Michael T.
  • Durham Region Ontario
  • Canada
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Michael T.'s Discussions

Joining flap form blocks

Started Jul 1 0 Replies

Hi guys I’m making my flap form blocksthey are pretty small triangles  ... 250mm long and 35mm on endfor these smaller type blocks do you use screws to join them to form the metal between?..or do it…Continue

Trying to solve a primer mystery

Started this discussion. Last reply by Paul (Buz) Mason Jun 25. 9 Replies

Hey everyoneDoes anyone know where I can buy the brush on water based primer Zenair/Zenith usesI called the factory and they said aircraft spruce sells it, call aircraft spruce and they dont know…Continue

What tool are you using to make flutes in your rib formers?

Started this discussion. Last reply by Michael T. Jun 22. 5 Replies

hi guysive been using a barrel sander to make my flutes on the rib formers. I bought the set at pricess auto(Canadian version of habor freight) but to make each flute I’m using 2 sander drum…Continue

dressing of relief holes

Started this discussion. Last reply by Perry delano Jun 15. 1 Reply

Hi guysI was working on making my rib blankson many of the parts at the corners there is the 1/4 inch relief hole at the bend linesI`ve been filling off the sharp edges with a rat tail file in those…Continue

 

Michael T.'s Page

Latest Activity

Mark Burrows left a comment for Michael T.
"Hey Michael, Thanks! I do still have it. I had to put it on hold for a bit, but will jump back in here shortly. I should be posting more in the near future."
Nov 5
Michael T. posted photos
Jul 6
Michael T. posted a blog post

Ch-640 Items

Posting some pictures of recent work done on the planeRudder ribs and formers for the wings, flaps, ailerons and elevatorSee More
Jul 6
Michael T. posted a discussion

Joining flap form blocks

Hi guys I’m making my flap form blocksthey are pretty small triangles  ... 250mm long and 35mm on endfor these smaller type blocks do you use screws to join them to form the metal between?..or do it like the rudder tip and don’t not use anythingthanks guysmichael in torontoSee More
Jul 1
Michael T. posted a discussion

Trying to solve a primer mystery.....

Hey everyoneDoes anyone know where I can buy the brush on water based primer Zenair/Zenith usesI called the factory and they said aircraft spruce sells it, call aircraft spruce and they dont know what I`m talking aboutthis is the link to the primer page...can anyone point me in the right direction?…See More
Jun 22
Michael T. posted a discussion

What tool are you using to make flutes in your rib formers?

hi guysive been using a barrel sander to make my flutes on the rib formers. I bought the set at pricess auto(Canadian version of habor freight) but to make each flute I’m using 2 sander drum cylinders.. I’m going to have to buy a set of cylinders for every 4 or 5 flutes at this rate..the barrel wears out pretty fast... the tool fits in my drill press... I must be doing something wrong or using the wrong toolim wondering what you guys have used to do this... the tools and the techniquethanksSee More
Jun 18
Michael T. posted a discussion

dressing of relief holes

Hi guysI was working on making my rib blankson many of the parts at the corners there is the 1/4 inch relief hole at the bend linesI`ve been filling off the sharp edges with a rat tail file in those holes. Is that all thats needed?ThanksMichaelSee More
Jun 14
Michael T. posted a discussion

time to be brutal...dont hold back

Hi guysIts been awhile in the making but I just made my first part for my CH-640 and welcome some critiquethe part is the bottom of the rudder, its wavy and has a 1/4 inch bowThe relief hole has a cut in it where I over cut with the snips...So...is this a practice part and I make a new one....orput some crimps in it, file out the cut and move onwhat would you do...do over or keeper?youre not going to hurt my feelings...so tell me how you really feelSee More
Jun 12
Michael Jones left a comment for Michael T.
"Hi Michael, how are progressing with the rudder. I would be interested to learn how you formed the spar. Regards, Michael J."
Jan 17
Michael T. posted discussions
Dec 16, 2017
Michael T. posted discussions
Nov 27, 2017
Michael T. posted a discussion

Zinc Chromate (Cortec) Primer source

Hi guysWas trying to source the zinc chromate primer that is brushed on. . I ve done a search on here and online but not found a link to a source. is it not sold anymore?Ive also seen the brand name cortec talked about, is that a good substitute for the old Zinc Chromate?If so whats a good source for cortec, I could not find it on aircraft Spruce.Thanks guysMichael in TorontoSee More
Nov 22, 2017
Michael T. posted discussions
Nov 17, 2017
Michael T. posted a discussion

