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New puzzle (mosquito)

G

Garyt

Well-Known Member
This a pin head (one of 16) that needs to be extracted. My challenge is to design and make an extracter (puller). As you can see the head is quite small with a narrow groove. The steel is not hard as it marks when gripped with pliers. No idea how stuck they are but I expect they have been there since 1944. They may be plane or tapered. They are held in place by a band clip (not in the photo)
I'm looking for suggestions.
Gary
PXL_20250119_022938049.MP~2.jpg
 
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I guess if it was me, I would machine a hole in a steel block with a ring to fit the groove in the pin. Then split it in half with a saw, and put in some screws/bolts to hold it closed around the pin.
THen pull on it with a puller. I might try some heat first to loosen things if they got busy and used loktite on that pin in there.
 
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You can only pull someting that is strong enough to be pulled against what is holding it and by the sounds of it , your pins are soft & weak so, if you have access to the other side I would grind the pin heads off & drive the pins out the other side.
 
Ironman said:
I guess if it was me, I would machine a hole in a steel block with a ring to fit the groove in the pin. Then split it in half with a saw, and put in some screws/bolts to hold it closed around the pin.
THen pull on it with a puller. I might try some heat first to loosen things if they got busy and used loktite on that pin in there.
Click to expand...
+1.

there should be sufficient strength when making a special tool that distributes the pulling force around the entire circumference of the slot which should be greater than 1" from what I see.
 
More details would be useful. If there is any way of tapping it from the other side? I'm 99% guessing not or you wouldn't be asking about a puller. It could be tricky if it was pressed or even lightly tapped (meaning little hammer). The issue can be over time some parts can get rooted together. Either by the good fit, or slight lubrication that has oxidized or turned into modern superglue. Drilling it out is last resort but if the puller doesn't work, say it shears across the circlip groove, then it might go that way.

One thing that might help, seems counterintuitive. Heat the exposed pin head with say 40W iron a few times. Not to expand to assist removal (because expansion is going the wrong anyway). But to cycle heat & works the joint a teeny bit that way. I've used this trick on parts bonded with Loctite or retainer & it works well. But on some I've discovered with no glue, just metal to metal, it also assisted. I'm talking threads here but same issue.

I visualize a micro version of something like this except 'simpler' and machined for purpose. You want the jaws to fit your groove as well and as much as possible. Sliding (adjusting) jaws are not required in fact will probably be too sloppy. & make for unequal pull. I cant find a pic of what I'm looking for but essentially it was a machined inverted cup with the jaw profile in the lip. Then just milled away half the cup so it could slide over the pin & you have 50% of groove contact area. I could draw it if this isn't clear. It might be worth making because I can imagine you will only have one go at it if its really stuck .
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Does the band clip go in the groove that is shown in the picture? If so, this side needs to be pushed on to remove pin. Or is there a clip on each end of the pin? As the Mosquito was very much a wooden bodied plane, much heat may not be of help. Does the pin have room/space to go into on the other end? What is the metal? around the pin? Appears to be a spacer on another metal surface/painted wood?
I will have to go over to look at all the projects again in the near future. A learning experience each time I am there!
Some of the engine design and workings are eye opening.
 
Do you need the pins to be reusable? If not then I would go for the caveman approach and use side cutters to grab and pry them out. This is a very common mechanic technique for removing pins. Or a good pair of vise grips. And if those don't work if you have a tig welder you could weld on a piece of scrap to them as a handle to pull on or pry on. This also has the added benefit of heating the pin to help break it loose. All these have worked for me in similar situations.
 
Machine a tapered collet, one end threaded 5/16” UNC, other end with an internal shoulder that fits the groove on the pin. Cut it in half lengthwise. Machine a mating internal taper sleeve. A nice solid chunk of tubing big enough to make a bracket to pull the collet and sleeve. A chunk of 5/16” threaded rod. Two 5/16” hex nuts and a couple of washers. Lower nut tightens the collet onto the threaded rod and captures the pin, upper nut pulls the pin. Maybe 3/8” or 1/2” rod depending on the dimension you use for the collet.

IMG_0069.jpeg
 
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whydontu said:
Machine a tapered collet, one end threaded 5/16” UNC, other end with an internal shoulder that fits the groove on the pin.
Click to expand...

A man after my heart. I LOVE making custom collets. Do it regularly.

PeterT said:
I could draw it if this isn't clear. It might be worth making because I can imagine you will only have one go at it if its really stuck .
Click to expand...

Is this what you mean Peter?

20250119_153649.jpg

20250119_153808.jpg
 
Who said er collet great idea sadly I was Un able to execute. I did manage to reduce the pin head from 0.250 to 0.240. So I did try. The head is only 0.25 in diameter.
The part is the flap actuator (hydraulic cylinder)
 
whydontu said:
Machine a tapered collet, one end threaded 5/16” UNC, other end with an internal shoulder that fits the groove on the pin. Cut it in half lengthwise. Machine a mating internal taper sleeve. A nice solid chunk of tubing big enough to make a bracket to pull the collet and sleeve. A chunk of 5/16” threaded rod. Two 5/16” hex nuts and a couple of washers. Lower nut tightens the collet onto the threaded rod and captures the pin, upper nut pulls the pin. Maybe 3/8” or 1/2” rod depending on the dimension you use for the collet.

View attachment 58279
Click to expand...
That is close to my imagined tool. But would have to engage te groove.
 
The materials are a steel cylinder with aluminum heads, the pins are about 1/2 inch with the 1/4 inch know on the exposed end.
Anyone wishing to visit the mosquito project should come on a Saturday.
 
For a one of,
My redneck approached would be to take a washer and drill a hole with the appropriate diameter to catch the entire lip. Silver solder that washer to the end of a 3/8" tube 6" long. Bandsaw cut the washer/tube along its length 4" . Pry it open over the pin head, squeeze the tube back together with hose clamp or.......... Snap a vise grip on the other end of the tube and tap, tap tap with a small hammer.
 
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