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Re: My 3π adventure [message #95711 is a reply to message #95710] Fri, 24 June 2022 20:25 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18321
Registered: January 2001
Illuminati (33rd Degree)

I have mine mounted to the bottom, but you can certainly mount it on the side.

Good job on the T-Nuts! And you're right - those prongs want to bend unless you are careful. I like using epoxy on them just like you have.
Re: My 3π adventure [message #95719 is a reply to message #95260] Sat, 25 June 2022 17:57 Go to previous messageGo to next message
ppkstat is currently offline  ppkstat
Messages: 35
Registered: February 2022
Baron
T-nut installation is done! I guess this is the last part on the list of things that can go seriously wrong Very Happy A couple of them are a bit hard to turn, I am guessing this is ok.

/forum/index.php?t=getfile&id=3088&private=0

This is a test fit (screwed in) of the woofer. It goes in beautifully.

/forum/index.php?t=getfile&id=3089&private=0
Re: My 3π adventure [message #95721 is a reply to message #95719] Sat, 25 June 2022 18:38 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18321
Registered: January 2001
Illuminati (33rd Degree)

Looks really nice! I love that midwoofer!

About the T-Nuts - you said a couple screws are hard to turn - be careful with those, especially since the T-Nuts are now epoxied in place.

I often see this on builds, and it's usually no big deal. But you can make it a bad deal if you're not careful. So let's go through it really quickly. I just don't want your T-Nut threads to get damaged.

Usually, when I see threading difficult, it is due to one of two things:

1. The position and/or alignment of the T-Nuts is just slightly different than the holes in the midwoofer.

2. The threads have been slightly damaged by the process of installing them.

So do this: Try to run screws into the T-Nuts using only your fingers. This is best done when no driver is in place. It is just to see that the T-Nut and screw threads are in good shape. They should spin freely, all the way down.

If one doesn't, find out if it's the T-Nut or the screw. Try a different screw first, and if another screw goes in easily, then discard the difficult screw. It may have damaged threads.

If more than one of your screws go in hard - assuming the screws are new and in good shape - then the T-Nut threads have been damaged. I sometimes encounter this when screws are used to drive the T-Nut into place. That's a great idea, but you have to use several "sacrificial" screws because the screw threads become damaged after repeated high-torque applications, and a screw with damaged threads will harm any T-Nuts its used with.

So if the T-Nut threads are damaged, then use a tap to clean up the threads. If you don't have one, go to a hardware store and buy a tap and tap-wrench. They're inexpensive, and they'll clean up the threads and make 'em good as new.

Once all the T-Nuts allow screws to thread in easily, now we can check for driver mounting hole alignment. Set the driver in place and hand thread each of the screws. If one goes in a little hard, slightly rotate the driver to re-index it. By leaving all the screws loose - just a few turns for each screw - you can get 'em all started. Once you do that, you can probably safely tighten each screw without cross-threading any of them. That's obviously the goal.
Re: My 3π adventure [message #95722 is a reply to message #95260] Sat, 25 June 2022 18:53 Go to previous messageGo to next message
ppkstat is currently offline  ppkstat
Messages: 35
Registered: February 2022
Baron
Thank you Wayne. I've already tried some of your suggestions, I think its an alignment issue. I will check again.
Re: My 3π adventure [message #95723 is a reply to message #95260] Sat, 25 June 2022 19:33 Go to previous messageGo to next message
ppkstat is currently offline  ppkstat
Messages: 35
Registered: February 2022
Baron
I checked again. Unfortunately in 2 of them I cannot turn the screw by hand. Bear in mind that I can completely put the screw in and out with a screwdriver, it just takes a bit of force. So I guess these are damaged.

I will probably try to find a M5 tap here, I am just nervous because I haven't used one before. From what you write I understand that I will probably get away with it without doing anything but what's the bad case scenario? Is that that the screw might get completely misaligned and further destroy the remaining threads?

I did use several sacrificial screws for this. They there SS Allen screws and they were used twice at maximum. I guess I overtightened them.
Re: My 3π adventure [message #95724 is a reply to message #95723] Sat, 25 June 2022 20:03 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18321
Registered: January 2001
Illuminati (33rd Degree)

Don't panic, because I don't think you've ruined them. But don't force them either. Take the extra effort to go get that tap and use it on each of the T-Nuts. They're super-easy to use - just like threading in a screw - but the tap is hardened steel and has cutting edges that will remove any burrs and put the threads back in place. You'll be glad you did it.
Re: My 3π adventure [message #95725 is a reply to message #95260] Sat, 25 June 2022 20:26 Go to previous messageGo to next message
ppkstat is currently offline  ppkstat
Messages: 35
Registered: February 2022
Baron
I am getting one on Monday then. They are definitely not ruined, I put a screw in and out several times with ease (when using a tool).
Re: My 3π adventure [message #95730 is a reply to message #95260] Sun, 26 June 2022 18:35 Go to previous messageGo to next message
ppkstat is currently offline  ppkstat
Messages: 35
Registered: February 2022
Baron
Just a few closing questions on crossover placement. Really sorry about that.

The proposed way is to mount it in the bottom, under the insulation by making a flap like this:

/forum/index.php?t=getfile&id=3090&private=0

This is the crossover and zobel in my cabinet.

/forum/index.php?t=getfile&id=3091&private=0

This is the most space saving solution as the zobel resistor can sit beneath the back sheet of insulation (the crossover is too high to do so). Even this way there is not a lot of space available in the front of the speaker for the insulation to be glued and make a flap. There is just 7cm from the edge of the pcb to the support of the front baffle (bear in mind that the internal space is somewhat reduced due to these supports). Is it feasible in this size?
Re: My 3π adventure [message #95733 is a reply to message #95730] Mon, 27 June 2022 08:49 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18321
Registered: January 2001
Illuminati (33rd Degree)

That's perfect. It'll work just fine that way.

You can put it on the side of the cabinet too, if you prefer. But I think the way you've shown above is easiest, and it works just fine.

Put a gasket underneath the Zobel resistor and the crossover PCB too. It will cushion them and prevent any possibility of buzzing. You can use cardboard, cloth or PVC sheet material.
Re: My 3π adventure [message #95734 is a reply to message #95260] Mon, 27 June 2022 08:56 Go to previous messageGo to previous message
ppkstat is currently offline  ppkstat
Messages: 35
Registered: February 2022
Baron
Thank you Wayne! As for the gasket, been there done that. There is 2mm EVA tape underneath that Zobel. In fact, everything on the speaker has EVA. The crossover is going to be mounted on 1cm EVA (part of camping mat) because the pcb is through-hole and soldered on the bottom layer.

I also repaired the threads with the tap today. There's one that still has some difficulty to it no matter how many times I pass the tap. I'll live with that I guess and I will be extra careful during the final assembly.
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