Metal Work

Re-acquiring my welding skills is proving to be more difficult than I thought.  I figured a few practice welds and I would be back in the groove.  It is not working out that way.  I am making progress, but not as fast as I would like.

Here is the welding setup:

This view shows the tanks.  Well, almost.  The shorter acetylene tank is to the left of the oxygen tank. The stack of boxes in the background is waiting to be flattened and put in the recycle bin.


I had been struggling with cutting the practice coupons.  I tried putting a metal cutting wheel on my trim saw.  That did not work so well.  I think the trim saw simply turns to fast.  I found that the hack saw with a really fine tooth blade works pretty well. I also have a variable speed jig saw.  I put a fine tooth hack saw blade in that, and it works OK, too.  But it really isn't any faster, or any less effort, than the plain ole hack saw.




And then I ran across a tip on the EAA site relating to turning a table saw into a cut-off saw.

So I mounted the cut-off wheel in my ancient Craftsman (actually Rockwell) table saw. This works extremely well.  The board clamped to the miter gauge makes it easier to slit sheet steel.  As an aside, they don't make tools like this old table saw anymore.  At least, not at prices us mere mortals can afford.  It isn't very big.  The  table is 16" X 24".  I have a 5HP motor mounted on it.  The thing is very solid and makes nice cuts.  It takes two strong people to lift it, despite it being rather small. The tilt arbor has no detectable run-out and the gears on the adjustments are smooth with no backlash. Pretty amazing.

Speaking of things that work extremely well:

The little tool mounted in my vice is a simple press brake manufactured (in Canada) by Veritas Tools and marketed by Garrett-Wade.  It is held in the jaws by the tabs on top and strong magnets.

Simply slide in the stock and tighten down on the vice.  This is a piece of 16 gauge and required practically no effort at all.

The finished bend is great.  I was worried that without any adjustments the little brake would produce inappropriate bend radii.  As the photo shows, not at all.  This simple, high quality tool produces very nice bends.  The specs say it can bend up to 1/8".  I'm not sure I am ready to try that in my vice.  But the brake ought to work fine bending small parts out of .090 chrome-moly. And what's to loose for under thirty bucks!

Relearning Welding Session 1

I got the chance to do a bit welding practice last night.  I was hoping that it would be like riding a bicycle.  Not quite.

I managed to create pretty good, though not even puddles.  But the penetration was not good.  I think the material I am using for practice is too thick for the tip I am using.  So I will be getting some thinner material in the next day or two.

A note on the blog...if you are not familiar with the blog format, the latest post is always on top.  Don't neglect to go to "Older Posts" see earlier history. 

Rib Completion

I thank all you faithful readers for your patience while it looked like nothing much was happening.  Between some health issues and dealing with my aging parents not much got done in February.  But the project is back underway!

The ribs are done, done, done!  The final step was getting them varnished.  My EAA tech adviser showed up and we spent a delightful afternoon dip-varnishing the ribs.

They have now been moved up to the hangar.

Here is our hero (Me!  :)  ) with the ribs hanging to dry.  I have enjoyed fabricating the ribs, but I am glad that phase is over and it is time to move on to the next phase.

Which is...fabricating the metal fittings needed to build the wings.  I have acquired welding equipment and will have the welding corner set up very soon.  Then I will need to spend some time re-learning how to weld. 

Though I have received some pressure to consider TIG welding, I am passing on that for the moment.  Not only are good TIG welders expensive, I would have to completely re-wire my shop (garage) space to accommodate a TIG unit with an acceptable duty cycle. There are nice TIG welders that can operate on 110 volts, but their duty cycle is very short.  That would be frustrating when I get to building the fuselage.  In order to get an acceptable duty cycle I would need to purchase something other than a bottom-of-the-line welder ($$$$) and bring 220 volt power into the shop (more $$$$$).

