[project] Nothing To Do With 205's, But Behold!

[M3Evo 0]

Last update of the decade!

 

Just bits of filling where there are some undercuts:

 

 

 

And a massive wodge of filler to to get the line of the plenum part up to where it needs to be. Seems the cardboard had sagged a bit under the weight of the resin and glass. No real biggy, just needed loooots of fibrofil

 

 

 

Happy New Year everybody!

[M3Evo 0]

And a merry new year to all!

 

First little bit of work for the year was to finish off bulking out the massive dip in the plenum.

 

Took an awful lot of filler to do this!

 

 

Lesson learned, make formers for for draping glass fibre over a little bit sturdier!

[gazzamec 0]

gotta say mate I've been following these mini builds over the last year or so and hats off to you, I too make forms and dabble in composites and know how hard it is and how frustrating it gets when you need to keep working on a plug.

 

I find very thin plywood with mdf ribs good for creating smooth radii, added bonus of being very cheap too.

[M3Evo 0]

The thin plywood would've been perfect for making that curved tank! Think that all of the filling and sanding has only really put it all back by a day though. It's good to be actually doing something and seeing progress though!

 

 

Hooray! Smoothing and filling all done on both sides now so it's time to start the flow coating and polishing stage.

 

Hope there's enough wax in this coat to make it set without remaining tacky

 

[oz. 2]

Balsa wood is a good alternative. Fairly cheap too, you can usually find it in model shops.

[M3Evo 0]

Will give ply and/or balsa a go when I come to do the filter enclosure.

 

Thinking about it, the thinner materials would've probably made better parting lines.

 

Although having said that, the thickness of the finished components will eat into the void left by the parting line so might not be that bad after all.

 

The gelcoat with wax in it is taking forever to go off in this weather though, would've liked to have had this finished within a couple of weekends but such is life

 

(Recent updates on the previous page )

Edited January 3, 2010 by M3Evo

[hman205 1]

how it setting now?

[M3Evo 0]

Think the wax was too cold when I did the flow coat so it's still all tacky.

 

No biggy, just have to wait for above 0 temps and try again

[M3Evo 0]

Brrr, still too cold to use the fibreglass at the moment so started spacing the front of the engine forwards today starting with the most complicated part to make, the seal housing spacer.

 

Started off by veeeeeery carefully boring the two doweled holes. The dowels are there to make sure the seals are concentric with the crank and jack shafts. Even broke out the boring head to make sure I could get the holes exactly the right diameter! Already marked and roughed out the basic external shape of the spacer with a hacksaw by this point.

 

 

 

Holes bored, it's time to make sure they're the right size and spacing before getting on with anything else.....luckily they are

 

 

 

And then it's on with cutting the inside of the spacer out with the mill:

 

 

 

 

All that needs doing now is to drill the little holes for the M6 bolts and machine off the bottoms of the legs. Left these over sized so I can get them exactly level with the bottom of the block. Also needs a little bit of a releif around the chain area.

 

 

 

Should get that all done tomorrow and can start making the new jack shaft, water pump and cam pulley spacers

 

Tis a lot of work just to avoid externally mounting an oil pump, but I'm just happier with the pump in the sump where it belongs and being driven by a chain!

[M3Evo 0]

Bit of a mixed bag today.

 

Very pleased to finish off the seal housing spacer complete with a little relief for the oil pump chain and all the holes drilled (do still need to cut the legs back though)

 

 

 

Next up was starting on the jackshaft.

 

Had decided that making a new one was better than extending the old one....for some reason.

 

Ordered up some hard material to make it from which doesn't machine all that nicely:

 

 

 

 

So then spent the rest of the day making a cylindrical grinder:

 

 

 

 

Which has improved things a little....but think I'll just extend the old shaft and be done with it!

[Bonzai 2]

I had the opportunity to photograph the composite repair i've been doing today, don't know if its of any interest to you...

 

Its a curved fairing, 0.750" thick honeycomb and 3 layers of glassfibre each side. The honeycomb had been crushed and thus the skin was delaminated. I'd spent yesterday cutting out the damaged honeycomb and prep'd the repair area by taper sanding for my repair plies. Today i made my honeycomb filler, 2 pieces of resin sheet on the bottom, and expanding foam around the edges, insert the honeycomb section and bagged it up ready to cook.

