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Knurling question

This is a discussion on Knurling question within the Gunsmithing forums, part of the M14 M1A Forum category; Newbie question. After poking around the forum, I was considering knurling my GI profile barrel to tighten up op rod guide fit. Friend has a ...


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Old December 17th, 2016, 01:59 PM   #1
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Knurling question

Newbie question. After poking around the forum, I was considering knurling my GI profile barrel to tighten up op rod guide fit. Friend has a hand knurler but only with diagonal (diamond) knurl wheels. Is that usable or do only straight/spline cuts work? Or is JB Weld without any knurling satisfactory?

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Old December 17th, 2016, 02:13 PM   #2
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Diamond cuts will work just fine as will JB Weld.

Tony.

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Old December 17th, 2016, 05:14 PM   #3
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Note that to do knurling right, you want to match pitch. Knurling wheels have a certain pitch, you can put on a set of calipers, measure the diameter, then multiply by 3.1416 (Pi) to get the circumference. You then count the number of knurls around the perimeter to determine the pitch of the knurl (let's say hypothetically that you determine it is 0.050" per tooth). Ideally, if you are going to knurl, you want your part circumference to be an integer multiple of 0.050, so when the knurling wheel does one complete revolution of the part, the teeth overlap with the indentation made on the previous revolution.

So if your part is 1.5" in diameter, it will have a circumference of 4.712". That is not an even multiple of 0.050. However rounding down, 4.700 circumference would be, at 94 teeth per revolution, and would require a 1.496" diameter (4.7/Pi). So when you start knurling, you would run the knurling wheel 0.002" deep (0.004" of diameter), and the teeth would phase correctly. Of course 4.65 circumference would work too, with a 1.48" diameter, so run the teeth 0.01 deep.

On your hand knurler, it will have a knob on a threaded shaft driving the knurling wheel. Get a pitch gage, and measure the thread pitch. Now you know how many thou pre revolution the drive is. Let's say it is a 28 pitch thread. So your pitch is 1/28 or 0.036 per revolution. In the above example, wanting to go 0.01 deep would therefore require just under 1/4 turn beyond where the wheel starts to leave marks.

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Old December 17th, 2016, 05:28 PM   #4
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Originally Posted by ShootingSight View Post
Note that to do knurling right, you want to match pitch. Knurling wheels have a certain pitch, you can put on a set of calipers, measure the diameter, then multiply by 3.1416 (Pi) to get the circumference. You then count the number of knurls around the perimeter to determine the pitch of the knurl (let's say hypothetically that you determine it is 0.050" per tooth). Ideally, if you are going to knurl, you want your part circumference to be an integer multiple of 0.050, so when the knurling wheel does one complete revolution of the part, the teeth overlap with the indentation made on the previous revolution.

So if your part is 1.5" in diameter, it will have a circumference of 4.712". That is not an even multiple of 0.050. However rounding down, 4.700 circumference would be, at 94 teeth per revolution, and would require a 1.496" diameter (4.7/Pi). So when you start knurling, you would run the knurling wheel 0.002" deep (0.004" of diameter), and the teeth would phase correctly. Of course 4.65 circumference would work too, with a 1.48" diameter, so run the teeth 0.01 deep.

On your hand knurler, it will have a knob on a threaded shaft driving the knurling wheel. Get a pitch gage, and measure the thread pitch. Now you know how many thou pre revolution the drive is. Let's say it is a 28 pitch thread. So your pitch is 1/28 or 0.036 per revolution. In the above example, wanting to go 0.01 deep would therefore require just under 1/4 turn beyond where the wheel starts to leave marks.
I'd have to go with JBWeld before I do math for an oprod guide. jBW would be setting up already.

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Old December 17th, 2016, 08:24 PM   #5
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Used JB weld on mine and it works well. If you have the tools, which I don't, then by all means knurl. A lot of people on this forum sing praises to Tonyben and rightly so. He recommends using JB weld if knurling isn't an option. That's good enough for me.

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Old December 18th, 2016, 03:26 PM   #6
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I'm dumber than dirt when it comes to math ,ya dont need no dern fancy mafemtics to knurl a barrel.

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Old December 18th, 2016, 05:07 PM   #7
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I recently asked the same question as the OP. Here's how I did it, and it worked like a charm! What I decided to do was to knurl the inside of the operating rod guide instead of the barrel itself. I mainly did this because I figured if I screwed something up in the modification process, it would be cheaply and easily replaceable. I did not have a knurling tool, so I went out and bought an automatic center punch. This worked well. I applied several punches to the inside of the operating rod guide, on both sides, all the way around. The raising of the metal was tight enough that I had to very carefully maneuver the guide over the upper band stop on the barrel. I had to drive the operating rod guide into it's spot with a rubber mallet. It is now very tight and not going to move anywhere.

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Old December 19th, 2016, 07:59 AM   #8
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I mainly did this because I figured if I screwed something up in the modification process, it would be cheaply and easily replaceable.
Tru dat! Wiser words have never been spoken. Always monkey with the cheapest part first.

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Old December 19th, 2016, 08:38 AM   #9
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Old December 27th, 2016, 06:58 PM   #10
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Diamonds work for me......




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Old December 30th, 2016, 11:07 AM   #11
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Loctite 238 works also works like you would not believe. Lets you install it without special tools and equipment.

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