Dimpling

[livendive]

Through trial and error I learned that not all dimple dies are the same. When you receive a Sling kit, it will come with a small (3/32) and big (1/8) dimple die. Simply put, if the die fits in the hole without play, it's the correct die. If the die almost feels like it will fit, measure the die with a caliper to the 100th of a decimal. If the die is oversize by even a little bit, it will likely fail. I'm guessing a little sanding will get it to correct size. I have not had to deal with a 2.5mm pre-drilled hole yet but I would likely drill it to 2.75mm.

When the die is pressed into the pre-drilled hole it will expand hole to a larger diameter but still undersized to the rivet it receives. As outlined in the intro KIA, the dimpled hole "should be cleaned out" with drill bit e.g. If using 3.2mm rivet, clean hole with 3.3mm drill bit.

The 3/32 120º dimple die is not a common die and is hard to find outside of ordering from Sling. A 3/32 100º dimple die will not let pop rivet sit correctly. I spoke to a few aircraft tool suppliers (ATS, Yardstore, Cleveland Tool Supply) and no joy. The next best thing recommended was a pop rivet 3/32 dimpler, which I tested and the quality of the dimple wasn't great.

Sarah's Sling Build blog also goes into detail on similar subject.
https://slingtsi.rueker.com/category/em ... tabilizer/

After spending some time yesterday looking for spares and confirming the 120° 3/32" die is extremely difficult to find, this morning I snapped the head off my small die while trying to grip them with vice grips to grind a side flat. Now I'm a bit confused by the sizing, more specifically the unit conversion. The KAI references 3.2mm and 4.0mm dies, which simple unit conversion would suggest are the same as 1/8" and 5/32", respectively, both of which can be found in 120°. But converting the *initial* hole sizes would suggest 3/32" and 1/8"...is that the disparity? Is the KAI referencing the expanded hole size, post dimpling, while the various websites selling dies size them by the initial hole size?

[Montreal]

That was my confusion too. I believe the hole they are referencing is pre-dimple/riveting, the hole drilled/punched from factory. Some holes will have to upsized to the smallest hole they prep for 3/32 dimple die. When my die failed, I submitted a Slingshot parts request for a defective 3/32 die and it was replaced for free (followup with an email to sling sales - scott@airplanefactory.com). The new one I received was superior in quality to the rusted die I received in kit.

Quote from Sling Technical (made things clear as mud ):
1) Yes, the hole column size is pre-drilled from the factory.
2) The dimple die size corresponds to the rivet diameter. The 3.2mm dimple die should be used for 3.2mm rivets and the 4mm dimple die should be used for the 4mm rivets. The nipple would be slightly smaller than the rivet.

[lutorm]

Supposedly, even dimple dies of the same diameter and angle are not interchangeable, because depending on the material they are intended for, the shape may be slightly different to allow for the "spring back" of the material to make it come out flat when the die is removed. I have no idea how large of a difference this makes in practice, but to be safe I ended up just buying a new die from my Sling distributor when I broke mine.