rattle_snake's random shop projects v0.1

[rattle_snake]

Fuel pump on the 72 Ford quit, luckily at home. I pulled the connector apart at the pump and measured 5 volts. Hmm.... wrong number. There is a 2nd connector that links main harness to the chassis harness. I eventually got it apart, cut the hell out of my hand, and found a burned up pin. I knew the weatherpack connectors were not rated for more than 20 amps but used them anyway. The 320 lph fuel pump draws 25. It worked for a while, but not robust enough. I imagine the inductive kickback doesn't help and is part of the cause. Once crusty, it self destructs from heat. I cut out the pins and went with **** crimps that cannot fail. Removes the modular aspect of my wiring system, but oh well for a mission critical wire. Switched to a two pin for the level sender.

 

[rattle_snake]

New Vortex rimfire scope on Mossberg 346BA .22LR. Looks much better thoroughly cleaned and oiled. Looking forward to getting it dialed in and plinking with it. Just need this heat to end...

 

[rattle_snake]

Updating a few car stereos to include Bluetooth connectivity. Tried a different single DIN with screen cheap turd in the 72 ford. It has horrible software. locks up, resets, bricks itself. Can't use any audio controls or sound is horrifically distorted. Can't save any setting as it resets all the time. If I change A/C controls, it resets from EMI. Otherwise it has great features like navigation and whatnot.

I put the older turd with it's different but annoying problems in the boat. The bezel/cover was shot so put a new one in and had to open up the hole in the dash.. 1.5" plywood with fiberglass on both sides.

 

[rattle_snake]

Cobra got a double-DIN upgrade. It's a cheap unit as well, but supports a back up camera. The unit for the truck came with a camera so I put it on the car. Have to use an app for certain things but got it working.


13 years ago I wired system with a kit from Rockford/lightning, not understanding that it was aluminum wire. 1/0 gauge and huge, but aluminum. Wasn't happy with performance, so hooked up an oscilloscope. Would incur big volt drops in calbes when bass hits. Big *** capacitor does nothing (too slow). Alternator would drag engine RPM down and then surge, disco headlights. Did nothing until now. I have learned a few things since them.
I ripped all that **** out and put in 2ga copper. Started with closed end crimps, and a real crimping tool. Adhesive heat shrink to seal the connection to prevent corrosion. No more flimsy open ended gold plated ring terminals. I replace the baked/cracked compression style maxi fuse holder with a stud style, to use seal crimps instead of just a set screw jammed into the strands. Made a bracket.


Put the fuse in the same place as before. I had already put in decent 2 ga copper grounds from bat to chassis and bat to engine block.


The main power wire used to feed a large cap and distribute from there to fuel pumps, nitrous heater and the audio system. Now it is just a lug until I go back and redo the rest of the wiring and system in the trunk. Big caps were the thing back in the day however they are too slow to deliver energy at the rate to maintain a constant voltage during a big load change. Also any cable length drops a lot of voltage a when current is really high (100-1000 amps peaks).

 

[rattle_snake]

The reason for wiring upgrade is to support more power, louder. The goal of the original system was light weight and easily removable for drag strip purposes. A single 10 and amps mounted to the bottom of the read deck. Now I want more of a retro look and feel. Subs facing forward, amps on the back of the box. A new box was in order with 2 drivers to double cone area. The rear seat opening will really only accommodate a 10, and I had recently bought two new Rockford P3D2-10s for the shop. The 10s in a sealed box aren't the best fit for shop so they will go into the car, and be replaced with 15s in vented boxes.
I farted around with box constraints but ended up using Rockford recommendation of 0.59 ft^3 for a Q of 0.95 (a hump). With driver each side is 0.666. The P3 are deep with big magnets, barely fit. Plan to go from a 500w mono sub amp to a 1500w for the pair.



Basic box complete. Next is a gasket to the back set and a trim bezel.

 

[rattle_snake]

In parallel building a set of boxes for the shop, for 15s. One box is too bulky and heavy to ceiling mount, so two it is. I originally wanted magnets out, but with odd size of the P3s, I just used what I had. Now I can cut the odd sized opening to face mount. Ports will be mostly internal like the 12s. The 15s will definitely need two 4" diameter ports to keep air velocity in check, but to get a low resonant frequency the ports have to be really long. With elbows, I should can get 25" inside the box and some tips to net 30 something. Box itself is just a simple rectangle, to fit in the small space above the A/C and between the others.


I fell into the rabbit hole of bracing again needing something functional yet simple, elegant and aesthetically pleasing (although not visible). I did some sketches and ended up with this


I knocked out the baffle brace. Need to add the 3rd axis supports still. The idea is to shorten the distance across an unsupported piece of MDF, to raise the resonant frequency above operating range (aka walls rigid)

 

[plain2car]

...... HOLY COW!!! ........ That's all I got Justin! .......

 

[fouckhest]

Your speaker box skills are very impressive!

