Panther Sport Aircraft Forums

Nice write up!
Thanks for sharing

Having just completed the riveting of my spars I thought I'd offer some observations.
Unless you are an experienced riveter expect a bit of a learning curve. Start slowly, observe, think.
What I accomplished I did to my level of satisfaction, to my comfort level. Yours may vary.
I'm NOT an A&P and offer these notes for educational purposes only.
I hope some future builder finds this information useful. Constructive criticism is always welcomed.
From those who have already finished their spars, perhaps they might add their thoughts and comments as well.

The squeezer at the time of this writing does not include a rivet gage. I simply used a dial caliper to check the finished dimension of random rivets. The finished shop head must be 1 1/2 of the rivet's diameter. Avoid over-squeezing rivets. First, one of my spars was hand drilled during the up-drilling phase whereas the other spar was up-drilled using a drill press. Were I to repeat the process I would only recommend using a drill press when drilling the spars. Some few rivets did not sit flush under their factory head against the spars that had been hand drilled. A reamer was the remedy. A properly aligned drill press assures truer holes.

As recommended, be sure to use some blocking around the squeezer to immobilize the unit. Fix the squeezer in place so that it is square with your workbench's edge. I did not enlist a helper during the riveting process and found it helpful to create a wooden bracket to hold the spar upright and to cover a 2x4 block with plastic for the spar to slide upon. Taking time to set up all the parts square, plumb and true to the squeezer pays dividends in reducing the number of rejected rivets. Clinched rivets (misshaped off to one side) happen and need to be replaced. I found out through trial and error that one pump of the press was enough to show if the rivet would squeeze into a properly formed shop head. With a little experience I was able to recognize after one stroke if I needed to back things off and tap the rivet straight or if I could continue squeezing the rivet. Under normal circumstances about 5 1/2 strokes produced a properly squeezed rivet. As the spar thickens inboard I switched from clecos to machine screws and fender washers. These kept assemblies tight through the riveting process.

As I worked along the spar from inboard sections to the outboard section the anvil portion of the squeezer extends further and further from it's base, a large, course threaded nut. This introduced a bit of "loosness" in the anvil which had a negative influence on the shop head formation. I suggest you add a bit of lift to the anvil when firming it up against the rivet to offset any drooping of the anvil. When I paid attention to this detail I was able to repeatedly produce a proper shop head.

When you lift the anvil and set to squeeze the domed rivets in the inboard area of the spar's base you will note it may take as many as 8 strokes to properly form the shop head. This is due to a degree of flexing (spread) of the squeezer's frame. It isn't an issue, just something you need to expect when you are working this area. You will also need to experiment with different combinations of pins and bushings to achieve the right height of the squeezer. Easy enough.

I found it an advantage to always keep the hydraulic ram and set on the far side of the spar and the anvil and pump on the side of the spar next to the builder. That way I could more easily observe the formation of the rivet while applying increasing pressure through each stroke.

Lastly, when switching from domed rivets to countersunk rivets do not neglect to change out your die set. You'll only make that mistake once. Ask me how I know.....
So, these are my observations. Please leave your comments, it's how we collectively improve our knowledge base.