Making a solid brass flange on lathe

[DaveInBucks]

I’m just getting started with my old south bend 9” lathe and have done some basic turning. I now have a need to make a flange for a furniture leg bottom that accepts a 1.25” diameter brass round. I have a solid 2” brass rod stock and figured I’ll turn the top part of the flag down to 1.5” and 1” high. Easy peasy.

Now I need to create the hole at the top that the 1.25 OD round goes into at a depth of 1/4”. If this was 3/4” or smaller I’d just drill it on my lathe and be done with it. But I don’t think I can get a 1.25” metal drill bit and this seems like what a boring bar and bit should do for me.

I’ve started looking into what kind of boring bar, holder, etc. I need but seems I’ll need to drill a hole first close to my finished diameter. Do I just use the largest drill bit I’ve got and go from there and does that then impact what size boring bar I need to use?

Just getting started with metal lathe so appreciate any pointers…

 

[Janderso]

Welcome,
Brass likes sharp cutting tools with a neutral or flat approach to the work.
No back rake.
Boring brass is an easy task. Great material to work with.

 

[Janderso]

I’m just getting started with my old south bend 9” lathe and have done some basic turning. I now have a need to make a flange for a furniture leg bottom that accepts a 1.25” diameter brass round. I have a solid 2” brass rod stock and figured I’ll turn the top part of the flag down to 1.5” and 1” high. Easy peasy.

Now I need to create the hole at the top that the 1.25 OD round goes into at a depth of 1/4”. If this was 3/4” or smaller I’d just drill it on my lathe and be done with it. But I don’t think I can get a 1.25” metal drill bit and this seems like what a boring bar and bit should do for me.

I’ve started looking into what kind of boring bar, holder, etc. I need but seems I’ll need to drill a hole first close to my finished diameter. Do I just use the largest drill bit I’ve got and go from there and does that then impact what size boring bar I need to use?

Just getting started with metal lathe so appreciate any pointers…

Also, brass can grab your drill bit, it’s best to be ready for it. Some will grind their drill bits to have less cutting ability.
I always drill as much as you can then bore to spec.

 

[wnchstrtnfldvlle]

It’s good to use the largest drill you can, which will cut down on the time spent with the boring bar. As long as you don’t need a flat bottom hole. Then finish to dimension with the boring bar.

Each boring bar will have a minimum bore requirement. You can always get to a larger bore diameter with a smaller bar, so buying a smaller boring bar will give you more versatility. But depending on the depth you still have to consider rigidity in the bar.

 

[DaveInBucks]

I need the bottom reasonably flat but not super precise. For a diameter like this and where I’m not going to deep is there a flywheel cutter or something like that I’ve seen people use on a mill? Or do I just drill largest size I got and gives me clearance for my bar and then it just takes time to bore out all that material?

 

[wnchstrtnfldvlle]

Say you use 135 degree drill for the initial hole. Then you’ll just have an indentation in the middle at the diameter of the largest drill you used for the hole. Then just bore to depth and diameter with the boring bar. Since it’ll be on the inside I don’t think you’d have an issue.

 

[DaveInBucks]

Say you use 135 degree drill for the initial hole. Then you’ll just have an indentation in the middle at the diameter of the largest drill you used for the hole. Then just bore to depth and diameter with the boring bar. Since it’ll be on the inside I don’t think you’d have an issue.

Ah I got you…my hole is 1.25 but the round (furniture leg) is 1/8th wall so I only need the first 1/8th inch flat from the putter edge of the hole. The drill bit will allow me to get the boring bar in there and I can ignore the center of the bottom where the initial drill hole is.

Now I need to figure out what size bar and holder to get…I have the grizzly hss set but not sure how that will perform. This part of the flange won’t be seen and I don’t need precision so as long as I can get a hole +/- 1/32”

 

[brino]

Since the depth is only 1/4" I'd just do it with a HSS bit.
No need for a boring bar.

Brian

 

[DaveInBucks]

Since the depth is only 1/4" I'd just do it with a HSS bit.
No need for a boring bar.

Brian

So same bit I use for turning the outside to diameter?

 

[Jake M]

... south bend 9”...

That brings the first question, what tool post are you using?

lathe and have done some basic turning. I now have a need to make a flange for a furniture leg bottom that accepts a 1.25” diameter brass round. I have a solid 2” brass rod stock and figured I’ll turn the top part of the flag down to 1.5” and 1” high. Easy peasy.

Dead sharp tool, no top rake, no chip breakers...

Now I need to create the hole at the top that the 1.25 OD round goes into at a depth of 1/4”.

How tight does the fit have to be? If it needs to be a precise fit, then measuring that might turn out more challenging than making it...

If this was 3/4” or smaller I’d just drill it on my lathe and be done with it. But I don’t think I can get a 1.25” metal drill bit and this seems like what a boring bar and bit should do for me.

You certainly could get such a drill bit, but it's going to be more than your lathe wants. And probably tear up the morse taper in the tailstock..... You want to bore that.

I’ve started looking into what kind of boring bar, holder, etc. I need but seems I’ll need to drill a hole first close to my finished diameter. Do I just use the largest drill bit I’ve got and go from there and does that then impact what size boring bar I need to use?

You must (within reason, there are ways.... but within reason....) you must drill a hole large enough to let your boring bar enter.
This will leave the "point" of the drill at the bottom of that hole. You can drill the hole to depth "plus the drill point", and after you bore the hole, it'll be flat on the bottom, except that "dimple" in the middle from the drill point.
OR, you can drill the hole to put the drill point exactly at the bottom of the finished hole. You'd then bore the hole, and it will be shallow, but at that point, once it's widened, 98 percent of boring bar options out there will let you "face" the bottom of the hole, bringing the whole thing to depth with no divots in the bottom.

But that's about all we can can give on the boring bar at this point. We've got to know how you're holding it to the lathe before we can give you any solid advice on "which" tool to buy.

Truth be told... At a quarter inch deep- You could grind a boring tool out of a 3/8 HSS blank and plow through that. With a little restraint, you could do it with quarter inch HSS, so another pertinent question might be "Are you getting a job done", or "Is this the job that is a trigger for filling out an incomplete tool collection? Both answers are valid, and warrant very different advice.