Forming aluminum around thin rudder form block

Hi guysI'm doing up my form blocks for the rudder, the top rudder tip block comes to a very thin 3mm at the end.Since its so thin I'm going to make those blocks out of plywood. Hoping that's lends some support.Any tips on shaping a rib around such a thin formThanksMichael in TorontoSee More
Nov 14, 2017
Michael T. posted discussions
Nov 11, 2017
Michael T. posted a discussion

How to put a 1/8 radius ona bending brake

Hi guys.I bought a 40 inch bending brake on sale $179.00 CND from Princess auto(Canadian version of harbor freight)whats interesting about this brake is many others that cost $1000 or more don't let you set the foot/edge back, this one you can move the foot back and forth quite a wide range.Nice looking tool but I want to put a radius on the foot, I can remove the foot to work on it easilyBut do you guys get good results with just a sacrificial scrap on the edge or should I put the radius on…See More
Nov 9, 2017

Profile Information

Aircraft Model
ZODIAC CH 640
Project Status
Just started
Building From
Plans-only
Engine installed (or plan to install)
Lycoming
Building Experience
Have worked on airplanes before
Flying Experience
None

Michael T.'s Photos

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Michael T.'s Blog

Ch-640 Items

Posted on July 6, 2018 at 9:30pm 0 Comments

Posting some pictures of recent work done on the plane

Rudder ribs and formers for the wings, flaps, ailerons and elevator

Comment Wall (26 comments)

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At 11:02pm on November 5, 2018, Mark Burrows said…

Hey Michael,

Thanks! I do still have it. I had to put it on hold for a bit, but will jump back in here shortly. I should be posting more in the near future.

At 2:25pm on January 17, 2018, Michael Jones said…

Hi Michael,

how are progressing with the rudder. I would be interested to learn how you formed the spar.

Regards,

Michael J.

At 2:14pm on November 2, 2017, Scott Stewart said…

Hi Michael,

I do have a materials list for the CH640.  I had to develop the list myself from the plans, because it did not exist when I started in 2008.  Also, I developed my own part layout drawing for the same reason.

I'm happy to share what I have.  Please contact me directly at scott_stewart@keysight.com.

-Scott

At 7:42am on November 2, 2017, Greg Harris said…

Since I haven't seen the CH640 plans, it's tough to know what kind of brake you'll need. Based on my experience with the STOL CH750, I'd strongly advise against building a Dave brake. He built a 601 with it, and it probably worked okay for that. I broke my Dave brake twice trying to form the upper firewall stiffener, which is .063" and 893mm long. I used a metal piano hinge from Home depot, and the rivet failed the first time. I repaired it with solid rivets and the second failure occurred when the piano hinge metal just stretched away. Even if you use a quality stainless steel hinge from the aircraft materials suppliers, I don't believe it will hold. Other builders have had similar experiences. I built mine 8 feet long, and that wasn't long enough to do my tail section spars (each of the 3 tail spares was almost 9 feet long). I have access to a 10' industrial brake with a modified shoe, so that it bends at a 1/8" (3.2mm) radius. I repaired and modified my Dave brake several times before I could do most of the plane, but it's still not the right brake for the job. I can't bent the thicker fuselage channels and the wing trailing edge skins.

You'll definitely want to look through your entire set of plans and determine what the longest bends are in specific thicknesses.  Around 1000mm of .063 will give you a lot of trouble on a Dave brake. If your spars/spar caps (likely in .040) require long bends, you'll need access to a brake that can handle that. Dan Hill has an excellent video series on building a HomebuiltHELP brake (free plans on their site). I'm assuming the CH640 has a lot of similarly formed components as the CH750. If so, you will have a hard time building a single brake that can do everything. The HomebuiltHELP brake (especially as Dan built it), will do probably 99% of the plane, minus the longest bends. 

The Dave brake is easy to build, but if you're going to scratch-build an airplane, building the HomebuiltHELP brake is an excellent project to start with. When my project is done (I only have a few skins and my cabin interior structures to form), I'm scrapping my entire brake. If/when I start building the CH640, I'll build up a brake similar to the HomebuiltHELP brake, but I'll also have a hydraulic press brake. In another thread, one of the builders  said the longest bends in the CH640 are the spar caps in .040, and they're almost 11 feet long (3218mm)! I am almost certain you will not be able to bend those on a Dave brake. Further, the Dave brake has no adjustable set-back, so you can run into trouble with different thicknesses and bending acute angles with it. If you have access to other brakes regularly, then a Dave brake might work for you. I would check out Dan's brake build series before you commit to a brake, though.

