I posted this before, but I think the details might have dissuaded anyone from attempting it. Here's a much easier version that works just as well. Turns out that one flute works as well as two since the guide keeps it so stable. That really simplifies the build.
I was getting something in Home Depot today and got an image in my head of a tool that anyone could build in order to cut a waveguide into a baffle with a drill press. If you have a jig saw and a drill press, this is very easy. No welding necessary.
The shaft is 1/2 inch "eye bolt" from Home Depot. It was the only bolt with sufficient length of thread. It's only nominally 1/2 inch (because they go cheap on their "1/2" inch eyebolts and measures 7/16 diam). That's fine.
The angle iron is just 1 1/2 X 1 1/2 X 1/8 and is available anywhere. They soak you at Home Depot so get it there only if it's your last option.
I got the eye bolt since the 1/2 inch machine bolts at HD only had about an inch of threaded section. As you'll see, we need more.
Cut off the eye of the bolt. Cut the profile in the angle iron using Zaph's template posted on his Waveguide TMM page. Again, for simplicity, I only cut profile in one side. The opposite side is cut about 1/8 inch lower so that it does not contact the workpiece. Drill 7/16 hole. Cut out half moon for the bottom nut to fit. All very simple. It took half an hour with a hand jigsaw.
This was an experiment to see if it would work, and it worked wonderfully in MDF. Only present catch is that the resulting profile is slightly off due to the need to offset the edge from the shaft center. It's likely to be close enough, but a little fine tuning in CAD would correct the original template for the offset.
This bit takes about an hour to make with common shop tools and did MDF just fine in my smallest drill press (1/2 hp Harbor Freight 39 dollar on sale little wonder). The mild steel needs rehoning with each WG recess completed. Easiest done with the small sanding drum on your dremel. It would take quite a few honings to alter the profile to any degree.
The 7/16 hole could also be cut as a slot. Interestingly, this would allow the bit to be adjusted to fit different sized tweeter diameters while keeping the same throat angle.
This waveguide enthusiasm might just die within a month.. who knows? Or someone might establish elliptical guides as so superior that nothing else will do and then we'll be really hard pressed to "roll our own". But for the time being, I'd love to see more experimentation in this stuff by the talented folks who are light years ahead of me in design. This is the most I can contribute.
I was getting something in Home Depot today and got an image in my head of a tool that anyone could build in order to cut a waveguide into a baffle with a drill press. If you have a jig saw and a drill press, this is very easy. No welding necessary.
The shaft is 1/2 inch "eye bolt" from Home Depot. It was the only bolt with sufficient length of thread. It's only nominally 1/2 inch (because they go cheap on their "1/2" inch eyebolts and measures 7/16 diam). That's fine.
The angle iron is just 1 1/2 X 1 1/2 X 1/8 and is available anywhere. They soak you at Home Depot so get it there only if it's your last option.
I got the eye bolt since the 1/2 inch machine bolts at HD only had about an inch of threaded section. As you'll see, we need more.
Cut off the eye of the bolt. Cut the profile in the angle iron using Zaph's template posted on his Waveguide TMM page. Again, for simplicity, I only cut profile in one side. The opposite side is cut about 1/8 inch lower so that it does not contact the workpiece. Drill 7/16 hole. Cut out half moon for the bottom nut to fit. All very simple. It took half an hour with a hand jigsaw.
This was an experiment to see if it would work, and it worked wonderfully in MDF. Only present catch is that the resulting profile is slightly off due to the need to offset the edge from the shaft center. It's likely to be close enough, but a little fine tuning in CAD would correct the original template for the offset.
This bit takes about an hour to make with common shop tools and did MDF just fine in my smallest drill press (1/2 hp Harbor Freight 39 dollar on sale little wonder). The mild steel needs rehoning with each WG recess completed. Easiest done with the small sanding drum on your dremel. It would take quite a few honings to alter the profile to any degree.
The 7/16 hole could also be cut as a slot. Interestingly, this would allow the bit to be adjusted to fit different sized tweeter diameters while keeping the same throat angle.
This waveguide enthusiasm might just die within a month.. who knows? Or someone might establish elliptical guides as so superior that nothing else will do and then we'll be really hard pressed to "roll our own". But for the time being, I'd love to see more experimentation in this stuff by the talented folks who are light years ahead of me in design. This is the most I can contribute.
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