Tool advice, please

[Radazz]

I need to pull the base from a Spencer model 13 microscope for restoration.
Can anyone tell me what kind of wrench is used to break loose the nut with two holes in it.
Can I get one?
If I can see a picture of one I can create something like it.
I already have some ideas, but I don’t want to mess up the nut.

Any advice would be most welcome.
Jim

[apochronaut]

It's called a pin spanner. A semi-circular spanner with two pins sticking perpendicularly out of it. Alternately, you could use a couple of pins; finishing nails or small concrete nails with the tips fashioned to a pin shape and clamped in a pair of long nose vice grips at the correct distance. Unless the nut is unusually tight, that will work well.

Pin spanners exist as adjustable versions but you have to be careful to select one with the correct pin size. Some have removeable pins and a selection of sizes to choose from.
https://www.ebay.com/sch/i.html?_nkw=pin+spanner, for the selection there.

[MicroBob]

Sometimes drill shafts come handy when such a nut has to be loosened. Drills are available in finely stepped sizes for little money and the shafts of HSS drills (corrected) are not hardened and have just the right properties.
I have two sets of drills from 1mm to 6mm in 0,1mm steps and use them frequently for tasks like this.

[apochronaut]

Sometimes drill shafts come handy when such a nut has to be loosened. Drills are available in finely stepped sizes for little money and the shafts of HHS drills are not hardened and have just the right properties.
I have two sets of drills from 1mm to 6mm in 0,1mm steps and use them frequently for tasks like this.

HSS drills?

[Radazz]

Thanks all

I had already decided that a flat-jawed, needle-nose vice grips with nails just long enough to fill the holes and not leave any extra to torque might be my best option. Drill bits are an intriguing option.

I just wanted to know if it was a common tool. Sounds like the above will work fine.

Jim

[Hobbyst46]

The most reliable and convenient tool is really a pin spanner. I was surprised: Googled "pin spanner" revealed several varieties in addition to the crescent...adjustable spanners etc.

[MichaelG.]

If you want to build your own ... [tech drawing] springbow Dividers, or [engineer's] internal Calipers, both make an excellent place to start.

Have a look at the 'Car Boot Sales' [UK terminology] for something suitable.

MichaelG.
.
This sort of thing: https://www.zoro.co.uk/shop/measuring-a ... ZT1017589X

[apochronaut]

When those nuts are really tight, there is no way a fabricated tool out of a pair of calipers is going to work. The amount of torque required can be quite significant.

[MichaelG.]

When those nuts are really tight, there is no way a fabricated tool out of a pair of calipers is going to work. The amount of torque required can be quite significant.

Sorry, I don't recall any mention of "really tight".

I'm sure that your knowledge of the Spencer Model 13 is several orders-of-magnitude greater than mine.

MichaelG.

[MicroBob]

Usually one doesn't know how tight it is before trying it.
I have experienced some really difficult to loosen nuts on microscopes.
Drills in a vise or held by pliers work for not so tight nuts.
In some cases the nuts are tight and there is little room too. Here it works best to make a round shaft with holes in the right distance in the flat end to hold the drill shaft pieces.

[MichaelG.]

I need to pull the base from a Spencer model 13 microscope for restoration.
Can anyone tell me what kind of wrench is used to break loose the nut with two holes in it.

For my education, Jim ... If it's not too much trouble; could you please post a picture of that nut, in situ.

Many thanks
MichaelG.

[apochronaut]

When those nuts are really tight, there is no way a fabricated tool out of a pair of calipers is going to work. The amount of torque required can be quite significant.

Sorry, I don't recall any mention of "really tight".

I'm sure that your knowledge of the Spencer Model 13 is several orders-of-magnitude greater than mine.

MichaelG.

The joint nut on any 60+ year old microscope can be unbelievably tight. I have taken quite a few apart in order to restore an acceptable tension and smoothness in the inclination action. I had to heat one once, to get it free. Sometimes they aren't but more often than not they are tight enough, that a flimsy tool will not suffice. There isn't much point in taking the time to fabricate a tool that will only fail under a small amount of duress.

[MichaelG.]

The joint nut on any 60+ year old microscope can be unbelievably tight. I have taken quite a few apart in order to restore an acceptable tension and smoothness in the inclination action. I had to heat one once, to get it free. Sometimes they aren't but more often than not they are tight enough, that a flimsy tool will not suffice. There isn't much point in taking the time to fabricate a tool that will only fail under a small amount of duress.

Thanks for that ^^^
I suspect that we may be thinking at cross-purposes ... The tool that I made about 30years ago from scrap internal calipers is far from flimsy. The pins are inserted through the [shortened] legs, not formed on the ends.
I also made one that's a simple disc of steel with two pins and a square central hole which fits my 'socket set'.

MichaelG.

[MicroBob]

The pins are inserted through the [shortened] legs, not formed on the ends. MichaelG.

A new entry on my to-do list!

[Charles]

There were spanner wrenches made with these scope but are hard to find.

Here are two examples which I have. One side has the pins running horizontal and the other side has the pins running vertical...probably so no matter what position the pin holes were, you could get a good angle to tighten or loosen the nut. If you make replacements, I would suggest a longer handle for more leverage.

Spanner Wrenches2.jpg (25.48 KiB) Viewed 13024 times

The other side:

Spanner Wrenches Other Side2.jpg (26.62 KiB) Viewed 13024 times

And on edge:

[billbillt]

Hi,

I think your easiest fix is the one suggested by apochronaut.... As he says, just be sure the pins are the correct diameter...

