Schrade 5Ot BrokenSpring Repair

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Jerlin
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Hi Jeff, I like your idea about machining a 2.5mm pin down to fit the hole in the new blade.
Another question. What type of pin material do you suggest I use for the pivot pin? The original pin was steel. I'm thinking using stainless steel or nickel silver. Your thoughts would be appreciated.

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Jeffinn
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

Personally I would use nickel silver but if you want to use steel I would find a nail that’s the approximate size you need and use that. Nails are made of a type of steel that can be easily machined and peened.
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Jerlin
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Jeff, thanks for the suggestion. I probably will try the nail since this will be my first attempt at this. I'll let you know how it goes.
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Jeff, I finally got back to the 50T. I found a nail just a little larger in diameter than the hole in the new blade to use for a pivot pin. I have machined it down to where it is a very tight fit in the blade hole. Do I want the pivot pin to be a tight fit in the blade hole, or should the pivot pin go in a little easier?
Also, the hole in the new blade is larger than a 3/16" drill bit, but smaller than a 7/32" drill bit. Since I need to make the holes in the handles larger for the new larger pin, should I make them 13/64"? Also, how do I get the pivot pin to fit flush to the bolsters?
Another question. I'm using 3/32" brass pins for the rocker pin and rear pins. They are a little loose in the knife, but I have not spun the heads. I just have the pins in the handle to hold the springs and locking bar in place. Do these pins need to be a tighter fit?
Thank you for your continued patience with me and your great advise.

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Jeffinn
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

Jerlin wrote: Thu Jun 18, 2020 10:19 pm Jeff, I finally got back to the 50T. I found a nail just a little larger in diameter than the hole in the new blade to use for a pivot pin. I have machined it down to where it is a very tight fit in the blade hole. Do I want the pivot pin to be a tight fit in the blade hole, or should the pivot pin go in a little easier?
Also, the hole in the new blade is larger than a 3/16" drill bit, but smaller than a 7/32" drill bit. Since I need to make the holes in the handles larger for the new larger pin, should I make them 13/64"? Also, how do I get the pivot pin to fit flush to the bolsters?
Another question. I'm using 3/32" brass pins for the rocker pin and rear pins. They are a little loose in the knife, but I have not spun the heads. I just have the pins in the handle to hold the springs and locking bar in place. Do these pins need to be a tighter fit?
Thank you for your continued patience with me and your great advise.

Jerry Johnson
That pin needs to fit in the blade hole with a little bit of clearance so the blade can pivot freely on it. Generally speaking the pin should fit snugly in the bolster holes but have just enough clearance in the blade hole so the blade can move freely.
To get the blade pivot pin flush on the bolsters you need to tap on each side hitting the pin hard enough so that you start to mushroom the head of the pin on each side. It takes some practice to get it right. Use a feeler gauge between the blade and liner to keep the blade from getting too tight.
For all of my knife pins I usually measure the old ones when I take them out and try to match the size for the new pins. For most of the pins the idea is the same, they need to be large enough so they fill the hole when you peen them but sized so the pin moves freely in the lock bar spring hole or pivot holes.
I’m not sure that drilling out the bolsters is the right approach. The pin you use for the blade should be close to the size of the bolster holes so that you don’t need to drill them out. If you’re retro-fitting a new blade and the hole size in the new blade is different then you might need to alter the bolster holes.
My approach for the blade pivot pin is to get the pin to the size where it’s just fitting into the bolster holes. If you do that the pin usually is the right size for the blade pivot hole. You can do this by feel, you don’t have to measure the fit. Most knives use fairly standard pin sizes but I have had a few oddballs on my bench.
Hopefully some of this makes sense. If not just pop back in and ask any questions you might have.
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Jerlin
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Thanks for the prompt reply, Jeff. It all does make sense.
Your statement about retro-fitting a new blade and the hole size in the new blade being larger than the original blade is my situation. Therefore, I am going to need to make the bolster holes larger.
From what you indicated, the pivot pins should fit the blade hole with a little clearance, but should fit snugly in the bolster holes. That being the case, I'm thinking I should drill out the bolster holes to 13/64" (or possibly use a 20.637mm drill bit). Then machine the center portion of the pivot pin down slightly so the blade can move freely. Does that make sense?
For the other pins, I did try to match the size of the old pins when I took then out. However, as I said, the new pins are slightly loose in the holes. Maybe I'll just have to experiment until I have done a few and get the feel of things.
Best regards,

Jerry Johnson
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Jeff, I just realized I made a huge mistake in converting inches to mm. It should be 5.159mm, not 20.637mm. I wasn't thinking.

