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Langdon Mitre box issues

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Forum topic by coopersdad posted 01-01-2018 02:01 AM 685 views 0 times favorited 14 replies Add to Favorites Watch
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coopersdad

32 posts in 1040 days


01-01-2018 02:01 AM

I recently restored a Langdon Mitre Box, Size 2, No. 73 (some photos in the restoration thread) , but I am having problems with it. I’ll describe what’s going on in hopes someone may have some insight!

The miter angles are right on, but some vertical cuts are off square. Miters with the saw 45 degrees to the left, and moving to lesser angles up to 0 degrees, I can usually cut dead square, but as I swing the saw to the right from 0, it begins cutting off square, getting worse as I progress to 45 degrees.

As I progress through the cut, I can feel the saw binding in the cut, and as the cut is completed, the saw plate “pops” back to vertical. In a 3 1/2” cut, the cut will be off 3/32” or so. After the cut, the wood will be touching the plate at the top, with a gap visible at the bottom.

The plate appears to be square with the bed everywhere.

I thought perhaps there was too much set on one side of the saw, but that should cause issues everywhere. I can take the saw out of the box and freehand cut dead square on a line without having to “steer” it.

This may be related to me not knowing how to properly assemble it after de-rusting. I adjusted the king bolt and the gib until the guides had no slop and swung smoothly. That was very fiddly, and for a long time it was tighter on the right side (where I’m having troubles)., but I finally got it so it was smooth. I don’t understand how that could put things in a bind, but maybe? Is there a proper procedure for this, and could doing it wrong cause this issue? Or is there a cutting techinique I could be messing up? Thanks for any observations!


14 replies so far

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bandit571

21741 posts in 2882 days


#1 posted 01-01-2018 02:56 AM

Problem MAY be in the saw itself? Maybe needs to have the teeth “set” again. Set may have worn off one side of the saw…saw will “pull” towards the set side.

Sometimes, when the saw starts cutting into that metal track ( saw stop is set too low) it will effect the teeth on the saw….when you get the saw redone, check how far done the saw goes, you don’t want it cutting the track..

-- A Planer? I'M the planer, this is what I use

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coopersdad

32 posts in 1040 days


#2 posted 01-01-2018 03:56 AM

Bandit, the set was my first thought. I tried stoning the side it was drifting towards a bit to remove some set and it didn’t help. I’d think the issue would be constant no matter the angle setting, and I think it would drift if cutting freehand, and it doesn’t seem to. The saw is pretty sharp, but I may go ahead and reset and sharpen it….just don’t relish all those teeth…..

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Poa

373 posts in 757 days


#3 posted 01-01-2018 03:56 AM

Man….just thinking geometry, it seems to me that a few things could be happening. Trouble is, I am not familiar enough with Langdons to make a knowledgable suggestion. Obviously, something is coming out of alignment when you swing the swingarm to the right. It could be the mating surfaces of the swingarm and frame, where it pivots, is worn unevenly. Could be a slightly bent king screw. Also, it could be a slightly twisted frame, that “racks” the swingarm when its locked, misaligning the guide posts in relation to each other. Just a few things to check. Please, if you resolve it, don’t leave us in the dark, let us know what you find.

-- Honest, honey, I found it in the trash.

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coopersdad

32 posts in 1040 days


#4 posted 01-03-2018 04:22 AM

I think I have found the issue(s) after spending way too much time on it. I tore it all apart and found nothing bent or broken, and there was no binding of the saw in any position. I then made dozens of cuts, trying to find a pattern. Some would be off, some would be perfect. If there was a binding or mechanical issue, it should manifest itself all the time, not just sometimes. When cutting taller pieces (the saw has 3 1/2” under the back) many would have bad cuts, but when I cut 3/4” to 1 1/2” stuff, almost all were good, no matter the angle.

With those taller pieces, the saw would start binding about halfway through. The cuts weren’t curved, but it appeared the saw was cutting fairly straight, then moving a few degrees and cutting fairly straight again.

I finally realized the saw post castings are spread out just a bit at the tops. When the saw is high, as when beginning a cut on taller pieces, there isn’t much guide post in the casting, and there is considerable wobble between the saw guides and the post castings – I can move the top of the saw 1/8” or so side to side. It’s tight in the guide slot – the movement is between the guide and the post sockets (one is a bit worse than the other). As the saw is lowered, the guides get tighter, with little to no movement. This is when the saw teeth are about 1 1/2” or so from the bed, which is about where I’d start to feel the binding.

