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Posted: 7/8/2017 3:48:43 PM EDT
[#1]
get the best drill bit you can find, trust me.
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Posted: 7/8/2017 6:26:25 PM EDT
[#2]
Quote HistoryQuoted:
get the best drill bit you can find, trust me. Before carbide was so common a cut off nail was used to spot soften the metal before drilling. Chuck nail in drill press, cut off the head, file to a flat. Place against metal and spin with a lot of pressure. When the metal has heated to dull red stop and allow to cool. Center punch and spot with a center drill and good drilling oil. Drill under size and ream to final dimension before threading. Taper, plug, bottoming (on blind holes). On a customers gun use new or nearly new taps and a LOT of cutting oil. Do-drill and tap-magic are both excellent and worth their nominal per job cost. One full turn (maximum) and then back at least 1/2 a turn. Use fixturing to start taps straight. Even fixturing on a drill press table then chucking the tap and turning the chuck by by hand works well. |
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Posted: 7/8/2017 7:09:12 PM EDT
[#3]
135° split point HSCO, if possible use "screw machine length". Gurhing, OSG, Union Butterfield, many other top manufactures. Paying extra for top quality pays back dividends in the quality of work you can do. The higher the Cobalt content the better.
Also use good cutting fluid Relton, Castorol Moly-D, etc. Be sure to set a stop to prevent over travel. Spot drill or center drill first, just enough to support the final drill tip size. Go easy on the feed until deeper that the spot/center drilled hole. And everything said above... |
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Posted: 7/8/2017 7:27:38 PM EDT
[#4]
Wow, thanks for all the help guys.
Is there a preferred drilling and cutting oil from whats been listed? Amazon has Tap Magic and can ship with Prime but if any of the other recommendations are better I'll try something different. Or is this more of a personal preference? |
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Posted: 7/9/2017 1:11:48 AM EDT
[#5]
DYI edm cutter,
http://pico-systems.com/edm.html This will peck a hole through that is smaller that the hole your going to cut, while at the same time annealing the metal at the channel as well. Hence you have to say thread the drilled channel afterwards, then you have to anneal the steel so you don't snap a tap instead. |
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Posted: 7/9/2017 1:32:43 AM EDT
[#6]
I've done two FSBs on nitride barrels.
I use an end mill to break the surface and make a flat area for the drill bit. Then I use a TiNi drill bit. I used a new drill bit for each FSB. |
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Posted: 7/9/2017 12:40:51 PM EDT
[#7]
The problem using a drill bit to drill the passage, is that a drill bit will always produce a channel that is wider at the top, then the bottom of the channel.
With a gas port, this means that the gas port will increase quickly as the bottom of the channel starts to plasma erodes from the bottom (flame source) upwards to the larger part of the channel. To do a gas port correctly that will hold is sized a lot longer, it really needs to under sized drilled, then final reamed. Hence the metal needs to be annealed enough that your not going to wear out/chip your reamer the first time you go to use it. |
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Posted: 7/10/2017 2:14:03 PM EDT
[#8]
Quote HistoryQuoted:
The problem using a drill bit to drill the passage, is that a drill bit will always produce a channel that is wider at the top, then the bottom of the channel. With a gas port, this means that the gas port will increase quickly as the bottom of the channel starts to plasma erodes from the bottom (flame source) upwards to the larger part of the channel. To do a gas port correctly that will hold is sized a lot longer, it really needs to under sized drilled, then final reamed. Hence the metal needs to be annealed enough that your not going to wear out/chip your reamer the first time you go to use it. Drilling and then reaming to finished size is how you create a uniform smooth hole. The drill should be at least a few thousandths of an inch under the reamer size. |
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Posted: 7/10/2017 2:55:09 PM EDT
[#9]
Missed the point, and since the drill bit is pulling up swarf as it cutting, it going to end up with the channel cone shaped to bottom, depending on the depth of the channel that is being drilled.
In the case of drilling a barrel, figure that the top channel that you start the drill bit, to the bottom of the channel as you are pushing throw, will end up with the top of channel at least .002" if you are peck drilling short amounts and removing the swarf from the channels of the drill bit, up to .005" if you don't relieve the swarf by peck drilling and blowing out the swarf in the drill bit channels each peck instead. |
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