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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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"Larry Jaques" wrote in message
... On Tue, 7 Jan 2020 16:45:55 -0500, "Jim Wilkins" wrote: wrote in message . .. On Tue, 7 Jan 2020 00:26:50 +0000, David Billington wrote: On 06/01/2020 21:46, wrote: On Mon, 6 Jan 2020 13:15:59 -0700, Bob La Londe wrote: On 1/5/2020 10:50 AM, Bob La Londe wrote: Ok, my previous deep drilling operations went off pretty well. Carbide 3 flute drills worse used on a couple of them. One to start holes for a hand ground split point, and the smaller hole with just a carbide jobber drill. Both actually met up in the middle close enough. One for a hinge pin and the smaller one for an injection cavity feature. They worked. Didn't actually do any gun drilling. Now I am looking at an application that will need to drill straight (size is not highly critical), for from 20 to 28 inches for a water jacket. The only machine i have I think would be suitable for it is the 14x40 engine lathe. Throwing a 20x30 inch piece of plate on the chuck is obviously not the answer. LOL. I was thinking to use some sort of tool holder in the spindle, and make a mount and support for the plate on the carriage. After doing a bit of reading gun drilling does not just use hydraulic pressurized oil. It is also done with pneumatic air mist under pressure. Now the trick I think is to figure out how to pressurize a spinning gun drill inside a lathe spindle. I have some ideas, but they are kind of vague at this point. The thought of buying and setting up a dedicated machine down the road is not out of the question. Right now I am looking for the shade tree get it done short term solution. I think I have most of it figured out if using the lathe is the answer. Just the details of the actual fluid delivery and recovery to work out, and you guys have given quite a lot of information to help figure that out. I figure I can mount a big right angle plate (I have one) in place of the compound, stand the plate on edge, and clamp it to it. I can stack blocks to get height if needed, and adjust with the cross slide. By putting the plate on edge it will virtually eliminate any material sag (a concern at 30 inches long) from over hang as long as the clamps do not slip. The whole thing gives me ideas for solving some of my other deep drilling issues as well. Making them easier. Next is a stop switch on the carriage, so I can walk away for a minute without fear of a crash because I got distracted. I think the same kind of roller micro switch as is on the chuck safety cover. Maybe with a mag lock mount for rapid positioning. Allow it to over travel as it comes to a stop of course. If only I could easily automate peck drilling with it. LOL. I just set up an air cylinder to release the half nut on the carriage. I used a proximity switch to sense the carriage and thereby close a relay which powers a solenoid air valve. It works very well and allows overtravel of the carriage past the switch. The system repeats within .003" Eric An interesting modification but I wonder how fail safe it is in the case of power failure, the lathe would coast to a halt so I guess it depends how close the stop point is to the chuck. The reason I mention it is that a guy I used to work with mentioned operating a lathe with an air chuck and they had a power failure and the air supply turned off and jettisoned the part narrowly missing the guy, they fitted a UPS to that circuit shortly afterwards. It's plenty safe because I'm at the lathe ready to stomp on the brake. I suppose I could connect the setup like all my other air operated clamping stuff so that when the power is off the part is clamped. So on the lathe power off would mean half nut disengaged. Eric You may already know, but this is a good place to show the motor control circuit that prevents the machine from starting unattended when the interrupted power returns. https://www.ecmweb.com/content/artic...circuit-primer JPGs not available. Keywords: magnetic contactor, right? "3 wire control" |
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