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| Deep hole drilling 101 on lathe? |
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| Jonny:
I tried a few A002 and A777 plus others from Dormer last year, they don't last long perhaps 1/8 a decent drill of a few years back. I sill have a fondness for most Titex, not far behind are Hertel on all materials in general. Some of the best drills found to date Oon hard stuff are the Titex 3 flute but i wouldn't like going more than 5D. Know exactly what you mean its a rarity I break a drill but now going through a phase 4 in about 1 1/2 weeks, no warning. Often I see a drill work great then start to flex like a banana If jobs work hardening its getting hot due to friction and will get worse if carry on. Some breakages or hard going can be contributed to the swarf not evacuating and why I mentioned keep drawing the drill out to clear the swarf. Never used gun drills but don't they use high pressure thru coolant forcing swarf out. |
| rowbare:
Pekka, Since you are building companion spindles, you might find the book "Workshop Practice Series no 27 Spindles" a good read. It is inexpensive and the author goes through the construction of several different spindles. bob |
| PekkaNF:
--- Quote from: rowbare on July 10, 2014, 02:58:59 PM ---Pekka, Since you are building companion spindles, you might find the book "Workshop Practice Series no 27 Spindles" a good read. It is inexpensive and the author goes through the construction of several different spindles. bob --- End quote --- Thanks. I read it often. I got lot some time ago and it's been both inspiration and frustration. The only of spindle only book I now for amateur and it has lot to recommend. Definately worth of the money and time spent studying it. It has it's own mindset. I some of the choices are very good. I's based on inch measurements and materials. Some choices and dimensions are outright weird, not sure is some "metric" size bearings are available at all, some material and threads are weird like M7 and many design considerations are based on myford measurements, which is fine if you got one. One part has three threads cut on it. All different dpi. Some measurements are nominal bar (material) size. Some opinions are given, not explained. But if anybody would be building spindles, I would recommend it. Specially, if you like imperial units, withworth thread and have Myford lathe. Pretty much only two more common design comes into my mind: Quorn spindle and Harold Hall WPS#34 has one pretty nice design. Does anybody know a design of a internal grinding spindle with long quill and double AC bearings at both ends? I bought a little of hollow bar. Have to check how it turns, but it would save a lot of boring for the shell. Also got some free machining steel of 22 mm diameter (hex bar). Drilling it should be a dream. I am not sure how well it would fare, if feels really soft for a shaft and tensile strength looks bad. But it machines overly easy maybe itīs weakness will be compensated more easily reached (possibly more accurate) dimensions. Anyway, reaming leaded steel is nice, offering a taper reamer on tempered steel is not. Pekka |
| shaddr3:
:update: on my progress. My 7.25" x 7/16" bore was done with the tailstock. It was brutal, took forever to keep removing for chip evacuation. My method using 6 point sockets (with set screws) to hold the aluminum hex stock worked out great. A few weeks later after getting the 25cfm air compressor setup I dived into the 11.25" x 7/16" bore using a through coolant bit held by a 3/4" boring bar holder on the QCTP. I purchased a cheap pneumatic air tool oiler, filled it with WD40 for my lubricant. I predrilled a 3" x 7/16" hole to center my through coolant bit. I was surprised it worked so well, and how the swarf was evacuated out of the hole. I still plan on buying an actual gun drill and modifying my lead screw once a few prototypes are finished. |
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