Working with Aluminum T-Slot Extrusion
There are a few techniques and concepts for aluminum extrusion that you need to understand while building an Archivist Quill. Please read this section carefully.
V-Slot and T-Slot
T-Slot aluminum extrusion is a long square beam with a slot on each of the four sides. T-Nuts can slide along inside the slots and be tightened to hold attachments to the tube anywhere along its length. This flexibility makes it easy to create any kind of furniture scale object using brackets that connect to multiple T-Slot beams at the same time.
V-Slot beams work the same as T-Slot extrusion, but have a slight angle all along the top of each slot. This angle allows V-Wheels to move along them like the track of a rail.
Some beams of this kit are V-Slot and some are T-Slot. When assembling them, they all work the same way. But the V-Slot rails are used when we want to allow smooth linear motion.
In the cradle wings, we use thinner beams than the rest. This helps reduce the weight of the cradle, but means that smaller screws and nuts are required.
Some extrusion in the kit may have a protective plastic coating on the outside. Before assembly, remove the plastic coating and discard it.
The special nuts that go in T-Slot extrusion are called T-Nuts. We use two different kinds in this kit. Single T-Nuts have a single threaded hole. Double T-Nuts have two threaded holes.
Each T-Nut has a smooth side and a bumpy side where the threaded hole protrudes. The bumps on a T-Nut always point towards the center of the beam. The smooth side always points outward. When screwing an attachment into a T-Nut, the smooth side is pressed against the smooth wall of the T-Slot and a solid connection is made.
In the cradle wings, M3 Square Nuts are used in place of T-Nuts.
It can be tricky to line up screws with T-Nuts when the T-Nut is already in a T-Slot beam. Preloading means partially threading screws onto T-Nuts before sliding them onto the T-Slot beams. The trick is to firmly attach the screw to the T-Nut while allowing enough of a gap to remain to allow the whole assembly to be slid onto a T-Slot beam.
To preload a plate, first see if washers are needed for the assembly. If so, place the washers on the screws to start.
Press the T-Nut firmly against the back of the plate. Make sure it is aligned with the holes in the plate.
On the front of the plate, push a screw through and turn it with your fingers until it is partially threaded on the T-Nut pressed against the other side.
If it is a Double T-Nut, you will need to screw in a second screw as well.
The instructions will show pictures for each plate indicating which holes need a Single T-Nut and which pairs of holes need Double T-Nuts.
Preloading Corner Brackets
On corner brackets, a Single T-Nut needs to be attached to each of the two sides.
Push a screw through one of the two holes.
Spin the Single T-Nut onto the screw until they are solidly attached. Leave a gap to allow it to slide onto T-Slot beams.
Repeat with the other side.
Sliding Preloaded Parts onto T-Slot beams
To successfully slide a preloaded part onto a T-Slot beam, two things have to happen.
First, the T-Nuts are rectangles and they must be properly aligned along the length of the slot to slide in. If they are at an angle, pushing them against the slot will simply jam them.
Second, there needs to be a gap between the part and the T-Nut larger than the thickness of the outer T-Slot wall. If there is not enough of a gap, the T-Nut will jam at an angle.
To make the gap bigger, press your finger against the screw to make sure that the screw is not sticking out. You may also need to loosen the screw until there is enough of a gap. If you loosen the screw too much, it will come off of the nut and you will need to re-attach it.
Snugging vs. Tightening
Once you slide parts onto extrusion, the instructions will sometimes tell you to 'snug' the screws into place. This means that they should be temporarily tightened. Do not use your full strength or leverage to tighten them, though, because they are only temporarily being attached in that position.
Other times, the instructions will tell you to 'tighten' screws. This means that the bracket is in its final position and you should make it very tight so that the joint won't come loose later on.
All of the T-Nuts that come with this kit slide freely in the slots. This means that loose screws and parts will naturally slip downhill. When attaching brackets to T-Slot, always try to ensure that gravity is neutral by attaching things along their sides. Whenever you have to deal with gravity moving pieces around, your job will become more difficult.
One other option when dealing with gravity is to snug parts into place while you are working so that you don't need to hold them there or worry about them slipping apart. You can always loosen and move them again later when you want them moved.