Is it too hot to be sewing? The temperature is 30C (86F) – we’re having a heat wave. My new 3D printed bobbins for Adler 87 suddenly started jamming. My old plastic bobbins for computerised Pfaff 7510 are also suddenly jamming! I blame the heat which makes the plastic expand.
With Pfaff and other machines that take standard bobbins, the solution is simple – switch to metal bobbins. You’d need to be on the surface of the Sun before those start jamming. Well, may be not quite on the Sun, but still in a rather hotter place than my sewing room. But these 3D printed bobbins have been printed exactly because metal bobbins are lacking! So, what to do?
Find a metal worker who can make them for you in steel. Yeah, right. 😣
Instead, I found some tricks for Adler 87 that allow me to use 3D printed bobbins even though they expand a little.
Here are the bobbins. You see how they are supposed to fit into the bobbin case – sinking into it a little. At the moment some of them are rising above the surface slightly. 😒
Winding the bobbin
First, I discovered that when the bobbin is being wound in the heat, its sides move outwards under the pressure of the thread building up. Adler 87 has a rather high thread tension for winding.
The tensioner has a spring under the big screw, so first of all I took it out.
That improved the situation but not by very much. This zig-zagging of the thread around the pins already puts a lot of tension onto it. If you don’t mind that your bobbins hold a lot less thread than they should, you can re-route the thread with fewer zig-zags and that solves the problem.
But I do mind, so I choose to restrict the thread closer to the bobbin.
This helps and the bobbin almost doesn’t expand.
Threading the bobbin case
If you have a slightly expanded bobbin and you thread it the usual way, you might find that although the machine sews perfectly, you cannot pull out bobbin thread when you stop sewing. 😤 This is impossible to work with!! But don’t panic.
First, I put the bobbin into the bobbin case the wrong way around. 😯 Yes, I know, completely illegal, but hey – 3D printed resin bobbins are also not exactly regulation issue. So where you normally put the bobbin in so that it spins clockwise, I put it in so that it spins anti-clockwise. It makes it nearly impossible to thread the shuttle though, so what I do is put the bobbin in properly, thread the shuttle and then pop the bobbin out and flip it.
This positioning reduces zig-zagging in the thread path and is often sufficient to allow you to pull the bobbin thread when it is fully threaded through the needle hole. I noticed no issues with sewing and did not have to adjust thread tension on the bobbin case either.
Change your habits
If the above tricks are not quite sufficient, there is another thing you can do, and this only applies to machines with the same hook as Adler 87 – the Wheeler & Wilson D9 type.
If you pop the bobbin case in, leave the slide open and slowly rotate the balance wheel, you can observe that the hook pressure on the bobbin varies throughout the cycle. And it so happens that the usual “stop” position with the needle and the take-up lever both at the highest point corresponds to high pressure on the bobbin from the hook. Hence if the bobbin is a little too thick, it jams when you try to pull the thread.
However, just before that, when the needle is already up but the take-up lever is still down, the bobbin is spinning freely! 😃
So here is my solution to a new sewing routine:
- When you want to stop sewing, bring the needle and the take-up lever to the highest point as usual.
- Now rotate the balance wheel backwards (towards you) a little – just to bring the take-up lever to its lowest point. Observe that the needle stays in the top position!
- Lift the foot and remove your sewing – the bobbin is now spinning freely.
- You are not done yet! Hold the threads firmly (mostly the thread coming off the needle) and rotate the balance wheel forward to bring the take-up lever back up ready for stitching. This will pull a length of thread off the spool, and if you don’t hold the thread, it will slink out of the needle instead.
With this method I can use even those bobbins that expanded quite a lot and are noticeably rising above the bobbin case edge. I found that even 1.5mm too high still works without the need to adjust bobbin tension for sewing!
I declare this a workable solution. But next time when I decide to get 3D printed bobbins done, I’ll start looking into different materials that can be used to make them. I know that ABS plastic would have been better as it is much harder, but the cost was prohibitive. I’ve got a good working compromise, so I’m happy with it.
Happy sewing! Even during a heat wave. 😊