Adler 67-gk-373 presser bar tension adjustment

[mcguyver42]

Well my Adler 67-gk373 is sewing pretty darn well.  After much grief to get it to that point, it turns out that I am a hand sewer and looking to sell it. The machine is normally set up for 138 thread and a little heavier material.  To get it ready to start showing it,  I set it up for 92 thread and was sewing off 2 thickness's of vinyl and noticed that it doesn't thump.  I was having trouble hitting the same holes while back stitching, but that could very well be a loose nut behind the wheel because I am no machine sewer.  I started putting 2 and 2 together and realized my presser bar tension might be off.  I looked through the adjustment manual, (which I was able to get through with all of your generous  help).  No mention of it, and I don't remember why I had it at the minimum tension setting.  I thought it might be a user adjustment, but found the user manual to be lacking.  Does anyone know what that knurled knob thingy on top of the double leaf springs is for?  Is it a user adjustment?  Surely you don't want it to be tighter than it needs to be, because that's a lot of stress on a lot of parts. 

[Constabulary]

aaaah, well - its for adjusting the foot pressure

[mcguyver42]

Well, that's what they say, but that's about all they say.  Of course there is no gauge to measure the pressure being applied to the material, that would be ridiculous, but is there some guidance beyond "tighten until it seems about right"

[Northmount]

3 hours ago, mcguyver42 said:

Well, that's what they say, but that's about all they say.  Of course there is no gauge to measure the pressure being applied to the material, that would be ridiculous, but is there some guidance beyond "tighten until it seems about right"

The required presser foot pressure depends on the material that you are sewing.  If it is heavy hard thick leather, you will need more foot pressure to keep the leather from lifting the foot (due to the needle on the up stroke) , destroying the loop, and skipping a stitch.  So more pressure for the thick hard stuff, and less pressure for thin soft stuff.  To limit the foot marking the top of vegtan leather, the foot pressure needs to be kept low.  So you have to test and find the sweet spot for the work you are doing.   Thus the statement to "tighten until it seems about right".

[mcguyver42]

Got it, for German machines the spec is  Gudentight for thicker denser materials and  lesserso for lighter materials until everything seems to be sewing properly, but always with the minimum tension needed.  Well thank you, that gets me moving forward again without wondering that I'm missing something.