Ohio Tool Plough Plane Rehab #1
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17 February 2015 at 6:16 pm #124760
Hello all. In December, I bought an old Ohio Tool Co. screw-arm plough plane (unfortunately with only one 1/2″ iron), thinking that it was a great find. But I didn’t look it over carefully enough initially. When I had some more time, I disassembled it and found several problems that I’d like to get some input on. This first post will be about the screw arms.
When I first got it, the fence was all the way in towards the body, hiding the threads that were damaged. The second picture shows the damaged threads on the front screw arm, but both arms are similarly affected. There is about an inch (25 mm) where the threads are completely missing. The four nuts are in pretty good shape. The thread size is unusual – no standard size that I know of. Approx., but not exactly, 7.5 threads per inch and maximum thread diameter of just over 13/16″ (caliper measures 53/64″). I don’t think this fits a metric size either.
So question #1 is: can the threads be fixed? Some searching indicated that you can build up the arm diameter using some kind of plastic or epoxy and then re-cut the threads, but I’m not sure I can pull that off.
Another solution might be to add a thick spacer to the fence and avoid having to use those damaged threads.
I’ve also been experimenting (limited success so far) with making my own threaded rod to replace the existing one.
And then there’s the possibility of scrapping the screw arms and converting the plane to a wedged-arm plane.
Any input on how to deal with this would be greatly appreciated.
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You must be logged in to view attached files.17 February 2015 at 6:44 pm #124764That’s too bad. I can’t think of anything to fix that screw section without major surgery, particularly if you can’t match the threads.
You could cut out the damaged sections, dowel and glue the good threads back onto the blocks if you want to use the existing rods but avoid the damaged sections. Your spacer idea is probably easier, though.
Maybe you can make a mold of the existing screw and cast a replacement set of screws to dowel into the blocks that would match the existing threads.
17 February 2015 at 7:57 pm #124766@delong1974 Hey Derek. Thanks for the reply.
I hadn’t thought of cutting out the damaged threads. But you’re right, it might be easier to put a spacer on the fence. I’d worry about getting the alignment right if I doweled the screw back onto the block.
I have seen some videos about cutting wooden threads. I may try more of that, but that would be a longer term solution.
17 February 2015 at 8:16 pm #124767There is a joinery plane tune up video out. I think by Bill Anderson. He talks about patching bad threads. Its time consuming but can be done. You plane may be an extreme case. I have a wedge arm plough, it may not lock as tight but I don’t have to deal with bad threads.
17 February 2015 at 9:37 pm #124782yea. Or you can see it through the popular woodworking shop class website. He just mentions how to fix the screws. It isn’t shown. I did the month access online thing. I saw it that way.
Though I cannot provide a link. Not so long ago I cam across a vidio, where the bloke basicly made a boarder around a good section of the screw. Then applyed a ? substance, to form a mould.filled that with another substance, then after making it to fit the damaged part of the screw.It worked. Appologies for not recalling better details. Cheers Peter
Is it an option to replace the threaded rods entirely?
You’d just need a screw box and matching tap.
There are some Roy Underhill videos where he shows that.
You’d probably have to replace the nuts as you won’t find the right size screw box anyway.At least the plane will be in good shape for a very long time.
Diego
18 February 2015 at 3:50 pm #124802Perhaps you could use the existing nuts to mark rods for cutting the threads. Wind it on a bit, check for bruising, and relieve those areas? That way you can keep the nuts and keep the restoration in as original condition as possible.
Alternatively, if you can measure the TPI, you can mark out the threads with paper. Once marked, fit a depth stop to a saw at about the right depth, and saw around the lines. Once you’re started it should track ok (I would think). Then pare down to your saw line from approximately the middle, and once you get close, test it with the existing nuts, making relief cuts where necessary. Realistically, that sort of approach is probably a whole lot easier than messing around with thread cutters and such. Afterall, you already have the nuts, and they’re the hardest parts to make.
18 February 2015 at 10:18 pm #124823@roofusson
I’ve heard of that, but not seen the video. He made a “dam” around the damaged thread section and filled the dam with some kind of plastic or epoxy. Then he cut new threads in that section. I think that is a little beyond what I’m capable of, unfortunately.
@alien8
There are some issues with making new screw arms. I’d really love to use the originals, and if it’s not possible I’d like to try to make a new screw arm with the same thread. That way I could use the original nuts. I’ve experimented with making a threaded rod from maple (with mild success), but I need to work more on that. I’ve seen Roy’s show on making a screw box and I may get more into that and try it.
@mooncabbage
Hey Moon. Using paper with lines and cutting to depth with a saw is the method I used with the maple. I need to try that again, being much more patient and accurate. I have to make the 13/16″ rod from square stock without a lathe, which I’ve gotten reasonably good at. But to replace the whole screw arm, I have to leave a rectangular pad on one end that gets attached to the fence with a screw. That will make it a bit more challenging to make the threaded rod.Thanks for the input, all. I’ll keep working on it. Might be a while …
30 March 2015 at 12:25 am #126085Update:
To “fix” the damaged threads on the screw-arm plough plane, I decided to use Derek’s (@delong1974) suggestion and cut out he bad section on each arm and dowel them back together. It worked great – I just had to rig up a guide to drill as straight as I could. The screw arms are about an inch and 3/8ths shorter now, but I can live with that. Not sure if I’d ever need to cut a groove so far away from an edge anyway. Thanks to all for the input.I experimented with making a screw box and tap to make new threaded rods, with limited success (read, poor results).
The first picture shows the bad threads cut off and holes drilled in the new mating ends. Second picture shows the dowel to be glued in. The last picture shows some work I had to do before this – one of the pads that attach the screw arm to the fence was broken and had to be re-glued. I used polyurethane glue (Gorilla glue) because of it’s expansion and gap filling properties since this was an old break and I did not prepare the mating surfaces before gluing.
Coming soon: Ohio Tool Plough Plane Rehab #2 – fixing stripped screw holes.
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You must be logged in to view attached files.30 March 2015 at 2:14 am #126090Nice job, Matt! Glad it worked out. Did you drill that dowel out by hand without a drill press? I’d be sweating bullets.
30 March 2015 at 4:54 am #126092@delong1974 I was sweating bullets the whole time – sawing, drilling, glueing. I wish I had a drill press for that (I have one, but it’s in storage). Here’s what I did. First I marked the center of the rod, using dividers to gauge from the sides to get close. With two sticks about 3/4″ wide x 1/8″ thick and longer than my screw arm, I clamped the screw between the two sticks in my vise so that the sticks extended about two inches past the end that I was drilling. I then added another stick, holding it by hand over the top of the stick-rod-stick sandwich, giving me three extensions to guide the drill. The first one came out perfect on both mating pieces. The second one I had a little problem on the pad end, so I elongated the hole and was able to straighten it out while gluing. I used 3/8″ dowels. We’ll see if it stands the test of time.
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