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SevenSixTwo - InDIYana 2018 Coax Design

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  • JavadS
    replied
    Yes what John said, worst case finish the cut with a hand saw and sand it clean with a sanding block.

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  • Kevin K.
    replied
    Sometimes the obvious will elude you Keith, John's suggestion should be the fix. I'm digging your project and it looks like they'll be pretty snazzy when all finished up! If you're still planning on wrapping the core of the cabinet in veneer, check with Tom for a video he made on a small subwoofer. Lots of cool little tricks in the video that could be very helpful. Oh, and make sure you use at least a 3/4" radius, 1/2" can be done but increases the pucker factor tremendously.

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  • jhollander
    replied
    Standing on end and table saw set to 30 doesn't make the cut? Make a 90 degree jig and clamp the piece to it.

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  • KEtheredge87
    replied
    Hey guys, tonight I find myself foiled by geometry and tool capabilities. When I was designing the coax chamber rear walls, I used some 30 and 60 degree angles. Turns out that none of my current tools have enough tilt, throat capacity, what-have-you... to make this cut! Even if I jigged up something to hold the piece vertical for the table saw, I wouldn't have enough cut depth to make it through the piece.

    I need to noodle on this a bit to figure out how I'm going to move forward. I guess there's always the old faithful hand saw, but I seriously doubt I can make a clean vertical cut with one. For anyone else perplexed, the piece is 1.5" thick, 8" wide, and about 9.5" long right now. I need to cut a 60 degree wedge off one end, and all my tools stop at 45 degrees of bevel! I really should have seen that coming.

    Either I come up with something not too hair-brained to make the cut, or I see what I can do to redesign that area for 45 degree cuts that I actually CAN make.

    Stoopid geometry

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  • marvin
    replied
    Agreed! Any true DIYer gets satisfaction from fixing something with an inexpensive part, even tho' it should have been warranteed. Good job.

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  • KEtheredge87
    replied
    Originally posted by marvin View Post
    I would think you could have exchanged that vac at Home Depot if it failed within 30 days
    Hey Marvin, yeah... I threw away the receipt in a fit of hubris. Also bought it using a gift card, and HD claims they can't look up receipts (I believe they said they absolutely can't look up receipts from gift card transactions). I find the customer service aspect of this particular transaction sorely lacking, so I'll be making a pointed stink on their facebook page after fixing it. Those thermal fuses are only $1 each, so I'm not out loads of money, but the principle of the matter is just messed up. If Menards can print receipts right at their front door, then HD just isn't trying to help their customers.

    Good thing I'm not afraid to do some research, turn a wrench, and solder some stuff! Anyway... back to MDF and wood glue this evening!

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  • marvin
    replied
    I would think you could have exchanged that vac at Home Depot if it failed within 30 days

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  • KEtheredge87
    replied
    Originally posted by jhollander View Post
    WRT to off axis measures, I design on axis and do a quick check off axis to see what's happening. Some times I end up leaving more dips as they fill in off axis. So looking off axis helps to guide my on axis design.
    Thanks John! Hopefully I'll be at that stage in the design before too long.

    While I'm posting... tonight I had to spend my time dissecting my brand new Ridgid shop vac to confirm the thermal fuse had tripped in there. That sucker is quite literally in the heart of the beast, wrapped up in the motor windings. While a replacement is on order, I picked up a tiny ShopVac brand vacuum to catch all the dust my router will throw. Definitely a speed bump I did not expect! Back to work tomorrow!

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  • jhollander
    replied
    WRT to off axis measures, I design on axis and do a quick check off axis to see what's happening. Some times I end up leaving more dips as they fill in off axis. So looking off axis helps to guide my on axis design.

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  • augerpro
    replied
    Originally posted by KEtheredge87 View Post
    I assume I should model a matching set of ~40 degree off-axis measurements in PCD to compare against?
    Yep

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  • KEtheredge87
    replied
    Originally posted by augerpro View Post
    Keith, coaxes can be pretty wonky on axis. At minimum, do a set of measurements at about 40 degrees off axis and use that as check on your crossover design.
    Thanks Brandon, I assume I should model a matching set of ~40 degree off-axis measurements in PCD to compare against? At this point I am operating more on a "model then listen" than a "model, then check with a measurement". Until I get better with using my ears to do the judging, using my eyes and some data can't hurt.

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  • augerpro
    replied
    Keith, coaxes can be pretty wonky on axis. At minimum, do a set of measurements at about 40 degrees off axis and use that as check on your crossover design.

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  • JavadS
    replied

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  • KEtheredge87
    replied
    Monday evening update - The glue-up for the top, bottom, front, and back went well. All the clamps did their jobs and held things in place. I set the newly glued cabinet pieces up for a flush trim and made the front baffle even with the top and bottom, and then made the top and bottom even with the back.

    The bummer of all that was my brand new Ridgid shop vac has a problem and would not turn on! I've been using that sucker with a fine dust filter bag in place since I bought it just before Christmas and it's been a champ. I'd prefer NOT to rip this one open to look for an issue since it should still be under some kind of warranty, so I'll have to contact Ridgid directly during business hours tomorrow. I'm afraid I will get the run-around... or some garbage about shipping the thing to a service center. The whole situation really chaps me though... I bought the Ridgid to replace a ShopVac branded model from Lowes that lasted more than 5 years of my abuse. Somebody please get in their time machine and bring me a shop vac from the 1970's. Bet those still work!

    Anyway... I've got the cabinet gluing up only one wall right now. I'm using the other wall as a caul to distribute the clamping force. I want to keep one wall unglued while I do my port length adjustments to hit the tuning frequency. My plan is to remove the whole MDF slot port assembly and trim it down on the table saw a little at a time until I get the right frequency. Once I'm set there, I'll glue and clamp it to the bottom of the cabinet.

    Also... this is further proof that one can never have enough bar clamps!

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  • xmax
    replied
    All Coax's seem to have some compromises in the FR plot often the power response makes up for it.

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