Click Clack

The Brother DB2-B791-015 was having some maintenance issues while finishing up the skunk and the NFCO. Or at least it was making some noise while the stitching for the main strap(s) were being sewn in. Of course this is probably the heaviest stitching that takes place on the Brother due to the 2″ dive belt webbing which is used – in conjunction with the Coats&Clark “button&carpet” thread, and the #21 gauge needle. These materials together take a lot of punching power and require a heavy press of the foot too, which is partly why it was so alarming that the Brother would be making the clickity clacking noise. You would think that even if something were loose, that under that much pressure it would not have that much room to wiggle. Not so, the machine was definitely making a noise that needed to be found. Essentially it sounded like the feed dog was loose, and rattling while it fed the material: or the feed dog was somehow out of adjustment and actually hitting the bottom side of the throat plate on it’s upswing. However, if the feed dog was hitting the bottom side of the throat plate it would not be a rattle-like noise, but instead a thud (if you will). Also, the throat plate was clearly tight, so it wasn’t that.

The first thing to come off was the face plate on the end of the DB2 head. Behind this plate, is the needlebar, and the presser (foot) bar, with their assorted clamps and driving mechanisms – all of this seemed to be tight and secure, so the face plate was re-installed. Now it was time to dig in a little and lift the massive (in terms of density at least) Brother DB2-B791-015 head off the table and take a closer look. The approach was to take torque-inventory from the inside, moving out, to be as thorough as possible: in other words, all the accessible nuts, bolts, screws, hex’s, etc. were checked for proper torque starting from as far away the hand could reach, slowly moving in towards the feed dog and throat plate. No time like the present. Unfortunately (or fortunately), there was not a loose screw to be found. Even getting into the feed dog and feed bracket, everything was tight. The only thing that had any play in it was the carriage for the bobbin case, which is situated within the rotary hook assembly. This little bit of play was quite small, and seems like it couldn’t have made the rattling that was heard, not to mention – all of the screws around this were quite tight. The other thing about the carriage for the bobbin case is that it is free-floating (so it can spin) which means that it always has a little bit of play.

That said. It is hard to say, just where this noise was coming from. Maybe it was a matter of stress on the machine? Maybe it is time for the Needlefeed & Company to think about a walking-foot? Since the tear down, the noise has been pretty much non-existent, which we can only conclude that it was simply the strain between the dive belt webbing and heavy needle’ing. This kind of situational rattling may take place again, but as long as we know that everything is tight and together, then maybe there is no need for alarm.

2 Comments so far

  1. Zeke April 21st, 2010 10:49 pm

    I get a loud slapping noise when I sew fire hose with my 791. Also, inner tube and other rubberized materials. I think that the presser foot spring is not up to the friction of the needle pulling upward thru the fabric, so the foot hops.
    A walking foot solves this, as it does not allow any upward slap of the foot – which is basically locked into it’s ‘vibration loop’.

  2. admin April 29th, 2010 7:57 am

    Interesting to hear, it makes a lot of sense though what you are saying. And that would certainly be a logical reason why the slapping was happening, as the Brother was stitching through multiple layers of the ever-heavy dive belt webbing. Thanks for the splendid food for thought. NFCO