Mason · Needle bar drive

Inside Defender’s head

I’ve been cleaning up my latest acquisition – A.G. Mason’s Defender, a vibrating shuttle machine very similar to White. These machines have a removable head that contains all the fixtures – the presser and needle bars with their drives, and the tension assembly. I was unfamiliar with this design and was having trouble because the needle was skewed.

How on earth are you supposed to fix that? I couldn’t figure it out, despaired and filed the needle groove slightly to get it right.

Turns out, that wasn’t necessary!

When I was varnishing the machine, I had to take off the head, and I discovered that actually it needed thorough cleaning because I could not move the needle bar by hand. This is wrong, it should move smoothly!

The needle bar is driven by a V-drive clamp that has a slider riding along a slit in the back of the head. But there is also a plate mounted inside the head. After I cleaned everything in sight, the slider was still not moving freely. I then had to loosen the screws holding the plate until there was reasonable free movement.

There are also two mysterious screws on the face of the head that seemingly go no where. They sit exactly opposite the needle bar, so they must help regulate the needle bar orientation somehow. But they don’t appear to have any effect, at least not now, may be there was some effect when the machine was new.

The presser bar is held in its clamp by a single screw and it rides on two sliders – one rides along a slit in the back of the head and the other along special grooves inside the head. That second slider has a screw to adjust its stiffness.

You can also see the tension assembly pin and the tension release lever, as well as the foot raising lever, but I didn’t mark them.

And finally, the head tilt adjuster! Once you close the head, you can adjust its tilt with this screw. Oh!

The head tilt adjuster is nice, but it only adjusts the lateral tilt – left to right. The head fits rather loosely over the arm and can be tilted backwards and forwards, so make sure you adjust it properly before tightening the screws.

If you need to adjust the height of the needle bar or the presser bar, this removable head proves really inconvenient though. You have to measure the amount of offset with the head on, then take it off, adjust the bar by that amount, put the head back on, check, swear, repeat. Not great!

When checking the front-back alignment of the head, make sure first that the needle is actually properly aligned inside the needle clamp. The flat groove in the needle bar is 3mm wide, while the shank of a 15×1 needle is only 2mm wide, so it is very easy to insert the needle at an angle. Yes, there is a small groove on the opposite side of the needle clamp which should help, but actually it doesn’t do much.

I must admit that being used to the precision fit of Singer machines, all this is rather disappointing. The head doesn’t reach the level of the rest of the machine, there is too much play here. But overall the machine is excellent and well worth the trouble of fine-tuning the head.

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