 

 

My hot bonder controls the heater mat (with 3 thermocouples) at 250^F and the vacuum at 19 inches of mercury

 

 

And 3 hours later, we have one core plug stuck nicely

 

 

If it's still there for me tomorrow i'll be sanding the honeycomb back and then doing the skin repair

[M3Evo 0]

Oooooh, that looks cool!

 

So in that process there, you just bonded new honeycomb into existing laminate?

 

How do you stop air being drawn through the existing laminate, or is that taken care of by the expanding foam?

 

Purely out of interest, how much does a hot bonder cost? Take it that it generates the vacuum and generally controls the whole process?

[Bonzai 2]

Oooooh, that looks cool!

 

So in that process there, you just bonded new honeycomb into existing laminate?

 

How do you stop air being drawn through the existing laminate, or is that taken care of by the expanding foam?

 

Purely out of interest, how much does a hot bonder cost? Take it that it generates the vacuum and generally controls the whole process?

 

Yep, bonded the section of honeycomb onto the internal fairing skin. With 250^ repairs, Boeing set a typical size limit of 12"sq so i was well within limits, bigger than that we can get away with a 200^ repair but it uses something different to the expanding foam, i cant remember what it is now. I guess the laminate and honeycomb is airtight, its not something i've ever considered before! In this instance i did bag up the internal skin of the fairing with a "caul plate" just to keep the profile, but when i replaced the external plies today it wasn't necessary.

 

Dont know how much the hot bonder costs but this is the ones we have, i think we've got 12 of them: http://www.appliedheat.com/150spec.htm I'm guessing they are pretty expensive though! You're right it controls the temperature through ramp up, soak (can be stepped) and cool down, with alarms that can be set if any thermocouple senses its too far off the target. It provides the vacuum and gauges what its at through a sense line, again with alarms if it drops below a set point. Its a very smart bit of kit and makes me look far more clever than i really am

 

So i only took one pic today as there wasn't much too show! I started off by sanding the core plug flush to the fairing keeping the profile. Made my wet layups, laid them ontop of the exposed core and "de-bulked" them, removing any excess resin from them by leaving them under a vacuum of 26"mercury, without heat for a minimum of 6 minutes, which left me with this:

 

 

And then i bagged it up to cook for 220minutes at 200^ and i did have a vacuum of 22inches to start with, which is what Boeing specify, but after 5 minutes it dropped to 21 and i couldnt get it back up again no matter what i tried. It didnt finish cooking by the time i left work so probably one of the boys will de-bag it in the morning, sand it back a little if it needs it and paint it once it passes an NDT inspection. Job done!

[M3Evo 0]

So do you have to put the tacky tape around the whole thing while you debulk?

 

Guessing that if you're using prepregs and only doing say 4ply laminates, you don't need to debulk, is that right?

 

Been thinking about the oven I need to make for curing my bits of prepreg when I finally get around to it.

 

My garage (if the sale of my house eeeeever goes through!) doesn't have any power. No problem I thought, I'll make a generator using something light like the little 1.4 engine from a 205 so it's reasonably manuverable and doesn't need electronics, can do lighting too.

 

Then it occured to me that mounting a generator to the back of the engine that can supply a 3kW oven reliably might be on the dodgy side soooooo, whadda we reckon to mounting a radiator in my oven (there'll be an external rad too on the back of the garage) and also having the option of routing exhaust gas through a heat exchanger in the oven too. That way I'm making use of maybe 50% of the heat available from the engine.

 

 

Anyway, that shaft's not worked!

 

The grinder wasn't really stiff enough so the finish on the shaft ended up being crap and polishing it up would've taken it below size for the bearings.

 

Thought "okay, I'll make an aluminium extension for the shaft, that'll be easy enough" Got the really accurate bit done.....and then realised that it wouldn't fit as where the extension slots over the original shaft is where the seal and housing goes!

