Robins 55 #1 Posted October 27, 2014 Hi All, Not really sure which section to put this under? I need to drill at least two, 34mm holes in some 20mm thick steel. How would you guys do it? My initial thought is hole saw, but 20mm thick steel, would a hole saw really last long enough! cheers, Daniel Share this post Link to post Share on other sites
Stormin 4,458 #2 Posted October 27, 2014 You could chain drill, chisel out the centre then file. What's the plates dimensions? Have you got a lathe? Will the plate go in a 4 jaw? Share this post Link to post Share on other sites
meadowfield 1,900 #3 Posted October 27, 2014 Hole saw every time. They work brill, look at the bendy thread. WD40 helps too... Share this post Link to post Share on other sites
Robins 55 #4 Posted October 27, 2014 What brand do you use of hole saw Mark? I really thought the teeth would fall off before getting through 20mm of steel. Its an attachment for my digger Share this post Link to post Share on other sites
Hillsider 16 #5 Posted October 27, 2014 Yes definitely can be cut using a decent brand of holesaw, try to use a drill with a slow to medium speed and plenty of cutting fluid (WD40 would do). The brand that we used to get for such jobs was Starrett and the largest hole that we cut was 4 inches diameter through 2 inch plate. Share this post Link to post Share on other sites
meadowfield 1,900 #6 Posted October 27, 2014 Starret and sandvik are the main ones I use, but the cheap screwfix and erbauer ones work just as well. I even use them in the lathe as by the time you've drilled a hole and bored it, the sawvhas done the job.... Share this post Link to post Share on other sites
Stormin 4,458 #7 Posted October 27, 2014 I miss read the first post. I was thinking jig saw. As said, Starret or Sandvik. Share this post Link to post Share on other sites
Robins 55 #8 Posted October 28, 2014 Thanks guys, i'll get one the right size and give it a go Share this post Link to post Share on other sites
neil 524 #9 Posted October 28, 2014 Starting now you could be finished by June 2015 using one of these Hole saw is the way to go , have used them to bore holes in RSJs on site 1 ranger reacted to this Share this post Link to post Share on other sites
meadowfield 1,900 #10 Posted October 28, 2014 Here's a 25mm hole cut through 20mm steel. Cheap screwfix hole saw and about 20mins of patience... Share this post Link to post Share on other sites
paul 64 #11 Posted October 28, 2014 Hi I have been drilling 30mm holes through 25mm thick plate at work today and we use a heavy duty arbour in a pillar drill . The bits are held in with two grub screws and they have teeth like a hole saw but are fluted, in the centre of this there is a pin which picks up on a centre dot and at the other end in the arbour is a spring loaded ball bearing so when the bit goes through this activates the spring to push the wasted drilled bit off. They are made by rotobore and are, and we use a lot in magnetic drills for drilling rafters and such on buildings in sitchu Share this post Link to post Share on other sites
meadowfield 1,900 #12 Posted October 28, 2014 Of course we never mentioned, rotobroach drill bits in a mag drill are the quickest and cleanest way. Just more expensive, I really ought to consider one.... They also oil the cutter too Share this post Link to post Share on other sites
Stormin 4,458 #13 Posted October 29, 2014 Of course we never mentioned, rotobroach drill bits in a mag drill are the quickest and cleanest way. Just make sure no idiot un-plugs the drill when drilling upside down. It has happened to me. 2 meadowfield and ranger reacted to this Share this post Link to post Share on other sites
Hillsider 16 #14 Posted October 31, 2014 Yes Mag Base Drill and Roto Broach type drills are very good but as you say the MagDrill is the expensive bit. I have not been involved in the hire of tools for a few years now but I do remember that some tool hire companies used to have them available. Share this post Link to post Share on other sites
Robins 55 #15 Posted November 2, 2014 A holesaw worked wonderful, i needed two 51mm holes in 20mm plate in the end as i decided to use a piece of thick tube as a sort of bushing to spread the load. I melted a Bosch drill in the process and the Makita drill is not sounding quite as fresh as it did, but the hole saw has all its teeth and still sharp which i was surprised so i drilled a further two 51mm holes in some 6mm thick angle for a brace the other side aswell. 54mm hole in 20mm plate. I'm adapting a forklift frame to fit my MF50b digger so i can move pallets of bricks, bulk bags of sand ect. with much welding and lots of thick bits of steel i have achieved what i set out to do. Only been putting this off for nearly 3 years. Holding the frame to the front bucket with a ratchet strap always seemed the easier option 1 nigel reacted to this Share this post Link to post Share on other sites
Stormin 4,458 #16 Posted November 2, 2014 Good job. Share this post Link to post Share on other sites
ranger 373 #17 Posted November 2, 2014 When I use a holesaw I change the pilot drill to a length of 1/4" silver steel,especially for thinner material, it keeps the holesaw running true otherwise the flutes in the drill cause the saw to run out of true. the correct drill for a holesaw has a flute length that ends before the saw starts cutting,but they have usually been replaced at some time or other doug. 1 Anglo Traction reacted to this Share this post Link to post Share on other sites