Sorry that was so long, but it's a complicated issue, and I'm planning on doing a video that addresses all of this. I get a lot a brake questions, so a brake video would seem prudent.

At 1:54pm on October 30, 2017, Scott Stewart said…

Hi Michael,

When I bought the plans, Zenair included a CD with lots of pictures. They also include a very detailed rudder assembly manual which describes the rudder skin drilling.  Did you get this CD?

The idea is that you should lay out the hole pattern on the rudder skin and drill undersize (3/32") rivet holes in the skin. The rudder skeleton should only have centerlines drawn on the spar and rib flanges. You then lay the skin around the skeleton and line up the pieces so you can see the drawn centerlines through the rivet holes. Once everything is aligned, you match drill the rivet holes into the spar and rib flanges, and then drill all holes to full size.

You use this same technique throughout the build: layout and drill undersize holes in the skins, align to center of ribs/spar, final drill assembly.

I made matching right and left blocks for my wing ribs. Every place I needed a forming block, I made two in order to firmly secure the aluminum. For those pieces, like ribs, where I needed to make left and right, I put fluting notches into both blocks. In single pieces, like the firewall, I put fluting notches into just one.

-Scott

At 2:41pm on October 26, 2017, Scott Stewart said…

Hi Michael,

You will want to make as smooth of a curve through all the points as looks good.  This may require you to offset from the points giving by +/- 1 mm.  The smoothness of the curve is more important than the actual measurements.  The lift performance will not change if the measurements are +/- 2 mm, but the drag will increase if the curve is not smooth.

You will notice on the wing ribs and the curved bulkheads that you will need a little artistry to achieve a good curve, using the numbers provided as only a guide.

-- Scott Stewart

At 2:20pm on October 25, 2017, Scott Stewart said…

Hi Michael,

Do not use the "~305" dimension they call out on your drawings.  350 +/- 20 is what you want.  I used 350 and this is how it looks completed:

Notice the position of the lightening hole relative to the rivet holes on either side.  If you used 305mm, you would overlap the rivet holes.

-Scott

At 2:07pm on October 25, 2017, Scott Stewart said…

Hi Michael,

It looks like Zenair revised the drawing.  On mine they showed "~405". I crossed that out and wrote 350.

For the tight Z-bend, you need to cut two matching pieces of wood to use as the forms.  For example, get two 2x4 pieces that are one foot long.  On each one, cut a 3/8-inch step down the full length into half of the long dimension.  The steps on each piece match together.  You then use a vise to smash the aluminum between the two wood form block.  The aluminum will bend around the wood step.

For smaller steps that needed to make later, I welded together two 1/8-inch steel bars shown here:

The aluminum gets pressed between them to form the bend like this:

At 12:11pm on October 23, 2017, Scott Stewart said…

Hi Michael,

Yes, I am still on the forum.

All in all, my plans build went fairly smoothly.  There were several parts that were dimensioned incorrectly, and I needed to remake them, but there was nothing I could have done differently about wrong dimensions on the plans.  I listed these incorrect dimensions on http://wiki.matronics.com/wiki/index.php/Complete_CH_640_Errata.  Some of the parts they call out are off, like the trim cable is the wrong length.  Also, I had to redesign the flap control a little because Zenith wanted to charge $900 for a $100 linear actuator.

As you progress through the build, keep me updated.  You will need to make or borrow several specialty tools.  For example, I made a series of hole flanging dies for the lightening holes.  You will find that many people are willing to lend out tools like this for serious builders.

Happy building,

Scott

At 1:20pm on October 18, 2017, Greg Harris said…

*continued:

I haven't shown a lot of measuring and drilling in my videos. I haven't done a rudder assembly video either, because HomebuiltHelp did theirs. However, my Horizontal Stabilizer video series shows that my skins were pre-marked and drilled before drilling the skeleton underneath using the method I described. I really recommend just to get going on the rudder components and finish the rudder assembly before starting anything else (you'll need a bending brake, though). It really will teach you most of what you need to build the rest of the plane. Hope that helps!

Cheers,


Greg

 
 
 

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