Marty d's CH-701 build log

And, you probably already know all of this, but I'm posting it here because I didn't....and because the spray shop guys assume everyone knows, they don't bother to tell you.

The attached pic, left to right top:

1. 3M full face mask. I wish I had bought this initially, instead of the half mask I did much of my priming in. Very comfortable and easy to work in. Folk assume they will be hot and fog up. They aren't and they don't, as the incoming air comes via the transparent part, flushing it all the time, while the moist outgoing air goes out the bottom of the (inner) mask. Clever. I wear glasses, so copied the glasses mount from their catalog...it's just a bit of #8....and wired a pair of $5 glasses in there permanently. Cleans up completely with prepsol after each use, so vision remains 100%.

The filters have 2 separate parts: the cartridges absorb organic vapours, on the outside of these go separate cloth pads that captures particulates. The outer pads blocks progressively with overspray, good to have some spares.

2. Measuring stick/stirrer. Big clear markings for mixing paint accurately. From paint shop.

3. Haydn masking tape with poly masking sheet attached to edge, in dispenser. The poly unfolds and comes in various widths, I think this one is 1.8metres wide. Perfect for fast accurate complete masking of large areas. From paint shop.

4. Tack cloth. Waxy cloth you wipe down with just before painting, picks up dust. From paint shop.

5. Disposable silicone gloves.

Bottom row:

1. Disposable lightweight microporous suit with zip front. I bought a couple, but one did all the final painting.

2. Paint mixing container. Needs to be more or less flat bottomed and straight sided so your measuring stick works properly. I was lucky to get a sack of these, unused. If using domestic containers, save as many as possible, as it's easier to throw them away after each use.

3. Disposable paint filters. Pour paint through a fresh one of these into the gun to avoid blockages. From paint shop.

You don't need a measuring stick or a stirrer if you get a callibrated paint cup from the paint store. They are clear plastic like a large single use water cup designed for a single use I think but I cleaned them with thinners & re-used them multiple times. They have all of the different ratios printed on the side & come in various sizes & only cost a dollar or less. You can also get 25 of them on Ebay for less that $20.00 but I only used about 5 in 2 sizes for the whole job. The best way to mix 2 pack is with a paint mixer on the end of your cordless drill. The procedure for the Dulux 2 pack paint I used was to pour in the well stirred paint to the level you want then top up with the hardener at the correct ratio marked on the cup. Mechanically stir for minimum of 3 minutes, stand for 10 minutes then remix and use.

Paint viscosity also makes a huge difference to the finish not only the mix ratio s it really is only for the setting mix. You will see in the paint specs they have special viscosity cups you fill up then time how long until it empties. Especially if you are using a low pressure gun which gives the best finish anyway. HLVP guns are ok but you can end up with the paint half drying before it hits the surface the HVLP guns give a better less orange peel finish... also usually used a lot in a base coat then clear system

Back to throttle cables - today I drilled the AN3 bolt that the two cables go through, installed the stop adjusters and cut the outer sleeve to size.

Quite happy with the results - it's got a nice smooth action and the carby springs on both carbs pull back to full throttle.

Full throttle:

Idle:

View of engine with cables on:

At the carb:

One thing I'm still having trouble sorting out, and hopefully someone out there will be able to enlighten me - installing the throttle itself, ie the sleeved push/pull rod between the knob and the crank.

In the photo below of the end of it, you can see that not all of even the inner rod actually goes through the firewall. How do you mount/clamp the outer sleeve so it's held tight? If that groove (see arrow) is where you mount it, that'll be well inside the firewall. Do you build a box structure to hold it?

Thanks!

Thanks to the other thread ("Laying up an aircraft", I think) I thought I should pull my finger out and do something to maintain the engine.

Bolted a "temporary prop" on - (diameter 33", pitch 0 degrees), popped out the top plugs and sprayed some RP-7 in the cylinders. I did have to consult the operator's manual to determine which direction it turned (anti-clockwise from front, apparently), then gave it a couple of turns. Plugged everything back up again.

(Oh, and removed the plank, just in case the kids got into the shed and decided to go turning it the wrong way!)

Finished running the throttle (built a box to hold it in the right spot) and ran the choke cable. Choke needed to be clamped so made up an L angle with a saddle which holds the outer sheath of the cable.

Next I have to crimp both choke pull cables to the push /pull wire - need to buy a 2mm nicopress from somewhere, I only have 3mm ones.

Our computer bit the dust the other day and having trouble posting pics from phone, so will add them when the new one arrives.

It took me a lot of deciding to choose acrylic over 2 pack. The disadvantages of 2 pack are that it kills you and, mainly, it adds about 5 kg more weight. Of course, 2 pack does look better.

For instance, Solagard?

