Roughed up underside when sewing

[tagfan]

Hi all - I've found this board to be a tremendous help as I learn the craft of working with leather on my Consew 206Rb.  I am having a problem though, and I wondered if anyone knew a workaround.  

My machine is currently stitching nicely both forward and reverse at a consistent speed.  However, when I slow down, the stitch length becomes much shorter. I am not sure if I misadjusted the feet and its not pulling the material through properly or what.  

Sound familiar? 

[nylonRigging]

that is Weird .. not suppose to do that, your lengths stitch should not change unless you manually change them . Probably something real simple that is hard to see right off the bat.

may not be the problem ? . But 'Only' thing that pops into my head is maybe raise press foot and hold it just above feed dog . Then carefully look and see if they are 'both moving exactly together' . when you manually slowly roll the hand wheel threw a few revolutions .

I don't have 206 RB,  but I do got a 146RB,  and one time I had linkage arm work loose that connects strait to he outside press feet . It went out of unison/timing with dogs just a little . Thread tension looked great top and bottom with sewing,  but it was doing some real  funky feeding with stitches that day and took me a couple hours of scratching my head before I figured it out .

.

Edited March 28, 2019 by nylonRigging

[Matt S]

I had this once with a W/F machine quite similar to the 206 -- somewhere above 1,300SPM the stitches would lengthen well above what I had it set to. Stitch length shortened back to normal when I throttled back. Not a huge surprise, it was rated for 1,200 or so. I figured something is either bouncing more than it's supposed to or is bouncing its normal amount and not being able to return to its starting position (under spring pressure) in time for the next stitch. Fixed by keeping the speed within the rated limits.

I've also had issues with W/F machines changing stitch length when the two feet bind against one another, when the outer foot binds against a step up, when the foot timing is off and when there's excessive tension on one side (most commonly with the needle thread catching on something). However none of these have varied with speed, except for the above story.

@tagfan what speeds are you encountering this issue at?

[tagfan]

Looks like it was just due to foot height. Material wasn’t being pulled evenly. 

Now I am dealing with this issue - the underside of my leather is getting all marked up. Wonder if I have to grind Dow something or whether my tension is all messed up. Stitches dont look great either. 

[tagfan]

Finally got the top stitches perfect and now the bottom side looks like this. Have a normal feed dog/plate on a consew 206rb. Should I get a Teflon feed dog or grind something down? 

 

The stitches don’t look great either...

[Matt S]

Looks like you have a few things going on there: marking, insufficient needle thread tension and maybe a little blowthrough.

If you back off the presser tension it should reduce the marking. If you keep backing off the for pressure at some point the work will start to lift with the needle, which will be the point at which you've reduced the presser tension too far and need to increase it again. At that point you'll more or less had to live with whatever marking you're getting. You'll probably have to rub or hammer out what little you're getting then. You can probably fill and/or grind any serrations on your feed dog and needle plate but that's almost a last ditch approach.

Tension is probably fixable by increasing the needle thread tension a little. Go up in 1/4 or 1/2 turn steps, sew a few inches of scrap material same as what you want to sew for real and adjust again. If you can't get the tensions balanced using the needle thread tension knob you'll have to decrease the bobbin thread tension but you shouldn't have to do that.

Blowthrough can be reduced by using leather specific needles but you're probably using them already. Getting the thread tensions balanced should help with it.

[tagfan]

22 minutes ago, Matt S said:

Looks like you have a few things going on there: marking, insufficient needle thread tension and maybe a little blowthrough.

If you back off the presser tension it should reduce the marking. If you keep backing off the for pressure at some point the work will start to lift with the needle, which will be the point at which you've reduced the presser tension too far and need to increase it again. At that point you'll more or less had to live with whatever marking you're getting. You'll probably have to rub or hammer out what little you're getting then. You can probably fill and/or grind any serrations on your feed dog and needle plate but that's almost a last ditch approach.

Tension is probably fixable by increasing the needle thread tension a little. Go up in 1/4 or 1/2 turn steps, sew a few inches of scrap material same as what you want to sew for real and adjust again. If you can't get the tensions balanced using the needle thread tension knob you'll have to decrease the bobbin thread tension but you shouldn't have to do that.

Blowthrough can be reduced by using leather specific needles but you're probably using them already. Getting the thread tensions balanced should help with it.

Thanks for that explanation @Matt S.  With your help I have lowered tension to an acceptable level and tightened needle thread tension. Stitches look much better, but I am still getting those 'blowthrough' marks.  Not sure how to deal with those suckers yet.....

[Matt S]

10 minutes ago, tagfan said:

Thanks for that explanation @Matt S.  With your help I have lowered tension to an acceptable level and tightened needle thread tension. Stitches look much better, but I am still getting those 'blowthrough' marks.  Not sure how to deal with those suckers yet.....

No problem TF, glad to help. Are you using leather-specific needles? Looks like you are but if not then they reduce blowthrough. Otherwise there's not a great deal you can do, other than rubbing and/or hammering the back side of the seam.

It's hard to tell from the "before" photo but is it definitely blowthrough you're getting, or is the leather getting smooshed down into the feed dog hole? If it's the latter as I said earlier you could reduce the pressure on the presser foot.

[tagfan]

Yeah I’m am using leather needles @Matt S  .  I think you’re right, it’s could be the leather getting crimped into the feed dog hole. I’ve got the tension completely unscrewed so not sure what else I could do to reduce tension other than raising the feet? 

 

I did increase bobbin tension a lot before. Wonder if that could cause something like this. 

Edited March 29, 2019 by tagfan

[garypl]

I just bought some new presser feet for my 206RB and the left and right outer feet had some pretty sharp serrations.  I filled the serrations with JB Weld and then sanded the surface smooth after it cured - no more serrations to mark the leather.  I also had to grind  the center foot and outer foot to prevent rubbing- the center foot was deflecting off the outer foot.

Gary

[CowboyBob]

What size needle & thread are you using? 

[tagfan]

@CowboyBobI am officially an idiot. Apparently the needles I used were 135x17, which I now know is a fabric size. I had assumed they had leather tips but they did not. 

Just bought some 135x16 tri tip needles and I hope that will solve the blow through problems. 

Thanks all - 

[Matt S]

1 hour ago, tagfan said:

@CowboyBobI am officially an idiot. Apparently the needles I used were 135x17, which I now know is a fabric size. I had assumed they had leather tips but they did not. 

Just bought some 135x16 tri tip needles and I hope that will solve the blow through problems. 

 You're not the first to do that. Spent a morning recently trying to figure why my machine was running so heavy with a poor stitch til I realised I'd pulled a pack of 135x17 out the drawer instead of x16.

[tagfan]

Well the new needles didn’t make any difference. I just ground down the middle of the feed dog with a dremel and that seemed to help a lot. Little more grinding and there will be no marks left at all. 

Edited March 30, 2019 by tagfan