24OZ Posted March 2, 2011 Share Posted March 2, 2011 (edited) Guys, I need to drill a 1" hole into the headlight backplate bowl, I am guessing that i need to buy a stepper drill bit? I am finding it difficult to find a stepper drill of that size, and ones close to 1" are quite pricey, at least over here in the UK. Is there an easier way of doing it neatly and what would be the best method of going about this considering the headlight backplate bowel is convex shaped. I don't have a bench drill either. Thanks. Edited March 2, 2011 by 24OZ Quote Link to comment Share on other sites More sharing options...
Warren Posted March 2, 2011 Share Posted March 2, 2011 1" hole saw with a longer pilot bit. DONE... 2 minutes max. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted March 2, 2011 Share Posted March 2, 2011 A knockout punch will do what you need. If you have a buddy that is an electrician it should cost you a beer. They can also be found on ebay. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted March 2, 2011 Share Posted March 2, 2011 I don't think a knockout punch would be ideal for anything but a flat surface. I'm not a fan of unibits. A hole saw is definitely your best bet. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted March 2, 2011 Share Posted March 2, 2011 (edited) If you choose to use a hole saw then get a 7/8" unit. With thin metal the pilot bit will wobble causing a good bit of runout. Try to hold the bucket against a piece of wood below the needed hole to help guide the pilot bit. Extra hands will come in very handy for this too. Hole saws are not known for accuracy. Once you get the basic hole cut then use a round file, dremel or die grinder to complete the task. This is typically needed to eliminate the sharp thin edge left by the hole saw anyway. Edited March 2, 2011 by ezzzzzzz Quote Link to comment Share on other sites More sharing options...
24OZ Posted March 2, 2011 Author Share Posted March 2, 2011 Thanks for the feedback guys. I just thought of ebay and found these drill bits - cheaper then I had thought, what do you guys think? This one: http://cgi.ebay.co.uk/25MM-HSS-DRILL-BIT-METAL-WOOD-AND-PLASTIC-25-MM-/270602377371?pt=UK_Home_Garden_PowerTools_SM&hash=item3f0128989b or this one: http://cgi.ebay.co.uk/25MM-Metal-Hole-Saw-Set-Hex-Wrench-Twist-Drill-Bit-Tool-/150571054371?pt=UK_Home_Garden_PowerTools_SM&hash=item230ebbf523 Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted March 2, 2011 Share Posted March 2, 2011 (edited) That first drill will cause hell trying to make a 1" hole in sheet metal. With only two flutes, as soon as it starts to cut through the bucket it will grab and pull you into it f'ing up the hole in the process. Such a drill is intended to cut through thicker material by it's very nature. I've used comparable drills on thin metal BUT only when I could sandwich that metal between two thicker pieces of metal or wood. The second one is a much better choice BUT should be used in a drill press with the bucket tightly clamped to ensure an accurate hole. A step drill or the smaller hole saw I mentioned are your best (I prefer to say only) options. You've been forewarned. Edited March 2, 2011 by ezzzzzzz Quote Link to comment Share on other sites More sharing options...
