28 Oct 2008, 12:41am
Sewing Machines
by Tom

2 comments

Turning your zig-zag machine into a straight stitch machine.

This could not be easier. You only need two accessories:

1. A straight stitch needle plate.
2. A straight stitch presser foot.

Zig-zag setup on left, straight stitch setup on right

Zig-zag setup on left, straight stitch setup on right

I found them on eBay for my machine, actually for a slightly later model, but they both use the same accessories. My machine is a 337 as I have mentioned before, the parts I got are for a 348.

Remove the zig-zag plate

Remove the zig-zag plate

It is only a matter of removing the zig-zag presser foot, pulling open the bobbin cover, and removing the zig-zag needle plate, then installing the straight stitch plate and foot in the opposite order. Of course if you need to use zig-zag stitches you have to change things back to the zig-zag configuration.

Straight stitch plate and foot installed

Straight stitch plate and foot installed

Does it make much difference? I found the stitches are straighter, lacking that slightly slanted look, and the material does not get pulled slightly into the needle hole. As a result the machine seems to sew more smoothly.

23 Oct 2008, 12:58am
Sewing Machines
by Tom

3 comments

Howto set your tension

I have seen many articles telling you what your seams should look like at the proper tension, but all of them have been really vague about how to go about adjusting the tension to get that seam.

First you need some kind of starting point. Older Singer machines were factory set to sew medium weight fabric with number 50 mercerized cotton thread and a number 14 needle with the tension dial set at 3. Nowadays that needs some explanation. As far as I can determine by medium weight fabric they mean something like a man’s dress shirt is made from. For thread I am using Coats & Clark Duly Duty Plus Polyester. I think it is a bit heavier than #50 cotton size wise (I am not real sure of that as I can not find any cotton thread around here to compare it to), but Poly stretches a bit so you usually use a slightly lower tension, because of that it seems to be about right. I also picked up some #12 Schmitz Sharp needles. Anyway I set my machine up so the dial is at 3 with that combination, and it seems to give a good range of setting for other thread and needles.

A side note: I said in the article about Needles, Thread, Fabric and Tension that all of them make a difference. With a bit more experience I now think the most important thing is to match your needle to your fabric. I found that medium heavy Duck breaks #11, and bends number 14 needles, but works fine with #16 needles. At the moment I am using #12 and #16 sharp point needles for most everything.

Now to the matter at hand, how to go about setting your tension when you have no idea what is going to be correct. Start with the dial set at 3 or the center of the dial if you have no idea what the machine is set for. Run a bit of a seam on a piece of dress shirt weight fabric folded double, a couple of inches is enough. I suggest marking one side so you can easily tell which side is the top. Examine the seam.

Step One:

If there are loops on top reduce your tension two dial marks.

If there are loops on the bottom increase the tension two dial marks

If there are no loops go to the next step

Step Two:

If it looks like sewing on the bottom, and just a straight thread on top, increase your tension one mark.

If it looks like sewing on top, and just a straight thread on bottom reduce your tension one mark.

If it looks like sewing on both sides go to the next step.

Step Three:

Look very carefully at the stitching,

If it looks loose on the bottom increase the tension ½ the amount you changed it the last time.

If it looks loose on the top reduce the tension ½ the amount you changed it the last time.

Repeat until you can not tell any difference in the two threads.

You programmer types will recognize that we and using a binary search to find the correct tension setting. For others what that means is we are moving the setting past what it needs to be and then back half way. We are reducing the error 50% or more each time we do that. Going from loopy to good enough only takes five steps; 2, 1, ½, ¼, 1/8. A couple of steps more and you are moving the dial only a hair and have it about as close at a really well set up machine will do because there is some slop in the train and it will wobble that much. You will also notice that correct tension is only about 1/8 a dial marking from incorrect.

Make notes of what is correct with each needle/thread combination you use, and you will be able to set the dial close next time you use that combination. From there it only takes one or two steps to get it just right.

18 Oct 2008, 6:26pm
Uncategorized
by Tom

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New look

I am working at making this blog a bit better thus the new theme. Really wanted something in beige, but could not find anything that appealed to me. So I went with the same theme I am using on Subject to Change. It is called Emptiness.

That is my old junk sewing machine up at the top, on the kitchen table. I look at the photo, and say to myself, “I really need to refinish that top-plate”. Actually it does not look that bad in real life.