I think that when starting a cut, I would be holding the saw to one side of the “wobble”, the cut would start, and when the guides straightened out, I’d feel the bind as it would cut a different direction. When cutting a 45 at the opposite side, I would usually get a good cut – my stance may be changed there and I was holding the saw slightly differently when beginning the cut.

I made a bunch more cuts and can usually get good ones by “englishing” the saw a bit at the start, at the angles where I was having issues. Not ideal, but it seems to be working. I won’t even try squishing the posts a bit tighter at the top. I’d either break them or I’d bend it permanently “wrong”. It’s such a small amount, I don’t think I could shim them, but I may mess around with that someday (JB weld?). I’ve already spent way too much time on this. But I learned a lot about it, and know what to look for if I run across another one.

I do need to reset and sharpen. In a fit of frustration, I stoned some set off one side and then the other, trying to change things. Now there’s so little set the plate is binding in wider pieces.

View Derek Cohen's profile

Derek Cohen

396 posts in 4167 days


#5 posted 01-03-2018 03:21 PM

Try sawing a vertical line without the mitre box. That will tell you if it is the saw (which I suspect it is).

Sawing off the line says that there is too much – or too little – set on one side. A saw binding says that there is too little set altogether to create a kerf to ride in.

If it is the saw, then remove the set, sharpen the teeth, and reset them.

Regards from Perth

Derek

-- Buildiing furniture, and reviewing and building tools at http://www.inthewoodshop.com

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coopersdad

32 posts in 1040 days


#6 posted 01-03-2018 03:53 PM

Derek, everything I read indicated it should be the set. But I can cut to a line with the saw outside the box with no problems. I did a bunch after I took this, and so long as I got it started correctly, no issues. My next job is to reset and sharpen, so we’ll see if that makes any difference. These things are frustrating, but afterwards I’m actually grateful, since I’ve learned somthing (usually something my grandfather would’ve said “well duh, everyone knows that…).

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theoldfart

10164 posts in 2650 days


#7 posted 01-03-2018 04:10 PM

Coopersdad, that was a fine bit of trouble shooting. Thanks for sharing. I own a number of Langdons and All Steels and having this info will be useful in the future.

-- "With every tool obtained, there is another that is needed" DonW ( Kevin )

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coopersdad

32 posts in 1040 days


#8 posted 01-03-2018 08:01 PM

Thanks. If I’m right. I often do stuff like this, think I’ve got it, and have missed something…

Do you have that kind of play in your posts when the saw is high or are they good and tight all the way down? I know cast iron doesn’t bend well, but I wonder, with the posts split as they are, over 100 years they may move a bit?

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theoldfart

10164 posts in 2650 days


#9 posted 01-03-2018 09:09 PM

I’ll have to check them, I don’t recall there being any play.

-- "With every tool obtained, there is another that is needed" DonW ( Kevin )

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Poa

373 posts in 757 days


#10 posted 01-03-2018 11:30 PM

Seems I remember a guy posting a while back about his guide posts being spread at the top. I remember how stupid I felt after I suggested he put hose clamps on ‘em. I’m pretty sure that was the morning after I was lobotomized. I’m better now, and can see the REAL solution is to wrap them in duct tape.

-- Honest, honey, I found it in the trash.

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Poa

373 posts in 757 days


#11 posted 01-04-2018 12:10 AM

And, just checked four of my All Steels, three 6 inchers, and a 5 incher. They all have a bit of slop when raised to keeper height, but the slop diminishes considerably when the keepers are released, and the guides begin to lower. There is enough play, even though it is minute, that a poorly set saw could drift slightly. Really, it just underscores the importance of a sharp and well set saw when dealing with mitre boxes. And, hate to harp on this, but it also illustrates why I am so partial to the double rod style of guide posts on the stanleys. There is provision to adjust any lateral play out of the saw, as well as adjustment of vertical angle in relation to the table. But with guide posts such as the Langdons, GPs, or the 23 series Stanleys, after the guide post or swingarm is tweaked in any respect, you might as well throw the box away.

-- Honest, honey, I found it in the trash.

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theoldfart

10164 posts in 2650 days


#12 posted 01-04-2018 12:45 AM

You better not buy any more Langdons then ;-) hehe

-- "With every tool obtained, there is another that is needed" DonW ( Kevin )

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Poa

373 posts in 757 days


#13 posted 01-04-2018 12:51 PM

B-b-b-b-but Kevin…I c-c-c-c-can’t help myself! I’m a s-s-s-s-sick man!

-- Honest, honey, I found it in the trash.

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theoldfart

10164 posts in 2650 days


#14 posted 01-04-2018 04:55 PM

me too!

-- "With every tool obtained, there is another that is needed" DonW ( Kevin )

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