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JimH
06-28-2007, 08:12 AM
Ok, I have a 3mm flat head cap screw that won't budge (other two came out fine). It holds a small diameter steel plate on the side of a larger aluminum drum. I have heated the screw as best I can (the large aluminum mass sucks all the heat away), soaked with penetrating oil, tapped on it with a hammer, etc. Does anybody have any other good tricks to try before I drill it?

Thanks,
Jim

A.K. Boomer
06-28-2007, 08:25 AM
Take a chisle and tap in direction of loosening, this works most of the time for me.

mochinist
06-28-2007, 08:27 AM
Sometimes you can budge them loose with a small prick punch, put the prick punch on the outer edge of the screw head and tap it in the direction that loosens it. Drilling it to just remove the flat head so the steel plate can come off will probably be best though, then you will have some screw to grab onto and twist it out.

cmiller231
06-28-2007, 08:30 AM
Any way you can make the alumunium drum cold?If drilling ,i would use a LF drill. Chris

JimH
06-28-2007, 09:09 AM
As the screw is of the hardened variety, I couldn't get a punch or chisel to get a bite on it to try and turn it. I was going to use a small carbide bit to drill a couple small offset holes on th head for that purpose.

The only way to get the drum cold would be to put it in the freezer. Was your thought to get it real cold and then apply heat to the drum to get it to expand faster that the screw?

Jim

JimH
06-28-2007, 09:11 AM
Should have added that I also am considering using a Dremel cutoff disk to cut a screw driver slot in the head.
Jim

A.K. Boomer
06-28-2007, 09:14 AM
I used to have a chisle that I built just for this job, it was for larger bolts, it had a sharp straight edge starter and then a flat blunt stop (it got re-ground for something else) the sharp edge will let the chisle get its grip and the stop keeps the chisle from tearing the side of the head all the way off, it also provides more direct power to turn the screw out ------ This is one of those --- "man i wish I had me a set of them for all different sizes" But I never will...

cmiller231
06-28-2007, 09:26 AM
Jim H I "am thinking that the aluminium will tighten up on the screw with heat and open up with cold.. I had a aluminium block v8 that i could not get three spark plugs out .I waited til winter and they broke loose as they should.How big is this drum?AS far as appling heat ,it would'nt hurt as aluminium and steel can really corode. chris

heavy metal machine
06-28-2007, 09:34 AM
if the flat head screw has a stripped allen socket in it and you already know what the diameter of the screw is...i would just drill the screw head with a dril of the same size as the screw. just becareful not to go beyond the thickness of the screw head. i have done this before. flat head screws tend to lock so tight that you strip the socket or screw drive flat. once you break through the head of the screw and it pops off then you can remove the one part and i would be willing to bet that you can take a pair of pliers and unscrew the portion left in the threaded hole because there is no more torque hold the fastener into place...that is unless the screw threads are rusted together.

ptjw7uk
06-28-2007, 10:49 AM
If the aluminium has corroded then it most probably never undo - drill it and save some trouble. Steel in contact will aluminium usually is no no unless you use some corrosion inhibitor I think they used ENSIS fluid or some such for ally engines.
Peter

Mike W
06-28-2007, 01:05 PM
Mig weld a washer on top of it and then a nut. I have gotten out some small screws loose that way. A 6-32 only needed a washer and than I was able to turn it with visegrips.

Willy
06-28-2007, 01:39 PM
Steel fasteners in aluminum are subject to galvanic corrosion, making removal difficult. If the head or socket of the fastener are still usable, one of the biggest life savers that I have used many times over the years has been an impact driver. Between the downward impact, which helps seat the driver to the fastener, and the twisting torque, it has been effective in the vast majority of cases that I have used one.
As an example, have a look at one in the link below.

http://www.leevalley.com/wood/page.aspx?c=1&cat=1,43411,43417,55987&p=55987

chipmaker4130
06-28-2007, 02:06 PM
Do you have one of those hand-held impact screwdrivers? If you adapt a bit to that, you can do wonders with judicious use of a hammer. If you donít have one, it is worth the $15 many times over for a good one. (I like the Lisle brand)

tattoomike68
06-28-2007, 02:13 PM
sharpen a drill bit left hand, drill a tiny pilot hole then hog the left hand drill into it hard and it should screw right out.

john hobdeclipe
06-28-2007, 02:21 PM
Ditto on the impact screwdriver...Mine has saved the day many times.

Evan
06-28-2007, 05:06 PM
Flush capscrews in aluminum can lock in place so tight that they are not removable with the allen wrench. It isn't corrosion either and can happen immediately on installation if tightened too much. It's cause by galling of the aluminum against the screw and the better the fit and finish of the countersink the worse it is. Drilling it out is the best option because much of the seizing action is in the head area rather than the threads.

heavy metal machine
06-28-2007, 05:53 PM
ditto what evan said...or wait a minute didnt i already say that. :D

although i will agree about the corrosion theory that has been mentioned here. i have seen that before also.

