Variac...

[KA9EGW]

Just scored a killer deal on a 220V 2-section variac, but it is missing either a bearing or a bushing on the bottom.  Should this be some sort of bronze bushing, plastic bushing, ball bearing, anything-that-fits?  73, Brian KA9EGW  ka9egw@britewerkz.com

[KL7OF]

methinks they are a bronze bushing.....got pictures??

[KA2DZT]

Lots of variations and models of variacs.  GR made Variacs.  Others made even more variations.  Try to get up some pics so we can try to help.

Fred

[KA9EGW]

Here they are...

[W7TFO]

Only GR made Variacs.  It is a copyrighted term.

Everybody else (Staco, Ohmite, eTc) had to call them something else.

Not that helps with your query.

73DG

[KL7OF]

That looks like it should have a bushing......I turned 3 of my autotransformers over....they are of 2 different brands..(no variacs) THEY ALL 3 HAVE BUSHINGS....You might be able to buy a standard bushing...(They still sell them at my local ACE hardware...) or a standard shaft collar...with a little hack artist work you could make it fit....There may be a bearing available in the standard bearing catalog that will fit in there as well....Plastic may be the answer for you...easy to make and will hold up under the high speed operation of a variac...how are the windings on you Variac???Some of them look like the varnish is coming off......Good Luck....Let us know...

[KA9EGW]

have lathe and delrin stock, will travel...   Thank you!

[KA2DZT]

have lathe and delrin stock, will travel...  Thank you!

I've spent the last 5 weeks rebuilding one of my lathes.

I have one of those 230 Variacs,  I'll dig it out and take a look, hopefully today.  On some variacs the wiper is in direct contact with the shaft, but the shaft will have an insulated sleeve over it.  Some, the wiper has an insulating collar between it and the shaft.  Looking at your pic, my first guess is there is an insulating collar missing.  Replacing it can be a PITA, easy if you have a lathe.

I just built a variac box with a meter and outlets etc using a variac similar to what you have.  I mounted the variac to the front panel using the bottom casting.  The shaft can be pushed through the bottom.

Took a look at my 230 Variac, it is a single section 230 type.  It is completely different than the one you have.  If the wipers have insulating bushings between them and the shaft, then you may only need a metal bushing.

You need take a close look at the whole thing.

Fred

[Opcom]

Mine like that used a plastic or fiberglass resin sort of bushing because the back end of the shaft was hot to the wiper wheel. Check how it's made. Look at the wiper, wheel or arm, and the shaft. See if they are electrically connected or not.

On mine there is a central metal shaft connecting two sections. Concentric with that but insulated from it are the metal shafts on which the wiper wheels are fixed. That is why the insulating  bushing on mine has a smaller hole.

[KA9EGW]

Well, I have some Delrin stock perfect for the job...and since it tests ok without a bushing [provided you lean on the knob just so  ] I figure I'll just turn a bushing, press it in place and call it done...the bottom spider is some sort of nonconductive fiberglass or something anyhow so whether or not the bushing is conductive strikes me as irrelevant, eh?. 

Many thanks to all for your help!

73, Brian KA9EGW

[MikeKE0ZUinkcmo]

You speak of "leaning on the shaft" to get output, and I wondered about this when I first read your earlier posts.  what mechanical means is used to establish, and hold the vertical position of the shaft relative to the transformer frame?    E clips, snap rings?

[KA9EGW]

By "leaning on the shaft" I mean that with the bottom bushing missing, the bottom end of the shaft can walk around enough to cause the brush to lose contact.  I expect with a new bushing all will be well...not sure exactly what holds the shaft in, but it is possible to pick the whole thing up by the knob...