Hot dimple machine. 1

[RoarkS]

(See attached images)

So I saved this thing from the scrap yard last week. Still trying to figure out what I'm going to do with it.

-Does anyone have a manual for the various dimple tooling bits? I'm only used to CP214 3/16" shank dimple and squeezer sets. I'm not familiar with what's installed on it right now.
-I'm pretty sure I'm missing the actual "hot dimple" attachments. Going to look for them today inside the control box(lots of stuff was in there).

Why I really posted here. Okay what actually has to be "hot" dimpled and where is a process spec?
I've seen an FAA question regarding magnesium sheet. I don't think the military guys I got it from were working magnesium... Ti? 7XXX or 8XXX?

Keep it? Let it go to the scrap yard?

 

[rb1957]

looking at the warning placards, I suspect that the tool heats the s/metal (prior to dimpling) so that it is more flexible, pliable.

Be careful heating Mg !!

another day in paradise, or is paradise one day closer ?

 

[berkshire]

This may help, check out page 7.

https://mmptdpublic.jsc.nasa.gov/prc/MIL-STD-403C.pdf.

B.E.

You are judged not by what you know, but by what you can do.

 

[RoarkS]

@Berkshire
There it is!
Thank you sir. Much appreciated.

 

[WKTaylor]

Just saying...

I would be astonished if You could find magnesium alloy sheet that would require hot dimple. It is scarce due to low demand and poor corrosion durability... even properly finished.

Likewise, dimpling of all thin sheet/sub layers [any alloy] after pilot drilling is terribly tedious/high attention work. When I worked at Fairchild Swearingen, many aft/forward fuselage skins and stiffeners were hand match-drilled and then tediously separated and then dimpled one layer at a time [for double dimples]... then re-assembled, final-drilled and then double-dimple flush riveted with aluminum solid rivets.

The 'nominal' cost-effective design procedures 'now' are to design for high strength thick[er] sheet that has a slight weight increase... or have milled/chem-milled pockets for weight reduction... and then fastening is ONLY along the thick lands by drilling/countersinking-for, an then installing, reduced head-height flush head fasteners [100-deg or 120-deg angles].

Another trick for 'low drag and thin skins' is to install very low head-height Cherry 'Unisink' [IE NAS9306 'flange-dome heads'] blind rivets. The rivet needs just a tiny/shallow Csk and most of the shallow protruding head rides above flush.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[RoarkS]

WKTaylor,

Huh... Wonder if I ever ran into you in San Antonio. I didn't do much there until after Elbit.

Honestly I live mostly in the GA and repair world anymore. Pretty much every Beech V tail has mag control surfaces. There's an open bounty on anyone who can replace them with something else.

Good to know about current standard. I have to say all this chem-milled stuff is nuts to me. Was just at Gulfstream in Savannah about 3 weeks ago... I was shocked. Only other time I had run into it was on the tail of a Bell 407.

 

[Sparweb]

I could go out on a limb and guess that hot-dimpling was a thing until chem-milling became the preferred method of assembly to get CSK rivets in without knife-edge. After that it was obsolete.

I recall getting stuck in a design "corner" with a repair long ago, and had to resort to cold-dimpling to solve the problem. I think I made use of very old OEM fastener test data to make any claim about joint strength, which probably omitted any consideration of fatigue. I don't think I'd do that again. Even in that case, a hot-dimpler wouldn't have helped because the sheet needing the dimple was the skin, and we were trying to to remove it for the sake of the repair.

Stepping away from the type-certified part of aviation, now...
You might find a taker among the homebuilt crowd. The Van's RVs and other sheet-metal airframes are still popular so maybe one of these builders would be interested in this tool.