Tom Cancelleri Posted June 1, 2016 Report Share Posted June 1, 2016 Here's my current dilemma, I need to run my 2-2-2-4 SER cable from my main panel to my sub panel in the shop. When I installed my sub panel in the shop version 1.0 60 amps would more than sufficient for my mostly 110 tools, and 1 220 tool. Now I need to upgrade that. I drilled 1" holes originally in the 2x8 or maybe 2x10 joists in the ceiling I originally used Bosch Daredevil pronged spade bits. Now I need to enlarge those holes to accommodate the larger cable and need roughly 1 1/4" holes. I've got to enlarge the holes of approximately 18 joists. Since the joists are in place space is a consideration as it needs to be small enough to get a drill in there between the joists. I was thinking maybe a board in front clamped to the joist to act as a pilot/center hole for 1 1/4" hole saw, this is actually a huge pain to do it this way, but it's about the only thing I can think of right now. I could drill new holes but I'd prefer to preserve the integrity of the joists and not make swiss cheese out of them. Any thoughts or ideas would be appreciated. Quote Link to comment Share on other sites More sharing options...
..Kev Posted June 1, 2016 Report Share Posted June 1, 2016 I would think a large tapered countersink would do the trick.. Just run it from each side of the joist.. Quote Link to comment Share on other sites More sharing options...
Popular Post shaneymack Posted June 1, 2016 Popular Post Report Share Posted June 1, 2016 A holesaw within a holesaw. I've done it before to make a door lock hole bigger. Works really well. Sent from my SM-N910W8 using Tapatalk 4 Quote Link to comment Share on other sites More sharing options...
Chet Posted June 1, 2016 Report Share Posted June 1, 2016 Just think out load here but would it be any faster/easier to get some 1" dowel material and plug the existing holes and then bore new hole close by? I am sure someone will come up with the better solution but this will give you something to think about in the mean time. 1 Quote Link to comment Share on other sites More sharing options...
Just Bob Posted June 1, 2016 Report Share Posted June 1, 2016 2 minutes ago, shaneymack said: A holesaw within a holesaw. I've done it before to make a door lock hole bigger. Works really well. Sent from my SM-N910W8 using Tapatalk This is really easy and fast. Quote Link to comment Share on other sites More sharing options...
Woodenskye Posted June 1, 2016 Report Share Posted June 1, 2016 I would move over as far as possible and drill new hole. Quote Link to comment Share on other sites More sharing options...
Chestnut Posted June 1, 2016 Report Share Posted June 1, 2016 @Just Bob @shaneymack I'd love to see a picture of how this works cuase i've ran into this problem a few times myself. Not with joists but with other things. @Tom Cancelleri If some areas are to tight to accomplish enlarging the hole or if existing holes are too close to the top or bottom make sure to center the hole you drill in the joist (as I'm sure you know). None of the strength of a wooden beam comes from the center part. Quote Link to comment Share on other sites More sharing options...
..Kev Posted June 1, 2016 Report Share Posted June 1, 2016 A 1 1/4 tapered cutter would do the trick quickly. No muss no fuss. HD carries them and I think they're fairly cheap.. Less than 20 bucks.. I've enlarged hole many times with them. I also used it to make the holders for my socket chisels and it worked awesome for that as well Quote Link to comment Share on other sites More sharing options...
shaneymack Posted June 1, 2016 Report Share Posted June 1, 2016 A 1 1/4 tapered cutter would do the trick quickly. No muss no fuss. HD carries them and I think they're fairly cheap.. Less than 20 bucks.. I've enlarged hole many times with them. I also used it to make the holders for my socket chisels and it worked awesome for that as well But why buy something if he has a holesaw set? Sent from my SM-N910W8 using Tapatalk Quote Link to comment Share on other sites More sharing options...
..Kev Posted June 1, 2016 Report Share Posted June 1, 2016 Just now, shaneymack said: But why buy something if he has a holesaw set? Sent from my SM-N910W8 using Tapatalk Because it's easier. You don't have to clear waste from the hole saw. You just drill it thru to the size you want and be done. 1 Quote Link to comment Share on other sites More sharing options...
shaneymack Posted June 1, 2016 Report Share Posted June 1, 2016 Because it's easier. You don't have to clear waste from the hole saw. You just drill it thru to the size you want and be done. Lol. Ok, i wont argue with you. Sent from my SM-N910W8 using Tapatalk Quote Link to comment Share on other sites More sharing options...
..Kev Posted June 1, 2016 Report Share Posted June 1, 2016 Quote Link to comment Share on other sites More sharing options...
Tom King Posted June 1, 2016 Report Share Posted June 1, 2016 Is !-1/4" going to be large enough? That stuff is not easy to pull any kind of way, and certainly worse with tight holes. I'd use a self-feed multispur bit (plumbing), a 1/2" right angle drill, and pop a line of new holes. The extra holes will make no measurable difference in the strength of the joists. I can send you a bit on loan if you need it. Quote Link to comment Share on other sites More sharing options...