Tin Falcon
06-28-2007, 06:51 PM
Because of what evan said you could put the other ones in to take the pressure off also a carpenters brace as in brace and bit. or a speed handle with pressure pad with an apex in it can help slip out and increase torque.
tin

CCWKen
06-28-2007, 09:03 PM
Forget "tapping" with a hammer. Give it hard whack. This compresses the area under the head and you usually remove them with your fingers. Drilling is the last resort as far as I'm concerned.

I had to remove a broken stud from aluminum engine block last week. I took a cold chisel shaped similar to a pin punch and gave the stud a good whack. I took a Dremel with a worn-down cutoff wheel and cut a slot in the top. The stud came out with a small screwdriver.

rbregn
06-28-2007, 10:16 PM
I would go with welding a nut on it. Zap it and be done with it. Give it a wack with a hammer if it still give you trouble. Welding it Will cause the bolt to expand from the heat, then when it cools it should come right out. On larger ones you can drill down the center of the bolt and fill it up with weld. That will shrink the bolt.:eek:I have removed hundreds of stuck bolts this way. Just don't weld the bolt to the metal beside it!:eek: The only problem I have had with this method is when a customer brought it in after he broke the easy out off in the hole he drilled off center! My opinion is easy outs should be outlawed!

Yankee1
06-28-2007, 10:27 PM
Hello,
I have had that same problem before. The way I got the Allen head socket screw out was as follows. Take a Allen wrench one size larger and cut off the bottom section so that all that remains is the straight shank. Then put a very slight bevel on the edges of one end, just enough so it won't dig in.
Then hammer the Allen wrench into the screw until it bottoms out. Then grasp the Allen wrench shank with a pair of vise grips down close to the screw head and turn. This has worked very well for me many times while working on air rifles.
Chuck

JimH
06-28-2007, 10:40 PM
First off, thanks to everybody for the many suggestions.

I couldn't find a bit to use with my impact driver. So I took a 1/16 carbide end mill and put a dimple to one side of the allen socket. Then took a prick punch and two whacks had it turning and out.

The threads were covered with some kinda thread locker. All six screws had some on the threads, but this one's threads were well covered. Inspecting the threads in the aluminum drum, all were shiny bright, with no sign of corrosion. The countersunk area in the steel disk had some brown tarnish that probably contributed to the removal difficulty.

Jim

speedy
06-28-2007, 11:11 PM
If the aluminium has corroded then it most probably never undo - drill it and save some trouble. Steel in contact will aluminium usually is no no unless you use some corrosion inhibitor I think they used ENSIS fluid or some such for ally engines.Peter

Once again I will suggest Chesterton nickel compound.

A.K. Boomer
06-29-2007, 12:26 AM
Flush capscrews in aluminum can lock in place so tight that they are not removable with the allen wrench. It isn't corrosion either and can happen immediately on installation if tightened too much. It's cause by galling of the aluminum against the screw and the better the fit and finish of the countersink the worse it is. Drilling it out is the best option because much of the seizing action is in the head area rather than the threads.



This is worth repeating, I built these into some of the smaller components on my bike cranks, never knew why they were so difficult to take back apart till now, I would torque them down and then a month later would go to remove and totally spiral the same high quality allen that I used to tighten...

darryl
06-29-2007, 02:45 AM
Well, you got it out, so that's good. I was gong to suggest that if you were to be using the dremel, then why not grind off two sides of the screw head- then pliers or vice grips would be able to grasp what's left.

Evan
06-29-2007, 03:16 AM
Steel in contact with aluminum is not an automatic recipe for corrosion. Corrosion requires an electrolyte, usually water with some ions to conduct electricity. If the assembly is kept dry or lubricated then corrosion is unlikely although over tightening can still pose a problem as stated earlier. The standard Never-seez Regular is suitable for preventing problems and is an appoved product for lubricating steel fasteners in aluminum.

BadDog
06-29-2007, 03:31 AM
Ahh, I love that anti-seize. I've got it in Copper, Aluminum, and some kinda synthetic gunk (I think) that I don't like and really should throw away. Seems like most everything I put together (well, not really, but allot) needs ether loctite to keep it together (re-1/2 the bolts on my Rock Buggy) or anti-seize so I can get it back apart (the other half of the bolts on my Rock Buggy!).

This made me think about a set of tools I made long ago that might help. Long ago when I owned/ran the auto rebuilder shop, I took a random collection of Mac/Snap-On/etc. hex drive sockets (bought "loose" from the used box on the trucks). Some were slightly damaged turn-ins and I got them for pretty near nothing. Anyway, I cut them off so that they were only sticking out a bit more than a typical socket head screw depth. My purpose was to fit in tight quarters and still be able to use a ratchet (ever taken out a SHC in tight quarters 1/6 turn at a time?), preferably air! Combined with a low profile ratchet, sometimes it was just enough. Anyway, if you took a set like that, cut short so it's all either inside the hex driver socket body or inside the SHS, then it might work well enough. Of course you may well shear it with very limited torsion, and you probably wouldn't want to be hand "bumping" it, but just something that crossed my mind.

oldtiffie
06-29-2007, 03:56 AM
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