chiangrai Posted February 10, 2016 Share Posted February 10, 2016 I have an electric drill with a 10mm chuck. I need to drill a 12mm hole in concrete. I need to buy a masonry drill bit with a 10mm shaft and a 12mm .....what's it. I've tried searching eBay and Google but can't find anything. I think the problem might be I'm not using the right search words. Does anybody know what these things are called or where I would find one for sale online. Link to comment Share on other sites More sharing options...
nev Posted February 10, 2016 Share Posted February 10, 2016 Lazada sells drill bits try a search on there. Link to comment Share on other sites More sharing options...
mikebike Posted February 10, 2016 Share Posted February 10, 2016 http://www.lazada.co.th/10150mm-long-sds-plus-rotary-hammer-concrete-masonary-drill-bore-bit-round-shank-intl-4379785.html Link to comment Share on other sites More sharing options...
lemonjelly Posted February 10, 2016 Share Posted February 10, 2016 Drill 2 x 10mm holes and you can save the 8mm left over in your toolbox for the next time you need a hole. Link to comment Share on other sites More sharing options...
Gsxrnz Posted February 10, 2016 Share Posted February 10, 2016 (edited) You're looking for a "reduced shank" drill bit. Shank 10mm to fit your chuck. Tip to be 12mm to suit your requirements. However, you probably won't find them. You'll find that if you get a 10mm masonry drill, you'll be able to get a bigger hole by wiggling the drill round while drilling. Drill over length, then retract to half way out and start to exert pressure in a circular motion. Unless you require an exact 12mm hole for a specific purpose, my method will make the hole big enough to use a 12mm rawl plug or whatever. Edited February 10, 2016 by Gsxrnz Link to comment Share on other sites More sharing options...
chiangrai Posted February 10, 2016 Author Share Posted February 10, 2016 thanks GsxrnG, Your right they don't have 12mm reduced shank for sale but a 10mm will do the job as you say. Link to comment Share on other sites More sharing options...
sipi Posted February 10, 2016 Share Posted February 10, 2016 Most towns will have a machine shop somewhere. If you can buy a 12mm bit ask someone to lathe down the shank to 10mm. 5 minute job should only cost a few baht. Link to comment Share on other sites More sharing options...
billd766 Posted February 11, 2016 Share Posted February 11, 2016 As an alternative perhaps you could by and fit a 13 mm chuck to replace the 10 mm one and then you can fit drill bits of 1/2 inch any time. Link to comment Share on other sites More sharing options...
chiangrai Posted February 11, 2016 Author Share Posted February 11, 2016 Good idea, My drill is black and decker. Do I need to buy a chuck of the same brand or are they universal. Link to comment Share on other sites More sharing options...
blackcab Posted February 11, 2016 Share Posted February 11, 2016 Universal. Have a look at this as an example: http://m.ebay.co.uk/itm/171062380695 Link to comment Share on other sites More sharing options...
sometimewoodworker Posted February 13, 2016 Share Posted February 13, 2016 You're looking for a "reduced shank" drill bit. Shank 10mm to fit your chuck. Tip to be 12mm to suit your requirements. However, you probably won't find them. You'll find that if you get a 10mm masonry drill, you'll be able to get a bigger hole by wiggling the drill round while drilling. Drill over length, then retract to half way out and start to exert pressure in a circular motion. Unless you require an exact 12mm hole for a specific purpose, my method will make the hole big enough to use a 12mm rawl plug or whatever. s-l225.jpg Reduced shank bits are not too difficult to find. This one was from DoHome Link to comment Share on other sites More sharing options...
kamalabob2 Posted February 13, 2016 Share Posted February 13, 2016 I paid 75 baht today for a Meta Masonry Concrete 12 mm drill bit. One of the Bosch Drills I have is a 10mm shank. More fun was buying more Netafim drip irrigation tape and pipe for my wife's little farming project in a Buriram Village. The reducing shank masonry drill bit might be widely available at any tool shop or larger builders merchant store in Thailand. Link to comment Share on other sites More sharing options...
sipi Posted February 13, 2016 Share Posted February 13, 2016 The shanks on masonry bits are normally soft, unlike HSS drills. Another option is to buy a 12mm bit and carefully file or grind 3 flats on the shank to fit a 10mm chuck. Link to comment Share on other sites More sharing options...
Thorgal Posted February 15, 2016 Share Posted February 15, 2016 (edited) Your drilling machine is designed to drill till diam. 10. It's not advised to 'modify' the drill if you consider seriously the lifetime of your machine. 2 mm is a huge difference in torque. If you need 12 you should go to SDS or SDS max drilling machines with appropriate drills. For a few holes I would consider to borrow the machine. Edited February 15, 2016 by Thorgal Link to comment Share on other sites More sharing options...
kamalabob2 Posted February 19, 2016 Share Posted February 19, 2016 (edited) I spoke English this morning with Mr. Wattana Armornmannant the current sales Department Manager of Hitachi Power Tools Thailand and his Japanese supervisor, Mr. Wataru Hama the managing director of Hitachi Koki Power Tools while they assisted expats and Thai home builders in Buriram at a family owned tool shop. Mr. Wattana had previously been employed by AEG Tools and started with Robert Bosh Tools in Thailand. I had brought in a Hitachi 18Volt garden hedge trimmer for a free adjustment by the normal technicians and some women hired for a special event who seemed very familiar with shaft and tool lubrication. The women were not aware that Hitachi Tools had purchased Metabo Tools in 2015, yet Mr. Wataru Hama was very aware of the European made tools now owned by Hitachi. Edited February 19, 2016 by kamalabob2 Link to comment Share on other sites More sharing options...
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