To keep is simple, once a drill (usually HSS) gets hot is will change color. If it turns blue or black it is trash and it is your fault. The bit has returned to it's pre-heat treated state (annealed) and is soft again. Have patience. If you are drilling soft metal like aluminum you can spin the drill about as fast as you would like since most hobbyist equipment (hand drills or drill presses) won't reach speeds capable of hurting HSS. Again, use coolant. Coolant helps the bit from "loading up". Soft material will stick to the bit which causes the bit to heat up (remember, that is bad). If you are drilling holes that need to be tapped or reamed do not spin the drill too fast or the hole will be oversized. Drills always make a hole .001-.002 over their diameter anyway and the faster you spin the larger the hole gets. If you need to replace a bit or you want to buy a set of drills don't try to save money especially if they are something you are going to use a lot. You should have a "beater" set that you can abuse. Don't use your good set to drill drywall or stucco. McMaster Carr is the best place I have found for replacement drills. You will be surprised how inexpensive small drills are to replace, usually just a couple bucks. www.mcmaster.com/#standard-drill-bits/=xf5wrrDrill bits are made of different materials. The most common is HSS or "high speed steel". Not all HSS is the same. In the past there has been a lot of trouble with Chinese HSS not being up to world standards but they have gotten better. That is where buying your bits from a good source is important. Harbor Freight drill bit set for $12, that is your beater set. Don't expect it to hold an edge for very long. Drills can be sharpened if they have not been annealed (heated up and returned to their original state). I am happy to show anyone interested how but as rocktechxj mentioned, there are probably good Youtube videos. Keep in mind that some frames, both trailer and vehicle, have been heat treated. They should not be drilled (in some cases can't be drilled) or welded (welding will anneal the steel). I have an excellent fractional/drill/tapping chart that I can copy for you if you need one for your shop. |
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