Back to throttle cables - today I drilled the AN3 bolt that the two cables go through, installed the stop adjusters and cut the outer sleeve to size.

Quite happy with the results - it's got a nice smooth action and the carby springs on both carbs pull back to full throttle.

 

Full throttle:

[ATTACH=full]51623[/ATTACH]

 

Idle:

[ATTACH=full]51624[/ATTACH]

 

View of engine with cables on:

[ATTACH=full]51625[/ATTACH]

 

At the carb:

[ATTACH=full]51626[/ATTACH]

 

 

One thing I'm still having trouble sorting out, and hopefully someone out there will be able to enlighten me - installing the throttle itself, ie the sleeved push/pull rod between the knob and the crank.

 

In the photo below of the end of it, you can see that not all of even the inner rod actually goes through the firewall. How do you mount/clamp the outer sleeve so it's held tight? If that groove (see arrow) is where you mount it, that'll be well inside the firewall. Do you build a box structure to hold it?

 

Thanks!

 

[ATTACH=full]51627[/ATTACH]

A bulkhead fitting might have been preferable but this is what holds that type of cable end...

Ath the bottom of page 170 on this PDF

https://drive.google.com/file/d/0B-4b8OLyanGNU0l3Nk51b1FCd3M/view

A bulkhead fitting might have been preferable but this is what holds that type of cable end...

[ATTACH type=full" alt="clamp1.jpg]52117[/ATTACH]

 

 

Ath the bottom of page 170 on this PDF

https://drive.google.com/file/d/0B-4b8OLyanGNU0l3Nk51b1FCd3M/view

I ended up doing a bulkhead fitting - two bits of sheet that together add up to the width of the channel, each with a slot one way so they go on the cable channel from opposite directions which forms a circle tightly around the cable. These are currently clecoed to a box structure on the inside of the firewall which holds the cable firm and in the right position.

Thanks for the PDF though, there's a Flexible Drive outlet locally and it's where I bought my throttle & choke cables and end adjusters, as well as the choke push-pull. They've got some good stuff.

Well, I bit the bullet and pulled the engine off again. I figure I really need to get set up for painting before I do anything else. I'll take off the rudder, HS and undercarriage next, then create a painting booth inside the shed.

Before removing the engine I rigged up a cross-beam between two ceiling joists and made a simple roller out of a bolt going through a tube sleeve. This sits on top of the beam with a heavy aluminium plate hanging either side, joined at the bottom by another bolt which holds all the strap hooks.

This allows me to suspend the engine at the right height to reattach.

Of course with the run on any sort of face mask it'll probably be a while before I can get proper protective equipment, but in the meantime there'll be plenty of study to do about painting.

Had two little helpers assisting with engine removal.

Well, I bit the bullet and pulled the engine off again. I figure I really need to get set up for painting before I do anything else. I'll take off the rudder, HS and undercarriage next, then create a painting booth inside the shed.

 

Before removing the engine I rigged up a cross-beam between two ceiling joists and made a simple roller out of a bolt going through a tube sleeve. This sits on top of the beam with a heavy aluminium plate hanging either side, joined at the bottom by another bolt which holds all the strap hooks.

This allows me to suspend the engine at the right height to reattach.

 

Of course with the run on any sort of face mask it'll probably be a while before I can get proper protective equipment, but in the meantime there'll be plenty of study to do about painting.

 

Had two little helpers assisting with engine removal.

 

 

 

[ATTACH type=full" alt="20200415_172210.jpg]52342[/ATTACH]

Don’t use a crappy dust mask, get yourself a a decent respirator with the correct filters

I doubt that there has been a run on decent respirators with replaceable filters. Bunnings sell 3M paint respirators with replaceable filters and complete cartridges. At $60.00 they are not cheap but work. They are in stock at our local Bunnings.

I doubt that there has been a run on decent respirators with replaceable filters. Bunnings sell 3M paint respirators with replaceable filters and complete cartridges. At $60.00 they are not cheap but work. They are in stock at our local Bunnings.

That was always the plan, I thought everything involving respirators had been bought out though. Obviously not, which is good.

I doubt that there has been a run on decent respirators with replaceable filters. Bunnings sell 3M paint respirators with replaceable filters and complete cartridges. At $60.00 they are not cheap but work. They are in stock at our local Bunnings.

And I'd take that $60 and use it to pay for (part of) a full face mask, 3M 6800 or similar.

Which is what I moved to when I realised the half mask wasn't adequate.

Then, once you have a hooded (disposable) spray suit and gloves, you're pretty well covered

Study up on the paint you propose to use, and utilise the recommended face mask and vapour and skin protection.

If you plan to use 2-pack, polyurethane or any paint with a hardener that contains iso-cyanates - then use an air-wash mask and hood (respirator mask).

