Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Construction Tips Construction techniques and tips

My first stereo PA
My first stereo PA
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th October 2017, 11:29 PM   #1
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Default My first stereo PA

I'm building a ST35 tube power amplifier.
Just finished my first chassis. I used a Hammond 1444 (aluminium), 12"x 8".

I find hard to completely remove all the aluminium tiny bits from the drilling/cutting. As this is a high voltage amplifier, it is very important not to leave any small piece of metal.

Can I use water (even dipping the whole chassis) to safely remove all the residue? I know that aluminium oxidizes easily.

I don't plan painting.

Thanks for advices and help!
  Reply With Quote
Old 12th October 2017, 01:34 AM   #2
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by Elerion View Post
I find hard to completely remove all the aluminium tiny bits from the drilling/cutting.
Can I use water (even dipping the whole chassis) to safely remove all the residue?
Use a dry, old toothbrush instead, and then masking tape to pick up some of the smaller bits.
Or, tap the chassis with a rubber hammer to jar them loose.
  Reply With Quote
Old 12th October 2017, 05:25 AM   #3
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Vacuum cleaner?

Mostly the chps fall to the bottom, may do no harm. However I did once "fix" a flaky PC by opening and stripping it, then beating it. Some factory flakes fell out. After that it was rock solid.
  Reply With Quote
Old 12th October 2017, 11:40 AM   #4
DF96 is online now DF96  England
diyAudio Member
 
Join Date: May 2007
Water may leave a stain. Some mixture of brushing, vacuuming and sticky tape should do it.
  Reply With Quote
Old 13th October 2017, 03:36 PM   #5
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Thanks for the tips. Done!

Now I'm thinking about painting. I have a small hammond chassis used in a much smaller project, to test with.

I got an aluminium epoxy primer, and polyurethane resin paint (for exterior use, and which is sold as being very resistant).

My plan is:
- Sand the surface with a soft sandpaper.
- Apply 1+1 vinegar/water solution until surface darkens.
- Dry using a hairdryer.
- Apply the epoxy primer.
- Let dry.
- Apply two coats of paint.

Please, any suggestion / caution ?
  Reply With Quote
Old 13th October 2017, 08:28 PM   #6
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
I didn't want to paint, but this is why:

close_surface.jpg

The chassis is so easily scratched.
And it is not even finished.
What would it be some years later...

Any recommendation?
  Reply With Quote
Old 16th October 2017, 05:37 PM   #7
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Default Painting my first aluminium chassis

As nobody replied, I just tested my plan on the small chassis, and it seemed to work quite well.

The exact steps are:

- Sand the surface with a soft sandpaper.
- Sand the surface with a coarser sandpaper (I bought it as "recommended for aluminium", whatever this means).
- Apply pure white vinegar on the surface. Let it dry. Then apply two more times. The surface didn't darken, but I carried on.
- Apply an alkyd resin based primer (sold "for aluminium" specifically).
- Let dry.
- Apply two coats of paint (polystyrene based enamel, not the cheapest one), letting paint dry between them.

The outcome is nice! It seems stiff and solid.
I have read that painting on aluminium is easy, but hard for the paint to stay on it. If I hadn't read it, I wouldn't say the result is fragile at all.

Is there something I can do to test it?
It would be great if other people share their experiences. I haven't found much (detailed, easy and affordable) information about this particular topic.
Attached Images
File Type: jpg primer.jpg (466.3 KB, 96 views)
File Type: jpg painted.jpg (625.6 KB, 90 views)
  Reply With Quote
Old 16th October 2017, 06:01 PM   #8
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
I've found blu tack very useful for picking up swarf and the like
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 17th October 2017, 01:51 PM   #9
Kay Pirinha is offline Kay Pirinha  Germany
diyAudio Member
 
Join Date: Oct 2011
Location: Somewhere in Germany
Quote:
Originally Posted by Elerion View Post
- Sand the surface with a soft sandpaper.
- Sand the surface with a coarser sandpaper (I bought it as "recommended for aluminium", whatever this means).
Why did you do it this way? Sanding and polishing usually proceeds from coarse to fine grains.
Best regards!
__________________
"Bless you, Sister. May all your sons be bishops." (Brendan Behan)
  Reply With Quote
Old 18th October 2017, 08:22 AM   #10
Elerion is offline Elerion  Spain
diyAudio Member
 
Join Date: Sep 2017
Quote:
Originally Posted by Kay Pirinha View Post
Why did you do it this way? Sanding and polishing usually proceeds from coarse to fine grains.
Best regards!
You're right. Anyway, it came out pretty good.

I just repeated the process on the final chassis, just inverting the order of sanding.

- Sand the surface with a coarse sandpaper.
- Sand the surface with a soft sandpaper.

Pay atention to the corners.

I applied the vinegar with a paint brush. Letting it fully dry. Three times. The surface seemed to darken a little bit under some angles of view.

Then, right before the primer, clean with nail polish remover (it will remove a lot of dirt; the cloth will come out nearly black ).

I was wearing nitrile gloves all the time, to avoid touching the metal surface.

Today I'll paint the chassis. Hopefully I'll post the result.
  Reply With Quote

Reply


My first stereo PAHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Mauro Penasa MyRef Rev C 3886 Stereo Amplifier with TDA7294 Stereo Woofer Amp VictoriaGuy Swap Meet 8 6th February 2017 11:16 PM
HELP needed - LEAK Varislope 2 Stereo + Stereo 20 with pictures... triole1 Tubes / Valves 13 28th March 2014 07:55 AM
My stereo amplifiers produce mono output with stereo source! tsiros Solid State 2 3rd November 2013 08:17 AM
Looking to make a mono sub from a stereo output while keeping stereo speakers. JForged Multi-Way 17 14th December 2012 02:37 AM
sony SVO-1630 hi-fi stereo vhs stereo recording/playback problem neazoi Analogue Source 1 7th October 2011 08:36 AM


New To Site? Need Help?

All times are GMT. The time now is 11:29 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki