Author Topic: What size screws?  (Read 5952 times)

Offline Roger B

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What size screws?
« on: June 02, 2011, 08:46:24 PM »
For those of you who attach underribs with screws, what size screw do you use?  Track sells 6-40 for this purpose in a fillister head, but that seems pretty large when I put them on the rib.  I intend to put the rib on ala Hawken (per Don Stith); Screwing the rib to the barrel & then peening/filing the heads.
Roger B. 
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Dave Dolliver

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Re: What size screws?
« Reply #1 on: June 02, 2011, 10:56:58 PM »
I use 6-48 Weaver scope mount screws from Brownells.  They also sell a piloted c's'k cutter for those screws which have a slightly smaller head than the usual c's'k machine screw.  They fit the narrow ribs better.

Dave Dolliver

Offline JTR

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Re: What size screws?
« Reply #2 on: June 02, 2011, 11:29:04 PM »
What's a c's'k?

John
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Offline Don Getz

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Re: What size screws?
« Reply #3 on: June 02, 2011, 11:32:57 PM »
Like Dave said above, I have always used 6x48 sight screws for installing underribs.   Usually do it on our vertical mill and
merely replace the drill with the tap and turn by hand....that way they are always lined up and you have much less chance
of breaking a tap.   I pre-drill the ribe with a clearance drill, then countersink for the head of the screw, then clamp the rib
in place...............Don

Offline Don Getz

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Re: What size screws?
« Reply #4 on: June 02, 2011, 11:34:42 PM »
John......I think it is an abbreviation for "countersink", he's getting lazy in his old age...............Don

Offline Roger B

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Re: What size screws?
« Reply #5 on: June 03, 2011, 12:03:28 AM »
Thanks guys.  I've never been able to get the hang of using my drill press chuck to tap with.  I always wind up with a mess.  OTOH, this rifle would look like a Swiss cheese if it didn't have so many wrong holes, so maybe that would be in keeping with the theme.  Praise the Lord for welding & maple dowels.

While we're on the subject, is there any advantage or disadvantge to soldering the rib?  I always wondered what would happen with barrel stress with a soldered rib when things heated up during shooting.
Roger B.
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Offline Dennis Glazener

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Re: What size screws?
« Reply #6 on: June 03, 2011, 01:48:07 AM »
Roger I just finished screwing a rib on a Hawken Squirrel rifle. Been putting it off cause I had never done one. I set the barrel up in the milling vise, clamped the rib in place then using the depth gauge on my Jet milling/drilling machine I drilled the tap hole through the rib into the barrel (.100). Then without moving anything I changed to clearance drill and drilled just through the rib. Then I took the drill bit out of the chuck and put a short center in the chuck and used it to fit the center of my small tap holder (keeps it aligned). Started the tap using light pressure on the quill. Once I was sure it was straight and started I used hand pressure to cut the threads as far as a plug tap would go. Then I used a bottoming tap to finish the bottom of the hole. Once the hole was tapped I used another drill to cut the counter sink for the head, again using the depth gauge to insure the proper depth.
All four holes came out perfect, I did end up with one head that I had to file a few thousandths off to make it flush with the rib. All in all a much easier job than I had been expecting. I think the key for me was never having to move the barrel/rib. Everything perfectly aligned.
Dennis
« Last Edit: June 03, 2011, 01:50:55 AM by Dennis Glazener »
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Dave Dolliver

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Re: What size screws?
« Reply #7 on: June 03, 2011, 03:17:59 AM »
I believe that many of the old guns did solder the rib to the barrel.  Apparently there wasn't a problem.  Rarely were the guns fired many times quickly and heat, therefore, did not build up.  I have soldered one rib to a barrel. Our Gunmakers' Guild was building an 1803 Replica for the Museum at Cape Canby State Park at the mouth of the Columbia and we wanted to make it as correct as possible.  I tinned both parts, wired them together, then applied heat to the BARREL since it was the larger mass, and the solder flowed quite well to join the parts.

