Tranny Washers

[J Rindt]

I did not see them in Doug's inventory, but I may have missed them.....
I need some of those plastic sleeves that fit the bolt of transformers, to prevent the bolt from contacting the lams as the bolts slide through. These are the bolts (long screws) that go all the way through the tranny lams, connecting the bell covers on each end of the transformer. I need a bunch of those. Should I just ask a tranny builder/winder, hardware store, Mouser....?
Thank You

[tubenit]

Check out Doug's nylon spacers/standoffs under board building materials.  IF those won't work, most Lowe's & Home Depot stores carry nylon spacers in various sizes/shapes.

With respect, Tubenit

[sluckey]

Just use heat shrink tubing.

[LooseChange]

Interesting:
I've noticed that even the bolt head and nuts are isolated with a flange on the insulators.
Can those bolts that go through the transformer make direct contact with the lamination's?

[sluckey]

Can those bolts that go through the transformer make direct contact with the lamination's?

Not if the insulating sleeves/tubes that J Rindt is looking for are in place.

[LooseChange]

Can those bolts that go through the transformer make direct contact with the lamination's?

Not if the insulating sleeves/tubes that J Rindt is looking for are in place.

Let me rephrase that:
Will contact between the lamination's and the bolts create a problem?

[sluckey]

I think so, but I can't offer any reasons, other than the manufacturers go to extra cost and effort to keep the lams electrically separated from the bolts. I also know that there are plenty of transformers that don't have the lams insulated from the bolts.

[bluesbear]

I've never used anything. In fact, I've never heard of anyone having a problem like this. I just buy a transformer and use it. Even in the old days when I was using reclaimed trannies, I never did anything special. Are you actually having a problem or just being careful?
Dave

[FYL]

I think so, but I can't offer any reasons, other than the manufacturers go to extra cost and effort to keep the lams electrically separated from the bolts. I also know that there are plenty of transformers that don't have the lams insulated from the bolts.

The bolts can magnetically short the lams if not insulated. Some manufacturers rely on the impregnation varnish, others go the extra mile and use insulated hardware.

 

[Willabe]

Ahh, so thats why they do that.

Thanks FYL for nailin that down.


               Brad       

[J Rindt]

Wow.....!
Thanks for all the replies.
I am not having any problems, but I have not fired up the tranny. I am re-using some old stuff, and those insulaters are missing. I have always read that those things prevent the screws from shorting the lams to the chassis. The lams are insulated from each other, but I guess it is just an extra precaution. Maybe the oxide is not as prevalent where the lams are drilled through, or maybe it is just insurance that the bolts do not scrape off the oxide and cause a short.....I don't know. Maybe it is just a precaution that a quality winder implements. It is only a matter of pennies for somebody like Edcor, Heyboer, etc. to insure they produce a trouble free transformer.
sluckey -
I should have thought of that. I have plenty of heat shrink. That is a good idea, and should work fine.....
Thank You

[jjasilli]

FWIW the diy hi-fi crowd is into this topic:  e.g.:  http://www.diyaudio.com/forums/tubes-valves/153727-non-magnetic-bolts-hold-output-transformer-together-2.html

[kagliostro]

Sometime ago I noticed that there is literature explaining that the laminations must be not electrically in contact as to achieve right performaces of the transformer

but there are many household appliance transformers (often microwave ovens) in which the laminations are soldered each other and there are no screws to obtain a compact lamination pack

someone can explain why in this appliance they didn't give importance to this "detail" ?

Kagliostro

[jjasilli]

someone can explain why in this appliance they didn't give importance to this "detail" ?  I can offer a guess:  that is why a distinction is drawn between trannies, even PT's, meant for test & audio equipment vs. general purposes.  That said, I remember posts of a Forum member who built amps with PT's pulled from air conditioners.

I recently posted some sites with a lot of info on vinatge components, including trannies.  But I haven't gotten to read much of it.  I bet there's some info in those old 1950's publications.  Not to mention that PRR probably knows!   :book1:

[FYL]

Consumer-grade microwave oven xformers are the epitome of modern bad design: they are really inefficient because of their minimal core size and weak windings - iron and copper are too expensive. They show dismal leakage inductance, work at saturation and heat a lot, but the manufacturers don't care, as consumers foot the bill at least twice - first by overpaying for Chinese junk, then by spending 60% more than needed when using them.
  

[jjasilli]

OK, I'm gonna hot rod my microwave oven with a Hammond PT!   

[bluesbear]

If it's an issue, why not just drip some liquid electrical tape in the holes and use a sacrificial bolt to keep the hole round? I've found the stuff at Home Depot in black so it wouldn't even show.
Dave

[dynaman1]

If you look closely, you'll notice a bead of weld that runs along the bottom of the OT's lams, endbells and a thick steel base. It's from a Peavey. I've owned two different Peavey OTs that were made like this. I don't think screw isolation is much of an issue with these trannys!

[J Rindt]

What is the story with that I wonder.?
But if you look at the PT, you see they have the plastic, iso washers.......

[FYL]

If you look closely, you'll notice a bead of weld that runs along the bottom of the OT's lams, endbells and a thick steel base.

Weld bead or varnish? Anyway, this OT is one of the largest I've seen for a 6L6GC PP...

[jojokeo]

Can those bolts that go through the transformer make direct contact with the lamination's?

Not if the insulating sleeves/tubes that J Rindt is looking for are in place.

Let me rephrase that:
Will contact between the lamination's and the bolts create a problem?

I don't think I saw this mentioned yet but what I recall was that some older power trannies can induce a lot of hum into the amp when not insulated or isolated from the chassis.

[dynaman1]

If you look closely, you'll notice a bead of weld that runs along the bottom of the OT's lams, endbells and a thick steel base.

Weld bead or varnish? Anyway, this OT is one of the largest I've seen for a 6L6GC PP...

I'm AWS certified through the Ironworkers Union and I've done a lot of welding. Aint no mistaking that fat bead for varnish!  The plate has heat discoloration right under the welds and it actually warped a bit from the contraction during cooling. The plate is 1/8" and tapped for threads instead of just having holes.

It's so big because it was pulled from a 100W Peavey amp with 2 and 4 ohm secondaries. I needed 4 and 8 for a 2X6L6 build, so.....

[jojokeo]

I don't think what we're talking about here applies the same w/ OTs as it does w/ PTs

[J Rindt]

I do not understand why it matters at all. Don't the bolts suffer the same induction and magnetization that the rest of the transformer does.?

[FYL]

Contact = better coupling, mo' problems. Insulation, air gap, etc. = weak coupling, no problems.

 

[jjasilli]

I do not understand why it matters at all. Don't the bolts suffer the same induction and magnetization that the rest of the transformer does.?

Tranny bolts are often made of stainless steel or brass to minimize these reactant effects.

[EL34]

Saw the subject line and thought it was about people who washed men that changed their sex to female.

I thought that would be unusual, just had to look. 

guess it's about hardware?

[jjasilli]

No, no this was all really a subliminal conversation as you say.   

[jojokeo]

  "...better coupling, inducing noises, hummming,..." 

[Tone Junkie]

         I think we slipped off topic