The beauty of air-wash or respirator hoods is that they assist greatly in preventing fogging and moisture build-up inside the mask.

I can assure you, if you get a lungful of iso-cyanate paint fumes, you will become very sick for a very long time.

Blokes who have sprayed iso-cyanates without proper breathing and face protection end up with industrial asthma - along with other nasty complaints such as greatly increased sensitivity to paints and paint smells, and allergies associated with paint.

Here's some highly recommended paint-spraying reading ....

https://www.paintandpanel.com.au/article/FDE814F0-7ACB-11E0-BFE9005056B05D57

And I'd take that $60 and use it to pay for (part of) a full face mask, 3M 6800 or similar.

Which is what I moved to when I realised the half mask wasn't adequate.

Then, once you have a hooded (disposable) spray suit and gloves, you're pretty well covered

Got one of these yesterday (yes I was out for a valid purpose too, donating plasma).

https://www.bunnings.com.au/3m-full-face-paint-project-reusable-respirators_p0216399

Also picked up a heap of drop cloths and a zip door to make the booth, plus the spray suit. Then had to come home and tell my wife I just spent $400 +...

Money well spent, Marty. Suggest you source some prepsol. Each time you spray, you'll get paint on the mask, I was surprised at how well and how completely prepsol took it off.

I got into a suiting up/painting/unsuiting routine, and the last thing off the end of that was wiping the mask clean.

Prepsol is good stuff. Do you use tack cloth to wipe for removal of dust particles etc just prior to painting. I use tack cloth and store in plastic bag for reuseing. Cheers and enjoy the painting task, don't race or push on the coat quicker than the schedule.

I'll second onetrack's comments. When I was painting, 2 pack with iso-cyanate required that you use an external air supply and have a head-covering mask with a hose to the air supply.

I knew a guy ( a Jabiru builder ) who did all this but still got ill from the fact that his external air supply compressor was not far enough outside and he got fumes coming through.

I don't regret using the auto acrylic on my Jabiru, but turbs is right in that it does chip easier than 2 pack. For some reason, this is much more so on the metal than the glass bits.

My mate ( the one with the cyanate episode ) reckoned that the 2 pack added 5 kg to the weight, while I reckon that my acrylic added about 1.5 kg. You don't get much weight loss from solvent evaporation with 2 pack.

But his plane did look good. I probably would use 2 pack on a metal plane.

Disassembly - removed HT & elevator (which involved pulling out the trim cable I so carefully ran), rudder, and main gear. She's flying again, suspended from the roof beams by three straps!

In one way it's a bit disheartening to pull apart things that've been put together, but it's been reasonably quick to do so and final assembly when everything is painted will be sweet.

Looks great, Marty, and as you say it'll go together again neatly and easily.

Looking forward to seeing what sort of paint job you settle on.

The first bit I topcoated was the firewall, in an off-white to show up any leaks. Looking at that bit now, it's a terrible bit of painting.....too much air, not enough thinners, so went on far too dry and didn't pull out flat......so I'm very glad it's hidden behind the engine!

Finally made the hatch cover... I had attempted this once before, plans call for a flat piece with a bend at the diagonals for rigidity - trouble is, when you do that the corners lift and I couldn't get it to sit flat.

I contacted Zenith to see if I could change it - the reply was yes, use anything you want, it's not structural.

So this time I simply used a flat piece of 0.016" with the edges bent over 20mm. This gave a nice doubled edge to screw through but still the lightness in the rest of it. Plus the folded edges stiffened it up a bit - I was considering riveting an L angle to the top for rigidity, but it's just as rigid as the rest of the bottom skin when the screws are in, so I'm not going to.

Hi Marty, a quick word on those doors:

My doors have the Lexan polycarbonate, I trimmed the protective film round the edges before fitting it...looks as though you've done the same.

When it came to masking, I then masked with regular masking tape and paper.

When I stripped the masking paper and the Lexan protective coating after spraying, the Lexan was lightly fogged in a blotchy fashion all over. Since the masking was tight, with the original protective coating still under, I can only think this was paint solvent penetrated in some way.

So I bought some sort of McGuires's auto product, and was very relieved to find that I could polish the fogging out.

Another time, I would make enquiries as to how to avoid this. A mate of mine is currently reworking a 185, and they seem to mask with foil, so maybe that's the trick?

(I should note that the Lexan was the same stuff in the same pack as the windscreen and roof, which are installed after painting, and which had no fogging, so I'm confident my Lexan was not 'pre-fogged'.)

Maybe someone here can add to this???

Thanks for the reminder ibob. I have been surprised in the past at how things can penetrate through newspaper.

Hi Bruce. Whatever this was went through the paper...no great surprise there. But it also went through the protective (polythene?) sheet that is on the polycarbonate from the manufacturers, and that you eventually peel off. That I did not expect...................(