3D Printed and Carbon Fibre Engine Mounts fit

I’ve created the front engine mount in CAD (another post to follow) and now I need to test the engine height with the mount and the bonnet fitting – it’s no good having a beautiful mount if the engine then doesn’t clear the bonnet. I’ve gone for a trial fit of the mount (several hours of CAD and printing) to be sure it works before I go through the process of moulding and making the CF part. What I wanted to do was put the mount in place (it cradles under the front of the sump and bolts on to the front of the dry-sump). It also needs to curve around the awkward external dry-sump pump which seems to get in the way of everything.

Having fitted it, here are a set of photos that attempt to show the bonnet in place, and the engine having about 30mm of clearance between the top of the engine and the bonnet. One of the other interesting things about doing this is it’s the first time in a couple of years that the car has had any bodywork attached. It’s gone (in my head) from an abstract chassis concept back to something that relates to being a car again.

From a reference point of view, the sump will sit between 115 and 125 mm from the floor, and my suspension is height adjustable so on a track I can lower it a bit more. Right now, I’m safe to go over a house-brick without writing off the engine.

Here you can see the bonnet resting on a clamped large table-mat as a reference line. (Clamped to the top chassis rail). The mat and clamps weren’t strong enough to handle the weight of the bonnet, so I needed another idea. So, what you can see sticking down is a piece of (cut to size) wood that represents the chassis rail height to the floor as a relative position. The table mat is now just sat there without any vertical load – it works well as a reference point.

 

With the bonnet properly propped, this a bit of a scrappy shot down the bonnet. There’s loads of clearance here, and you can see the CF footwell and gearbox.

 

 

 

 

More of the same here and you can make out the 3d printed blanking plates I made.

 

 

 

 

And again – hopefully you can see the oil filler cap at the front a good 30mm below the bonnet.

 

 

 

 

Here it is from the top down. It looks a tiny bit like a car again.

The tub is out of the mould

So, it’s been a while since I posted, but a lot has been achieved, and there are videos below to share the love. So, the tub has been infused, it’s been extracted, the peel ply and infusion mesh have been dragged off the back (that was a sweaty day), it’s been partially fitted and baked.

I’ve got three videos below to show what happened. There’s the infusion setup, followed by the resin going in, and finally the lovely tub once it’s out.

The infusion setup

The actual Infusion going in

The Tub out of the mould – ta-daaaaa

3D Printing improves degassing

So, Degassing is the process of getting all the air out of the mixed resin. This leads to stronger parts with a better cosmetic finish – you aren’t fighting tiny bubbles that appear in the resin, or that start to appear as the resin warms through the exotherm and the gas expands.

It’s simple to do – you put the resin in a chamber – evacuate it and watch the resin bubble up as the air comes out. As the bubbles near the surface, you let a little air in to equalise the pressure, the bubbles subside and you continue until under full vacuum, no bubbles appear.

However, it’s NOT SIMPLE TO DO: I lied. There are subtleties to this, and if you just open the tap carelessly,it’s easy to let the air in too fast and get resin everywhere. Also, you end up shooting air into the resin you were trying to clear of the damn stuff. This is also how you trash a degassing chamber, and they aren’t cheap.

The following youtube video I made illustrates this with water. Read on to see how I fixed this with a simple 3D Printed part.

So, I designed and printed a part that moved the air and vacuum over to where it was needed:

So, using some gum-tape to fix the air-guide in place, I now have a degassing chamber that lets air in without worrying about shooting it back into the resin.

Infusion Stations

So, after scrapping my first CF tub, I decided I needed to improve a lot of things (thanks Vic) before I should commit lots of materials for the next tub. First of all was to improve my vacuum management.

What I wanted to achieve was:

  • Make it much easier to route vacuum where i needed it
  • Be 100% sure that I have no leaks in certain parts of the vacuum chain
  • In my case, I want to be sure that everything from the new vacuum manifold inwards was leak proof
  • Prove everything from the manifold to and including the catch-pot was leak-proof
  • have a solid, reliable catch-pot

 

Firstly, I created a vacuum manifold, printed a bracket and mounted it on to the side of the compressor. The manifold is actually a gas manifold for a caravan gas supply, and I got it new from Ebay for about £30. The manifold itself actually has a non-return valve in each tap assembly, so I had to fettle that. Not a hard job and subject to a different post.

 

 

Next I mounted the catch-pot onto the vacuum tank (or an old compressor I repurposed). This was relatively painless – again I printed a bracket. This time it’s the orange thing under the catch-pot. All it is is something that is curved to the tank on one side, and level on the other. Thus I could mount the catch-pot on the level. I bonded it onto the tank with metal-epoxy, and used double-sided tape to stick the pot to the mount. The tape is monster tape – it’s fearsome stuff won’t let go easily. It will let go if I need it to.

Finally the whole thing was piped up (below) and tested.

Once I had this working, I decided I wanted another bench manifold, and made one out of push-to-fit pneumatic connectors. This means I can put my degassing chamber on the bench and not have to connect it directly to the vacuum pump. There’s little time between degassing and infusing, especially if you have 3kg of resin in a bucket – it’ll start exotherming quite quickly. With my manifold setup, i can hold the part under vacuum whist at the same time degassing the resin. Then I just need to connect the feed line to it and I can go.

