Monday, 6 October 2014

Catching Up

I have been slowly making progress on the replacement bonnet catch. The last update I had made a mould from the region of bonnet inner where the catch would be mounted - I then proceeded to make a part from this mould which would form the basis of the new plug.

I pressed my CNC machine into service to machine some tooling resin to shape which then had to be ‘let in’ to the fibreglass, the gaps closed off and a good fillet of filler applied to the base to minimise any stress from opening, closing and driving vibration. 

This new plug could then be covered in a plug finishing resin, sanded to a good finish with ever finer grades of wet and dry, before the final step of 6 wax coats as a mould release.

I was then able to make a new mould from this plug which needed minimal finishing before it received its own 6 coats of wax

I was finally able to pull the actual part in the same colour as the bonnet itself – quite a lot of effort to get to this stage!

This replacement piece was then trimmed to size and used to mark up for the far more scary job of trimming my pristine bonnet inner skin to accommodate it. With some careful cutting and sanding I was able to get a reasonable fit between the two parts – almost done!

Since fibreglass is not great at accepting the threads for the bonnet catch mounting screws, I had a metal insert machined (thanks Colin) which would be sandwiched between the upper and lower panels. This was bonded onto the upper skin by screwing it to the new piece then mixing resin and micro balloons (tiny glass beads) to make up an adhesive paste which could then be applied to the insert and the whole thing put in place. Once cured, the adhesive held the insert in place well enough to remove the ‘cap’ and reinforce the joint with resin and fibreglass.

The cap could then be finally installed using more resin and micro balloons paste on the insert and all around the opening in the bonnet skin. Quite hard to describe, but the pictures should explain it! Once this was cured, I ground a small groove along the join line, and applied gel coat to fill it in. This could then be cut back and polished to form an apparently seamless joint.

With the bonnet modification complete, I was able to hinge it to the body and install and adjust the bracket which mounts the other side of the catch. This will be getting a cosmetic cover in due course and I still need to decide on the most appropriate position for the release handle along with routing of the cable, but having this job done clears the way for finally mating the body to the chassis!

1 comment:

  1. This is exactly what I was about to try and find a way to create - but of course 1000 times neater! mind if I steal a little of your genius?