So, at least for the time being, I am sticking with oxy-acetylene.  I have a Victor medium-duty torch for heavier (by aircraft standards) welding, such as cluster welds.  The Victor has a cutting attachment, which I needed.  I also have a Harris "airline" torch for working on the lighter gauge material. There is no cutting attachment available for the Harris torch.  I acquired the Harris torch on eBay for a very reasonable price and it will be ideal for working with the light gauge steel used in aircraft construction  However, the hose and tips had to be special ordered.  They are on their way.

I started off with the idea that I would order the "downstream" accessories for the Harris (hose, tips, tanks, etc.) ala carte.  In view of the need for a cutting torch, it proved less expensive to purchase a complete Victor "kit" and purchase the tips and hose for the Harris separately.  In pulling together the ala carte idea, the cost rapidly ran up to $500.  I was able to purchase a Victor kit that included the torch, cutting attachment, suitable tips, regulators, hose, goggles, and striker for under $300. 

Of course, by time I added tanks, a cart (you have to have a means of securing the tanks upright), acetylene, oxygen and the governor's share the whole bill took a major bite out $1,000.

The table you see in earlier photos is being converted to a welding bench by adding fire brick to the top.  I am also modifying my trim saw into a cut-off saw by replacing the wood cutting blade with an abrasive cut-off disk.  It should work fine and saves the cost of a cut-off saw.

I have a small supply of mild steel which I will cut into "coupons" on which to practice welding.  I will post the joys and sorrows of that task.

Arrangement

I spent some time today re-arranging the shop and getting setup for the varnishing party.

Here is the shop all set up, with a rib hanging from the drying line. 

Trough

February has been a difficult month for progress on the airplane.  Between family, ministry and work obligations there just hasn't been much shop time.

But I did get some time in to prepare the "trough".

The plan is to varnish the ribs by dipping them in the varnish in the above trough.  Some of you may recognize that this is the rib jig turned upside down.  With some modifications.  The rib jig did not have the end pieces.  The near end piece is not installed all the way to the end because spar varnish is expensive and I want the trough to be only as large as it needs to be.

The seams have been sealed with Titebond III.  I used that adhesive because it was handy and it will suffice to do the job.  The lighter patches are Durham's Water Putty covering over places where screws, as part of the rib jig, came all the way through.

Now I just need to find the time to re-arrange the shop and go shopping for the spar varnish. 

Ribs are Finished

Well, perhaps the title is a bit of a stretch. But rib fabrication is complete.  They still need to be varnished in order to be considered "complete".

This photograph illustrates the differences between a "standard" rib and a tip rib. The one in front is the tip rib.

The final tally?  Rib construction required (for me) 136 hours over seven months.  The cost in my cost sheet is a bit misleading.  I show $692.00.  But I have quite a bit of material left over.  Some of it will be useful later in the project, but I definitely over-estimated by maybe 10%, which isn't too bad.

I have a definite feeling of accomplishment.  There is a lot of work in building these ribs.  While it has been fun, it feels good to be done with it. 

Rib Home Stretch - Again

This is what the stack of full cross-section ribs looks like.  The foot-rule is there for scale.  There is something just over 1,000 gussets in this stack.

These have all been inventoried and tied to the drawings.  They are stacked in order with #1 Left on the bottom, then #1 Right and so forth.  One little task I do need to do is go through them all and make sure the tops and bottoms are smooth.  There are incidents where gussets or glue drops are "proud" of the capstrip.

The rib jig has been modified for fabrication of the two tip ribs, one for each wing.  These ribs have a somewhat narrower cross section than all the others.

Yes, I built this jig over the full size drawings supplied with the plans.  I figure this will work just fine for the two ribs.  I wouldn't do that for all the others.  If building wings again (not likely) I would use the same procedures I have used for all of these ribs.

The nose block and tail block are in place ready for the capstrip.

After an afternoon...

Side "A" of the first tip rib is all glued up.  Depending on the weather, Side "A" of the second tip rib and Side "B" of the first one will be glued up tomorrow afternoon.  The weather is a factor, because if good VFR conditions exist, I will go fly the C-150.  :)