Stitch Length HELP needed Consew 287R

[CustomDoug]

Hello - I'm using a somewhat older Consew 287R (Japanese made copy of Singer cylinder arm 153Wxxx with reverse).. I'm attempting to top-stitch a French seam into upholstery vinyl using 138 thread, and the max stitch length is coming out too small. There is a stitch length & reverse lever on the front - I have it set all the way up... at the "5", which I believe represents 5mm per stitch, but these are more like 3mm and/or less. I have raised the feed dog in an attempt to correct the problem.

One thing I'm noticing is that there is more resistance of the thread when pulling it at the needle end, then when pulling it from the bobbin (not sure if that has anything to do with the stitch length problem) - should the resistances be the same? 

Thanks for any help.

[Pintodeluxe]

Upper tension should normally feel stronger than bobbin tension.  That part is normal.  

  

[CustomDoug]

30 minutes ago, Pintodeluxe said:

Upper tension should normally feel stronger than bobbin tension.  That part is normal.  

  

Ok, that is good to know.. 

[CustomDoug]

..there is a large hole (maybe 3/4") just under the 'length-adjust-lever' on the front of the machine .. with a large screw inside of it. And also the same hole on the back-side directly in line with the front hole - which gives access to an Allen bolt. Are these there for stitch length issues? 

I think my alternating presser foot is only moving about 3mm on max. This machine should do 6mm IIRC.

 

[Uwe]

Can you please post a few photos of your machine?  It appears to be a Seiko design, not a Singer 153.

One thing to check is how much the needle actually moves at the throat plate level. Rotate the hand wheel so the needle is at throat plate level at the max front position. Hold a ruler next to the needle and flip the reverse lever, observe how much the needle actually moves.

Sometimes the max stitch length is limited due to incorrect feed timing.  A short close-up video of the feed dog and needle movement is the best way to judge that. 

Some machine designs allow a mechanic to purposely limit the max stitch length for projects with small-opening throat plates, etc.. This avoids accidentally damaging the machine if the operator could select a larger stitch length than the installed gauge set allowed. 

Edited September 30, 2020 by Uwe

[CustomDoug]

All the way forward:

All the way back:

Well, close to 6mm, real close to it when tested as you suggest. But it's not translating to the stitch.

Edited October 5, 2020 by Northmount
uploaded photos here

[CustomDoug]

@Uwe

Here's a shot of the stitches I'm getting on maximum, I'd say they are 3.5mm (pic actually makes them look better) [I've obviously removed the rear foot for the pics - but if it makes any difference the alternating foot is serated and the other is smooth] & again, size 138 poly thread... surely this machine will do bigger stitches than this?: 

Edited October 5, 2020 by Northmount
uploaded photos here

[Uwe]

Try making some stitches in cardboard or thick paper without thread and measure those hole distances. That’s kind of the best case scenario for max stitch length - without anything slipping or stretching. (I made a stitch length measuring template that you can download and print out if you like: http://docs.uwe.net/slg.pdf )

Observe the feed timing one more time. The descending needle and inner foot should arrive at the top of the throat plate at the exact same time as the rising feed dog from below (this is a kind of reference position.) There should be no more forward movement at this point - needle, feed dog and feet should all start moving towards the back immediately after that reference position. If this is not the case, your feed timing may need to be adjusted.

Try a few slow, hand-turned stitches with material and threaded needle. Closely observe how the material and the needle move. If the needle enters the material before it reaches the very front of its movement, that will result in shorter stitch length.

If the material moves forward under the foot while the knot is being pulled tight (thread take-up lever at highest position.) that’s another problem that reduces stitch length. Too-high thread tension may pull the material forward as it’s pulling the knot into the material. In general, the thread tension should not be higher than really necessary to make a good stitch. Increasing foot pressure may also help alleviate that problem. But here also, the foot pressure should not be higher than really needed to firmly hold the material in place.

Different materials range from very sticky to very slippery, causing differences in how well the material can be moved or held in place. Thickness of material and force needed to pull the knot into the material also play a role. Try one needle size up to make it easier for the thread knot to get pulled into the material. Vinyls tend to be elastic and close up the needle hole around the thread again, veg tan leather on the other hand does not tend to close up the needle holes again. Vinyl and some leathers is also somewhat stretchy. If you stretch the material as you sew the stitch line will shorten again afterward. 

When sewing, don’t pull or push on the material, just guide it with a light touch. Let the machine do the feeding. Otherwise you may introduce other problems if you pull the needle one way or another while it’s trying to do its job.

[CustomDoug]

Cardboard got me 4mm holes... switched back to the vinyl and now a contrasting yellow 138 thread and it too showed a solid 4mm stitch length at maximum. I can't help but think it's an internal slip of a rod/gear. 

[Uwe]

Is your stitch length the same in reverse? Is there any play when you try to move the needle bar back and forth by hand?

It’s possible the feed mechanism is out of balance, thus increasing stitch length in one direction and reducing it in the other direction.

I still don’t know exactly what your machine looks like. I can’t find a parts diagram for a “ Consew 287R”  online, or much else for that matter. I’m guessing we’re talking about a rebadged Seiko CW-8B-2 like this: