Countersinking screws
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Countersinking screws in a home shop without the proper tools can be frustrating...If you have a drill press and can securely clamp the panel so that it cannot wander, you might succeed...Even so, the bit itself can flex and chatter, resulting in a triangular hole...Feeding the bit into the cut very slowly helps, but it is no guarantee that it will not chatter...
It is next to impossible to countersink holes using a hand held drill motor even if the panel is clamped in a vise...The cutting angle of twist drills is not necessarily uniform...It depends on the hardness of the material they were intended to drill into...Bits bought from surplus clearing houses are sometimes sharpened to odd angles... In industry, countersinks have a smooth pilot-pin protruding from the center of the cutter that is the same size as the screw hole...The pilot bears against the sides of the hole and keeps the countersink from wandering...These tools have from 4 to 6 cutting edges, resulting in smooth cutting...Twist drills only have 2 cutting edges and no pilot and this causes chatter...These countersinks have a built in adjustable depth controlling device...If you do not cut deep enough, the screw will protrude above the panel...If you cut too deep, the screw will seat below the surface of the panel and you will have a silver ring of bare metal showing all around the screw head... I would not advise trying to countersink the screws in your prized K-2 unless you have the tools and the skills... Jerry, wa2dkg _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I use a mill/drill to countersink and a MicroStop countersinking tool
with a pilot pin. I've still screwed up my share of countersink jobs, however, as it takes but a moment's inattention to cause a problem. Still, I've had a much higher success rate with the Microstop than with other tools. You can find the MicroStop tools at places that cater to the home built aircraft hobby, such as Aircraft Spruce http://www.aircraftspruce.com/menus/search.php. Search for MicroStop model AT442SLS countersink. You will then need to purchase the correct cutter (both diameter and angle) and the pilot. The Microstop countersink makes it possible to successfully countersink with a hand drill, if you are careful, as it ensures that you are (1) square to the surface being countersunk; (2) coaxially aligned (via the pilot) and (3) that you stop at the correct depth (via the adjustable stop, settable in 0.001" increments.) Countersinking a painted surface also normally requires the no-mar nylon (?) ring for the Microstop for best results. That being said, I would use a hand drill only if there were no other alternative, even with a Microstop, as it's still to easy to mess up a hole. A Microstop without any bits and pilots runs about $80, so you are looking at over $100 for a Microstop, one bit and one pilot. My K2 still has the stock screws, by the way. Jack K8ZOA Jeremiah McCarthy wrote: > Countersinking screws in a home shop without the proper tools can be frustrating...If you have a drill press and can securely clamp the panel so that it cannot wander, you might succeed...Even so, the bit itself can flex and chatter, resulting in a triangular hole...Feeding the bit into the cut very slowly helps, but it is no guarantee that it will not chatter... > > It is next to impossible to countersink holes using a hand held drill motor even if the panel is clamped in a vise...The cutting angle of twist drills is not necessarily uniform...It depends on the hardness of the material they were intended to drill into...Bits bought from surplus clearing houses are sometimes sharpened to odd angles... > > In industry, countersinks have a smooth pilot-pin protruding from the center of the cutter that is the same size as the screw hole...The pilot bears against the sides of the hole and keeps the countersink from wandering...These tools have from 4 to 6 cutting edges, resulting in smooth cutting...Twist drills only have 2 cutting edges and no pilot and this causes chatter...These countersinks have a built in adjustable depth controlling device...If you do not cut deep enough, the screw will protrude above the panel...If you cut too deep, the screw will seat below the surface of the panel and you will have a silver ring of bare metal showing all around the screw head... > > I would not advise trying to countersink the screws in your prized K-2 unless you have the tools and the skills... > > Jerry, wa2dkg > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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