I have a question on the correct procedure to adopt while bonding fabric to wood with Stewart systems Ekobond.
The instruction steps that came with the product says to first apply the cement to about 12 to 18 inches of wood at a time, then WAIT FOR THE CEMENT TO DRY, and only after that press down the fabric to the dry cement. It also does not say clearly whether to immediately apply cement to the other side of the fabric along the glue line to saturate the weave with glue. In between it says to use the iron at 250 degF to loosen the dried cement so the weaves can sink in.
I tried today that method to glue fabric to some test frames, and was not quite satisfied with how it worked.
I prefer to use the method given in the Max 103 construction manual, ( which probably is for a generic cement and not for Ekobond in particular ) and which is : apply cement to a length f about 12 inches at a time, press down the fabric - Importantly, it does not ask that we wait for the cement to first dry before placing / pressing the fabric on the cemented area. Also it says immediately apply some cement on the reverse side of the fabric to saturate the weave, and press the fabric down to ensure adhesion. This method is simpler.
In the Max 103 generic procedure, the iron is used only to tauten the fabrc to drum-tightness, and plays no role in attaching fabric to cement. In the Stewart method, we need to use an iron at 250 deg to press the weave down into the dried cement - the heat being applied to loosen the cement bed which is already dry.
I hope I have been able to explain the difference clearly (?)
Does anyone who used Ekobond recently have any suggestions or improvements to offer.
I also saw Stewart company's how-to-video on YouTube, which by the way, follows the procedure shown in their directions that came with product.
So my question really is : Is it OK to just apply cement to the wood, as well as both sides of the fabric, all at the same time, as you go along, instead of first allowing the cement bed on the wood to dry ?
I used the Stewart System, but will admit I've not gone back to re-read the instructions or watch the how-to videos.
What I recall is that I applied the glue to the wood, but did pretty long sections if not the whole perimeter of a piece being done. When the glue changes color, blue to green or green to blue (whichever it is) indicating the glue has "dried" it takes on a stickiness very similar to the glue on a post-it note. Fabric can be placed on the structure, pulled up to adjust, and finally when everything looks nice with the fabric snug, no wrinkles etc. it can be "set" in place with the hot iron but only over the glue areas. If I recall correctly that when I applied the top coat over the glue areas, wiping as much of the glue back off the fabric, but not wiping it completely away so that the fabric is completely encapsulated with glue. Then the fabric tightening can be done in steps of increasing heat, being sure to shrink things evenly so as not to warp any structures.
On parts like covering a wing where the ribs are inside the perimeter of the structure but eventually the fabric should be glued to them as well. I avoided gluing the fabric to the ribs until the whole wing's fabric was tightened. I didn't want each bay tightened separately thinking that it might build in stress or side loads on the structure if one bay was tighter than another. I did go over the ribs with the glue then, to saturate the fabric and glue it to the ribs.
This is all just from several years ago and as well as my memory allows. If my described process varies from what has been read in the instructions, or seen in Stewart's videos (covering a Citabria aileron as I recall?), I'd just call Stewart Systems and clear up uncertainties. Perhaps, if my memory is correct, it will reinforce what you think you've taken from instructions or videos but were just unsure.
I hope this helped and apologize if I've only muddied the water or needlessly burned up electrons.
Lynn, thanks for your detailed response. What you did is exactly as per the company's directions.
The reason I asked this question is because I am trying to avoid rib stitching if possible. (Or at best do about 3 or 4 stitches per rib, as an insurance against a catastrophic fabric rip-away ). So it is important I have a proper fabric to wood bond.
Also the technique in the company's instructions seemed a bit counter-intuitive because we seem to be using the tacky dried base-coat merely as a mechanism to hold the fabric in place while setting up, and using the final application of cement on the obverse side to seep into the weave and saturate it. It might work, but it looked more intuitive to also have a liquid base coat to enable weave saturation on the fabric surface facing the wood.
we seem to be using the tacky dried base-coat merely as a mechanism to hold the fabric in place while setting up, and using the final application of cement on the obverse side to seep into the weave and saturate it. It might work, but it looked more intuitive to also have a liquid base coat to enable weave saturation from the fabric surface facing the wood.
I think you summed it up pretty well when you said "using the tacky dried base-coat merely as a mechanism to hold the fabric in place while setting up". It's kind of a "test fitting". The top coat then ties the base coat, fabric and top coat all into one.
The Ecobond dries so quickly trying to position the fabric into wet glue would be pretty intense. I have done that though, on another plane, putting a small patch in place. It worked quite well but I'd hate to try to do an entire wing with that "wet bedding" method.
Now rib stiching, you're opening up a whole new discussion there! The manual says it's not necessary on at least the lighter, small engine models. Some suggest it should be done on all. I didn't rib stich my 1100 and if I were to build another I wouldn't rib stich on it either. Let the disagreement commence.......
Now rib stiching, you're opening up a whole new discussion there! The manual says it's not necessary on at least the lighter, small engine models. Some suggest it should be done on all. I didn't rib stich my 1100 and if I were to build another I wouldn't rib stich on it either. Let the disagreement commence....... Lynn
From what I could make out from the construction manual, rib stitching is an optional step, depending on the builder's comfort level with quality of his fabric to wood bonding.
I am keeping an open mind on whether to do it. It all depends on how strong the covering comes out.
On this issue, I was thinking of tucking the fabric back an extra inch into the wing, so it is bonded to the inside of the outer fabric to provide additional grip at the trailing edge of the wing. I am not sure if it will come out clean or not.
Hi all, I have a question on fabric covering of the wings..
I noticed that after shrinking, the top side fabric seems to rest on the top of the rear spar due to curvature of the wing surface. The fabric is touching the top of the spar all along , except for a couple inches on either side of each rib. The construction manual recommends that only ribs be glued to the fabric, ( besides the leading and trailing edges, of course.)
Is it a good idea to glue the fabric with a touch of fabric cement at this location - on top of rear spar ? I was thinking to apply cement for a length of about 8 inches towards the center of each section of the spar between adjacent ribs.
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