 

What you can see here is one branch of the manifold. There’s a t-piece at the bottom, and a valve in the middle. The top is the output. Again, I printed some brackets to give me just the mounting I wanted, and the white bracket in the middle is actually a 15mm hinge-clip for attaching standard poly-pipe when plumbing. They’re £6 for 100, so I bought 100. I have many spares. The top blue bit is the outlet at this part of the manifold. It lets me plug an 8mm pipe straight in to the quick-release connector.

 
This is the final manifold – the picture isn’t great, but you can see three outlets. It’s set on an old tool-board I used which I didn’t need anymore – far better reuse that (considering it was already bonded to the wall).

3D Printed Intake Trumpets

Or ram pipes, or velocity stacks – whatever.

I’ve made these trial pieces. The plan is to have a veritably huge amount of length variations, so when I set my engine up on the rolling road, I can mix and match to get just the variances in length I need. When I say I, I mean Damien from Daytuner, but you know what I mean.

3d prints under the microscope

3D Printing – Can I Get That in Carbon Fibre?

Yes, but only by printing the part, taking a mould, then infusing the part. But hey – this is the future right? Food is blue, Boris is Foreign Secretary, and I can buy things and my watch pays for them.

I’m using a Velleman Vertex bought from The Electronics Shop in Cullercoats, Whitley Bay.

The Target Pieces

image1

Here we have the two target pieces, 60mm  * 40mm * 6mm thick. I was experimenting with quality settings to see what is useable for moulding.

 

 

 

 

Lower Quality Settings (the default)

  • Support Matrix: 10%
  • Wall Thickness 0.7mm
  • Speed (max) 48mm/s

This is the top layer – you can see plenty of holes

0714_1This is the top layer, and you can see plenty of holes – If I was to take a mould off this I’d struggle – it’s an excellent keying surface. I may get away with a lot of brushed on thick PVA release agent, but if I was aiming for fine surface tolerances I’d not get it. Best bet would be to cover with gel-coat, polish then mould.

 

 

0714-2This is the bottom surface, which has a different setting (I don’t remember) but you can see the holes are pretty uniform and it picks up dust a bit.

 

Higher Quality Settings

  • Support Matrix: 20%
  • Wall Thickness 0.1mm
  • Speed (max) 43mm/s

0714-3

This is the top surface with the number of supports in the hollow space doubled, and a thicker shell (1mm) added. If you look closely in the top picture, you can see the cross-hatching that is the support matrix, and the differences between them.

Increasing the shell thickness has also laid down a lot more plastic, making for a virtually sealed surface, but still with some tiny holes.

 

0714-4

 

The Base here isn’t much better – I didn’t make any significant changes to the base, and I don’t think I would – If I design parts that are assemblies, I’d just use the base as my adhesive point. I’d use epoxy as well.

 

 

0714-5

 

This organic looking beauty is a 3mm hole with a 1/2mm counter-sink. I wanted to see what I can do to leave dimples in the part. Dimples are important because I’d have dimples in the final part, which would make for an accurate drilling point if it needs to be demountable (such as the fuel-pump hatch in a petrol tank).

Praise for The Electronics Shop and Velleman

I can’t recommend the team enough here, and Anthony, with whom I dealt. They have the printer in stock, and all the consumables, spares and upgrades as well. I can’t emphasise the quality of service enough with these guys. I had a question about alignments whilst I was building the printer, and got an immediate helpful response. When I tried the printer for the first time, it printed exactly like it was meant to do, like a piece of consumer electronics, not a cutting-edge piece of manufacturing equipment.

3d printed plastic that is petroleum resistant

So, NinjaTek have released a new very hard filament which is petroleum resistant – could be useful for making my composite tank. I still need to understand if the regs require foam filling, or if flap gates are adequate. I could then completely print the pump mounts, flap gates swirl pot, etc.

This comes on the back of this post about making tank bladders.

3D Printing ideas

So, even though I’ve got my Velleman 8400 printer and not assembled it, I’ve been thinking of what to do with it. Needless to say, with 3D printing that started in the community there’s not only a great set of community based CAD packages, but people like Autodesk are in on it as well with TinkerCAD and a quite interesting suite of free apps as well (including using your i-device as a 3D scanner).

I think my first project (I have some 3D experience with CAD anyway) will be to rework my composite fuel tank. I had to junk the original plan – it wasn’t possible to really make a part from the moulds – I had returns greater than 90 degrees on some flanges and that just doesn’t work.

What I’ll do this time is print a framework that bolts together, and bond on to that framework a set of plastic panels. The end result will be a completed tank that can then be moulded from. I’m also going to simplify the design with far fewer faces, but some of the curves (radius curves so the carbon can go in) will be much easier to make more accurately. I think I’ll make two halves that slot into each other much like the top and bottom of a Matryoshka doll.

I will make the panels out of (maybe) 3mm polypropelene sheet. It has great release properties, but then of course, is difficult to bond to the framework. Nothing that a good keying and epoxy won’t fix. I can use other plastics of course, and if I’m a little rough with the cut, then I will fill the gaps with wax. It’s only a tank and not a display item.