DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 21 Feb 2018, 04:31

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 28 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post subject: Steel vs Wood
PostPosted: 30 Mar 2017, 19:45 
Offline

Joined: 30 Oct 2015, 07:44
Posts: 82
Hello all,

I'm starting the assembly of a new project. With this project I've decided to build a wooden chassis made of walnut with a steel top. I had intended to prime and paint the top and leave the underside untreated. The wood chassis frame has a rabbet edge to allow for the steel top to sit down and become flush with the wood. My thinking for leaving the underside untreated was to minimize the possibility that the paint might stick to the wood and become difficult to remove if necessary and if I had to force it off, my concern is that it might damage the wood. I plan to treat/finish the wood with a tung oil.

After having been working on this for a week or so, the top going on and off several times, I'm noticing some sort of blackening of the wood where the steel makes contact. It even looks as though something may be reacting with or leaching into the wood. I haven't yet applied any paint to the metal and the wood is still unfinished. I plan to save these two steps for near the end after all my test fitting is complete.

Has anyone run into this before? Are there some best practices I should know about?



Thank you,
-Steph


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 31 Mar 2017, 00:34 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2160
Location: Chilliwack, BC
Uh, I haven't :confused:

Do you know the alloy of steel?

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 31 Mar 2017, 06:21 
Offline

Joined: 30 Oct 2015, 07:44
Posts: 82
I surely do not. It's a 14 gauge panel that I picked up at the hardware store. I've cleaned it and it's been exposed to the open air (albeit rather dry climate here) for a few weeks now and there doesn't appear to be any discoloration of the metal and no surface rust. At this point I'm considering a strip of painters tape around the bottom side near the edge where it may contact the wood.

thanks for the consideration.


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 31 Mar 2017, 06:28 
Offline
User avatar

Joined: 05 Aug 2016, 14:35
Posts: 215
What is the wood? Oak will get darker when exposed to any sort of finishing chemicals, moisture or for any of several other reasons. Whoops - I see you wrote Walnut! Walnut will suck up any microscopic materials on the steel, so the rolling lubricant is now the most likely suspect.

Unless you need the steel panel to be unfinished for grounding and connection reasons, a half-dozen light coats of Krylon Workable Fixatif (accept no substitutes), will do a good job of sealing the steel from the wood, without changing the appearance. If you do need to connect to the steel and have good contact, install these little rings at each fastening point, ( http://www.target.com/p/binder-hole-rei ... lsrc=aw.ds ) prior to spraying the Krylon. It works.

Keep in mind that steel sold in the manner you describe is pretty much straight off the rolling mill, and is covered with a very fine layer of rolling lubricant. This stuff is an interesting mixture of rendered fat, wetting agents and other materials and is probably the actual cause of your darkened wood. Removing this stuff takes either a very strong solvent or extremely hot water and a very strong cleaning agent such as TSP - altogether environmentally nasty. But in small amounts, not so bad.

Oxalic Acid will remove the darkening from Walnut - use it with great care, however. This may be had at about any hardware store or paint store.

Good luck with it!


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 31 Mar 2017, 11:51 
Offline

Joined: 30 Oct 2015, 07:44
Posts: 82
That's some very helpful information...thank you very much!


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 31 Mar 2017, 11:58 
Offline
User avatar

Joined: 05 Aug 2016, 14:35
Posts: 215
You are most welcome! People who build their own chassis are to be admired!


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 31 Mar 2017, 13:32 
Offline

Joined: 30 Oct 2015, 07:44
Posts: 82
Well, this is my first attempt at this. I raised the grain a few days ago getting ready for sanding and finish so it's still very dull looking. I'm hoping that after sanding and oil that the purple heart miter splines will pop out a bit. I've got a lot of work to do yet.

Here are a few photos...not quite sure how to do this.

http://imgur.com/a/PA2hc

http://imgur.com/a/LTgRb

http://imgur.com/a/3yWGC

http://imgur.com/a/aiZnx


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 01 Apr 2017, 15:50 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1393
Location: US Pacific Northwest
Looks awesome! Good work!

_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 01 Apr 2017, 16:42 
Offline

Joined: 30 Oct 2015, 07:44
Posts: 82
I thank you sir for the kind words.


Top
 Profile  
 
 Post subject: Re: Steel vs Wood
PostPosted: 17 Apr 2017, 06:50 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4834
Location: Australia
I always prime and spray my top plates. I use an etch primer and epoxy enamel paint. The metal surface is prepared with a 320 grit. I never spray the underneath of the top plate. But my bases are always sealed before the Al top plate goes on. Sometimes oiled or spray polyurethane. Therefore there is always a sealed layer between metal and wood.

Your base looks good.

_________________
Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 28 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy