When to stop and turn the material

[Uwe]

Perhaps I'm missing something. I've been wondering for a while now why I keep coming across variations of "A good time to stop and turn the material is when the needle has come back up a little bit." Even Al Bane says something to that effect in one of his videos. That guideline just goes against my understanding of the stitch cycle.

Generally, folks stop to make a turn while the needle is buried in the material because it provides a good pivot point. In that situation it seems to me that the only really BAD time to stop and turn is when the needle has come back up a little bit, the thread is still busy forming a loop but the hook has not yet caught that loop. Thou shalt not mess with the loop, in commandment speak. 

So why do so many folks recommend to stop and turn the material exactly during that most vulnerable period? Is it the thrill of playing Russian roulette with skipped stitches?

In my mind, a good time to stop and turn the material is either:

A.) While the needle is still going down

OR 

B.) AFTER the needle has come back up again far enough so that the hook has had a chance to positively catch the loop.

I really am curious about the reasoning behind the common recommendation and I'd love to hear from others.

Edited June 17, 2016 by Uwe

[dikman]

Uwe, I've wondered this too. The last time I had to regularly stop and turn material I was sewing an "infiniti" pattern on a gunbelt using my Pfaff 335. Every now and then I would get a dropped stitch and couldn't figure out why (it was always at the turning point). I've been pondering this for quite a while, trying to visualise the hook/needle operation when stopping. The only answer I could come up with is that sometimes the needle may have been on the upstroke and turning the material twisted the thread and prevented the loop forming properly. With this in mind I figured it's better to stop right at the bottom of the downstroke, before the loop can form (although stopping on the downstroke, as you say, also makes sense).  Don't know if I'm right, but it sort of makes sense to me.

I shall await, with interest, comments from the more knowledgeable here.

[Wizcrafts]

I recommend making every adjustment a machine is capable of to obtain the strongest loop possible. This includes trying different settings and tensions on the check spring and fine-tuning the timing of the hook. It must also take into account any unusual twist the thread might have, such as in double dyed black bonded nylon thread. With a maximized loop the needle can be just raising from pickoff time as you lift the feet and turn the material.

My Union Lockstitch machine used to drive me crazy by routinely dropping the loop after picking it off the barbed needle, on hard right, but mostly left turns.

[Wizcrafts]

If one is experiencing dropped stitches, one should remove the throat plate and observe what the heck is going on with the loop. The loop might be too small, or might twist away from the approaching hook. I've had situations where a particular needle and hook timing led to too much of the loop forming on the left side of the eye of the needle. The hook that was approaching on the right had a hard time getting enough thread loop to pick off. Sometimes a smaller needle cures that problem. Other times the check spring needs to be readjusted. Still other times, the needlebar may need to be raised slightly so the forming loop clears a cutaway on the left side of the shuttle (meant to aim the loop towards the hook).

[Constabulary]

Seems to depend on the machine and hook a little bit. On my 133K3 the best needle position for a turn seems to be when the needle is on the way up and almost leaving the material / the tip is still inside the material. My 111G156 and 307G2 do not have these problems at all.

Basically I think the best needle position is all the way down (BDC) before the loop has been formed or when the stitch has been almost completed and the needle tip is still inside the material. But thats just a rough guess. But my 133K indeed acts a bit different...

[RockyAussie]

OK this driving me mad now. I don't often get this problem. I went and checked a couple of my machines and the vari stops are set to stop just as the needle is coming up a bit. If i twist the leather around a lot the thread can come out of the needle groove and I get a very small pull to the bottom. Then I tried just putting the needle barely in but enough to spin the leather about quite safely and no problems at all. I noticed that the thread tension check spring is under tension at this point but lifting the feet did not effect it. Maybe that might be a safer way? I respect all of your feedback and look forward to your thoughts.

[dikman]

Rocky, having the needle barely in the material on the downstroke also makes sense, although timing it might be a little more critical. Ensuring the thread is taut when twisting the leather is probably very important, as I'm sure what you describe was happening to me. I'll have to do a bit of experimenting now that I've got some ideas where to start.

I wonder if it makes a difference whether the shuttle/hook is horizontal or vertical?

[Colt W Knight]

I cant turn the material as the needle is entering the leather on the down stroke because turning the leather in this position will deflect the needle sideways which will eother caise the needle to break of the finish downstroke, shred the thread or drop a stitch. 

[graywolf]

I guess, I have not read as widely as I thought, because, I have never seen it recommended that you pivot your work after the needle has started to rise. Even in light fabric, I have always found that is a sure way to drop a stitch. While I have never sewn heavy leather like you guys do, I would think that it would be even more of a problem.

I am with Uwe on this, messing with your loop is a bad thing. After all that is the most critical point in the sewing cycle.

If you do not know how the rotating hook actually works, check out this from the rotating hook wiki.

As you can see from the bottom up is where all the action is. however that wiki is slightly off, because the loop forms slightly after the needle starts to rise while the wiki makes if look like the hook just grabs the thread from the needle. It actually grabs the loop that is formed when the needle starts to rise. Anything that makes the hook miss that loop is going to cause a missed stitch.

Also anything that keeps that thread from being pulled up is going to cause a mares nest under your work or in the bobbin area. So, that is why I say everything from when the needle starts to rise is critical, and stopping the up cycle can cause problems.

[mikesc]

I always turn after the needle has entered, and pierced all layers , but well before the rise begins..made more sense that way, for all the reasons given in posts above..

Edited June 17, 2016 by mikesc

[brmax]

Kinda splitting hairs here but I think when the hook is a hair past tdc and enough to retain any available slack in the loop its ok.

A or one reason is the needle is not pulling a lot of tension as going up but maybe another parts function in time " wow" I'm done.

Have a good Friday everybody

Floyd

 

[CowboyBob]

The best time & to be sure you don't get a skipped stitch is to stop & turn after the thread is caught on the hook ,so this is on the upstroke (approx. 1/4")

[gottaknow]

Ok. You guys are over complicating this issue. On machines with needle positioning, the needle should stop down after the hook has picked up the loop. If your check spring is set correctly, it will take care of any slight variations in needle thread slack while making the turn. Wiz is always stressing how important the check spring travel and tension are. The heavier the leather and thread, the more important. When sewing commences, your next subsequent loop will be formed no matter how much twisting and repositioning of the work while turning. It also important not to move the handwheel during the turning process. On machines without needle positioning, turn the needle all the way down and then up far enough to accomplish loop formation and the hook picking up the loop. I train operators to note the position of the take up lever rather than the position of the needle since it's easier to visually see it. Horizontal and vertical hook orientation makes no difference.

Regards, Eric

 

[Uwe]

I made a video some time ago that shows the underside of a loop-pickup on a vertical axis hook machine. It may help visualize what's going on down there.

 

[graywolf]

Very nice Uwe, it also show why SPM are 1/2 of RPM, which seems to confuse some folks.

[graywolf]

3 hours ago, gottaknow said:

Ok. You guys are over complicating this issue. On machines with needle positioning, the needle should stop down after the hook has picked up the loop. If your check spring is set correctly, it will take care of any slight variations in needle thread slack while making the turn. Wiz is always stressing how important the check spring travel and tension are. The heavier the leather and thread, the more important. When sewing commences, your next subsequent loop will be formed no matter how much twisting and repositioning of the work while turning. It also important not to move the handwheel during the turning process. On machines without needle positioning, turn the needle all the way down and then up far enough to accomplish loop formation and the hook picking up the loop. I train operators to note the position of the take up lever rather than the position of the needle since it's easier to visually see it. Horizontal and vertical hook orientation makes no difference.

Regards, Eric

 

I am going to have to give way to Eric's experience, since he has worked on, maybe, a million more sewing machines than I have. That said, I think I will stick to what works for me in my own sewing

[gottaknow]

2 minutes ago, graywolf said:

I am going to have to give way to Eric's experience, since he has worked on, maybe, a million more sewing machines than I have. That said, I think I will stick to what works for me in my own sewing

There's only one thing I know to be fact in sewing, and that is there are no absolutes, but lots of grey areas. I do tend to paint with a very broad brush when I describe things on the forum here. The reason is because I've been head mechanic in factories with 350 operators where I had 4 mechanics working for me and I had to keep them all on the same page. Because factories sew at high speed, things have to be set very precise. I've seen machines in upholstery shops set so poorly I was amazed they worked. My adjustment techniques and troubleshooting methods are time tested for the masses. I know that if all my machines are set to position after the loop has been picked up. I have less problems. If I were perfect, and my machines were perfect, I wouldn't have a job. There are so many variables with industrial machines, I change opinions on things all the time. About the time I think I have something figured out, it proves me wrong. I've been a mechanic for 36 years and there are days in a factory I feel like it's my first day. I am always in learning mode and have learned a ton here on the forum. Back in the days of big factories, I would adjust/repair about 75 machines a day. No wonder I have grey hair.

Regards, Eric

[dikman]

You still have hair? So it sounds like the optimum time to turn material is just before the needle exits on the upstroke? (But while the needle is still below the needle plate so that the needle is still supported and won't bend/break). That will ensure that the loop has formed, I guess. Looks like I'll have to experiment with my machine to see what it's happiest with.

 

Thanks for starting this, Uwe, lots of good info has come out of it.

[dikman]

I did some experimenting, using the Singer 166 with #69 and #138 thread, and stopping at the bottom of the stroke, part-way down and with the needle just through the leather. All worked fine with no dropped stitches. So, feeling confidant, I stitched a dress belt that I promised a club member (I'd been putting it off due to dropped stitches on the last one I did for him). Got a dropped stitch at the turning point on the belt tongue () and some thread got caught up at another turning point on the pattern ().

AAAAARRRRGGGGHHHHHH!!!!!!

[Uwe]

So that's what it was - I thought I had felt a disturbance in the Force.

Edited June 25, 2016 by Uwe

[dikman]

Yup, that was me, lots of naughty words (luckily my shed is far from the house). I think the "thread bunching" underneath was due to me lifting the pressor foot too much while trying to see where the needle was going while trying to adjust the stitch spacing. It just shows how easy it is to stuff up the stitching if the tension is let off at the wrong point. The inner foot only has a hole in it for the needle, I think I need to cut a slot at the front so that I can actually see the needle point as it enters the leather (the foot on my Pfaff is like that).

[RockyAussie]

Dremel cutting blade and polish mate. When turning at belt tip corners and against the guide remember the force against the needle presses it away from the hook. The angle of the belt here also needs to be held upward more than every where else.Anyway why not use the post for this it helps with the curve around. STOP laughing I am serious I do but i hate flat beds. Regards Brian.... PS come up to Rocky sometime and swap notes.

[dikman]

I was already thinking of getting out the Dremel, as you suggested. If I can see where the needle is going (as in hitting my guide line) then it will be easier to adjust the spacing at the belt tip. The last belt I used my Pfaff cylinder arm, but I'm having problems with it using #138 thread - it doesn't seem to like it - whereas the Singer is quite happy with it. I'm thinking though that perhaps I should have used #69 thread and closer stitching as it may have looked neater. A bit of experimenting is called for.

Wouldn't mind visiting Rocky, but timing would be critical as my wife and I dislike hot weather and humidity (has to do with getting old, I suspect ). My daughter worked as a Pharmacist up there quite a few years ago, thought it was pretty nice.

[RockyAussie]

Weather wise then now would be the best time, as its bloody cold by our standards. AT least it doesn't rain much here in winter. I admit that I mostly use for my dress belts a 40m (#69) thread due to them having a 1.6 to 1.8mm filler which makes mis stitching a common thing to watch for. These dress belts are coc top and chrome liner.Can I ask what type of thread you are using and needle style? A terko satin M25 may be a better option if you want a thicker look as being softer than Strongbond (ex Venus) it tends to lay down flatter and appears near as wide as the M20 (#138). There is a spare double bed in the factory next to our cabin if you want to find a weekend sometime.We are about 20 k out of Rocky and 3k short of the Caves area on our property.Google Garn Hatch Lane Etna Creek and you should see a map showing where we are. This is an easement on our place. See pic of the factory. Regards Brian

[dikman]

G'day Rocky, sorry I didn't get back earlier been a bit busy. I used a Schmetz needle, size 21 and is a leatherpoint (marked R TW  and LR, not sure what they mean). Thread is Serafil, M20 (#138) and I think it's a poly/cotton (twisted). I finally got it stitching ok, but when I waxed/polished the item the thread started going a bit fuzzy from the polishing cloth! I've got some Coats poly thread which I think might be better (so far I can only find one place here in Adelaide that sells thread and their range is limited).

 

I've been trying to get the Pfaff working, as it started occasionally snagging the top thread underneath somewhere. I finally stripped it to check the needle settings and after fiddling around a bit ended up re-setting the needlebar height/hook alignment, hook spacing and setting the needle a bit lower to ensure the loop was forming early enough. I also touched up the hook and polished the end. Now I can run a stitch line of #138 top and bottom, which I couldn't do before!

 

I think I'm slowly starting to understand the relationship between all these bits and pieces, but boy they can be finicky!!

Edited June 29, 2016 by dikman