Using Facing Cuts to Make Holes in 3/16" Mild Steel

[schuylergrace]

I need to make six ~2" holes in some pieces of 3/16" mild steel plate, but I don't have hole saw/annular cutter large enough or a trepanninig tool. So, I was wondering if there is any reason I shouldn't or couldn't just face off most of the unwanted material in the lathe and clean up and size the hole with a boring bar or a standard turning tool. I figure taking facing cuts would be more efficient than running the boring bar in and out of the hole, and I wouldn't have to deal with the slug trepanning creates. Is there something I'm missing? Thanks!

 

[francist]

It might get a little dicey when the material gets thin — could be a tendency to crumple and catch the cutter if you’re not careful. But, I’ve not done it to be able to say for sure.

-frank

 

[schuylergrace]

It might get a little dicey when the material gets thin — could be a tendency to crumple and catch the cutter if you’re not careful. But, I’ve not done it to be able to say for sure.

-frank

That was my biggest concern, but I couldn't see how it would be worse than whatever happens with the slug you get from using a trepanning tool.

Thanks, Frank!

 

[Martin W]

Ox tool on YouTube has a good video for making a trepaning tool.

cheers
martin

 

[schuylergrace]

Ox tool on YouTube has a good video for making a trepaning tool.

cheers
martin

Thank you, Martin. I've watched a bunch of his videos over the years, but I haven't seen this one, yet. In fact, I was considering making such a tool, and this will come in handy. But right now, I just wanted to knock out these holes with what I have, and I wasn't sure if I was about to do something totally stupid, as I'm wont to do at times.

 

[Martin W]

How accurate does this nee to be? I have tack welded a bunch of pieces together and then mounted the whole thing in a 4 jaw. Centre drilled and then drilled as big as I had a drill. Then finished with a boring bar. Ground the tacks and buffed with a flap wheel. Not sure if this could work for you. 6 pcs at 3/16” is only 1-1/8” tacked together
cheers
martin

 

[schuylergrace]

How accurate does this nee to be? I have tack welded a bunch of pieces together and then mounted the whole thing in a 4 jaw. Centre drilled and then drilled as big as I had a drill. Then finished with a boring bar. Ground the tacks and buffed with a flap wheel. Not sure if this could work for you. 6 pcs at 3/16” is only 1-1/8” tacked together
cheers
martin

Thank you, Martin. This only needs to be woodshop accurate, and I was debating whether to stack, drill, and bore them, since that would make the drilling and boring operations more efficient. But I got to thinking about why I'd never seen or heard of anyone essentially facing a hole. Especially on the YouTubes, folks will do things the weirdest ways; sometimes for good reason, more often because they just don't know any better and they have a video camera. I figured this must be some kinda crazy idea, if not one other person has said it's absolutely the best way to bore a hole.

 

[Martin W]

I have never personally faced a part to create a hole in such a thin piece. Like Frank mentioned above, it may crumple and catch. Being thin you are not going to be able to chuck it very tight or it may crush. Do you have any chuck stand offs to back up the piece, so it wouldn't slip? May work or may not. Might be worth a try if you are careful.
Cheers
Martin

 

[schuylergrace]

I have never personally faced a part to create a hole in such a thin piece. Like Frank mentioned above, it may crumple and catch. Being thin you are not going to be able to chuck it very tight or it may crush. Do you have any chuck stand offs to back up the piece, so it wouldn't slip? May work or may not. Might be worth a try if you are careful.
Cheers
Martin

Yes, I do have standoffs. But you raise a point I hadn't considered--crushing the piece in the chuck jaws after the extra material is milled away. I was only thinking about what would happen when I thinned out the steel to the point where it would start to crumple/tear on the tool point. So, I may try this (very carefully) on a piece of scrap, but I think I'm going to follow your recommendation to stack, drill, and bore the pieces.

Thanks, Martin!

-Schuyler

 

[RJSakowski]

Without knowing the rest of the part geometry, it is hard to say what would be the best approach. I would consider using a faceplate with hold down clamps and a sacrificial backing plate. If the hole is predrilled with a pilot hole. the hole could be located using a center in the tailstock and clamped down. If a faceplate isn't available, a plywood plate could be mounted in a four jaw chuck and the work fastened to it.

For machining the hole, I have done trepanning using a 1/4" tool bit ground to fit the purpose. There needs to be sufficient relief to clear the diameter of the hole but 3/16" is a piece of cake. Far easier the machining out the entire material in the hole. (Bonus, you end up with a 3/16" thick washer blank which can come in handy on other projects.)