Also, glad to see that you still use MDF, I built a box last year for one of my cars and went back and forth between MDF and doing Baltic Birch, but price was just crazy different

 

[rattle_snake]

Thanks. MDF has better acoustic dampening properties than plywood. I rather work with plywood.

 

[rattle_snake]

Finished out the basic box of one of the pair.

 

[ntsqd]

Out of silly curiosity, how does the PVC tube behave with regards to damping, resonance, etc.? I'd expect that it being thin and not terribly dense that it could be doing some weird stuff, that may or may not be detectable.
Makes me wonder if wrapping it with something like Dynamat would even be noticeable? Or maybe only wrap the middle third of each straight section? Sorry, just my bored mind wandering about.....

 

[rattle_snake]

I think even the thin wall pipe is rigid enough. Interestingly, the pressure in the port is in phase with the cone and box pressure. So it is balanced. That is, when the cone goes forward, air comes out of the port. This seems backwards to what happens when you manually push the cone in, air comes out the port as it is displaced. At the tuning frequency of the box/port system (about 30 Hz in this case) the air in the tube is in resonance and in-phase. This is why vented designs are inherently are 3db louder.

Typical port problems are turbulence, from abrupt ends and/or excessive air velocity. The 15" driver w/ 15mm xmax has swept volume of about 1.5 liters. At 100 Hz, there is 10 ms to move it all through the port.

 

[rattle_snake]

Assembled the twin of the 15 boxes. Building from inside out this time.

 

[rattle_snake]

One of my new drag radials has a slow leak in the sidewall. Likely from manufacturing process. Working with vendor but may take a while so went ahead and stripped all the audio gear out of the trunk. This was old setup attached to underside of rear package tray.


With amps removed I was able to test fit the new box. Since the driver trim ring is about 1" tall, the box needed to be spaced back from rear seat backs. The goal is to have decent performance with rear seats up in usable position. To achieve this an air path is needed from cones to the holes in the rear deck (from stock speakers that are gone). I made some spacers out of MDF, wrapped in carpet, and screwed them to the rear seat structure.


Made a trim piece for the baffle to add some style. Plan to paint the baffle silver and wrap the trim bezel with charcoal vinyl.


The amps will be mounted to the back side of the enclosure. To hide the wires and give some style, I made trim piece out of 1/2"ply using crown molding style cuts. It is removable for access to the amp's controls. Mounted with speaker grill type ball and socket connectors.

 

[Boosted1]

nice work on the speaker boxes.

 

[OutlawDrifter]

I dig the hidden wire "crown molding" idea

 

[burger]

I'm impressed with the details on the speaker cabinets! I'd love to know more about the math behind the dimensions and tuning, but I'm sure that would take a book. How did you make the radius cuts in the MDF? Table saw?

 

[rattle_snake]

nice work on the speaker boxes.

Thank you

I dig the hidden wire "crown molding" idea

After test fitting the box a square style bezel would interfere with access to the nitrous tank valve knob and the spare tire.

I'm impressed with the details on the speaker cabinets! I'd love to know more about the math behind the dimensions and tuning, but I'm sure that would take a book. How did you make the radius cuts in the MDF? Table saw?

Thanks!

The math is complicated but there are online calculators for that. There are not that many parameters to adjust. For a simple sealed box you just have box volume, which impacts the frequency response. A big box will be flat, and a small one will have a hump.

A vented box is the same, just adds the port and it's associated tuning frequency. You can choose the port tune frequency by its length. When using a smaller box that degrades low end response, a port tuned low can help restore the performance. A port tuned to the same frequency of the box's 'hump' nets a bigger hump.

Loudspeaker enclosure calculating with Thiele Small parameter

Loudspeaker enclosure calculation with frequency and step response group delay voice coil impedance output diagrams

www.micka.de

Radii are done with a router and a circle jig.

 

[burger]

I never knew about circle and chamfer router jigs and went down a rabbit hole this afternoon. This could cost me..

The speaker box calculator looks awesome, but holy cheesesteaks, what the hell is going on there? Looks like a lot to digest.

This brings up a question about the box you built to fit behind your rear seat. You said:

“The goal is to have decent performance with rear seats up in usable position. To achieve this an air path is needed from cones to the holes in the rear deck”

What did you mean about the air path from the cones to the holes in the rear deck and why?

 

[rattle_snake]

“The goal is to have decent performance with rear seats up in usable position. To achieve this an air path is needed from cones to the holes in the rear deck”

What did you mean about the air path from the cones to the holes in the rear deck and why?

Simple explanation, allow the sound to more easily get from speakers in the trunk into the cabin of the car.

When the rear seats are down the speakers face into the cabin so all is ideal. When rear seats are folded up, that path is blocked. The rear deck has large holes in it from the old rear speakers that were removed. So this can be the air/sound pressure path from trunk to cabin. But if the speakers are hard up against the seat backs, they will be muffled, so the whole box is moved back a bit to allow sound up and out though the rear deck holes.

