lynnmor 7,302 #26 Posted January 31, 2020 1 hour ago, wallfish said: Now I'm kinda obsessed with this. I need to figure out why my expensive masonry bits are getting destroyed when they hit metal. Talked to the guy about it today and he turned off the hammer action on the last one he burnt up. I was thinking the hammering might be the cause but now it's back to sq 1. A masonry bit is just a steel drill with carbide inserts at the cutting end. Carbide will quickly dull or crack when subjected to intermittent cutting. The grade of carbide used in masonry drills will stand some impact drilling in concrete and is not ideal for steel, but it will work well enough. There are special silicon or diamond grinding wheels for sharpening those bits, but a regular fine bench grinding wheel can be used, albeit with much wear. The carbide drills shown above may cost more but they will be fine, just keep them sharp. Carbide should be run at high speed, just be aware that heat will quickly dislodge inserts that are silver soldered in place, so short dwell times are essential. Yes, I own a tool & die shop. 2 1 Share this post Link to post Share on other sites
wallfish 16,983 #27 Posted February 1, 2020 (edited) Seems the heat is melting the carbide inserts off and the drill is not high speed RPM. It just leaves a shiny spot on the metal and the bits are ruined. I'm not too concerned with sharpening them as they run through concrete with ease for a very long time. I understand how they're made but not why someone can drill tool steel and mine smoke in less that a few minutes.. The problem is when they hit rebar or steel plates inside the concrete. It's very easily noticeable (apparently just to me) when the drill stops digging through the concrete and stops, but somehow my guys don't care and don't give up on the hole. They're not drilling it for 20 minutes either but maybe a good 5 minutes. Multiple times this has happened. This is a 1" bit but most of the time we use 1/2 or 3/4. one 1" got smoked too. I can do a $60 demonstration video and burn one up.. https://www.mcmaster.com/8809a17 I don't want to drill through steel with them, in 99% of the cases the hole can be moved to avoid the steel. Edited February 1, 2020 by wallfish Share this post Link to post Share on other sites
lynnmor 7,302 #28 Posted February 1, 2020 4 hours ago, wallfish said: Seems the heat is melting the carbide inserts off and the drill is not high speed RPM. It just leaves a shiny spot on the metal and the bits are ruined. I'm not too concerned with sharpening them as they run through concrete with ease for a very long time. I understand how they're made but not why someone can drill tool steel and mine smoke in less that a few minutes.. The problem is when they hit rebar or steel plates inside the concrete. It's very easily noticeable (apparently just to me) when the drill stops digging through the concrete and stops, but somehow my guys don't care and don't give up on the hole. They're not drilling it for 20 minutes either but maybe a good 5 minutes. Multiple times this has happened. This is a 1" bit but most of the time we use 1/2 or 3/4. one 1" got smoked too. I can do a $60 demonstration video and burn one up.. https://www.mcmaster.com/8809a17 I don't want to drill through steel with them, in 99% of the cases the hole can be moved to avoid the steel. The drill needs to be sharp to cut steel, concrete will just crumble as the drill hits it and a dull drill will work just about as well as a sharp one. The operator needs to immediately quit when steel is encountered and then temporarily change to a sharp bit. Those inserts are not supported well on the back side and will fail when caught on an obstacle. Striking rebar will almost always cause an intermittent cut since it will likely be to one side, that will cause failure unless the operator very carefully advances so the drill can cut small slivers. Pushing ahead will lock the drill and destroy it. In metalworking, you learn to have the tool cutting or get off the work piece quickly, if it ain't making chips, sharpen the tool. If you can flush the hole with water, that would go a long way in extending tool life. Share this post Link to post Share on other sites
Retired Wrencher 5,441 #29 Posted February 1, 2020 (edited) I found this site Mike. It has to be HSS bits. https://home.howstuffworks.com/best-drill-bits-for-hardened-steel.htm I found a good bench press or stand alone drill press works best. Buy hand is harder. If need be I have a good bench press. It was made in the early 60`s. Edited February 1, 2020 by Retierd Wrencher 1 Share this post Link to post Share on other sites
Sparky-(Admin) 21,300 #30 Posted February 1, 2020 On 1/30/2020 at 6:12 PM, Sparky said: I am torn about “wrecking” a brand new 56” plow edge. Will update this thread with how it goes. So I couldn’t bring myself to chop up and drill out this new old stock 56” plow edge. The little Wheel Horse guy in my head kept telling me to save it . Had this piece of scrap metal layin around my garage, it’s been here for years. I had no problem shortening it and drilling out 5 holes in it. Bought all new stainless hardware and it’s done ! No it’s not made of hardened steel or whatever the real ones are made of but it’ll keep me going for a few years before I need to flip it. 103618 is the part# off the plow edge I can’t bring myself to cut/drill. Picture 4 is the old 48” edge on top of new one, is definitely thicker. 4 2 Share this post Link to post Share on other sites
Cvans 1,009 #31 Posted February 1, 2020 You have two cutting edges there so it will last a long time. Just make sure to flip it over before it wears into the blade. 3 Share this post Link to post Share on other sites
Stormin 9,981 #32 Posted February 2, 2020 12 hours ago, Cvans said: You have two cutting edges there so it will last a long time. Just make sure to flip it over before it wears into the blade. When I built my plough/dozer blade that's all I did. Just two sections of flat bar. Didn't have a piece long enough for a full width one. 2 Share this post Link to post Share on other sites
DougC 2,641 #33 Posted February 3, 2020 As a man who values a dollar and enjoys it more when it's saved and not spent...... You made me proud with your decision to fabricate material already on site and preserve a piece of Wheel Horse history for the future........ 1 1 Share this post Link to post Share on other sites