Sanding down Hammond transformers - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 19th December 2010, 12:57 AM   #21
diyAudio Member
 
Join Date: Sep 2010
Location: Melbourne
Quote:
Originally Posted by leoparleur View Post
Thanks also for bringing up the welding practice. I don't know if Hammond process this way (I don't think so as I did not noticed them) but it's a good point you brought up there.
I doubt that hammond weld the lamination stack, it is more common with rugged industrial and automotive devices alternators, welding transformers and chokes being the main users of this technique I have also seen a few electric motors with welded stacks.

As for thinners entering the lamination stack, even if they did the insulation between the laminations is a specially formed oxide layer which is unaffected by heat and solvents.
  Reply With Quote
Old 19th December 2010, 02:55 AM   #22
diyAudio Member
 
Join Date: Oct 2007
Location: Quebec
As basic I thought this thread would be, I'm happy from all your input as it is very informative on the different techniques you are proposing and on the expertise you have gained over the years. It'll certainly help other people in the future also.

Hammond (the rep) confirmed that he have spoke to engineers and confirmed that it was ok to sand down to bare metal without problem. He will ask if the stacks are welded and come back to me early this week. I told him that I would take care of fixing the lamination finish but I asked so they send me a new 193M choke since the baked varnish peels of too easy. After all they are under warranty and he mentionned that I need to be satisfied with the product I purchased. Good thing to know from hammond.

If Hammond weld the stacks, would it be visible? Generally, is it visible from the lamination side or from the surface side?
  Reply With Quote
Old 19th December 2010, 03:01 AM   #23
diyAudio Member
 
Join Date: Oct 2007
Location: Quebec
Quote:
Originally Posted by BudP View Post
After you have spent some time with the lacquer thinner try using Acetone, same amount in a metal tray. Use double vinyl or other protective film gloves to avoid poisoning your self. This will melt the polyester resin that is likely the varnish used. Just wipe the core edges with a wet strength paper towel now and again until you get it as smooth as you want. Once the resin has reset, lightly sand the paper residue off and paint.

I am a transformer engineer and this is what we do in our plant to refinish or dismantle the transformer core. I would remove the endbells and bolts. keeping the isolation washers where they are on the bolts. Don't loose those, ever!!!!! Then perhaps rebolt the core with some appropriate size just to keep the pieces of I lam from dropping out.

Bud
Thanks for being precise on the whole cleaning process. Can't I use the original bolts and washers while I'm doing the job???
  Reply With Quote
Old 19th December 2010, 03:50 AM   #24
diyAudio Member
 
Join Date: Sep 2010
Location: Melbourne
Quote:
Originally Posted by leoparleur View Post

If Hammond weld the stacks, would it be visible? Generally, is it visible from the lamination side or from the surface side?
Yes it would, The welding is to hold the lamination stack together and prevent vibration Hammond appears to use bolted stacks. The welding is always on the outside of the stack with a clearly visible bead.
  Reply With Quote
Old 28th December 2010, 04:05 AM   #25
diyAudio Member
 
Join Date: Oct 2007
Location: Quebec
Thanks to all who posted. I decided to go the shortest way and sand down the plate edges since Hammond confirmed it was ok to proceed that way. It went very well, the varnish (or whatever it is dipped in) came off easy. I made sure to remove dust with lacquer thinner afterwards. Take a look at the pictures, I added copper finish paint.

BTW, I noticed also, that Hammond transformers are assembled very quickly. One of my OPT has phenolic washer and the other one had plastic sleeves. The PT had two crushed plastic sleeves. That lets me perplex about their Quality department.

What's the use of plastic sleeve? Is it only there to center the bolt and isolate it from short circuit? Considering I have phenolic flat washer on one OPT, I estimate there are risk (electrical) if the bolt touches the lamitions?

I will contact Hammond on that situation.

Now it's time to solder up the components and think wisely how to best route the point-to-point wiring.

Thanks!
Happy New Year!
Attached Images
File Type: jpg DSCN0363_20101227_195901.JPG (644.5 KB, 56 views)
File Type: jpg DSCN0358_20101227_195742.JPG (526.4 KB, 55 views)
File Type: jpg DSCN0360_20101227_195801.JPG (535.8 KB, 53 views)
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
hammond transformers? ipop07 Tubes / Valves 21 14th June 2011 03:00 AM
For sale: Hammond transformers eitanwaks Swap Meet 4 6th September 2007 08:33 AM
hammond transformers eitanwaks Swap Meet 0 13th May 2007 09:20 AM
Hammond Transformers Ham Swap Meet 2 16th March 2007 10:45 PM
Hammond Transformers Gabevee Tubes / Valves 0 5th April 2004 02:47 PM


New To Site? Need Help?

All times are GMT. The time now is 06:34 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2