I know that this is not really a langmuir related question but I know a lot of you on here can help me with this. I need a really good way to cut large holes in plate 3/4" diameter and bigger. I only have a standard floor drill press but im willing to spend a little money on the right equipment and cutters. I do not have a budget for a milling machine right now.
typically I will cut my parts on the crossfire with a small pilot hole then I will drill my holes. I have used step bits but on anything 1/4" plate or thicker its a bad idea.
I really want a good looking cut on my holes especially when I’m being paid for work and when the hole quality and dimensions matter.
drilling nice holes kinda seems like it should be obvious Fab 101 but I’m not embarrassed to say that fabrication is a skill that I’m completely self taught on and asking knowledgeable people is how I got to where I am (not saying much). Any advice is appreciated.
I appreciate the advice and I understand where you’re coming from but I do not live close enough to that kind of resource for it to be practical. I know I said occasional but that’s still way too often for me to drive 35 to 40 minutes and pay machine shop prices for. If I have more specialized work I need done then that’s exactly what I do but drilling holes in plate is way too basic in my mind to not consider an option in my own shop.
I’d vote for a mag drill with annular cutters. I’ve been watching the used market around Colorado Springs, but they don’t show up often.
I’m sure it would be a case of getting what you pay for, but the direct from china on fleabay isn’t too spendy. But I have a policy of nothing with a cord (or where metallurgy counts) from china if I can avoid it.
My issue is not so much cutting a quality hole for general purpose but when I need a 1” hole for an HD link pin, the hole needs to be as clean and square as possible and the best plasma cuts I have ever seen are not square or clean enough (IMO). I also need this for several other applications that I can’t put on the plasma table
what size is your drill press? a decent size drill press should do the job just fine. you need to progressively work your way up from small drills to your finish size, start with a spotting drill or a center drill, 1/4", 3/8 or 1/2" then your 3/4". you need to predrill with a bit that is just slightly larger than the web thickness of the next larger bit you are using since the web of a twist drill doesnt cut, it just displaces metal…
if you want a really good finished hole (to size) you should drill one size smaller and ream to size.
also if you’re not getting a goot straight hole with a drill press you probably dont have your work clamped to the table good enough and its walking on you.
I have a pretty average drill press. To clarify My holes are square on my press and I can pretty easily drill a 3/4” hole with my current equipment. What I want is the ability to do really nice clean, square holes with .75” and bigger at least 1.5” but maybe 2” and I want to do it in plate up to at least .5” I feel like my basic drill press is inadequate to handle that kind of torque and provide that kind of stability for cutters that big.
I do use the method of increasing my hole size but for much bigger holes it seems very cumbersome. The annular cutters seem much more efficient since your not cutting all that meat in the middle.
I think I have made up my mind on the mag drill and annular cutters. Doing some more research on the inter webs and it seems like that is a preferred setup for a lot of people especially when you have a large project that is difficult or impossible to put on the drill press.