Industrial sewing machines differential feed

Posted by Kathleen Fasanella on Dec 21, 2007 at 1:56 pm / Glossary, Operations, Product Reviews, Rants, Sewing / Trackback

This is definitely one of those things I rarely write about because I think everyone already knows it (and probably more than I do) but what the heck. This is (circuitously) about differential feed on industrial sergers. I’d been playing with the mobius scarves again under the guise of making “Christmas gifts” but the activity would be more accurately described as making dual-duty prototypes, the advantage being the results are pawned off as genuine product. Heh. I’ve got two done (and discovered two other ways not to make them) with one to go. Maybe Mother-in-Law will get the good stuff, hers being the last one in the series. You all don’t ever do this, do you? Didn’t think so.

In making these, in spite of all caution and diligence, one seam kept coming up short, nearly two inches worth over a very long seam. Odd. Being that the scarf is a geometrical (topological) puzzle, I thought it had something to do with the geometry of it. I put Eric -resident math whiz- to work on it but there was no solution forthcoming after two envelope backs (literally) of scrupulous math notation. Math obviously wasn’t out to save me so I looked for something else, preferably something simpler. One thing I did notice was that the seam was puckering just a tad. I was thinking it couldn’t be the feed on the machine because the overlock is brand new and presumably in A-1 condition. Below is a photo of a sewn sample, (this isn’t one of the prototypes doing double duty as a gift). The photo has also been enhanced to dramatize the slight puckers on the bottom half of the seam. In real life it’s barely perceptible:

So I thought, what the heck, maybe it’s the differential feed. The mechanism that governs how the fabric is fed through the machine via the feed dogs. The manual

–Formerly occupying this space, was a rant. Specifically, three hours worth of writing about the state of industrial sewing machine manuals –

wasn’t very clear about how to determine the setting of the feed. In fact, there’s no way to work your head in there to even see it. However, it was possible to stick my camera in there and take a picture of it! [below]

From the picture, I could see the raised dot on the indicator arm was resting midway between 0 and 1. The manual said for even feed, the arm should point to 0, like so:

There’s a little hand turn knobby thingy (toward the front, not shown) that’ll move that rocker arm up and down (for fine tuning). To make dramatic adjustments, you need to loosen that large screw (dead center in the photo), adjust the arm and then tighten the screw afterward. Long story short, here’s what a sewn sample looked like after the adjustment:

In summary, my pattern problem was really a machine adjustment problem. Adjusting the differential feed on an overlock is pretty simple and quite useful too. If you want to gather a skirt and attach it to a shorter fixed length ungathered bodice, you can do that in one pass on the overlock.

The numbers on the indicator refer to ratios. If you want the fullness to be 1:2, you’d adjust the arm to the 2 and so on. One of the things a pattern maker can do for you, is if you can indicate your preferred level of fullness (gathers), they can make the pattern specific to the setting on the machine. If you want it set to 1:3, they can make the pattern to fit in evenly. This saves tons of work, a lot of people still run a basting thread to draw up gathers but it’s often not necessary.

———-
One last thing about this machine and its manual (this is not the aforementioned deleted three hour rant). I won’t mention the brand because I actually like this machine and think it was a great buy (and would even recommend it to you) and I don’t want to give you the wrong impression about it but I had a very bad experience following the instructions in the manual.

Being a new machine, it needs oil. Industrials usually have reservoirs, unlike home machines that only have given points you stick a dot of oil into. The manual said to put in oil until you could see the oil rise midway between the two indicator lines. Well. I poured in oil. Then more oil. And more oil. The more I poured in, the more my dismay and unease grew. I only bought one gallon and was distressed because I also needed some for this other machine I’d recently moved and cleaned and needed fresh oil for. I thought if this overlock took this much oil, it is inordinate to the extent it should be mentioned. Anyway, I poured in oil. Finally the oil breached the top, it’d bubble down a little to where I could pour in a little more since the indicator was still showing zip. After the third time of waiting till the level dropped, I decided this was ridiculous and got up to call the guy who sold me the machine -and nearly fell flat on my butt; under my feet, there was oil everywhere. It was dripping out of the bottom of the pan. Oh my. Now I was really distressed.

So I get the guy on the phone, very upset that the machine is overflowing oil but the indicator isn’t working and this is a brand new machine, never even turned on -and I was counting on this machine!- and he said that not only did the machine already have oil and didn’t need any, but that you’re supposed to put in oil until the indicator was black. If it was white, you needed oil. Black, it was okay. I told him that’s not what the manual said and he said they thought they’d changed it. Well, that didn’t help me any. Crud. So, I had to pull off the belt, pull the machine head out of the table and drain the machine and start over. It was such a mess. Oil was everywhere. By the way, like I’ve said many times before, you don’t need carpeting in your work areas, I strongly advise against it.

I think next week or maybe the week after, I’ll put up some entries on industrial sewing machine manuals. There’s four kinds. I’ll bet you didn’t know that. There’s Instruction or operations manuals (threading, stitch settings etc), Service manuals (adjusting and repair), Parts manuals and last of all, product features, sometimes called “service line” manuals which explain which machines you need for which operation. Just finding manuals is a nightmare. For some reason, there’s this big karmic pox on industrial sewing machine manuals. Buy a new machine and chances are fifty-fifty you won’t get the manual with it. I made that a condition of sale for this one and I still didn’t get it, only after the fact.

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