When is a tool beyond restoration?
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23 October 2014 at 11:33 pm #120093
I was given an old probably unused Marples dovetail saw in need of severe attention and restoration. I’m wondering if it’s beyond restoration with my limited experience and all sensible advice is welcome.
The plate is rusted through under the handle I need to snap off this section and file back. The handle is cracked where it meets the plate – a good glue should sort that. The screws and buttons are bent and mishaped – dont know what to do.
The most irritating at the moment is I cant get the plate away from the brass back to get started.I tried holding in vice and lifting the brass back but nothing.
Anyone any ideas or is beyond restoration in my hands?
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You must be logged in to view attached files.24 October 2014 at 2:50 am #120102I like to use a product called “Evapo Rust”. It’s a soaking agent so you drop your rusty gear into it and wait for it to be cleaned up. Depending on how rusty the metal is and how long you’ve been using that batch of Evapo Rust (you can use one batch for quite a while) that can be from an hour to over night.
I’m thinking that IF what’s holding that brass back to the steel is the rust from the steel blade then the Evapo Rust might release it. I don’t believe it would have any effect on the brass at all. I had a Bailey plane I couldn’t get the brass depth adjusting knob off so I just dropped the frog in with the knob still on it. The brass didn’t show any problems the next day when I fished it out but the rust was all gone.
I agree with Dave that you’re going to lose an inch or so no matter what you use to remove the rust. I’d take a look and see how pitted the metal is around the teeth. If there’s significant metal loss there then I don’t think you really can bring this saw back to user status.
Just my two cents. Let us know how it goes.
John
John,
I certainly think you can bring the saw back to life.
Plus one on the Evaporust. I’d submerge the whole blade, back and all in the Evaporust overnight,rinse ( don’t forget to save the Evaporust)and scrub off the black residue with a green scrubbie pad and cleanser like BonAmi or such.
Dry.
The best rust penetrant is a mix of ATF (Automatic Transmission Fluid) and Acetone 50/50 by volume. If you can get it, add a couple drops of pure Wintergreen Oil to the mix.
Pour the mix into the hole formed in the blade back at the handle end. This carries some lube into the squeeze point of the back and blade.
Place the blade into your vise up to the back and tighten Tight. Allow about 3/4 to 1 inch of the back to extend beyond the vise jaws and use a hardwood block end grain against the back bottom edge. Give it a sharp blow upward to get the back to release. Once started you can be a bit more gentle it moving the back off the blade.
Once off you can assess whether or not the plate can be salvaged.
If you decide to replace the blade, save the old one as a template for the holes.
There are several tutorials online for doing all this ,Blackburn Tools is one.
There are a couple of sources for saw bolts and plates that I’ve used:
tgiag.com and blackburntools.com
Have fun.
Best,
CraigGiven the scarcity of brass back saws in the U.S. (where I’m from), I’d definitely restore it.
I’d use Liquid Wrench penetrating oil all over and in the spine and let it sit overnight. All penetrating oils are not created equal. Some are essentially useless for severe cases (like WD40). I used to be able to get an industrial penetrating spray called 12-34, that stuff worked like magic. Liquid Wrench is the only readily available stuff I’ve tried that works.
I’d try my best to save the plate with aggressive abrasives (like 80 grit), but if there’s not enough good steel left then I would replace the plate.
The handle looks nice. I’d clean it up, maybe sand it a little, and glue the cracks by thinning down some PVA with water and oozing down in there. I’ve also used small wood cleats on the end grain just ahead of the screws to stabilize cracks which reach that far. Yea you can see it, but it doesn’t look near as hideous as putting a cleat on the side I think.
25 October 2014 at 9:14 pm #120120There is absolutely none of those products available where I live so it was good old elbow grease and WD40 which makes me nauseous.
I cut back the spine by an inch and sprayed WD40 into the spine and around it and left it for a day. I placed the plate in the vice place without clamping and the spine resting on the vice top. Gave it a few mild taps on the plate with my Thorex and it separated. Success! but I didn’t have the courage to separate the two.I scrubbed with 120 sandpaper and more WD40 , there is alot of pitting but worth continuing.
I transferred over the hole diameters and heel edge profile and cut with a hand grinder over a number of passes. There was no heat generated. Drilled out the holes gave the handle a very quick sanding and reassembled.
The tooth profile on the plate is unusual as below – large valley, peak, small valley peak, large valley geometry which is repeated.
Two swipes of a saw file per tooth and a cut test on pine. It works but not perfectly yet. It seems less aggressive than my Veritas 14tpi tennon saw.
Thank you for all your help, I am curious about the saw tooth pattern though.
John
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You must be logged in to view attached files.I think you might need to re tooth that saw. Basically joint the saw teeth flat and recut the teeth to your desired tpi. Paul has a video on YouTube showing how to do this. A good resource for saw filing templates is here http://norsewoodsmith.com/files/file/saw-filing-templates.pdf
I just filed my dovetail saw today and this is what it looks like
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You must be logged in to view attached files.26 October 2014 at 9:38 am #120129That’s a pristine job Dave, well done. What file did you use as a matter of interest?
I do resharpen and set my panels saws and tenon saws with caution but I wouldn’t be confident enough to re-tooth a saw. The teeth cut without breaking so I’m guessing the pitting isn’t really an issue on he cast steel plate. It binds at the handle side as the toothed edge is concave so it definitely needs re-toothing. PS methods are excellent and without him and the WWMC I wouldn’t be able to do any of this.
So it back into storage for this speckled beauty as this is as far as I can take it for now.
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