Sunday, December 23, 2012

John and I are rehabbing sponge bars

All kinds of knitting machine problems are solved by replacing a worn-out sponge bar.  The bar holds the needles down against the needle bed, yet allows them to move and "play" a little bit.

I had reached the point where nearly every sponge bar I had was worn out.  This idea of recycling sponge bars makes both economic and environmental sense, and once in a while, you get a machine for which brand-new sponge bars can't be located. 

Wonderful information on redoing sponge bars is available here:

Over the years, we've acquired our own quirky ideas about redoing sponge bars.

First of all, Kathryn's advice to get rid of the awful petroleum-based gunk that was originally used to stick the foam to the bar is very good advice.  Attaching the new foam with white glue is SO much better!

Secondly, I really do like the interfacing idea on Kathryn's site for the covering for the foam.  I've tried some other things that worked, as well, in particular first aid tape, but the interfacing is very inexpensive and easily cut into strips using a rotary cutter. 

At first, I used the 1/2" craft foam from Jo Ann's that Kathryn recommends, and that worked okay but didn't last as long as weatherstripping that we had tried before we ready Kathryn's great instructions.  We now use 3/8" wide by 5/16" thick weatherstripping for our sponge bars.  We glue the non-sticky side down with the white glue and use the sticky side to attach the interfacing. 

We played around quite a lot with the different foams and thicknesses.  In the craft foam, 1/2" is the stuff to purchase, but in the weatherstripping, that would be too thick.  The weatherstripping is a more heavy-duty foam.


  1. I have an SK 120 with the LK 120 ribber. The sponge bars that fit this machine are very very thin, they're soooo difficult to change! I've had a bit of success with weather stripping but the sponge is so hard to get into the channel, that I'm seriously considering getting a new bulky (even though I love the SK 120!)...

  2. We have a guy here in MN that repairs knitting machines (he's trained, and the only repairman in the state), and he strongly cautions against using weather stripping. It's not the right kind of foam, and can actually damage the inside of the machine where you can't see the damage, by wearing away the metal slots the needles ride in. He gave us a full day seminar on the proper care and cleaning of our machines. Unless you don't have a choice, always buy the proper sponge bars for your machine. Turns out they're much more delicate than we all think they are, and too expensive to replace to use shortcuts. Just as you wouldn't use vegetable oil in your car as a cheap alternative to proper lubricant, you shouldn't use a cheap alternative for your knitting machine.

  3. Heidi, I agree with him, at least in part. Too-thick weatherstripping would be a BIG mistake on a sponge bar. It would put much too much pressure on the needles, and of course, every mechanism that is affected by the needle movements. It is very difficult to find weatherstripping that is the right thickness. Most of it is too thick. We had to go to about 4 hardward stores before we found the 5/16" thickness. Note how much thinner that is than the 1/2" often used in the fabric store foam yardage.

    I have also observed that different machines have had different grades of foam in them, originally.

    I do not have to change factory sponge bars as often as many other people. We really should take the sponge bars out of our machines when we're not knitting and let 'em rest.

    My husband, who is mechanically savvy and very particular about parts and materials, said he sees the thickness as the real issue. The proof, of course, is in how easily the needles move. You're trying to achieve the same pressure as a factory sponge bar.