 

It's literally just occured to me writing this that the next thing to try is to machine a step in the end of the original shaft, make a steel extension which is a press fit on this step so that the diameter remains constant through the seal.

 

Fingers crossed!

[Bonzai 2]

So do you have to put the tacky tape around the whole thing while you debulk?

 

Guessing that if you're using prepregs and only doing say 4ply laminates, you don't need to debulk, is that right?

 

Yes debulking is carried out under a vacuum, and the tape is there to get an airtight seal. When it comes to pre-preg, im not sure if its necessary because the FG/resin mixture should be spot on? I'll have to double check this week...

[M3Evo 0]

I've read in the tech specs for the prepregs that if you're doing something thick you should debulk once in a while, be interested to hear what you find though. For the 4ply laminates I'll be making it's not going to be necessary I wouldn't have thought.

 

 

This is a bit more like it!

 

Did a little bit of work on the charge cooler pattern, just gave it a gel coat which will be followed by a flow coat during the week. That can then be flatted back and polished which means we're not too far off taking molds from it

 

While that was all curing, went to my folks' house to see if I couldn't sort this shaft out once and for all. Discovered I didn't have quite enough steel to make the extension in one hit, so decided to make it in two parts.

 

First up, turning a step in the shaft:

 

 

 

Think the seal needs to run on a steel part rather than aluminium so then made up a sleeve which is a press fit over the step:

 

 

 

Couldn't be bothered today, but last thing to do is make up an aluminium spacer which gets pressed into this sleeve and which has a hole in it to take the dowel for the little pulley. It's probably not strictly necessary, but might as well put it in.

 

Feel like I've finally made some progress on this shaft now!

[Bonzai 2]

I checked the manual tonight and there is no mention of debulking for pre-preg repairs (atleast not the ones i do upto 250^F), but i cant see there would be any harm in doing so, it just comes down to how much time you have then.

[M3Evo 0]

Guess if the repairs are only a few plies thick they wouldn't need it.

 

Certinaly for whatever I do it won't be necessary!

 

Don't suppose your magical boxes of tricks there ever get replaced and the old ones sold off cheap do they?

 

 

Been working on my last ever private project this weekend and have finally managed to finish it off!

 

Here it is, in all it's glory:

 

 

So with that all done, spent a couple of hours tinkering with the jack shaft (there are a million jokes to be made there!)

 

All that needed doing really was making a little top hat bit that's got holes in the right place:

 

 

 

And then pressing it into place, making sure that the holes for the dowel line through!

 

 

So that's the spacer for the seal housing, crank pulley and jackshaft all done.

 

Next up is getting the cam pulley spacer made and also coming up with some way of making the cam adjustable

 

Also on the cards for the near future are getting some molds from the charge cooler pattern (it's a bit cold again at the moment to be using the fibreglass) and also making new vacuum capsules.

 

Used diaphragms from Stromberg CD175 carbs last time so the capsules ended up being massive, ugly and slow......but powerful. Have revised them to CD150 diaphragms and am planned to machine a die which lets me make some nice and shiny carbon capsules

[cybernck 402 1 Cars]

The plenum is beautiful... though a bit too close to the brake servo?

[M3Evo 0]

It's just kinda resting in there at the moment, (you can just about see a bit of pipe holding it up at the front )

 

Might recommend that the guy installs a little neoprene packer on the servo to be sure though

[M3Evo 0]

Minor update, have been sanding back the charge cooler pattern over the last weekend. It's taking AAAAAGES! LOL

 

Think it'll need spraying too before I can take molds from it which I'd hoped to be able to avoid doing.

 

In other news, not content with just getting on with the car as it is, I've started looking into making something else for it......now can anyone guess what?

[welshpug 1,657]

carbon bonnet?

[M3Evo 0]

Got one of those on the list already, along with doors, front wings, sunroof and boot lid.

 

Nope, for once my new idea doesn't involve carbon fibre!

 

It's castings this time

[Bonzai 2]

wheels?

[M3Evo 0]

bingo!

 

Just wheel centres as I've already got the rims, but I wanna adjust the front offset and make the rears look uuuuuber deep