> For the complete documentation index, see [llms.txt](https://delta-robotics.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://delta-robotics.gitbook.io/docs/hardware/nitinol/mounting-and-wiring.md).

# Mounting and wiring

How to anchor Delta Nitinol wire and springs, make reliable electrical connections, set the right pre-tension, and why soldering Nitinol is a lab-only process

Getting Nitinol anchored and wired is half the battle. This page covers how to hold the wire or spring mechanically, how to connect it for high current, how much to pre-tension it, and why soldering is a lab-only process.

## Physical mounting

Anchor both ends of the wire so it can pull against your mechanism without slipping.

| Method            | Works for         | Notes                         |
| ----------------- | ----------------- | ----------------------------- |
| Screw-down clamps | All sizes         | Best mix of secure and simple |
| Wrap-around posts | Light-duty setups | Tension the wire well         |
| Crimps            | Low-force only    | Fatigue risk at higher loads  |

Springs ship pre-mounted with 5052 aluminum fixtures on both ends, so for most spring builds you bolt them straight in and go.

## Electrical connections

Nitinol actuates by Joule heating, so the connection has to carry real current without heating up itself. Use heavy-gauge wire and keep connections tight. For the current each diameter draws, see the [Wire](/docs/hardware/nitinol/wire.md) and [Spring](/docs/hardware/nitinol/spring.md) specs; for what the driver delivers, see the [TF Node Controller](/docs/hardware/thermoflex/tf-node-controller.md).

| Method          | Works for       | Notes                                                  |
| --------------- | --------------- | ------------------------------------------------------ |
| Screw terminals | Most setups     | Best choice, simple to adjust and high-current capable |
| Alligator clips | Prototypes only | Handy but not reliable for real use                    |
| Soldering       | Not recommended | Lab-only process, see below                            |

The aluminum spring mounts are conductive, so clamp or screw them into your terminals. Soldering to a spring mount is possible but hard: the large aluminum surface makes it difficult to get the solder to temperature.

{% hint style="warning" %}
High-current connections that are loose or undersized overheat and can fail or ignite. Keep every connection tight, keep wire runs short, and never run more than a few amps through jumper wires. See [Safety essentials](/docs/get-started/safety.md).
{% endhint %}

## Pre-tension

A little pre-tension makes the actuator respond faster and take up slack, but too much shortens its life.

* Pre-tension slightly. Do not stretch the wire or spring to set it.
* Stay under 5% strain in use. For long cycle life, aim for 3 to 4 percent.

## Experimental: soldering Nitinol

**Do not try this at home. Seriously.**

Soldering Nitinol is technically possible, but only after a hazardous surface-prep process. In order, you have to:

1. Strip the oxide layer with hydrofluoric acid (do not, unless you are trained to)
2. Electroplate the exposed metal with nickel
3. Then, maybe, your solder will stick (still experimental)

{% hint style="danger" %}
**Hydrofluoric acid is extremely dangerous.** It causes deep burns that can be painless at first and delayed for hours, and skin contact over even a small area can be fatal. Never attempt this without professional training, dedicated handling procedures, proper protective equipment, and calcium gluconate on hand. This is done only in a controlled lab, never as a hobby project.
{% endhint %}

We only do this in the lab, and we are trained for it. This is not a weekend project.

## Related pages

* [Wire](/docs/hardware/nitinol/wire.md): Wire specs, force, and cooling data.
* [Spring](/docs/hardware/nitinol/spring.md): Spring specs and pre-mounted fixtures.
* [TF Node Controller](/docs/hardware/thermoflex/tf-node-controller.md): Deliver current to the actuator.
* [How to Train Nitinol](/docs/learn/how-to-train-nitinol.md): Shape the wire before you mount it.