Sunday, 21 November 2010

Eight (18/11/10 - 21/11/10)

Well a lot has happened since the last update:
  1. Laminating the front and rear components has been abandoned
  2. The original former for the jig has been destroyed
  3. Moved onto the emergency back up design 
Why did I abandon the lamintating? Well for one, the edges after the curve would jut out as seen in the photo:

Even though these parts are excess and would be cut off, they had an effect on the curve which is the vital part, this effect is that they have stretched it out of the radius I need, turning it into a more eclipse segment than a circle. I can't think of a reason for this as the jig disallowed any movement for the plywood and I had enough clamps (both horizontally and vertically) to hold the formers firmly in place:

The middle photo is where I had to rip one of the side parts off to get the laminate out once it dried, this leads on to why the former was destroyed. As there is immense pressure put onto the plywood, some of the glue on it drips out of the side, thus gluing the laminate to the jig, in hindsight I should've removed the side bits completely when doing this, but having learned from heat bending acrylic, it does have a tendency to veer off to one side. For a simple fix I made these side bits removable so that I could just unscrew them and slide the laminate out, but alas this didn't prevent it breaking; having left the plywood dry over night I began removing the clamps and formers, only to find the smaller, original one stuck to the laminate. I pulled it off only to have the plywood, which was glued and nailed, peel off:

For what it's worth the newer former was fine, even though that was to be the last time I laminated.

Before I put the jig behind me, I noticed I didn't have a photo of it and the two formers:

As you can see the plywood was slotted into the trough thus leaving no room to jut out after the curve, so it perplexed me why it did. Although I didn't want all of this hard work and plywood going to waste I used a laminate to create the middle component which has a slight curve either side, although it's so slight it's hard to tell from the photo:

Moving on swiftly to the backup plan. This idea of splines running between segments of the front and rear components came to me once I started laminating. The hinge is my Achilles heel as it was always going to be the most fragile part even though it'd be the part which is most used. Having used Tensol on my earlier tests with acrlyic, finding a strong enough substitute to attach the acrylic tube to the plywood was always going to be a tricky one, in the end I was going to rely on epoxy resin. After little thought I knew that wasn't going to be enough so I thought of having splines between segments of the laminate which had the outline of the rod attached, these would not only be glued to the laminate but also threaded with 1.5 copper rods going into the laminate sgements either side:

The acryic tube would then have its ends glued to the splines and attached to the laminate down its length. Once the laminating didn't work out I had to resort to the idea of just using the splines, with 0.5mm styrene cladding to give the appearance of it being solid, when in fact it's hollow:

This does have two advantages over it being a solid; it's that much lighter and its profile is more accurate. On the downside though; it's that much more fragile and being hollow attaching the tuck-tite locks is going to be a problem.  However as the middle component is solid and segmented by the splines it doesn't suffer from these issues, which is a good thing too as the handle (when it arrives) will be attached via screws.

No comments:

Post a Comment