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beechboy (Aeronautics) (OP)
10 Sep 07 2:40
hello. does anybody out there know of a comercial tool available that helps remove these? i.e grinds the lockring out while protecting the surrounding structure.
40818 (Aerospace)
10 Sep 07 2:52
Yup, a drill and the right size drill bit!!

Apart from that you could get a hammer and sharp chisel, knock the head off and then with a small punch, pop the tail out. Of course blind rivets are used where you cant get access to, so unless you can get something in to remove the left-overs then you will have some bits rattling around.
beechboy (Aeronautics) (OP)
10 Sep 07 4:42
Have you tried drilling off a cherrymax rivet? And when its used in light structure hammering at it with a chisel distorts the surrounding structure. Normal procedure is to grind the lockring out. But just lately ive seen some very distructive grinding been done by so called experienced engineers.
40818 (Aerospace)
10 Sep 07 7:43
I have taken many cherrys out in my old life on the shop floor. The difficulty comes with the structural set-up. If the joining materials are flimsy, or the rivet material is hard then you can get into trouble. grinding is also an option which i had forgotton about to be honest, (been a while), but i suppose the level of associated damage is in relation to the skill of the engineer. if you could come up with a device that works then you could make some money!!
However, if memory serves, then i think its impossible to remove without any of the aforementioned methods. If there were another method (i.e better) then i'm sure it would be standard practice for use.
One thing you could do is to get yourself some thin gauge titanium/steel and drill a hole into it (slightly bigger than the rivet head), then overlay your strip onto the rivet and you can use it as a sacrificial wear plate, just incase the grinder slips. Make as many strips as you have rivet head diameters.
thruthefence (Aerospace)
10 Sep 07 9:56
Works good unless you have a flush cherrymax. As far as "knocking the heads off" a protruding head cherrymax rivit?
These things have a locked in steel stem.Worst shop practice I can imagine. It sometime takes two men & a bulldog to drive out the stem even after the collar is removed.
giantguy (Aeronautics)
11 Sep 07 5:23
The technique I teach and was taught:
Light structure - carefully drill centre of stem with no 40 cobalt drill approx 0.050" deep. Then with no 30 drill, drill out lock ring to depth of head. 1/8 punch will pop off the head with a flick of the wrist.
Heavy structure - specially ground punch, short tip 1/16 diameter will punch down the stem below the lockring enabling the ring to be flicked out. Then with no 30 drill, drill out lock ring to depth of head. 1/8 punch will pop off the head with a flick of the wrist.

These both assume a 1/8 fastener. For larger fasteners use the corresponding larger drill. Be careful when you pilot drill as sometimes a drill will simply push the stem through once lockring is compromised. You will find this technique usually works for most lockring type blind fasteners such as Huckclinch, Huck & Cherry blind bolts.
dgapilot (Aeronautics)
11 Sep 07 20:47
I use a 3/8" tape sander to sand off the center, then drill and pop off the head. Doesn't work to well for flush though.
sszuch (Mechanical)
15 Sep 07 19:15
When I worked on the shop floor, the common practice for cherry max removal is as giantguy describes. The only difference is, after the stem is drilled past the lock ring, a punch is used to drive out the remaining stem. The rest of the fastener is removed in the same manner as solid rivets. This method works for both button head and counter sink fasteners. Personally, I have never had any difficulties removing the stem after drilling past the lock ring. There shouldn't be anything left holding the stem except friction from the bulbed end in the shank. It is my opinion that "knocking the heads off" like it was a solid aluminum rivet is probably the worst method because it results in damaged holes and parts, especially thin materials. I have seen people grind down the protruding heads with a die grinder and a sanding disk, but this is at the risk of the operator. Many times I've seen careless work that ended up damaging other parts with this method. But then again, any method is subject to the operator's skill level and care.
thruthefence (Aerospace)
16 Sep 07 21:54
First off, I'm not a sheetmetal guy, just a little here & there; from my perspective, the problem is the stem never breaks off totally flush. There, a little "tit" on the fractured stem that allows the drill to "walk" when drilling the lock ring off. Not so bad on a protruding head, when you can grind a little off, but a flush head, very dangerous to the structure.

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