pinning anomaly and question

Hi, I just pinned up the pivot side of a Boker restore and noticed an anomaly that I have not seen before and can't explain. I pinned the rod to the tightness I like but when I swiveled the blade in its arc I noticed that it had a "soft spot" that travelled along with it. That is to say that at every stop along the arc the blade came to rest in a spot of a few degrees where the blade was in a pocket of looseness. Beyond that few degrees in either direction the tightness was perfect, but within that same few degrees...looseness. What gives? The tang hole is not too big (it was perfect coming out of it's old scales)...I used Microfasteners gear for everything...the scales are cowbone (just polished)...my technique was as usual (with a very high success rate). Is it possible that I have bent the pin in the pinning process. It's the only thing that makes any sense. Thanks for any advice.

I bet the thickness of the tang varies a little and may be a slight wedge shape so that when the 'soft spot' appears the area of the tang closest to the wedge is thinner than the rest of the tang. This is not uncommon.

Joed, yes the tang is pretty "wedgy" at the pivot hole which may account for the binding. Being that this problem is as common as you say, how do people get around it? Should I file a slight coke bottle shape into the pin where it passes through the tang to relieve the bind or pass a slightly larger drill bit through the tang to relieve the pressure there? Obviously I'm going to have to repin this thing so maybe tearing it apart and "reading" the scratches will answer some questions. Any help from the board is always appreciated. Thanks

You pinned using inside bearing washers??? if so the when you take it back apart check to see how those washers sit on the tang, some times the tang can have a slight indent toward the pivot hole.. If that isn't it then sand the inside of the scales again using a sanding block to assure evenness.. and if that ain't it I am outta ideas :shrug:

are you using custom made scales or originals?

As you suspect,Would bet you bent the pin.

Yes, I am using new scales and they were flattened on plate glass and 400 grit. The washers are Microfasteners and seemed flat when I installed them but I will check for scuffing or abrasion when I take this thing apart. Would I be doing myself a favor by supergluing the thrust washers to the scales before assembly thereby eliminating one source of rotational problems? Just a thought. The part that confuses me (easily done) is that the "soft spot" occurs throughout the entire range of the arc. 360 (or almost) degrees. That would mean that the bind couldn't be because of the wedge shape or the bind would loosen up as it entered the thick or thin side of the wedge. I'm probably beating a dead horse, here, but I thought maybe someone else might have run afoul of this problem and had a quick answer. I guess I'll sit with a glass of absinthe then start the repinning process. Just kidding about the absinthe (Glen) but I have to admit I have been fascinated with this spirit having watched a program about it some time back. Thanks for all your help, guys, and keep the suggestions coming.

Pixelfixed, my money is on the bent pin, too.

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Originally Posted by steveg

Pixelfixed, my money is on the bent pin, too.

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Did you mock up the sacels using a Nut & Bolt from MF first ????
This normally eliminates all of the above except a bent pin :) I guess I should have asked that before ????

Yep, must have had the thing together and apart a dozen times admiring my work..I mean test-fitting. I thought maybe the thrust washers were rotating and stopping at a set interval but he "soft spot" is so consistent throughout the entire arc that it can't be them. I'm sure it's a bent pin and as soon as I get this thing worked out hopefully it will prevent the same thing from happening to someone else. I'm currently waiting for the battery to charge on my camera so I can take some pictures of the razor for a friend and when that's all finished I will get this thing over to the drill press and figure out this mystery.

OK...got this thing torn apart and here's what we've got. First off the pin is as straight as straight can be. The insides of the cowbone scales show even and equal wear patterns from the thrust washers. The thrust washers show even and equal wear on both sides. The blade shows even and equal wear from the thrust washers. the tang hole measures out to .082" and is straight and clean. The pin stock measures out to .061" and spins around in the tang hole with no binding. My money was on a bent pin, but beyond that I'm stumped. I'll put her all back together with fresh parts and see if I get the same results. Stay tuned...it may take a while before I can get around to this. Oh, and yes, I will test fit with Microfasteners nuts and bolts before final pin up.

I wonder if the wedge is not off a little, the angle of the wedge specifically.

Well, I wondered about wedge geometry, too, but I just got it all back together and here's what I've got. I used Microfastener's nut and bolt combo with fresh everything and tightened her right down. The "soft spot" was still there so I took another turn on the wrench and the problem seemed to get better...I took another couple of turns on the wrench and the problem got a lot better. I worked the blade through its arc a few times and it loosened up and started the soft spot thing again. I got under bright light and noticed that the thrust washer (on one side) was lagging then catching up while the blade moved from soft to hard spot. That begs the question...are the thrust washers supposed to remain solid in their positions during the rotation of the blade or do they rotate with the blade. Or beyond that, do they sit tight on the blade and rotate on the scale surface. I have to assume that they must sit tightly on the scale surface and only move against the blade in its rotation. I assume this from taking razors apart only to find that the thrust washers have stuck to the scales and not the blade. Anybody got any ideas, here? My next step will be to put a dab of superglue on the thrust washers in their proper positions and see if that alters the results. Any thoughts about this procedure?

Sand the inside of the scales at the pivot with 220, re-assemble and see what happens.. basically rough up the scales :) just a touch...

Am a perfectionist as much as most,but is it really that much of an issue?