 

[rattle_snake]

Decided to make a sleeper platform for the back of my superduty. Was planning on taking a trip with my dirt bike, one nighter. The cab-over and trailer are nice, but more effort than I want to spend for one night. A tent works OK if dry, but still something to fart with.
The cab is 6' wide at the windows, enough to stretch out. I wanted to be able to open either rear door and utilize the space below. Seems easy enough. Cut a 26"x 72" piece and added ribs to keep it from sagging.


Sewed up some nylon straps with adjustable buckles to suspend the platform from the handles and head rests.


Covered with some close enough matching fabric, and some leftover carpet I had on hand.


I have some 3" foam I can use on top. Unfortunately the usable length decreases as the windows curve in at the top. Still enough to stretch out but tight for me. I'm 5' 11'. Didn't end up going on the trip, and now have to find someplace to store this thing....

 

[rattle_snake]

Put some Kilz oil based primer on the speaker boxes.


Silver metallic spray paint on the face and back of the box for the car.


Made patterns on the back of the charcoal vinyl to cover the box.






Won't really be able to see the sides, but stitched them anyways.

 

[OutlawDrifter]

Can you loop it through the rear upper seatbelt mount rather than the headrest? Seems like the headrest post might be questionable on weight bearing ability.

 

[rattle_snake]

Yes I think that would work also. I bought big roll of strap.

Plan A was to rest on the door itself, which works well. The strap idea came later so the doors could open.

 

[rattle_snake]

Sanded the primer and rolled red paint with hardener added on the boxes.

 

[rattle_snake]

Wrapped the amp trim ring in vinyl. Not perfect but with equipment and in the trunk should look OK.

 

[rattle_snake]

Test fit the box one more time.

 

[rattle_snake]

Made some stickers for my dirt bike.

 

[burger]

Speakers are coming out great! The one in the Mustang should be really loud! I was telling a buddy about it last weekend and he showed me an enclosure he built for a single 8" in a C4 Corvette. The single 8" blew me away so I can't imagine what your Mustang will be like!

 

[rattle_snake]

Somehow I was able to let the paint harden an extra whole day before trying to ruin it. The mounting scheme is still with engineering dept but I installed unistrut as basis on each box. For safety reasons I like to anchor into more than just top piece of wood. I used three 1/4" lag screws, one into baffle and the other two into the center brace. The goal is to minimize the height of the mount hardware.

 

[rattle_snake]

One of the new drag radials had a pinhole leak in sidewall causing a slow leak. Received a replacement tire from Summit racing. Choosing not to go back to Discount as they will charge another $40 to mount the replacement tire. Already spent over an hour waiting in line to get this far, so worth driving across town to have a friend do it for free.


Flat tires and dead batteries are part of fleet ownership. Wife's explorer had battery go bad. It's under the cowl and a PITA to access. Got it swapped out and back on the road.

 

[plain2car]

MAN!! much rubbing issue with that?

 

[rattle_snake]

No, I was able to get a 315 tire to fit and tuck up even lowered. I rolled the fenders, and use a 0.4" concentric spacer to get things to fit.

 

[Cane]

MAN!! much rubbing issue with that?

According to ai and Harry Hogge.....rubbins' racing....

I don't know it's late and I need to go to bed....

 

[rattle_snake]

Puttering on mounts for the new shop speaker boxes. Considered cutting on plasma and trying to bend in press, but decided to start with some 2x4 0.187 rectangular tube and cut out the shape needed. Going to weld some DOM to make a shackle-ish thing.

 

[rattle_snake]

Took the dirt bike to Flagstaff to ride in the cinders, first time. Beautiful area, tons of wooded trails of all difficulty levels. Some with nasty steep hill climbs. Switchbacks of ledges, roots, loose gravel.
1st ride we did the series of big open hills. BIG long WOT hill climbs. With just a knobby tire and 7-8k elevation the bike is limited compared to sea level dunes and a paddle. Need more traction/power. Physically demanding to ride in and thin air. Front end washes out easily but without a paddle you have to stay in the throttle for awhile to keep it vertical.
Pictures just don't show the scale of the hills.


This hill was steep. About 45*, bottom is deep loose whoops. My buddy tried a few times, can just make out him and the bike in this pic about 1/2 way up. Somebody made it, well almost.

 

[Bigblue&Goldie]

The Cinders are a trip, it's so different than anything else it's like being on the moon! The elevation and the cinders themselves are hell on equipment and tires. I think the last time I was up there was for a AZOP race; all the kids on 50cc bikes couldn't go anywhere as they were getting stuck and just spinning their tires! The pictures definitely don't do the scale justice.

 

[rattle_snake]

I was expecting tire damage but didn't have a problem. Next time I will take the paddle tire also and do some of the crazy stuff a knobby won't.

 

[PugetDude]

I was expecting tire damage but didn't have a problem. Next time I will take the paddle tire also and do some of the crazy stuff a knobby won't.

You need nitrous.

 

[rattle_snake]

Yes of course. Always.


Reality is that the hills are so big and long that bike is at WOT for a really long time. Would be easy to overheat the piston and have a ring failure. Given it is rich at altitude the small, dry (no extra fuel) motorcycle kits would be OK.