Tom Cancelleri Posted June 1, 2016 Author Report Share Posted June 1, 2016 8 minutes ago, Tom King said: Is !-1/4" going to be large enough? That stuff is not easy to pull any kind of way, and certainly worse with tight holes. I'd use a self-feed multispur bit (plumbing), a 1/2" right angle drill, and pop a line of new holes. The extra holes will make no measurable difference in the strength of the joists. I can send you a bit on loan if you need it. I've got access to a 1/2" right angle drill, and bits galore. My dad used to do plumbing for steam radiators, and installing boilers and such. I appreciate the offer. Maybe I'll drill new holes. 30 minutes ago, Chestnut said: @Just Bob @shaneymack I'd love to see a picture of how this works cuase i've ran into this problem a few times myself. Not with joists but with other things. @Tom Cancelleri If some areas are to tight to accomplish enlarging the hole or if existing holes are too close to the top or bottom make sure to center the hole you drill in the joist (as I'm sure you know). None of the strength of a wooden beam comes from the center part. On a hole saw you have the pilot arbor which has 2 flat sides and you position the saw portion on that part of the shank. If you put a smaller hole saw on the arbor first, you put the larger saw on top of that so they are nested. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted June 1, 2016 Report Share Posted June 1, 2016 The center of the joist most certainly does matter. This is why you are limited to the outside thirds of the span. Drill nowhere in the center third. Quote Link to comment Share on other sites More sharing options...
Chestnut Posted June 1, 2016 Report Share Posted June 1, 2016 1 minute ago, C Shaffer said: The center of the joist most certainly does matter. This is why you are limited to the outside thirds of the span. Drill nowhere in the center third. Wrong center center height wise not length. You are correct on the length part. Quote Link to comment Share on other sites More sharing options...
Tom Cancelleri Posted June 1, 2016 Author Report Share Posted June 1, 2016 Correct 1 Quote Link to comment Share on other sites More sharing options...
Dave H Posted June 1, 2016 Report Share Posted June 1, 2016 If you need to enlarge a hole you drill the sized hole in some scrap screw the scrap over the existing hole, centered of course the scrap with the hole guides the bit negating the need for center spur easy-peasy. 1 Quote Link to comment Share on other sites More sharing options...
Tom King Posted June 1, 2016 Report Share Posted June 1, 2016 better check here: https://engineering.purdue.edu/~jliu/courses/CE479/extras/Notching_&_Boring_Guide_A11.pdf edited to add: Sorry, was looking for a link while others were posting. This is good stuff to know. Even if you use generous sized holes, it still helps to keep them in a straight line. I snap a line on the joist bottoms, and use a combination square to put an arrow where I want the hole center. A self-feed bit doesn't require a push on the drill until sometimes right when it breaks through. Quote Link to comment Share on other sites More sharing options...
Janello Posted June 1, 2016 Report Share Posted June 1, 2016 Get a sharp self feeder in a hole hawg on low speed, start it on an angle in the old hole and straiten it out when it starts to bite. Man up! Quote Link to comment Share on other sites More sharing options...
Tom Cancelleri Posted June 1, 2016 Author Report Share Posted June 1, 2016 I like these bits http://www.baddogtools.com/rover-bits.html they're ridiculously expensive but you can turn then mid hole Sent from my Nexus 6P using Tapatalk Quote Link to comment Share on other sites More sharing options...
drzaius Posted June 2, 2016 Report Share Posted June 2, 2016 I'm going to back up the bus a bit & ask why you need more than 60A? You can run a 5 HP collector, 3 HP table saw & 3 HP compressor all at once, all at full load with not problem. Unless you have electric heat and/or a big AC unit. Quote Link to comment Share on other sites More sharing options...
Coop Posted June 2, 2016 Report Share Posted June 2, 2016 I've done it the way Shane suggested, with the smaller hole saw being used as the pilot bit and works great. 1 Quote Link to comment Share on other sites More sharing options...
Ronn W Posted June 2, 2016 Report Share Posted June 2, 2016 You can easily use up to 2" holes in 2x10 joists. You can move over about 6" from your current holes and drill new. There are 2 considerations in the strength of a joist. One is "shear" which is greater near the supports and least in the middle of the span. The other is bending which is greatest in the center of the span and least near the supports. Shear is resisted by the entire cross section of the joist so you don't want holes one above the other, but holes in a row about 4 to 6" part would be OK. Bending is resisted most by the top 2" and the bottom 2" of the joist so you do not want keep your holes in the middle of the depth of the joist. Holes are OK in the center third of the span where the shear is the least provided they are in the center of the depth of the joists. Actually notching a joist is never a good idea without an analysis. Quote Link to comment Share on other sites More sharing options...
Popular Post wtnhighlander Posted June 2, 2016 Popular Post Report Share Posted June 2, 2016 Do it like a real woodworker, man! Make a 1 1/2" hole template from MDF, clamp it over the existing hole, and route it with a pattern bit. 3 Quote Link to comment Share on other sites More sharing options...
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