I have a loose plunger tube in a S70 LW Commander. I've ordered the Gun Runner tool from Brownells. I have a replacement plunger tube on the way, but I'm going to try restaking the Colt part first. Gun in question has been NP3'd inside and out; as an FYI, loctite does NOT adhere well to NP3.
I understand the need to bevel/relieve/open up the holes on the inside of the frame prior to staking the plunger tube. I have read mention of a 1/8" carbide Dremel bit as the tool of choice to bevel the holes... but now I start to get cold feet, as in my experience Dremel tools and guns are usually a bad combination. I'm guessing a lower speed motor, like a variable drill, is a good place to start.
Questions about opening the holes:
1) I see no way to get a straight shot into the hole with the bit; it looks like this will result in an inconsistent, out-of-round opening-up of the hole in the frame. Would someone who's done it mind telling me how you got it done?
2) How deep into the frame do you go? Is it an eyeball thing, a "just a little bit" thing?
I would be very reluctant to reach in there with the Dremel.
You need Kuhnhausen's Manuals IMO, some good info there.
You can try restaking it, but I've done that twice to my 70S Super
I would wait for the new tube - it will have longer tenons to work with. After you remove the old tube, it might very well be that the original depressions are deep enough to stake into without any additional metal removal.
I recently bought the same tool and restaked a friends S.A. G.I. with no problems using an EGW plunger tube.I also used blue Loctite but his gun wasnt finished in NP3.And I didnt relieve the holes for the tube as it looked to me there was enough bevel from the factory.I hope this helps.
If a visual inspection suggests that the holes are not sufficiently beveled on the magazine well side of the frame, they can be opened up with a 1/8" round ball cutter. Using a drill rather than a Dremel to reduce the speed is a good idea, although a drill isn't as easy to manipulate. If you deal with Harbor Freight Tools, they offer a little rotary tool for $9.95 that they try to make look like a Dremel. It isn't. It's a 9-volt toy that runs off an a/c adapter/transformer. The speed is more than a drill, but it has no real power so it's VERY difficult to cut too much with it.
You don't go in through the holes from the outside of the frame. You go in through the top of the magazine well and allow the ball cutter to settle into the hole, and then to create a small "dish" wround it.
+1
The ball bit is very forgiving as far as centering the bit over the hole. It can be at quite an angle and center fine. If chattering is a concern then try a diamond burr. I just created a white dot sight with one on a plain serrated front sight and I was able to hold the bit nearly at 90deg to the blade to get the position correctly spotted.
And the light bulb clicks on... I think
So what y'all are telling me - I think - is that it isn't necessary to approach the holes (from the inside, of course) at a steep (straight up and down) angle? I have been thinking of it in terms of operating a drill, and needing to approach it from the standpoint of drilling a hole in something. Instead, since the ball bit is round, you just get the spherical ball to the hole and let its shape do the work? (Am I saying that right?)
That makes much more sense to me - if I'm reading you correctly.
Try a small hand turned pin vise. Mine is made by Stanley and has a chuck like a drill and a handle like a screw driver. It takes more time/effort this way but is worth it.
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Instead, since the ball bit is round, you just get the spherical ball to
the hole and let its shape do the work? (Am I saying that right?)
Correct.
Dremel makes a 1/8 in ball cutter, excellent quality, ACE hardware sells them.
FWIW, Kuhnhausen, Vol II, page 80 shows a reverse countersink & pin vise for chamfering. The countersink's shank is inserted from the inside and then chucked up in the pin vise to do the job. Reverse countersinks are available, but I've never seen one with a cutter or shank with a small enough diameter.
Maybe Kunhausen made his own.
A small ball bur would work except the smallest shanks I've seen (1/8") are too big to fit through the holes in the frame - unless the shank diameter is ground smaller. [Edited: Brain cramp; reducing the shank would get it in the hole, but there would probably be no teeth that close to the center to do the cutting!]
I'm no help at all, am I?
Actually, everyone's been a great help. Seems like a fairly simple thing to do until you come face-to-face with cutting metal out of your holy grail gun. It starts to get real complicated real fast, if you get my drift.
This gun is new to me: Novak tuned, NP3'd... it's the gun I was always going to have built but never got around to. Shoots like a dream. Then after about a week or so in my hand, the plunger popped out. Go figure. The really sad thing is, knowing nothing about it first hand, I think I can probably do a better job than my local 'smith (who has done a not-so-great job on a couple of similar small projects for me in the past.)
This is a really good forum. After joining and browsing for a couple of months I know more about the working of my favorite sidearm platform than I ever thought I'd learn.
If you get Kuhnhausen "The COLT .45 AUTOMATIC". On page 73 is a good explanation as well as a picture.
Does it give any source for the little reverse countersink?
No he shows the procedure using a Dremel. I know what you mean, but can't find a source for the reverse counter sinks. Like you I think he made them, but they might be available in the manufacturing indistry.
The next time my plunger tubes comes loose on the 70S .38, I'm going to put in a new one.
Before my original post, I was trying to figure out how to get the dremel bit inserted from the inside and still get it to cut. Couldn't figure out how to do that... shoulda thought about a reverse countersink on my own, but still wouldn't have a clue were to find it. I'm confident that if I take my time I can get it done with the dremel bit, an overabundance of patience and either a pin vice or slow speed electrical gizmo.
Robert is NP3'ing another tube with longer legs for me, but I'm going to try restaking the original rather than just wait on the replacement.
How does one remove a plunger tube without tearing it up? the front leg still holds pretty well... would running some stiff wire through the tube give me a good way to do that?
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would running some stiff wire through the tube give me a good way to do
that?
Yes, invest in Kuhnhausen Volume 1 you won't regret it.
An 1/8" ball burr will do the trick and you can do it with a Dremel. A Foredom with a foot pedal is better. You can get enough angle for the side of the ball to cut, and you can also use an 1/8" ball on a 3/32" shank, really not a big deal, I do understand the reluctance, you can practice on a piece of metal with a same size hole.
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How does one remove a plunger tube without tearing it up? the front leg
still holds pretty well... would running some stiff wire through the tube
give me a good way to do that?
Kuhnhausen (Vol I, page 73) mentions that method with frame in vise, .70 to .80 wire looped through plunger tube, ends twisted together and pulled off with vise grips.
He mentions this method to avoid marring the frame, but doesn't say whether the plunger tube gets marred in the process.
Where do you get the burs, points (whatever) with 3/32" shanks? All I can seem locate is the 1/8" shanked ones.
Harbor Freight Tools sells an accessory kit with a bunch of very small burrs, buffing wheels, etc., for that hand grinder I mentioned. The ball burrs have very small shanks. The tool itself comes with an assortment, and for the $10 it costs, it's worth having around. Definitely not powerful enough for serious material removal, but the lack of power is an asset for things like making the relief cut for staking plungers and sights, where you really don't want to get too ambitious with the removal.
I buy from CTI which is a manufacture here in SoCal, but Lowes and HD have a pretty good selection of Dremel brand.
Oops - please disregard. Just found some 3/32" jobberdoos in (of all places) my Dremel catalog!
The #7117 would put a nice 45° chamfer on the hole when inserted from inside the mag well after shortening the shank, but it's too big (3/8" dia.) to do the aft hole. Hmm-m-m-m.
Wonder what (if anything) could be used to reshape a diamond coated point? Aaargghh!
Yup, like you said, just practice doing it from the inside with a ball cutter.