Pixelfixed...when the razor flops around in the handles while you're trying to get a grip on the thing it is. I'm not really a perfectionist, but I feel that my restores should at least operate like most of the originals on the market. And besides, this is an engineering problem and I'm fascinated with stuff like this. Having said that, here's what I've done since the last post and the results thereof. First, I roughed up the surface of the scale (inside) and the scale side of the thrust washer to see if stopping the movement between the two would help. Actually I ended up putting a drop of superglue between them so now they are permanently attached to the scales. Then I took a piece of 1/16" I.D. aluminum tubing and turned it down on my dremel to slipper fit the tang hole. I pressure fit that and filed it flush, cleaned up the hole and reassembled the razor with a nut/bolt combo. After a good tightening I gave her a whirl...the blade flops out of the scales about 1/2" then comes under tension. The tension is pretty good until you reach about 10 o'clock (holding the razor horizontally and opening from left to right) then she lets up pretty good until you reach about 2 o'clock when the tension comes back. It stays under reduced tension until you are completely around in the arc of the razor. This is just crazy...the only thing left is the relationship of the wedge shape of the tang to the parallel surfaces of the scales. I do notice that the scales will bow in and out quite a bit as the blade is rotated in its arc. Well, I guess I'll give this thing a rest for the night and reassemble and pin again in the morning and see what I get. Thanks, everyone for your suggestions and more importantly your patience.

Hope you get it fixed,am at a loss as to what it could be,Might consider sending it off to M.I.T.

Pixelfixed, thanks for your support. I was just sitting here fiddling with the disassembly for tomorrows pin up and noticed that my Microfastener bolt was thinner than 1/16" and wondered if that had anything to do with it. I got my piece of 1/16" brass rod and fit it up by hand and squeezed it all together and guess what?...no binding! I may be on to something here. I'm all in for tonight, but stay tuned as I'll be anxious to get after this deal in the morning. When I was in 8th grade, I was given a math problem that I just couldn't solve. My aunt was visiting at the time and she offered to call her nephew who was, at that time, head of the mathematics department at the Jet Propulsion Laboratory in Pasadena. After about a 3 hour wait and using all the resources available to him, he called back to say that he and the staff had come to the conclusion that the problem was written is such a way as to not be solvable. Don't for a moment think that I wouldn't send this thing off to MIT!

I hate to be throwing ideas out there, being as I AM considerably new to razors, but...I feel compelled. A couple have people have already mentioned it, and it doesn't seem like the idea is getting much attention. It sounds to me like the shape of the tang isn't a perfect square at the pivot point. It's hard to explain without an illustration, and I admit I have zero experience reassembling these things. Having said that, if the angle of the stamped sides are not not equal, it seems to me it could cause an issue. That issue might not be the issue you're describing, but it's a guess. Another thing you might consider is tightening down that pin while you have the blade sitting at the position in the scales that it's normally loose. If you tighten it through the loose position, and then your scales do some crazy flexion during opening/closing, you've pinpointed the problem as the issue I previously mentioned. You'll be looking at the blade ditch ( just made that up), seeing if it the individual sides twist away from each other, or towards each other. Now that I've said my piece, somebody please point out my silliness for even attempting a post this early.

Let us get this fixed,paint the tang with Dykum,let dry,assemble razor.work the blade back and fourth once or twice,disasemble,you will have your answere.

Microfasteners.....
That might make it easy to test some things
if you have not peened them down.

Think like a machinist and check
all the parts including any references.

Do you have washers between the tang and the bone of the scales?
With microfasteners you can add or remove washers. Even thin shim
like washers cut from brass foil. The tail of the razor might be oddly
shaped so washers that minimize and localize the contact area could
help.

What you describe may be a small mismatch in pin size in a
hole that is just a little bit large. There are three holes: each side of
the scales and the hole in the razor tang to check. Given the
length of scales a small difference is all it takes.

Probe for a gap in all three places with a thin shim
of brass foil and adjust if it bothers you. It would not
bother me for the most part.

The other thing to check is the way the scales were drilled
at both ends and also the way the razor was punched. Anything
other than a nice clean vertical hole might be the issue. This
includes the wedge end.

This is manifest on some of my Razors, I assumed that it was that when the blade first started to move it would rotate in relation to the washers, but that for whatever reason, it then took the washers with it and the perceived friction changed because the washers then rotated with the blade in relation to the scale. No idea why and never thoght of it as a problem.

Good morning, all. Well, after a good night's sleep I went to the shop to see what could be done with the Boker. I got to thinking about the wedgy shape of the tang and what niftyshaving had said about reducing the contact area of the thrust washers. Since my large thrust washers were superglued in place I opted for relieving the surface of the tang which I did with my trusty Dremel tool. I dug 2 "wallows" on the forward sides of the pin hole and refitted the blade with 1/16" brass rod. Voila! No slack, no drag, no catching...beautiful, smooth action throughout the entire arc. In conclusion (finally), I'd have to say that the original problem had to do with the taper of the tang as it rotated in it's arc around the 2 parallel surfaces of the scales. The large thrust washers exacerbated the problem. Anyway, the Boker is now buttoned up and closer to its delivery with my thanks to each and every one of you who offered your suggestions...all of which had validity and in some way helped to solve this anomaly. Again, thanks.