Practical 3D Printing: Step 5: Finishing
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Step 5: Finishing
04.11
| 00:00 | With our parts back from the supplier, now's the time to review them and make sure we're happy. |
| 00:04 | If anything is wrong, we want to try to sort this out with the manufacturer before doing anything to them. |
| 00:10 | In our case, the mounts came back looking great, and the initial test fits with the carbon tube showed a suitable fit, not too tight and not too loose. |
| 00:19 | So,me finishing touches had already been done by the supplier as we requested glass bead blasting. |
| 00:24 | From here we could finish the parts with other coatings to protect them, but in this case we want to leave them as is to somewhat match the cast aluminium parts in the engine bay for that clean OEM look. |
| 00:35 | So, the next steps are to complete the construction of the strut brace with the carbon tube. |
| 00:40 | With the car sitting on a flat and level patch to ensure the strut towers are evenly loaded, we'll remove the nuts from the strut tops. |
| 00:48 | Before we risk scratching the paint, we'll apply some clear tape to the bottom surface of the mounts. |
| 00:53 | The tape we used is specifically bare all -weather tape. |
| 00:57 | It's designed for heavy-duty surface protection so it's tough, somewhat like paint protection film or PPF. |
| 01:04 | Next, we need to accurately measure between the flanges of our parts to determine the length of the carbon tube. |
| 01:09 | In our case this measured at 719mm. |
| 01:12 | The tube was modelled at 720mm long and CAD, so we're right on the money with less than 0.2% difference. |
| 01:21 | We then need to remove the mounts from the car again in preparation for the adhesive. |
| 01:25 | The carbon tube can be cut to length using a drop saw. |
| 01:28 | We just need to be careful when clamping the tube to avoid crushing it and make sure it's level so we don't cut it on an angle. |
| 01:35 | We included some engraving in the design on the spigot face to help provide some mechanical interlocking for stronger adhesion. |
| 01:42 | The surface texture is also relatively rough so there's really no need to key it with sandpaper. |
| 01:47 | The inside of the carbon tube is very smooth though so we did give it a quick scarf with some 3D ink. |
| 01:53 | To prepare for the adhesive, the spigot surfaces and the inside of the tube also need a thorough clean with an isopropyl alcohol and some clean shop towel. |
| 02:03 | Finally, we'll add some masking tape around the adjacent surfaces of the tube and the mounts so they're protected from any excess adhesive that makes its way onto these parts. |
| 02:12 | The specific product is HPR5 from Adhesive Technologies and needs to be mixed at about 4 to 1. |
| 02:19 | Or in other words, as the supplier states, for every 100 units. |
| 02:23 | To get to 100 units of part A, we need 26 units of part B. |
| 02:26 | So, using our digital scales zeroed with our mixing container, we'll add 20g of part A and 5g of part B. |
| 02:34 | This can then be mixed together using a popsicle stick. |
| 02:37 | It's critical they're completely mixed together otherwise we'll risk an incomplete curing reaction and a bond that'll likely fail. |
| 02:44 | Once mixed, we can use a disposable chip brush to apply adhesive to the spigot surface and the inside of the tube in a thin film. |
| 02:52 | It is important to get full coverage, but we don't need too much because it's quite a tight fit. |
| 02:57 | Then it's just a matter of pressing the aluminium parts into the tube, making sure they're in the correct orientation because it is possible to get this wrong. |
| 03:05 | We've also made sure that the seam of the carbon tube is on the underside so it's not visible when the parts are installed. |
| 03:11 | Any excess adhesive is easy to wipe off with an isopropyl alcohol on a shop towel and then we can remove the masking tape and give it a final wipe down. |
| 03:21 | It's important to leave the brace mounted to the strut towels so it's held in place while it cures. |
| 03:25 | For this specific adhesive, full cure is relatively slow at 24 hours but this will result in an extremely strong structural bond. |
| 03:34 | After 24 hours we can remove the strut brace and check that it's bonded well. |
| 03:38 | We don't want to purposely damage it but it shouldn't have any chance of moving by hand. |
| 03:43 | With that we're done. |
| 03:44 | We can reinstall the strut brace, torque the strut mounts and admire our work. |
| 03:48 | We've got a completely unique, good looking and high quality strut brace. |
| 03:51 | High performing strut tower brace and just as importantly we've made it ourselves. |
| 03:55 | For those interested the factory strut tower brace from this RX-7 weighed 1.9 kgs and we've almost halved that at just under 1 kg. |
| 04:04 | We haven't gone to the effort to measure their relative stiffness but let's be honest our new brace is much cooler. |
