I am looking to purchase some 6061 aluminum plate for a tube amp, but have a question regarding the thickness that I will need. The size of the plate will be 12"x24" and the transformers will be about 35 pounds in total weight.
What I am wondering is what thickness of plate would I need to use and not have to brace the underside of the amp.
Input anyone? What are your experiences with this and what do you use? Most of what I have built in the past has been on poplar or oak boards, but I want to make something that won't kill the cat.
What I am wondering is what thickness of plate would I need to use and not have to brace the underside of the amp.
Input anyone? What are your experiences with this and what do you use? Most of what I have built in the past has been on poplar or oak boards, but I want to make something that won't kill the cat.
The thickness of the aluminum plate depends a lot on your construction technique.
You could use 16ga for example, and use appropriate bracing under or even above the chassis.
To build above or below the nominal chassis surface one could use what would be essentially a "sub chassis" which might be a thicker plate or braced plate(s), or even an actual box or [ shape (rotated with the long part up - this is a cross section).
Or you can buy thick stuff like 1/4" to whatever in thickness and machine it.
The possibilities are pretty broad - perhaps it is better to get past the "box" and think beyond the simple "box". Makes for a more interesting looking build anyhow.
_-_-
You could use 16ga for example, and use appropriate bracing under or even above the chassis.
To build above or below the nominal chassis surface one could use what would be essentially a "sub chassis" which might be a thicker plate or braced plate(s), or even an actual box or [ shape (rotated with the long part up - this is a cross section).
Or you can buy thick stuff like 1/4" to whatever in thickness and machine it.
The possibilities are pretty broad - perhaps it is better to get past the "box" and think beyond the simple "box". Makes for a more interesting looking build anyhow.
_-_-
Check out 5052. It is fine for use a sheet and can be bent if needed for reinforcement. Normal chassis is .062" or 2 mm. For a heavy transformer you can go 50% thicker. But it is a lot more work if you are using hand tools. A bit of bracing is a much better approach.
Hi There;
I assume that most of the mass will be near the support walls and not dead center. That would be the usual way to go.
For no bracing I think I'd go for 3/16" and make sure that that stuff is plate; not sheet (not sure if sheet is available that thick anyway but just in case). You could check the ALCOA website or Metals Supermarkets or even McMaster Carr. Thicker is also better because you could also tap threads for mounting tube sockets etc. With 3/16 you could get almost 1.5 diameters of thread engagement for a 6-32 screw; more for smaller.
Sounds like an interesting project.
Matt
I assume that most of the mass will be near the support walls and not dead center. That would be the usual way to go.
For no bracing I think I'd go for 3/16" and make sure that that stuff is plate; not sheet (not sure if sheet is available that thick anyway but just in case). You could check the ALCOA website or Metals Supermarkets or even McMaster Carr. Thicker is also better because you could also tap threads for mounting tube sockets etc. With 3/16 you could get almost 1.5 diameters of thread engagement for a 6-32 screw; more for smaller.
Sounds like an interesting project.
Matt
Thanks Soundchaser... that's what I was looking for.
My goal is to not have bracing, but the entire weight handed by the thickness of the plate itself. As for machining, I have a craftsman 150 drill press and 1" aluminum doesn't even slow it down. The issue becomes thickness vs price for the plate.
My goal is to not have bracing, but the entire weight handed by the thickness of the plate itself. As for machining, I have a craftsman 150 drill press and 1" aluminum doesn't even slow it down. The issue becomes thickness vs price for the plate.
Why don't you want to brace?
if you use aluminium angle and only fasten it to the fixings for the plate so the plate rests on the angle there are no fixings to drill.
I always support the transformer section even with 3mm aluminium plate.
Regards
M. Gregg
if you use aluminium angle and only fasten it to the fixings for the plate so the plate rests on the angle there are no fixings to drill.
I always support the transformer section even with 3mm aluminium plate.
Regards
M. Gregg
Select a "harder" grade.
soft aluminium is indeed quite soft.
H2 or if you can get it H3.
But the much harder grades are more difficult to bend and will show some stress on the outside of the bend.
Heating before bending helps but interferes with the hardening. Not sure if this is permanent, or comes back after time.
soft aluminium is indeed quite soft.
H2 or if you can get it H3.
But the much harder grades are more difficult to bend and will show some stress on the outside of the bend.
Heating before bending helps but interferes with the hardening. Not sure if this is permanent, or comes back after time.
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I'm not looking to brace anything because of the type of enclosure that I want to build, hence the question of what thickness would be required to support 35 pounds without flexing or bowing.
No bending required. This will be a solid flat plate.
Picture this.... a top plate with all components, tubes, transformers. Then brass standoffs from the bottom of the top plate to another plate underneath. From there whatever type of "feet" that I decide to use.
Just figured that it would look pretty cool.
No bending required. This will be a solid flat plate.
Picture this.... a top plate with all components, tubes, transformers. Then brass standoffs from the bottom of the top plate to another plate underneath. From there whatever type of "feet" that I decide to use.
Just figured that it would look pretty cool.
If you are going to use two plates separated by standoffs then just place standoffs strategically under the transformer section to transfer the weight to the lower plate. The structure will gain significant stiffness from the distance between the plates as long as the standoff attachments are tight enough to restrict motion between the plates and standoffs. That will allow you to use reasonably thin material without any compromises in structural integrity.
you could sit a car (1200kg automobile @ 300kg per wheel) on a 5mm 6061 and not see much deflection in a typical amplifier sized base plate.
Imo, it's not just about the thickness, but the finish of the aluminium stock that matters. For an old tube amp project of mine i got some "natural anodised" 4mm aluminium, and it looked great when i got it and continues to do so.
With thinner stock and large cutouts you run the risk of a slight flex, assuming a non-uniform weight distribution.
3mm would probably have been fine too.
With thinner stock and large cutouts you run the risk of a slight flex, assuming a non-uniform weight distribution.
3mm would probably have been fine too.
I used 1/4" aluminium plate on a similar project so i could drill and tap. Worked great and looked great?
Jp
Jp
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