Adler 104 stitch length - adjustment manual

[Bert51]

My 105-6 has the lock pins (wing nuts) on the Forward and Reverse Lever and I just set them where I want and sew. I know I have the stitch length where I need it.

Bert.

[Constabulary]

And how often do you really change the stitch length? Sure - depends on the project, how many items you sew and so forth.... but most folks I think will sew at 5-6mm stitch length on heavy machines like this.

[Bert51]

Normally I play before each project and get the stitch length that I want, both ways, if I am going use other size stitch lengths I mark the flat plate with lead pencil, but as I said I only use one stitch length.

If you look carefully you can see my marks in pencil on the flat plate.

Bert.

[Pterytus]

You're probably right ;-)

At first I thought it was/is a matter of adjustment. In that case, I would have preferred to get it right. So maybe it got a little out of hand once I realized it is a built in "feature". But at least I found That out in the process, so I think it was worth discussing anyways.

[shoepatcher]

Cannot believe no one in Germany beside Constabulary can help you with this problem!  That is Adler home territory!!!!

glenn

[Pterytus]

So I DID go a bit further and collected some data ;-)

The first graph shows F and R stitch lengths in blue and red (x-Axis is number of revs of knurled SLL-nut) - measured data and approximated quadratic equasions to ease calculation.

So if you reduce lever travel below the intersection at 5.2mm stitch length (F) accordingly you'd end up with equal stitch lenths F and R by just flicking the SLL up and down.

The second graph shows pivot point of SLL (0|0) and flat SLL-frame surface at x=59mm in blue. Changing lower SLL-frame geometry from blue to red would result in the required lever travel reduction. True: You'd lose approx. 1.5mm F stitch length, because R only goes up to 8.1mm - which should still be ok. Maybe it's just a matter of opening up upper SLL-frame. This should be possible because the rest of the machine is capable of 9.7mm.

The red line in the second graph is roughly a straight line so it would not even be necessary to machine some complex contour but just add some kind of wedge etc. to make the modification possible.

I'm not sure if it really is necessary/worth to realize that in hardware (see above) but it seems realistic and not too challanging.

Anyway I wanted to share my findings with you guys :-)

 

[Constabulary]

a mad scientist you are Reminds me of curve sketching and things - didn´t like it as well as stochastic (I get goose pimples )

Edited December 14, 2019 by Constabulary

[Pterytus]

Ah, I've been called much worse! ...and with reason ;-)

And sorry, did not intend to give anyone geometric nightmares, they're THE WORST! Next time I'll just show you the (completely non-stochastic) formulae, btw., they're y_F=-0.021x²-0.433x+9.654 and y_R=-0.018x²-0.264x+8.082, that better? :-D

Anyway, NOW would be a good time for a 3D-printer. Just to verify (or falsify) my madness. So it's metal-or-nothing for me now...

[Bert51]

Some of us think we are quiet sane, but there again I have also been told I am as mad as a hatter, I think you maybe in good company.

Sit down put up your feet and stay awhile, you will enjoy yourself.

Bert.

[Constabulary]

11 hours ago, Pterytus said:

y_F=-0.021x²-0.433x+9.654 and y_R=-0.018x²-0.264x+8.082, that better? :-D

Definitely better - now I get it. So what you need is a curved center piece from the flux capacitor,  I think. Flux capacitor parts are universal fit and solve everything.

Sorry can´t really help much more here. My way would be the angle bracket with 2 limiters like they have used on the later 104´s. Thtas probably something even a later buyer will understand (one day you will / have to sell it)  instead of riddling what this "odd shaped / non standard" piece is. And when it is worn (if printed out of plastic materials it will be worn sooner or later) he will be screwed. Keep things simple!   My 2 cents.