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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

Yikes, that’s quite a difference.
To give you a better idea about pin clearances look a the photo below. All of those pins could be easily installed by hand (no hammer needed during this phase). You should be able to rough fit your knife together on the bench by hand. Slide the other handle on and then check the knifes functionality. Keep it simple an it should be fine.
F4886521-FABA-4C24-924A-9C25E86631F6.jpeg
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

And a 5.159mm pin seems awfully large....
It seems like my 5ot pivot pins were in the 3mm range (3.2mm maybe?)
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

I might have already asked you this, but what size is the hole in your blade?
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Jerlin
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

The hole in the new blade, which is a blank, is between 3/16" and 7/32". Therefore, I'm guessing 13/64". The hole in the new blade is larger than the hole in the original blade.

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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

The blades with the 7/32" hole take an insert to allow for the use of a smaller pin.With the insert you'll use a 3.15 mm pin (which is probably close to what your bolster holes are).
IMG_4071.JPG
IMG_4072.JPG
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Jerlin
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Jeff, Any idea where I can find the insert? I have looked here locally and cannot find one the correct size.

Jerry Johnson
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Jeff, I also could use a 3.15mm pin. Your suggestions are always appreciated.

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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

For the blades that I have with the larger hole (.187” hole size) I used the bushings from USA knife maker. (Without having your blade in front of me I can’t say that your blade hole size is the same).
You can look at them here:
https://usaknifemaker.com/bushing-stain ... 6-oal.html
The ones in the link (And in my picture) are stainless steel, they also make them in brass. They have to be filed down a bit to get them to the correct thickness for your blade.
I know Dale and a few of the other guys bought tubing at the hardware store and cut some spacers from that. So that’s an option as well.
Jeff
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jeffinn »

Here’s two different 5OT’s disassembled. One has the regular sized blade hole and the other has the enlarged hole:
8CF26128-F121-434F-BEEF-A9EE72424381.jpeg
A 3.15 mm pin fits in the bolster hole of either of these knives;
708CA5A1-7973-4A56-9952-42BCFCA2C831.jpeg
Here’s the two different blades, one with the large hole with a bushing installed and one that doesn’t need a bushing installed;
41E978D1-2584-47EB-9A01-E75710E9EC61.jpeg
563A2B72-0636-4229-A8B5-B490E62FBFFE.jpeg
For the rest of the knife use pins that closely fit the holes.
Jeff
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Jerlin
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Re: Schrade 5Ot BrokenSpring Repair

Post by Jerlin »

Jeff, I thought I had sent a reply shortly after you sent your last post. I must have done something wrong, because I do not see my reply to you. In any event, I greatly appreciate all the time you have devoted to me in getting my 50T back together. I did check out USA Knifemaker. Their bushing the size I need is about $2.25 each, plus about $11.00 for shipping. I wouldn't mind paying that much shipping if I had a larger order, but for a single $2.00 part, that is a little excessive.
I have a request of you that I would prefer to ask in a private message, if that is all right with you. Please let me know.

Jerry Johnson
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Re: Schrade 5Ot BrokenSpring Repair

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I sent you a private message.
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JonTerry
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Re: Schrade 5Ot BrokenSpring Repair

Post by JonTerry »

got to follow this as I am going to attempt the same thing
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Re: Schrade 5Ot BrokenSpring Repair

Post by orvet »

One comment to Jerlin, when you need a hole that is between sizes in fractional bits, I always use number drills. They are +/- a few thousands difference between the fractional drills. It makes it much easier to get a hole that allows enough clearance for the pin to fit easily in the redrilled hole.

You can Google number drills and find out what their diameters are in thousands of an inch. I have a chart which I picked up at my local tools store, which gives me the diameters of all of the number drills from size 60 to size 1. You won't need a full index of number drills, just one that is the proper size for your task.
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OLDE CUTLER
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Re: Schrade 5Ot BrokenSpring Repair

Post by OLDE CUTLER »

JonTerry wrote: Sun Jan 15, 2023 2:49 pm got to follow this as I am going to attempt the same thing
This is a years old thread by someone who has not been active in awhile, so there may not be an answer.
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Raccoon
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Re: Schrade 5Ot BrokenSpring Repair

Post by Raccoon »

Is there a website that sells backsprings? If not, is there a place that sells the metal for them? I saw some for sale on eBay but they aren’t the exact ones I need. I am looking for something similar to pin stock that I can work with.

I am just getting started (wish me luck) in cleaning up some old knives I have and 4 have broken backsprings. This could be a rabbit hole I don’t know what I am in for.

Thanks for any help.
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Re: Schrade 5Ot BrokenSpring Repair

Post by OLDE CUTLER »

I have a spring stock assortment that is 1075 steel that I got from Brownells. Try their website. It is the assortment #149, and has 3/16" to 3/8" widths that works for double ended springs.
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Re: Schrade 5Ot BrokenSpring Repair

Post by Raccoon »

I did not see it on their website at this time but thank you for the suggestion. I suspect it’s best to buy a junk lot and and salvage from other knives.
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