Greetings everyone,
What is the general consensus on a 12"x8"x2.5" chassis that is made from .090 aluminum? Will it withstand 10 lbs of iron?
Here's the vendor: GUITAR AMPLIFIER CHASSIS'
Thanks,Ray
What is the general consensus on a 12"x8"x2.5" chassis that is made from .090 aluminum? Will it withstand 10 lbs of iron?
Here's the vendor: GUITAR AMPLIFIER CHASSIS'
Thanks,Ray
I have used some aluminum of that thickness. I had a slight sag so I bought some aluminum channel and cut it to run the length of the chassis and it definitely help stiffen up the top. I used two pieces of channel so that both sides of transformers were supported.
Would a steel chassis from Hammond be a better choice? I believe their steel chassis is only .036" thick. Would I be in the same boat? Can .036" steel be stronger then .090" aluminum?
Sheet metal materials
Check out this site...scroll down to where you see this:
Check out this site...scroll down to where you see this:
There is a table there.
Hi
You will need to etch prime the alloy first before under coating .Some high fill primers have an etch in them but UI would still etch separately .
Also look at different grade's of aluminium different grades will be stiffer .
The other thing you could do is use another sheet/plate on top to get the required stiffness ,even use a different ferrous or non ferrous material .
Cheers
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Unless you use a special primer like zinc chromate, painting is not good. The primer is very caustic.
Alternatives are powder coating or anodizing.
Powder coating is pretty easy and works well. If I remember correctly, AR2 did a tutorial here a couple of years ago.
Stiffness for a given material is determined by it's elastic modulus (Youngs Modulus), and virtually every grade of wrought aluminum alloy has an elastic modulus of about 70,000 MPa +/-. The different AL alloys have different yield strengths and differences in other material properties, but they all have roughly the same stiffness for a given thickness.
The agreed upon upper limit of a chassis thickness is about 2mm. Anything thicker than that most sockets will not have a long enough supplied thru-bolt. Clearances to the pins gets really tight at that limit.
________________________________________________________Rick.........
________________________________________________________Rick.........
Thicker plates do add a bit more work ,but you can always blind drill and thread so no screw heads show . I used 5mm copper plate .
Cheers
Attachments
Have used Hammond 2 mm aluminum chassis for a project, never again! Even marking it made it dent.
I have used several of those exact chassis for a couple projects. They hold up really well with the larger guitar amp power transformers. Once they are mounted they are actually very solid.
I prefer the one he sells with the inward lip on the end, they help cut down on cab size. The overall length of the outward style lip is an additional 1.5 inches.
The combined transformer weight on the last one I used was just over 13 lbs including choke.
There is a vendor on ebay that sells a similar chassis minus the pre-installed mounting nuts for around $18+ shipping. He will make them any size you want.
Ebay Chassis
What are you using for tools, stone chisels?
My chassis is 0.040" (1 mm) and I was able to manage.
I did use a 1/4" aluminum plate under the transformers and another 1/4" bar under the center of the chassis.
How did you guess ?!?!?
I'm sure it would be better if i did the same, but it was my first project and I used Flintstone technology.
Ha, Ha!
I remember when I was in high school and I was looking for a job as an electronic technician for this one company and I brought in one of my early tube amps to show my resolve.
The interviewer looked at the "Flintstone Technology" with all the rough sawed holes and the naked truth of primitive hand tools and remarked that it was not good enough for what we build.
I wasn't so much insulted as surprised. It's one thing to have a machine shop, but when all you have is a cheap saber saw and a hand drill you can't get perfection. Heck, I built my first folded bass horn using hand saws because it was all I had. At least I had initiative.
OK, not THAT bad. (I m not THAT young, either 😛 )
It's an AX84 P1 I made for a guitarist friend. After 4 years, he's still in love with it (despite the Flintstone paintwork). Don't you love the bridge that's hanging from its 2 legs (left side off the tagboard) ?
Very badly. You need to anodize it before you paint. This requires some specialized (and nasty) prep that you're not likely to pick up at the corner Ace or True Values.
Any other method is likely to look good for a little while, until the paint bubbles and peels. Aluminum is difficult to work with.
Aluminum looks nice enough natural finish for most folks. Most chassis are 5052H alloy as that is the common cheap and bendable alloy. .090 is reasonably stiff.
To paint it you will require lye and special acid etch primer. Sherwin Williams sells it in gallons along with the special thinner. I have also seen it in cans marked NAPA auto parts. First you clean the entire surface with a very caustic lye in water solution. You know you have enough lye in solution when the aluminum gets shiny an a minute or so, bubbles when you stick the aluminum in mean too much lye. Not enough and the aluminum doesn't get bright and shiny. About 2 teaspoons to a gallon works. Test with aluminum foil! After the bath in lye has dissolved your fingers rinse the chassis with clean water and towel dry. You now have 15 minutes to prime it. The primer requires a spray gun, it really is not brushable. The primer then suggests you paint within 30 minutes. You can do all this in a garage with the door open and one of the paper dust masks (I use the ones with active carbon inserts.) Of course a mask with external provided air inside a rated paint booth is the right way to do it.
The biggest problem is that lye is no longer sold in small amounts as it can be used to make controlled substances.
To paint it you will require lye and special acid etch primer. Sherwin Williams sells it in gallons along with the special thinner. I have also seen it in cans marked NAPA auto parts. First you clean the entire surface with a very caustic lye in water solution. You know you have enough lye in solution when the aluminum gets shiny an a minute or so, bubbles when you stick the aluminum in mean too much lye. Not enough and the aluminum doesn't get bright and shiny. About 2 teaspoons to a gallon works. Test with aluminum foil! After the bath in lye has dissolved your fingers rinse the chassis with clean water and towel dry. You now have 15 minutes to prime it. The primer requires a spray gun, it really is not brushable. The primer then suggests you paint within 30 minutes. You can do all this in a garage with the door open and one of the paper dust masks (I use the ones with active carbon inserts.) Of course a mask with external provided air inside a rated paint booth is the right way to do it.
The biggest problem is that lye is no longer sold in small amounts as it can be used to make controlled substances.
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