Porch Glider #9: Metal Working

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Blog entry by Jimi_C posted 04-01-2012 09:01 AM 2728 reads 0 times favorited 3 comments Add to Favorites Watch
« Part 8: Stressful! Part 9 of Porch Glider series Part 10: Schwing »

Eventful two weeks. I ordered a 6’ bar of 1/8” x 1” of 304 steel for the swing arms and angle braces, as this plan calls out making all parts yourself and not using anything pre-bought. McMaster Carr got the steel here fast, as in 2 days, which really surprised me. I also ordered the flanged bearings from them, which got here a couple of days later.

I had originally planned on doing all the metal working myself, but after drilling a single 3/16” hole in a test piece and seeing how long it took me (not to mention I started having concerns about an overheated piece of metal starting a fire in my dusty shop), I decided to contract the work out to a machine shop near my house. These were the same guys I had press the bearings into my rehabbed bandsaw, so I had been there before.They did the work for $45, while their regular hourly rate is $75, so they gave me a bit of a bargain. That’s still twice as much as I paid for the raw material, but hey, it saved me a weekend of drilling metal.

Here’s the raw material, all that’s left from the 6’ bar.

And here’s the angle braces I had made. These were custom designed by me, as I had concerns about the plan’s version. I designed it to be sure the screws coming up into the seat frame would not be anywhere near the pile of mess that is the rear corner (which I’m pretty sure is at least 50% screw at this point). I drew up some plans to scale on graph paper and went over them with the machinist to be sure he understood what I wanted, and he definitely nailed it. I had them bend these pieces, since I wasn’t sure I’d be able to bend it to 90 degrees without snapping it.

And here’s one of the finished swing arms, which has 2 3/8” holes drilled in them. I hit the steel with some 220 sand paper to give them a nice satin looking finish and to remove all the markings (including permanent marker from the machinist):

I did the bends in these, as well as rounded off the corners with my wet grinder (which now needs some serious truing…). The plan called for them being completely circular on the ends, but I thought that was wasteful and unnecessary so I just gave them a nice radius to remove the sharp corner.

The angle works out to be about 10 degrees, which doesn’t seem like much until you tip it up.

And here’s the mockup of the arm rests. The seat slats are getting their final sanding, just 4 more left to do (after doing 8 I got really sick of sanding and took a break).

The plan here calls for the arms to flush with the inside edges of the seat ends:

But I think I like it better with a slight (about 5/8”) overhang on the inside edge:

From the front:

Here it is as the plan calls, with the arm flush to the inside edge:

And from the front here:

Here’s the piece (part letter U) that ties the arms together across the back. This will actually be joined via half-laps to the arm rests, not like I have it clamped up here:

There is one final piece (part letter V), which has a 15 degree angle – same as the bottom brace. V gets screwed to the underside of U, as well as to all of the back slats just like the top brace that’s already attached. This locks the seat back to the arms and along with the angle braces prevents racking. After that, there’s just a couple corbels that help support the arm rests on the outside, and that’s pretty much it.

So, what do people think? Stick with the plan or go with the overhang. I am leaning towards the overhang, as I don’t really like the way it looks perfectly flush to the inside edge, and I don’t see anything in the plan that would cause it to be a problem.

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

3 comments so far

View Sarit's profile


552 posts in 4638 days

#1 posted 04-03-2012 08:17 AM

When I had to drill several holes in my steel trailer frame, I discovered that you have to use some sort of cutting oil or it will take a long time and heat up like you said. I used some 3 in 1 oil and just kept adding it before it got all flung off. It was like a night and day difference. I also used regular titanium coated bits, but I hear the cobalt ones are the best for hard metals.

View Jimi_C's profile


507 posts in 4734 days

#2 posted 04-03-2012 08:32 AM

I tried using some Boeshield, but then realized that was probably not a great idea as it would probably burn easily if overheated from going too fast. I had my drill press (cheap Ryobi with the electronic speed control) turned down as slow as it would go (about 600-800RPM), but it was still smoking a bit if I tried to drill down too fast.

If I hadn’t been drilling in my workshop, I wouldn’t have been too concerned, I just didn’t want to have a stray piece of overheated metal or burning oil start a fire. I thought about hauling the drill press up to my garage, but honestly I just wanted to get this done and not deal with having to lug equipment up from my basement :)

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

View Sarit's profile


552 posts in 4638 days

#3 posted 04-04-2012 06:40 AM

I actually did my drilling w/ a corded handheld drill, but at 3/8” you might be pushing it. The oil will keep the bit lubricated and cooled enough to keep it from burning.

When you don’t have oil, the bit heats up, then gets dull faster, which makes it heat up more, and so on. That’s why I say its really a night and day difference.

Here’s a video that shows the process. It really does work like this.

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