Derek Posted March 2, 2011 Share Posted March 2, 2011 If you use the chassis punch (which would be my recommendation) put the cup on the convex side and the punch on the convex side. Much more civilized than drilling! Derek Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted March 2, 2011 Share Posted March 2, 2011 (edited) If you use the chassis punch (which would be my recommendation) put the cup on the convex side and the punch on the convex side. Much more civilized than drilling! Derek Absolutely second that. Punch/knock-out tool works great on curved metal. I've used them on formed metal on my Z for holes through the radiator core support. Nice clean hole. A bit will often times grab or jump on a curved surface because one side of the outer edge hits the surface before the other does. After doing it a few times now, a knock-out tool is the only way I would approach putting a big hole in thin metal. Hole saws are good if you want to "texture" the surface of the metal... and your flesh. Edited March 2, 2011 by Dan Juday Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 2, 2011 Share Posted March 2, 2011 I hate hole saws, but came across and interesting one recently. I was doing some tilework and bought a hole saw to cut through the tiles. It had a plastic guide which came with a couple of double sided tape stickers that attached to the bottom of the guide and the tile. Then the diamond hole saw was stuck into the guide and it simply couldn't wobble around for lack of space. This is SO MUCH BETTER than your traditional hole saw I couldn't believe it. I would imagine that diamond blade would cut through aluminum no problem, haven't tried one on steel, but it wasn't more than $10 at the hardware store, so if you try it and it doesn't work, no big loss. DO NOT use that 25mm drill bit you posted. that will just tear a jagged hole in sheet metal. Here is one like I used: http://www.homedepot.com/h_d1/N-5yc1v/R-202205611/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053 Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted March 3, 2011 Share Posted March 3, 2011 A diamond cutting surface would burn up pretty fast on steel. Might make it through once if you're lucky and just toss it, but you could probably use that foot with a different hole saw right? Hole saws don't have to have that much runout if you're careful, especially if the guide is steady. They tend to grab and bounce around if the guide is free to float. Definitely a rough finish and will need deburring though. A knockout punch would obviously give the best finish to a hole, I just think on a highly curved surface it will try to crush it to in the process and will end up somewhat flattened out. Quote Link to comment Share on other sites More sharing options...
dangerboy Posted March 3, 2011 Share Posted March 3, 2011 I personally love the unibits but only the ones made by GreenLee. Home Depot and others made knock offs that are totally inferior. GreenLee also makes hole saws designed for metal with a shallow cup and a spring loaded pilot bit though on a curved surface it may not meet your needs. I agree with the above posts however on that large ebay bit, as soon as it breaks through it will pull in, bind, and distort the hole. Quote Link to comment Share on other sites More sharing options...
bjhines Posted March 4, 2011 Share Posted March 4, 2011 Hole saw all the way... Twist drills are a big nono on sheet metal. knockout punches are good, if you can fit them into the piece you are working on. These things do take some experience to use properly. I can do things with bits and saws that would make your mother cry and the insurance company drop your ass. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted March 4, 2011 Share Posted March 4, 2011 I can do things with bits and saws that would make your mother cry and the insurance company drop your ass. I'm confused. Is that a good thing? Quote Link to comment Share on other sites More sharing options...
Scott_M67 Posted March 4, 2011 Share Posted March 4, 2011 You said you wanted a cheap way to do it, do you have a die grinder and burr bits, dremel tool, or even a rat tail file and you can do it by hand. Quote Link to comment Share on other sites More sharing options...
stwrangler Posted March 7, 2011 Share Posted March 7, 2011 you could drill a 3/8 hole and then use a round file. Quote Link to comment Share on other sites More sharing options...
24OZ Posted March 13, 2011 Author Share Posted March 13, 2011 Thanks for everyone's input. Wanted to update you. Rip260Z came round this weekend and gave me a hand, we used a hole saw with a pilot centre adjustment. Worked a treat, see photos. Can't take the credit Rip did the work! Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 14, 2011 Share Posted March 14, 2011 Looks good! My question (much belated) would have been "how 'round' does it need to be?" A series of chain-drilled holes that you nibble/snip/grind out to the 1" round circle drawn on the back of the bucket probably could have been done by you with nothing bought. But what fun is not having an extra tool laying around to impress drinking friends when the go out to The Shed? If there is going to be a rubber grommit on the hole, the real 'finish' and exact 'roundness' of the hole is not really that critical. I would think being in the UK this choice would have been some sort of Ingrained Instinct. There, buying a new body panel is just not proper. Everybody knows you have to make it from flat sheet! In that same vein, chain-drilling a hole would seem natural! Quote Link to comment Share on other sites More sharing options...
240zip Posted March 14, 2011 Share Posted March 14, 2011 http://www.aircraftspruce.com/catalog/topages/knockout2.php Would using a sheet metal punch be considered 'expensive' for this application? Quote Link to comment Share on other sites More sharing options...
4everDATSUN Posted March 20, 2011 Share Posted March 20, 2011 step drill Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.