BillT

[billbillt]

Sometimes drill shafts come handy when such a nut has to be loosened. Drills are available in finely stepped sizes for little money and the shafts of HHS drills are not hardened and have just the right properties.
I have two sets of drills from 1mm to 6mm in 0,1mm steps and use them frequently for tasks like this.

HSS drills?

The shank part that is chucked on is usually soft... HSS drills are generally made with a "butt welded" process where the shank is soft metal(relative).....

[Radazz]

Holes are ~12.5 mm c to c

[Radazz]

Not too clear, reducing the photo size to attach whacked it
Next chance to get to the hardware store, I’ll pick up the pliers.
Will update upon conclusion.

[Hobbyst46]

If it is the pivot screw nut, the one that serves as axis of rotation, the holes are visible in your photo, when zoomed in.
Yesterday, I had a similar problem with a two-hole nut on a condenser. I turned to a mechanic friend, but he had no pin spanner at hand, so he outs with bent needle nose pliers, which did the job rapidly. It is not on the same level as pin spanner, but if in a hurry, and if (0.001% chance) the nut is not very tight, then perhaps...

[MichaelG.]

Not too clear, reducing the photo size to attach whacked it

That's good enough to see what I wanted to ... thanks.

I hope it goes well for you.

MichaelG.

[desertrat]

Holes are ~12.5 mm c to c

I'm fairly sure the hardware and physical measurements on that stand are in inches, so the hole spacing is probably 0.500 inches, or 12.7mm.

[Radazz]

Drill bits in a pliers did the trick, but I can’t get the bolt out.
Nothing to grab it by but threads, and I’m afraid to try to tap it out.
Oh well, on to the next project.

[Charles]

I believe most of these bolts are tapered. One side is bigger than the other, so it can only come out in one direction.

[Hobbyst46]

A strong magnet to pull it out, perhaps?

[Radazz]

I’ll try penetrating oil or perhaps benzene at a future time.
Rewiring an AO 120. Got it working fine. This is actually a very nice microscope!

[coominya]

I had to remove a small one last week and I used circlip pliers, these are good if the nut or bolt isn't too entrenched, so to speak.

[einman]

I agree with Apochronaut. The spanners are easy to acquire and relatively cheap. I have more than one as I use them to remove watch backs for replacing batteries. The pins come in various sizes and shapes, round, square etc.

[wporter]

Sometimes it's possible to make your own tool, if the commercial ones don't fit or don't work for some reason or another.

I recently had a problem with a partial Balplan chassis that I got cheap, and which had a coarse focus knob that would not turn. Removing the fine focus knob revealed that the locking ring (image #1 & #2, the ring with the two holes in it) was extremely tight. After trying the usual spanner-substitutes (retaining-ring pliers, lense spanners, pins & pliers, etc) to no avail, I was almost convinced that someone had superglued the ring in place. Rather than risk damaging the ring any more, I decided to bite the bullet and fabricate a custom pin spanner. This would also prove useful in tightening up & adjusting the ring after refurbishment of the microscope.

I started with a 5/8" (about 16mm), 1/2"-drive (about 13mm) hex impact socket, and cut off most of the hex-socket part with a 6" (15cm) abrasive cut-off wheel, and drilled two 0.0625" (1/16" or about 1.6mm) diameter holes about 0.30" (~7.6mm) deep, in the end, at a spacing equal to the holes in the microscope locking ring, and cut two pins of 0.625" music (piano) wire about 1/2" (12.6mm) long to fit the holes (a press fit). See image #3.

The microscope locking-ring screws onto a finely-threaded shaft, which protrudes somewhat past the side of the ring, and the bore of this shaft also has the fine-focus threaded shaft protruding about an inch (2+cm), image #2, so it was necessary to cut a narrow bore into the cut-off end of the socket, so that the face of the socket with the pins would lie flush against the locking ring when used. The socket end was also faced off in the lathe at the same time (#4). The pins were driven into the holes with a small hammer. The pin ends were then ground down to about 1/8" (~3mm) long on a grinding wheel (to preserve the hardness of the heat-treated music wire, this step was done slowly, with plenty of dipping in water to keep the metal cool); see the final tool in #5.

In image #6 you can see that the end of the new wrench lies flush against the locking ring. This helps prevent bending of the pins, as most of the stress on the pins is shear, rather than a bending moment; also the socket tool can be pressed against the locking ring without tilting.

#7 shows the pin tool in action. The microscope is laid on its side, locking ring up. The tool pins are placed in the locking ring holes and a socket wrench square drive is inserted in the back end of the socket as it normally would be (mine couldn't be inserted all of the way because of the fine-focus stud, but it could have if I had used a deep-socket instead of a regular-length one, or if I had cut off less of the socket). A rubber strap wrench is wrapped around the coarse focus knob to hold it from rotating (by means of a clockwise counter-torque), and is held by an assistant. The socket wrench is cranked counter-clockwise while pressing firmly downwards (to keep the pin tool engaged) to loosen the locking ring.

It worked like a charm, and though it took a bit of work, was worth it to prevent further damage. It helped to have a lathe and a drill press, etc., but if you don't, often you can get a friend to make it for you. A commercial machine shop would want a fortune. It could conceivably be made with a hand electric drill, embedding the pins into a thick-walled aluminum tube or some kind of iron plumbing fitting, instead of a socket.

[wporter]

Whoops, it wouldn't take all the photos; here's #1 & #2: