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| boring a small hole |
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| Dean W:
Colin, this may help with visualizing some of the angles: http://www.sherline.com/grinding.htm The main thing, and I mean most obvious once you look at it for a few minutes, is to keep the part of the tool that is directly below the cutting edge from rubbing on the work. The top of the cutting edge of the tool tool needs to be right on the centerline of the work piece. On the front edge of the tool, that is, the end that faces directly toward the lathe headstock, it needs a small taper from the cutting edge back toward the center of the tool so the entire front surface of the tool does not hit the bottom of the hole at once. Another way to do it is with an old drill bit. If you grind the end of a drill bit flat and look at the end you just ground off, you will see that it forms two sides that make a kind of a 'hook' shape on the flutes. One of the flutes can be used as a boring tool edge. Remember, drill bits are quite flexible, so go at it easy. Also, if you grind off the end of a tool bit, take care not to get it too hot. They represent a rather thin section of metal, and will over heat quickly. If you get it too hot, especially if it a carbon steel bit, it will loose its hardness. That's not so much of a problem with HSS bits, but you still shouldn't get them really hot. What Lew asked is pertinent. What machine are you using for this? It would also be good to know what material you are cutting. Steel, brass, aluminum, etc. ? Dean |
| 75Plus:
Could this job be done with a 1/2" center cutting end mill? I would think so unless I am missing something. Joe |
| Ned Ludd:
Hi Colin, You say you do not have a means of heating a D bit, do you not have a cooker or some other means of heating your food? Microwaves excepted of course. Gas rings are great for heating tools, especially if you only have the use of one hand, as there is no need to hold a torch. Ned |
| Lew_Merrick_PE:
--- Quote from: Ned Ludd on July 01, 2010, 09:40:41 PM ---Hi Colin, You say you do not have a means of heating a D bit, do you not have a cooker or some other means of heating your food? Microwaves excepted of course. Gas rings are great for heating tools, especially if you only have the use of one hand, as there is no need to hold a torch. Ned --- End quote --- Ned, Electric stovetops rarely work for heat treating. American natural gas is often so poorly plumbed as to be worthless (my current kitchen is supplied by an incompetent gas company). Anything larger than ø.250 inch is "challenging" on our stovetop -- which is why I have 70 lb propane cylinders. It's currently in storage, but I have a foundry/forge made from a 24 inch truck brake drum. The tuyere is a piece of 3-1/2 inch pipe with a PVC elbow at the bottom (to melt out if I spill a load) coupled to a set of 4 24 VDC muffin fans with a variable voltage power supply. I have several ceramic "spacers" that allow me to throttle down the size of the fire area, but I can heat 20+ inches of 2 inch bar to hardening temperature quite easily. Just be careful when discussing coked coal around cops. A friend of mine and I were discussing "coke" at a bar some years back. About 50 cops came screaming in thinking that they had some major "dealer" to hand when they overheard us discussing "pounds of coke"... |
| colin563:
thanks for all the great replies the machine im using is a myford super 7 cooker is electric if you look at my post here you will see how much room i have http://madmodder.net/index.php?topic=1611.0 needs updating :worthless: the item is a mild steel its for saddle clamp from hemingway kits i have got a 6mm boring bar from rdg replaceable tips i dont trust my grinding yet hoping this will do the job just got to practice a lot more :( thanks colin thanks colin |
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