I think I have the tension problem mentioned in Beginer’s Woes about sorted out. I replaced the corroded tension disks with a set I got from eBay. That made thing worse. After searching the web, and asking on a few forums, I finally got pointed in the right direction and was able to locate and fix the problem in about twenty minutes. There were a couple of rough spots on the bobbin case that were holding back the thread as it was pulled around the bobbin just enough to balance the roughness of the tension disks. When I replaced them there was too much funny tension on the bobbin side. That caused the tension to change with speed, so it could not be set properly. It only took a few minutes with a fine stone to smooth the spots out. Nowhere on the web could I find an answer to  “tension changes with speed”. There the search engines ought to find that and the next person will not have to scratch their head for a week.

Which brings us to a book review: Hutchison, THE COMPLETE HANDBOOK OF SEWING MACHINE REPAIR, Tab Books, 1980. The information in the first two chanpers you can get out of your sewing machine’s manual. Chapter 4 covers old Plaff SM’s. Chapter 5 covers old White SM’s. Chapeter 6 covers New Home SM’s. Chapter 7 covers one Brother SM. Which leaves chapter 3. Chapter 3 is the useful one. It tells you what needs to be checked and set rights. However it does not go into much detail as it is only 17 pages wrong. These are selling for $30 and up, way up, from used booksellers. Save your money unless you have and old Plaff to fix. As an aside, the writer does not seem to be a sewing machine mechanic, just a writer trying to make a buck; in other words, the book is not authoritive.

Your comments and corrections are always welcome

15 Oct 2008, 2:07pm
Scissors Sewing
by Tom

2 comments

Scissors

I once worked at a place where I used scissors rather a lot. When I went to work there, they gave me some gloves. Nice people wanting to protect my hands. Not so, what happened is I used those scissors until I developed blisters. Then I used them some more until the blisters broke. And some more until my hands were bleeding. That was what the gloves were for, to keep my blood off the product. So I kind of consider myself something of an expert about scissors. At least enough of one to know that those were not simply scissors, but heavy duty industrial bent trimmers, heavy duty fabric shears in other words. Industrial shears like that would be called tailors shears in a less intense job, and would have had a highly polished chrome rather than nickel and paint finish. Next down the line are industrial bent trimmers. Those are less fancy versions of your dressmaker shears. Then there are the straight trimmers, they are a heavy duty version of what are called sewing scissors.

OK, we have mentioned scissors and shears. There are also snips. What the heck is the difference? Well, it is not exactly what I read on the web. Shears have two characteristics that scissors do not: One, they are asymmetrical, one blade and handle is different than the other. Usually the bottom blade is heavier and may be sharpened at a different angle that the top blade. The top blade usually has a finger ring while the bottom usually has a thumb ring, however that is not always true never mind what the web gurus claim. Two, they are heavier duty than scissors. While scissors typically have two same size finger rings, and symmetrical blades (Unless they are designed for some special purpose, then the blades can be very different). Snips tend to have short, high leverage blades.

Basically scissors (Using the term generically here, confusing, huh?) have one of three different bevels to their edges. The sharpest is the so-called knife edge. The knife edged blades are beveled at approximately a 45 degree angle. Scissor edged (Boy, we are sure getting a lot of use out of that word, aren’t we?) are something like 60 degrees. And finally the last which I never heard a definitive name for is near 90 degrees. You see that one children’s safety scissors, pinking shears, and on some real heavy duty stuff. To understand what that means you have to know how scissors cut.

If you look at a pair of good scissors you will see that they are somewhat bowlegged. Hold them up to the light with the blades closed and look at them edge on. You will see that they make contact at the tip and maybe the hinge, but that there is open space between them just like between the bowlegged guy’s knees. When you open them up you will se that the blades are making contact at the base near the hinges. Then as you slowly close them the contact point moves up the blades towards the tip. Scissors cut by shearing action right there at the contact point, the reason they cut so easily is because all the pressure of the sharp edges is on that tiny point, like just a couple of thread in your fabric, which moves up the blade and thus down the material. Now look closely at the beveled edge of the blade. You will notices that it is ground crosswise leaving tiny crosswise ridges that make the contact point with the material have a micro saw tooth edge. That edge grabs the material and prevents its slipping so the shearing action can work on it. If the edge is too smooth the scissors push the material along ahead of it instead of cutting. The slippier the material the rougher the edge needs to be. Think about that the next time some self appointed expert tells you to sharpen your scissors by running a stone along the length of the blades. There is a way of using scissors with very smooth very sharp edges; that is call slip cutting where you keep the scissor blades in one position and push them along the material. In that case they are not shearing the material they are cutting it like a knife, only from both sides at once.

