Opening spanner screw heads cleanly

[JPiettro]

Wait! - I now recall the main reason why I started this thread.
Quite oftten you can clearly see by just looking at the holes of a spanner screw that it was opened at least once. Since the screw metal ia a brass alloy it can easily be deformed if the tool that was used to work on the screw had sharp adges at the points of contact with the screw holes.
To extract the screw 'cleanly' (that notoriuos key word!) the tool pins should fit the holes exactly: should have exact spacing and be completely round and cylindrical and not coned. Actually, if they are coned they will tend to slip out of the holes unless some oppposing force is used to hold them in the holes.
In the last case however the coned surface will somewhat destort the holes but I'm sure that's not a big problem since the cones will contact the holes' inner surface evenly. It's much more important for the tool to have no edges and be of the proper round shape - be it a cone or a cylinder.

 

[aizan]

How are these bits sized - in what steps? What is the spacing of the smallest "fork" available?

the smaller ones come in standard sizes #4, 6, 8, to 14. size #4 is 2.4mm center-to-center.

you can also get them in metric sizes, but the only way i've found to get those is in one of those security bit sets, which bottoms out at 4mm.

if you have the tools, you can make a pin-faced screwdriver. that's what i was looking for to replace the bellows of my fuji gs645, but they're nowhere to be found.

 

[JPiettro]

the smaller ones come in standard sizes #4, 6, 8, to 14. size #4 is 2.4mm center-to-center.
...
that's what i was looking for to replace the bellows of my fuji gs645, but they're nowhere to be found.

Thanks and can't you replicate the bellows? I understand that's possible and manageable as DIY. No?

 

[aizan]

i got a chinese bellows on ebay (which doesn't smell like glue), but i couldn't find a pin-faced screw driver. 🙂

 

[hanskerensky]

For Pinhole Screws make yourself a tool like this :


DIY Pin-face Screw Tool (11) by Hans Kerensky, on Flickr

See for more information this Flickr album :
https://www.flickr.com/photos/29504544@N08/sets/72157630089095178/

 

[Dan Daniel]

I have one of these and although they get the job done, they are very sharp and you can very easily scratch metal.

The photo of the dividers was pulled off of the web and shows a new product. For use you need to grind the tips to a proper shape! You are right, the stock sharp points will make a mess of things.

 

[David Hughes]

Just an aside but I would call the tool needed a peg spanner; like we all had when bicycles came with just one tool that did (after a fashion) everything.


Regards, David

 

[hanskerensky]

Using a "normal" lens spanner for a pinhole screw is a bad idea. The tips are tapered and the chance that a tip will leave the hole and scratch the surface is big. Better to make something like my DIY Pinhole tool.

Here the text at my first image in that album :
The dreaded Pin-face Screw.

Present on many a vintage camera and often in sight so any scratch made on it is painly visible :-(

First choice to remove it would be of course a friction tool. i.e. Something made from rubber.

However, sometimes, like with this screw of a Rollei 35B, there is more force needed then can be transfered by a rubber tool. So what to do next ?

Of course one could get a nice professional and foremost expensive tool from shops like i.e. Microt__ls but now we live in a time of financial crisis and, besides that, i need to save money for a new nice cool MF filmscanner.

In the past i also used fine tipped spanners and compasser needles etcetera etc. but never felt very comfortable about it.
First of all the shape of such a spanner. It's tapered to the point so the bulk of the force while turning will go to the upper outer edge of the pinhole and easily could deform that, more over a turning force will also result in a force upwards out of the pinhole.
Secondly it is hard to apply equal downward force to both points so it could easily happen that one side flips out of the pinhole and makes a nasty scratch on the screw face. Oughh !

So guess only save and cheap option is to make myself a DIY Pin-face Screw Tool 🙂

 

[JPiettro]

I agree with everything you said. How did you manage to allocate the pins at exactly the distance from each other they needed to be? That's 10-s of a mm!

Using a "normal" lens spanner for a pinhole screw is a bad idea.
...

So guess only save and cheap option is to make myself a DIY Pin-face Screw Tool 🙂

 

[Arbitrarium]

Two panel pins and a bit of wood!

 

[David Hughes]

And how do you measure the dia of the holes?

Regards, David

 

[hanskerensky]

I agree with everything you said. How did you manage to allocate the pins at exactly the distance from each other they needed to be? That's 10-s of a mm!

There is always a little play so you do not need to be that exact.

Here is how I took the measurement :

DIY Pin-face Screw Tool (04) by Hans Kerensky, on Flickr

And how it was transferred to the tool :

DIY Pin-face Screw Tool (05) by Hans Kerensky, on Flickr

 

[hanskerensky]

Two panel pins and a bit of wood!

Wood (unless it is tropical hardwood) can split easily. Better to take the plastic handle of a screwdriver.

How I did that :

DIY Pin-face Screw Tool (02) by Hans Kerensky, on Flickr

 

[hanskerensky]

And how do you measure the dia of the holes?

Regards, David

I do not measure that. I bought several sets of cheap Chinese mini-drills ranging from 0.5 till 1.5 mm. Then just pick out the ones that fit best into the pinholes.

Please also note that the end opposite the drilling tip has to go into the pinhole. The drilling tip is much too sharp.



DIY Pin-face Screw Tool (06) by Hans Kerensky, on Flickr

 

[JPiettro]

That's a clever idea. I salute you, master!

 

[pyeh]

Hans Kerensky, I have to say that's pretty genius, the whole method.