Actually, it's not difficult at all!

We only change the lower knife, since the upper one practically does not wear out because it is made of a harder metal. By the way, it is not necessary to buy a set of new knives. A worn knife can be sharpened and used again.

Remember, when making any repairs or replacing parts in sewing machines, do not forget to clean and lubricate them!..

So, we have two knives, while only the upper one is movable, and we change the lower one.

On new overlocks and coverlocks, before replacing, for convenience, we raise the upper knife and take it away.

Then, loosen the fastening of the lower knife and remove it from the recess in which it was located.

We put the new knife in place of the old one and fix the screw holding it.

Then you can lower the upper knife and sew off the sample.

On the overlock class 51 and on analogue models, the lower knife changes in the same way.

But the adjustment after replacing the knife is more difficult, since in the 51 class overlock the knife is not fixed from below and you will have to adjust its height relative to the upper knife yourself.

Adjustment is best done by gradually shifting the knife and periodically sewing off the stitch patterns.

And a little tip: if you sew with your own hands, it is better to master the simple overlock adjustments and perform them yourself. This will not only allow you to save on the call of a fitter, but also allow you to fine-tune for certain types of fabrics.

See also video master classes on how to replace overlock and how well other edge seams do well with overcasting.

You will also be interested video tutorial on how to set up an overlocker and how to sew stretch on it.

And in conclusion, I will bring to your attention an example of a product sewn mostly on an overlock with a knitted seam - watch the video master class on sewing a hoodie jacket with your own hands.