As in my previous post, I’ve been modelling parts of my loom. This update covers the two most recent.
Pinch Rollers
At the back of the loom there is the pinch roller mechanism. This is used to control the tension of the warp threads from the back of the loom towards the front. High tension is needed when weaving, but it prevents the lifter bar (referred to later) from lowering properly. Using the pinch rollers, the tension in the loom can be dropped by moving the warp threads forward at the back of the loom. Then when the pattern has been set and the lifter bar raised, the tension can be reintroduced by winding the cloth up at the front.
The bobbin frame support structure, in the previous post, connects to the back of these rollers. The bobbin winder, also in the previous post connects to the lefthand side of the pinch rollers as shown.
The LDraw model for this can be found at: http://jander.me.uk/LEGO/loom-parts/Pinch%20Rollers.ldr
Adding the pinch rollers, bobin frame and support, and bobbin winder all together, the over-all model now looks like:
Lifter Bar
Whilst the back of the loom was off – I had to remove the pinch rollers to work out how I’d built them originally – I decided I’d model one of the most important parts of the loom, since it was visible. This is the lifter bar. It is one half of the mechanism that provides the Jacquard ability. It has 32 pins in it, that when one is engaged into the bottom eyelet of a heddle allows that one to be lifted up. There is an equivalent static bar at the front which holds the heddles down if needed.
This mechanism slides up and down along some long axles. These pass through the holes in the ends of the bars, and through some of the holes in the frames. There are gear racks at the back and sides which provide the lifting force. The lifting mechanism has to be offset away from the pins as the pin setting mechanism rides along underneath the whole Jacquard structure.
The LDraw model for this can be found at: http://jander.me.uk/LEGO/loom-parts/Lifter%20Bar.ldr
What Next?
Well, I’m going to put the loom back together, and check that all my new parts actually do what I wanted them to. It’s still loaded with wool from the Mytholmroyd show at the end of January, so I’m going to run that through and then empty the loom.
I’ve then got a little bit of coding to do, to support the bobbin winder – i.e. change the direction of the motor. There’s no need to use the pinch rollers to wind the warp threads on to a drum anymore, so I can repurpose that function to the winder.
I’ve got some other things I need to focus on, and this 3D modelling is quite intensive, so I’m going to take a break from that, and will look to model some more parts in a few weeks time.