Had a slower weekend this week due to family commitments and couple of cars breaking down. Everything happens in three's so not sure what's next. However, I did decide to tackle the often talked about process of applying Hysol 960. I've read many threads, including Builders Tips and Hints and decided to go with John Pitkin's idea of using syringes. I bought a few capable of holding 100 ml and thought that should be big enough. Well, they were too big as it turns out.
The first bonded rib assembly off the rank was the trimmable tailplane. All ribs were sanded and adjusted in length using conical and cylindrical grinding bits attached to the vertical drill press. The angle on the conical bit proved an excellent way of providing just enough taper on the trimmed LE edge of the ribs to match the angle of the front tube spar. Front and rear tubes were roughed up with 120 grit wet and dry and wiped with isopropyl alcohol after scuff and just prior to adhesive application.
I taped everything off with painter's tape and loaded up the first syringe with about 30 ml for attaching the rib stiffeners - I bonded the rib stiffeners prior to loading the ribs into the assembly. I couldn't believe (a) how much heat is generated by the adhesive during the curing process and (b) how quick this stuff cures. The brew I made got me through bonding the stiffeners I made up but I had about 15 ml left over. I cleaned the syringe (a messy job) and let the bonds set overnight. Next day I located most ribs in place on the assembly, did a mix of about 100 ml thinking this would be about right. Way way too much yet again. Loads of heat generated and the mix seemed to go off even quicker. So the lesson I learned here is, if anything, work out what you think you would need, and then halve it. The photo I've included showing the empty and used syringe gives you an idea of how much I've wasted. From my experience I would say mix no more than 30 to 40 ml at a time, unless you work real fast.
I took JP's advice regarding the syringe outlet nozzle. The standard syringes I bought have about 1/8" diameter opening. I opened it up a bit more (5/32") and the adhesive seemed to flow really well. I got quite a good bead of adhesive, probably about 1/8" surface contact on both the tube and rib. When cured, the painter tape was removed and there was minimal cleanup involved. You have to be careful when positioning the tape adjacent to the bond line because it can actually shield part of the tube from accepting adhesive. So there are a few areas I need to redo.
All in all, not as many hours spent this weekend but I learned heaps about bonding. And as Josh said on his thread, you get better at it the more you do.
About 80 hours total "hands-on" into the build to date.
(I've added a few photos which hopefully give people the idea of what I'm babbling about.)![]()