Welding a 4" core bit

[technoid]

I thought some might find this useful info. I had bought a 4" concrete core bit in a yard sale for $10. It had the drive end broken off inside the threaded end of the core bit. My hammer drill is a 1" millwaukee SDS drive. I could not find an SDS drive that would fit this core bit. So I cut the shaft off an old 3/4 SDS masonary drill. Took my Hobart 187 mig and turned up to #6 with about 30 on the feed for .30 wire. Carefuly tacked welded around so it would stay true on the core bit. Then welded short beads side to side to keep it from warping off. I did not think this trick would hold under the amount of force from the hammer drill. The shaft was a little off and made the tool wobble during the drilling. But to my surprise I was able to bore through 10" of solid cement with out the weld cracking. So if there are any back yard welders like me out there you can count repairing masonary tools with your mig.

[dumb as a stump]

Oh we need pictures of that...

[DamageInc537]

a 4" core bit on an sds drill? no base? wet core or dry core?

if i was asked by my forman to core through a 10" slab with a 4" core on a hammer drill, i might have laughed in his face... if that thing ever caught the OP would be in some serious pain.

[farmshop]

I am still amazed that a core bit works at all let alone on a sds hand held. Used a 6" that we held in place with a backhoe to get down pressure. Just dont tell the rental guy.

[technoid]

I thought some might find this useful info. I had bought a 4" concrete core bit in a yard sale for $10. It had the drive end broken off inside the threaded end of the core bit. My hammer drill is a 1" millwaukee SDS drive. I could not find an SDS drive that would fit this core bit. So I cut the shaft off an old 3/4 SDS masonary drill. Took my Hobart 187 mig and turned up to #6 with about 30 on the feed for .30 wire. Carefuly tacked welded around so it would stay true on the core bit. Then welded short beads side to side to keep it from warping off. I did not think this trick would hold under the amount of force from the hammer drill. The shaft was a little off and made the tool wobble during the drilling. But to my surprise I was able to bore through 10" of solid cement with out the weld cracking. So if there are any back yard welders like me out there you can count repairing masonary tools with your mig.I used water in a spray bottle on the bit. Took my time with just enough pressure to allow the bit to do its job. Stopping every 2 mins to allow the hammer drill to cool down. You have to clear the hole of the cement debris too. The job took over an hour. You can't be in a rush using core bits. Thats how guys damage tools. And always use water. I'll try to upload a picture of my weld. The weld looks like S#@T but it held and thats all that matters to me. I was drilling a hole for a dryer vent in a basement.

[farmall]

Demonstrates what ya can do with care and patience.