Advice on restore a cast steel marking gauge
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21 May 2017 at 8:00 am #312141
Hi,
I bought a marking (mortice?) gauge on the flea market. Now I wonder how I should proceed with restauration. After derusting a little bit and applying some linseed oil I could take one of the bars apart. The other one is still sticked to the wooden bar and doesn’t move at all.
Also the pins are very tiny and round. How would you replace them?
I think the cast iron was originally painted black. Would you repaint it or leave it like it is?Thanks for any advice.
Greetings from Germany
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You must be logged in to view attached files.21 May 2017 at 12:13 pm #312146Well the only real option to replace the pins on the iron bars is to carefully grind/file off the remnants of the old ones and weld new pins in place, which is best left for professionals.
As for Painting i would at most paint the Grip and the exposed face of the Pin bars, the reference face and the 3 sides of the bars sliding inside the wood are best left blank and polished to reduce friction.
Regards Philipp
21 May 2017 at 6:48 pm #312147I wouldn’t repaint it, personally. Linseed oil works wonders on slightly corroded steel.
21 May 2017 at 7:24 pm #312148Thanks for the hints.
Welding would be the proper way, but I’m not able to do it.
After cleaning up the bars, I realized, that the pins are attached through a hole somehow. Maybe it would be sufficient to drive a kind of tapered pin through a hole in the bar, and/or solder it.
Yes, I think, I won’t paint it.21 May 2017 at 9:24 pm #312153If it really is cast iron be very very careful with any kinda tapping/hammering, it tends to be somewhat brittle, driving a hardened steel pin through it could break it.
the Original Pins were probably drilled in/through and chances are that they were welded or soldered in place.
If you cant weld yourself then go to a local metalworker and let them do it for you, i highly doubt that welding 2 pins in place would cost much, though if you wanna do it yourself with soldering you should probably file and grind down the old pin till its flush then drill it out to the diameter of the new pins.Paul shows how to replace regular Mortice Pins with Piano Wire in one of his videos.
What about fitting a new Pin (piano wire) into a short length of wood, and glueing that as an extension to the end of the sliding metal bar? The pressure is taken-up by the wooden channel behind the bar (and its new extension) relieving stress on the glue?
I would first try to replace those pins with thick Piano-wire as Paul demonstrates in wood.
If that failed, e.g. the metal bars proved too brittle, then I’d be content having saved the Handle, Adjusters, and Wood. I would then replace the Iron with new bar-stock/square-section Steel or perhaps Brass, and add new Pins to that.- This reply was modified 6 years, 11 months ago by Alan.
25 May 2017 at 9:45 pm #312345Im not sure if there ever was a Video but theres plenty of blog posts like this one that mention the piano wire, just use the search. https://paulsellers.com/2015/10/old-combination-gauges-worth-repairing/
I was beginning to wonder whether I really saw it at all.
It may have been a short aside, something mentioned during one of Paul’s other videos?Anyway, the blog-text covers all we need to know.
Thank-you for that link @kamikazekrieger!maybe a bit late here, but you could carefully grind off the old pins and drill holes as close as possible to the originals. shorten and point the drill bit/ bits and use them as new pins.
keep them short or they’ll break in use. drill the holes a fraction bigger than the new pins and set them in place with a bit of epoxy. A pillar drill would be best for the job,take it handy, with the bits well up in the chuck or they’ll break.Use a centre punch to locate your starting point for the holes.
I thought i heard Paul mention something about using piano wire of a suitable gauge for pins which maybe a better job.
don’t try to weld anything it will mess up the the steel slide and set fire to the timber .
in any case it would be impossible to weld something so smallLikewise, I apologise for coming into this a bit late. Firstly the metal square section holding the pins will be steel, not cast iron. In fact, from the patina on the handle, I think that the handle is also steel and not cast iron. Grind or file the pins back to flush with the square section bar, centre punch them and drill out the old pins, if you have a drill press (or access to one). Drill the holes just slightly undersized for the Piano wire that you wish to fit.
Then either use an inexpensive tapered reamer (small scale modellers use these to open up holes slightly) to sneak up on the diameter of the piano wire and fit it to the hole while there is still an interference fit OR, alternatively, heat up the steel bar, drop the cool piano wire pins in and cool down the steel bar (yes – shrink fit the pins!). Just wear some leather gloves for protection. I know that this sounds difficult but you only have to go up in temperature by 150 degrees C or so for the steel to expand just enough to clamp the pins in place. You could also chill the pins in ice to help maximize the difference in size but they would not stay this cold for long.
The alternative to this shrink fitting is holding the pin and the bar together in a vise and “peening”over the flat end of the pin. Piano wire would not be a good material choice for the pin in this case though (far too hard). You would just have to accept a pin that didn’t keep its edge quite as well. I suspect that you will find that the original pins were not hardened steel either – if you can file them they were just softer steel.
I hope that this helps.
Cheers
Mark -
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