K9 Diaries - Saturday Morning and All is Well

K9's head ready for more glass

K9's head was a bit of a mess, as I'd managed to get runs of resin on the sides and top as well as bits of fibreglass strands stuck on here and there. Fortunately they cleaned off fairly well, but it's something to look out for in the future. I'll have to look over the areas I'm not working on after, and clean off any spillage before it sets.

Front, with dams.

Today I was supposed to crack on with K9's fibreglass, but life conspired against much progress.
I did manage to start preparing the front end of the body shell, which takes longer than you might think, but then had to stop, as the fibre glassing can take 2 or 3 hours, when you take setting time of gel coat and clean-up time etc.

So Sunday morning I managed to get back into the garage and get some glass on.
First you cut out the fibre glass into the sizes you think will best suit what you're going to cover. Then you mix the gel coat apply that and wait 45 minutes. I went for a walk in this time. I've taken to doing a 5 km walk at a brisk pace to try and get into shape, so this was an ideal time. On my return, it was straight on to mixing a batch of resin, applying a coat and starting with the first layer of fibreglass.

Front completed.

Getting into corners is always interesting. On some of the hardest ones on the head I've used chopped strands of fibreglass then applied resin. It can be a bit messy as the strands like to stick to your paint brush. It does seem to be a good way to get into corners though.There was the usual misalignment's and patching.

It's getting quite exciting now, just the sides remaining, which might take less time as there are boundaries to set-up as they are already there. Just a strip along the bottom.


I've not decided how to handle the panel cut-out yet. Perhaps I should set up a boundary of some kind where it'll be cut-out? It seems a waste to cover an area that isn't required.

The same with the monitor aperture, it will take a little extra setting up time, but will save materials.

K9 Diaries - Does My Bum Look Big In This?

After work today, I was eager to get into the garage to see it I can peel the boundary pieces off.
and here is K9's bum, coated in fibreglass :), as you can see the boundary pieces pealed off easily with no problems, so that was quite a relief.

Also K9's head pattern, with one section of the mould attached.



Work stopped for the rest of the evening because we went to see Wyrd Sisters, a play adapted from Terry Prachett's book,  so back to it tomorrow.

I can see these moulds being finished in a few days, but there is still the side panel and control panel to consider. Only five weeks and 1 day remaining until Whooverville 9. If I keep at it I might just make it. As long as there are no disasters along the way.

Debs is telling me that I should splash out on the proper lights/switches on the control panel. I was going to try 3D printing some bezels and using the lenses I'd sourced, I will have to mull it over, but quickly.

K9 Diaries - Trying New Things

As I mentioned before there was a wax on then way off process. This is to build up a layer as part of the mould release, so the fibreglass resin doesn't stick to the pattern.  But this takes several hours as once the wax is applied you have to wait 5 to 10 minutes before polishing off then another 4 layers with 30 minutes in between each layer. And this has to be done for each section where fibreglass is applied.

In an attempt to cut down the time required, I’m trying the release agent recommended by Easy Composites. This is just applied then given a rub over to level any uneven coating. So instead of the hours it takes for wax and the hours it takes for PVA to dry, easylease dries in just 5 minutes Yay.

I've also switched to using putty wax rather than plasticine which is a lot easier to work with. Here I've filled the seems all round, and just need to add some keying features.

I'm a bit nervous about the release agent, as you can't tell that it's there! I don't think I'll have time tonight to finish this section so I started work on the head as well.

Thursday 27th July 2017 and it's gel coat time. I'm really nervous about this release agent, but here we go. Here's the gel coat applied, now wait 45 mins approximately.

And then the glass, it took a lot more resin than I thought as well, I can see another order for resin happening in the near future.

And while I was at it I did a bit on K9's head as well. I has some issues with consolidating the layers.

I've bought these rollers, but they seem to push the fibre glass about rather than squishing the air out, lets just hope It'll turn out alright.

So, only three more sides for the body mould, and three more for the head.

K9 Diaries - New Experiences

K9's Top

Fibreglass, a new experience for me. I've been putting it off for far to long. K9 did need the extra work to get him all smooth so that I could get to this stage, but maybe if it wasn't completely new I would have been a lot quicker.

But here we are. Above, as can be seen is the top, with dams added to act as boundary for the fibre glass.

My First Fibreglass.

K9's mould has to be made in 5 sections as otherwise k9's body shell just wouldn't come out of the mould, due to the recesses.

I'm starting on the top as it's a relatively small straight forward area to do.

As you can see the PVA mould release didn't cover well on the wax, leading me to believe that maybe I could have done without.

Showing dam clean surfaces.

You can also see the keying features, made from plasticine, cut into flat topped pyramids. These are to ensure that the moulds fit together exactly the same as they came apart.

Here is the same with the dams removed. The double sided tape That I attached the dams with left a sticky mess, which took some cleaning off, so I need to look for a better solution to fixing these in  place temporarily.

K9 Diaries - The Return of the Wanderer

K9's body has returned from Manchester, where Matt has been making him sooth and sleek ready for the mould making, and what a lovely job he's made of it.

So much so that it seems a shame to plaster fibreglass all over it. I could almost just add a coat of spray and mount the head and we'd be away.

But no, I must resist the urge to cut corners, and so starting on the top, I'm now doing the old, wax on, and wax off, routine, like a character from the Karate Kid!

This is followed by PVA release agent. Sadly the process didn't go brilliantly, because the spray gun didn't deliver the fine mist I was anticipating, and the PVA tended to pool in blobs rather than leaving a nice, smooth even coating.

So I spread it around as best I could with a cloth and hoped for the best. He he!

K9 Diaries - Accessorise

CAD Assembly of Antenna

Prominent on K9's head are his ears or more accurately his radar dish antenna.  I modelled a frame to mount the 2 mini servos, as well as the collars and clamping bit, to make up an experimental assembly.

I plan to have an Arduino Nano to control the position of the Ears, receiving instructions via I2C instructions from the Raspberry Pi.

The Arduino is going to have several sequences which can be called on, possibly with optional speed settings.

After procuring some mesh and some coat hangers I had a go at silver soldering, which wasn't too bad but could be better.

The results are not the finished article but something that could be pressed into service if time runs short.




Then it was on to the nose laser. I'm not sure how that's going to be mounted yet, but I'm sure it will involve more 3D printing.

I've also devised a tail mechanism and printed some parts but not assembled yet, photos to follow.

K9 Diaries - Filling Time

K9 Traction Unit CAD Model

Alongside the body shell building, there are also the other systems, notably the base with the drive system, I'd done the modelling, so now it was time to export the parts and 3D print them.

The speed of the motors requires a double reduction. The chain output sprocket has to be matched to the same spec of sprocket and chain. The seconds chain will be the old sprockets from Chompalot, from when it had 4 wheel drive. The bits I needed to make on my printer were the interfacing bits, such as between the wheel and sprocket, or between the intermediate sprocket and the shaft. Also holes for the bearing.

After much printing and adjusting and reprinting I finally produced the platform which K9 would sit on. 

Initially I tried using the motor controller I had originally sourced, however it soon proved not to be up to the task, and with a puff of smoke, the decision to buy a 2x32 Sabretooth was made. Once it arrived it was swiftly plumbed in, and worked beautifully.

Also progress was made on the side screen to be driven by a Raspberry Pi. Below is the rear of the assembly showing the Pi mounted on the back of the display. an 8 inch 4:3 ratio LCD HDMI input monitor, again source from eBay.