Dave Dolliver

Offline Dphariss

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Re: What size screws?
« Reply #8 on: June 03, 2011, 03:43:22 AM »
For those of you who attach underribs with screws, what size screw do you use?  Track sells 6-40 for this purpose in a fillister head, but that seems pretty large when I put them on the rib.  I intend to put the rib on ala Hawken (per Don Stith); Screwing the rib to the barrel & then peening/filing the heads.
Roger B. 

Brownell's sells 5x40  fillister heads screws but they will need trimming.
I like the 5-40 since they have a smaller head.
If you drill the counter bore to less than screw slot depth they will clean up better.
MSC sells a wide variety of screws.
These are zinc plated but the plating is instantly removed by a dip in muriatic acid.
http://www1.mscdirect.com/cgi/NNSRIT2?PMAKA=67420000&PMPXNO=2022588&cm_re=ItemDetail-_-ResultListing-_-SearchResults
 
Counterbores run from about 20 bucks up to 50+ but cut a flat seat for the screw head. I think .205 is the proper size for a 5-40 screw head. The pilot is about .115 IIRC.

Brownells screws are blued but pretty expensive, 5.99 per 12, since they sell in smaller packaging.

I do use some of their smaller screws for set trigger adjustment screws.

Dan
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Offline Lucky R A

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Re: What size screws?
« Reply #9 on: June 03, 2011, 02:14:35 PM »
    I have soldered a bunch of ribs on half stock rifles.  I built five of one style last year.  I have found that if you apply soap stone to the side flats of the barrel where you don't want solder, it will not stick. This is a big help when cleaning up after the job is finished.  Tin both parts as Dave said, but I use the large spring clamps to hold the rib tight to the barrel.  The spring clamps will apply constant pressure downward and result in a good tight almost invisable joint.   (Remove the plastic no mar tips from the spring clips before using them for this purpose--but you already figured that out ---didn't you?)
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Offline Don Getz

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Re: What size screws?
« Reply #10 on: June 03, 2011, 02:38:29 PM »
Dennis...........there is an easier way to do what you just explained.   Pre-drill the underrib with a clearance drill, also drill
the countersink hole for the head of the screw.   Clamp the rib in place on the barrel using two of those little steel parallel
clamps (couldn't build a gun without them).    Then, hold the barrel in your mill vise, put the tap drill in your chuck and line
up each hole, one at a time, and drill the hole.  Then replace the drill with the tap.   I found what when the tap bottoms
out, it will just slip in the chuck.....so easy, have done so many that way..............Don

Offline JTR

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Re: What size screws?
« Reply #11 on: June 03, 2011, 03:29:13 PM »
Thanks Don.
 ;D My old brain was having trouble getting around c's'k, but countersink seems to fit.
John
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Offline Dennis Glazener

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Re: What size screws?
« Reply #12 on: June 03, 2011, 04:29:56 PM »
Quote
Dennis...........there is an easier way to do what you just explained.   Pre-drill the underrib with a clearance drill, also drill
the countersink hole for the head of the screw.   Clamp the rib in place on the barrel using two of those little steel parallel
clamps (couldn't build a gun without them).    Then, hold the barrel in your mill vise, put the tap drill in your chuck and line
up each hole, one at a time, and drill the hole.  Then replace the drill with the tap.   I found what when the tap bottoms
out, it will just slip in the chuck.....so easy, have done so many that way..............Don
Don, thought about doing it that way, have read that somewhere else but I was concerned about getting the barrel tap hole perfectly aligned with the rib clearance and countersink hole. I am not a machinist, just a jack-leg one!
Dennis
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Dave Dolliver

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Re: What size screws?
« Reply #13 on: June 03, 2011, 05:22:39 PM »
Try drilling the rib with the tap drill, then clamp the rib to the barrel and use the rib as a drill jig to drill the tap drill holes in the barrel.   Remove the rib and enlarge the holes in the rib to the clearance drill size  and countersink them.  Tap the holes in the barrel and install the rib.

Dave Dolliver

Offline Roger B

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Re: What size screws?
« Reply #14 on: June 03, 2011, 08:05:52 PM »
I like Dave's procedure.  I've seen barrels drilled into the bore & thats what has me skeered. 
Roger B.
Never underestimate the sheer destructive power of a minimally skilled, but highly motivated man with tools.