| From: Tom Vogl
Subject: Zen and the art of J-* Repair. (written by Tom and vetted by Dale.) Please, if have any comments, suggestions, corrections, additions, etc., do post (or send me) a message and lets make this as complete and accurate as possible. Also, Dale tells me that he has made a video explaining some of this material. As soon as I get a copy I will make it available for circulation. Let me know if you are interested by sending me your snail mail address and the tape will circulate in the order in which requests are received. Now for the nitty-gritty: All looms, being mechanical devices with moving parts, often moving under considerable stress, are subject to loosening up and other foibles that such devices are heir to. One way of preventing the potentially serious consequences of running a loom that is loose or otherwise not in good adjustment is that it will break down on you at the most inconvenient times. This has just happened to me and the purpose of this piece is primarily for me to have a record of what happened and what I did and, more importantly, to record what I need to do in the future to prevent relapses. As a result, what I am recording here is a mixture of diagnostics (DX) and presciptions (RX) for preventative maintenance (PM). The first thing to remember is that everything I am going to describe is far easier done when the loom is not dressed. Therefore, in the future, I plan to go through this check list every time I finish a warp, i.e., about every six months, before I start beaming a new warp (although it can all be done with the warp beamed but not sleyed, in which case you have to be far more careful with the oil). There are basically only four classes of things that can go wrong with with a J-comp (and first three with a J-made). What follows below is detailed for the J-comp but the generic sugeestions apply to all looms. 1. Nuts can loosen on bolts and allow for pieces that should be rigidly
positioned with respect to each other to slip.
The first thing to do is to establish a baseline. You cannot tell what is not right unless you know what is right. So, before anything goes wrong, take the back panel off the loom and take off the horizontal panel underneath the frames. Look and note where the cables run and twang them like a guitar string so that you know what the correct tension is. Do this with the right treadle both up and down. Notice how various things move and engage and disengage as the treadles move and note where the axles are around which they pivot. Note where there are bolts and what they do. By definition, anything held on by a bolt can, under sufficient duress, come loose. On the J-comp, note how the three microswitches that are activated by the right-hand treadle are activated and when. Also note the row of microswitches under the walking beams at the top of the loom. They activate the top row of lights on the display panel. Notice that they all are attached to a single piece of wood that, in turn, is held onto the loom by bolts. A few generic rules: Always use pure silicone to lubricate any point where metal moves against wood (such as where the shafts that drive the worms go through their woden support blocks); do not use oil. (Oil makes the wood swell and will make the problem worse; silicone will lubricate without swelling.) Silicone is incredibly slipery stuff. It usually comes in spray cans. If silicone gets on the floor, watch out - you can go flying! DW-40 is a good, general purpose, metal-metal lubricant, although you may want to use grease (your local garage will generally gladly give you a small paper cup full which will last you for years) on the worms and worm gears on the beams. In humid climates, wipe down all steel parts with a cloth or paper towel satured with oil to prevent rust. If something sounds 'wrong' or 'different' there is probably something amiss. To avoid more serious problems later, take the time to diagnose (and fix) the problem. Things to particularly watch out for: new noises and a change in 'feel'. (Is it getting harder to treadle or harder to apply tension?) Is one treadle or groups of treadles misbehaving? In what way? Under what circumstances? Etc. Listen to what your loom is trying to tell you. Generic PM: At least once every six months: Lubricate all moving/bearing points. This includes in particular :the U-joints, the worms and worm gears, the shafts on which the beams turn, the bearing shafts on the treadles, and any other moving parts you can find. As Dale says: "You can dip the entire tie-up box (on J-comps) in DW-40 and it will only do it good. Pay particular attention to where the brass rods (pushed by the springs) go horizontally through the rectangular brass rod. Check each one. If it binds at all, you will have problems with the shaft it controls -- DW-40 it generously. Check for tightness of the bolts holding the microswitches up against the walking beams, the cap bolts on the wooden box on which the right treadle rides, and the bolt that can be seen through the hole through which the right treadle passes and hold the pulleys. Check all cable tensions and make sure none have jumped off their pulleys. [A change in treadling force is a strong suggestion that something has gone wrong with one of the two cables running from the left treadle to the tie-up box (J-comp). Don't wait to check and fix that.] A few ideas about DX for J-comps: If there are some shafts that consistently have their light on when they are, in fact down: Check to see whether it takes less force to move them from the down position to 'free-flaoting'. If it does, tighten the brass nut on the top of the walking beam. In the shafts that have this problem are grouped together, particularly if it is the very high or very low number shafts, check the microswtiches below the alking beams and make sure the bolts have not come loose and that end of the board has not slipped. If there are some shafts that will not come up: If they are a group of odd or even numbered shafts, check the cable that runs horizontally around the tie-up box. Facing the loom from the cloth beam side, the odd shafts are on the right, the even shafts on the left of the tie up box, low numbers to the front, high numbers to the back. If it is only specific individual shafts, check whether the rods that go through the brass rod are binding and lubricate them. Even the slightest hesitation will cause problems. If there are problems with the dobby computer program not advancing with treadling: The problem is probably with at least one of the three microswitches to the right side of the right treadle. If some of the lights stay on when the left treadle is down but you can turn them off by pushing down of the frame (which is almost all the way down): Check to see if the two cables on the left treadle are too loose - the left treadle should not quite be all the way down to the floor when it is fully depressed (about 1/2 inch clearance is correct) and the tie-up box should then be touching the upper supports at both the front and the back. If there is a problem with the rear shafts not lifting properly (or staying up), the problem may be that the box on which the right treadle rides may have slid down a little because the two nuts holding it in place became loosened. If the box rides too low, the tie up unit will not go all the way to the top of its motion and the rearmost shaft picks will bind and not latch those shafts properly. I do hope this is helpful to you. Cheers, T. |