Scissors dull in two ways. First, the edge folds over, leaving a narrow wire edges just like on a knife. Then that wire edge breaks off leaving the edge rounded. Once the edge is rounded the scissors need to be resharpened. You can delay that by occasionally stropping the edge to remove the wire edge before it breaks off. My favorite strop for scissors, and knifes, is the card board on the back of legal pads. It has just the right texture and hardness to remove a wire edge without damaging the bevel. You do not want to press hard; you are polishing, not honing the blades. Honing, resharpening, can be done by hand, but if you do not know quite a bit about putting new edges on tools you are probably better off having it done by a pro (Yes, I know, not everyone who claims to be one is one; but often you can send the scissors into the distributor for resharpening. I know that Gingher offers that service for $7.50 including return postage as of the time I am writing this).

That brings up brands. In the USA as of now there are three major vendors of forged scissors (If you are not buying forged ones, just toss them and buy new when they get dull it costs about the same): Wiss, they are an old American brand, but sold out to Cooper Tools who has them made, I guess, by the lowest bidder. They are still a decent scissor, but they are not pushing the retail market seemingly preferring to go for the industrial trade. Gingher was a German company. They were bought by Fiskars, and are made in various places around the world just as are Wiss. The ladies love them, probably because they are sold at JoAnn Fabrics. The third is Mundial. Mundial scissors are made in Brazil, but they have been made there for a long time. I understand that they started out as a German company but moved the whole kit and kaboodle to Brazil about 50 years ago. They seem to make the widest range of patterns of the big three. All three make hot drop forged high carbon scissors, that kind holds its edge better than stainless steal does so stay sharp longer. There are some Chinese, and Pakistani made forged stainless steel scissors at pretty nice prices out there, but I am not sure of the quality.

The next tier down are the flat, stamped stainless steel scissors, the top brands seem to be the Japanese Kai, and the American Wolff, Fiskars also makes this type of scissor. They seem to be a good value, but as I said, I would not bother having them resharpened.

There are also some small makers out there that make extremely fine scissors, at extremely dear prices. I do not know much about them, I go into convulsions at the thought of spending $350 for a pair of scissors.

The only other maintenance scissor need is an occasional drop of oil on the pivots, and a wipe with a very lightly oiled cloth. Your sewing machine oil is fine for this. The way I do it is to wipe the excess oil from oiling the pivot off with a soft cloth and then use the cloth to wipe the blades. Usually just the right amount of oil. If it looks oily, wipe again with an oil free area of the cloth. The purpose is to prevent rust, and insure smooth cutting.

Your Comments and Corrections are always welcome.

3 Oct 2008, 6:50pm
Sewing
by Tom

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Beginner’s Woes

I have sewn two simple learning projects: 1. a dust cover for the sewing machine 2. A dust cover for my inkjet photo printer that does not get used a lot as I have a laser for routine printing. Both were made out of an old blue bed sheet.

Sewin machine dust cover

Sewin machine dust cover

The sewing machine cover was really to test the machine (And I found out that it had a tension problem that I have only done a jury rig fix of until I can get a new tension assembly; which I have ordered). I designed it as a wrap over with sewn-on in ends. It went together fairly easily. I did have problems sewing along the edge of the bottom hem. The needle wanders too much for the adjustable hemming foot which has stitches only about 1/32 of an inch from the fold over, and the zig-zag foot is not accurate enough to maintain a even edge either but I was able to sew farther from the edge (1/8 inch) and do an acceptable job, for a first try.

The inkjet cover I designed as one cruciform piece with just four seams. Made a pattern from craft paper, and when I went to make it today, I found I did not have a big enough piece of sheet left to do it (it started life as a fitted sheet and had a few holes I had to work around). So I changed it to the same style as the sewing machine cover. Only I wanted to try using fusible tape instead of pins.

The fusible tape makes stitching real easy, but is a bit of a pain. You have to have the temperature of the iron just right, very hot, but not too hot. It oozes out and gets on the ironing board cover and the iron (I found that using a sheet of paper under it helped with that problem); it also is not obvious how to make the corner seams between the sides and top of the end pieces and the wrap over piece. I now have a zipper foot so it was not difficult to control the edge stitching on the hem.

What I found out, besides making sure you have a big enough piece of fabric (grin), is that you do not need an inch of ease on a dust cover, one-half inch, or maybe even none, would have been enough. The sides do not need to be as tall as the top of the object to be covered because of droop. So both covers are bigger than they needed to be, but I guess that is better than too small. That you should check your seams for tension every so often, I had a couple that were loose on the top tension for some reason while all the rest were fine (I have since figured out that the cause of that was not enough pressure on the foot). That one needs to work carefully and not get impatient; I have a problem with that especially when things don’t go the way I planned. That running upstairs to use the iron, and back down to use the sewing machine is a pain. That I really need a tee-square and a couple of curves for laying out patterns.

I think my next project will be something with curved seams; and my next article will be about scissors as I find that there is a lot of no-sense about them on the web.

Your Comments and Corrections are always welcome.

 
  
 

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