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Old 16th April 2011, 11:20 PM   #1
Derekva is offline Derekva  United States
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Default Is it OK to drill mounting holes in transformer laminations?

I've got an S5 K-501 mono power transformer that I wanted to pretty up a bit. One idea I had was to remove the clamp-on mounting bracket and horizontally mount the transformer with a bell cap from Edcor. However, the laminations don't have any holes drilled in the corners. Would I cause any damage to the transformer if I drilled four mounting holes in the laminations (not the bobbin)? I'd be sure to tape up the lamination to avoid getting steel shavings from the drilling process lodged in the transformer.

Thanks!

-Derek
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Old 16th April 2011, 11:32 PM   #2
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yep - there is every chance that you will end up shorting each of the laminations together and hence get the magnetic equivalent of just a block of iron instead of a laminated core.

I'd suggest its a whole lot easier to make some covers or under-mount the offending item.

Or in fact to just buy a prettier piece of iron - at those ratings and your location, they are comparatively cheap.
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Old 16th April 2011, 11:33 PM   #3
Derekva is offline Derekva  United States
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Quote:
Originally Posted by aardvarkash10 View Post
yep - there is every chance that you will end up shorting each of the laminations together and hence get the magnetic equivalent of just a block of iron instead of a laminated core.

I'd suggest its a whole lot easier to make some covers or under-mount the offending item.

Or in fact to just buy a prettier piece of iron - at those ratings and your location, they are comparatively cheap.
No idea what the ratings, etc. are on the transformer.

If drilling isn't an option, would epoxying the covers or otherwise gluing them in some manner cause any problems?

Thanks,

-Derek
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Old 16th April 2011, 11:56 PM   #4
seanvn is offline seanvn  Viet Nam
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I would likely have a minimal effect on the transformer. The metal screws that go into the laminations might get a bit warm because of extra losses in them compared to the laminations. You could use nylon screws. I am not sure if you can drill and tap the high silicon steel laminations so well, you would have to check that out.
Anyway nice question. I will try out your idea.
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Old 17th April 2011, 08:11 AM   #5
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by aardvarkash10 View Post
yep - there is every chance that you will end up shorting each of the laminations together and hence get the magnetic equivalent of just a block of iron instead of a laminated core.

I'd suggest its a whole lot easier to make some covers or under-mount the offending item.

Or in fact to just buy a prettier piece of iron - at those ratings and your location, they are comparatively cheap.
Derekva,

aardvarkash is correct. If you look at an Edcor Tx you will see small plastic insulators under the screws that go through the laminations.

The laminations are insulated from each other with an oxide coating. The screws "bolts" are put through the plastic insulators to stop connection with the laminations. If two of the bolts contact through the laminations you get a shorted turn. This is created by the bolts that would connect each side of the Tx to the other. If you drill and short the two sides "front & back" togeather the Tx wll over heat and burn out!

Even if it does work after the intial drilling you have to insulate the bolts from the Tx core. Your idea could trash the Tx. Then again its your Tx!

Regards
M. Gregg
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Old 17th April 2011, 10:26 AM   #6
AJT is offline AJT  Philippines
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Quote:
Originally Posted by Derekva View Post
I've got an S5 K-501 mono power transformer that I wanted to pretty up a bit. One idea I had was to remove the clamp-on mounting bracket and horizontally mount the transformer with a bell cap from Edcor. However, the laminations don't have any holes drilled in the corners. Would I cause any damage to the transformer if I drilled four mounting holes in the laminations (not the bobbin)? I'd be sure to tape up the lamination to avoid getting steel shavings from the drilling process lodged in the transformer.

Thanks!

-Derek

not a good idea, and certainly not with a hand drill,

more so if there are leads on either side of the coils...
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Old 17th April 2011, 03:17 PM   #7
Derekva is offline Derekva  United States
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Quote:
Originally Posted by M Gregg View Post
Derekva,

aardvarkash is correct. If you look at an Edcor Tx you will see small plastic insulators under the screws that go through the laminations.

The laminations are insulated from each other with an oxide coating. The screws "bolts" are put through the plastic insulators to stop connection with the laminations. If two of the bolts contact through the laminations you get a shorted turn. This is created by the bolts that would connect each side of the Tx to the other. If you drill and short the two sides "front & back" togeather the Tx wll over heat and burn out!

Even if it does work after the intial drilling you have to insulate the bolts from the Tx core. Your idea could trash the Tx. Then again its your Tx!

Regards
M. Gregg
Understood.

Which brings me to my second question. Is there any risk in gluing / epoxying covers to the outside of the transformer? I would think not, but I was wrong about drilling (glad I asked about that).

Thank you,

-Derek
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Old 17th April 2011, 06:37 PM   #8
K.A.B is offline K.A.B  Sweden
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Quote:
Originally Posted by M Gregg View Post
Derekva,

aardvarkash is correct. If you look at an Edcor Tx you will see small plastic insulators under the screws that go through the laminations.

The laminations are insulated from each other with an oxide coating. The screws "bolts" are put through the plastic insulators to stop connection with the laminations. If two of the bolts contact through the laminations you get a shorted turn. This is created by the bolts that would connect each side of the Tx to the other. If you drill and short the two sides "front & back" togeather the Tx wll over heat and burn out!

Even if it does work after the intial drilling you have to insulate the bolts from the Tx core. Your idea could trash the Tx. Then again its your Tx!

Regards
M. Gregg

Hellö,

Thanks for the information about the tx, but then I have a question I have a tx made ​​by an European manufacturers. It is welded through all laminates the tx gets hot, are this is due to welding or is it designed to be welded.

K.A.B
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