Countersink and screw slot alignment

[QuanLoi]

A problem I've never quite figured out is how to judge the amount of countersink to drill in order to get the screw slots to line up a certain way.  Also, how does one countersink so that the bevel is equal around the drilled hole?  I'm using an electric variable speed drill (the only power tool used on the gun I'm building).  And the countersink bits I have measure 90 degrees and 82 degrees.

How do you line up those slots?

Thanks in advance. 

[volatpluvia]

trial and error.

[Mark Elliott]

Don't try to line them up.   It is out of place on most longrifles.    It is one of those things that will make it look manufactured.    Just put the screws in flush and leave them.   Either filed flat or oval are both correct.    I like to file flush, then back out and round off the sharp edge a bit.    Unless you are going for a high end contemporary piece,  the finished product shouldn't look too refined.   Very few of the originals where.   If you are reproducing a very high end original, that's great, but most weren't.   Remember you are trying to strike a balance between perfect and just get it done.   That is called a "workman like manner" which is actually a legal term of art that also applies to gun making.  If you look at your contracts for various household and construction services,  you will see that term.   it means don't expect perfection, just the level of work most trades people deliver.   The standards where much lower in the 18th century.    If your gun looks like it was machined and assembled by a robot,  you got it wrong.

[Acer Saccharum]

High grade shotguns have aligned screwslots.

Buy the gunmakers screws with extended heads(a wood or machine screw with an extended cylinder for the head), screw them into place, then mark on either side for slot alignment. Take the screw out of the gun, cut the head down, then cut the slot in the marked position.

[KLMoors]

I like to see the tang screw lined up. Just my taste.

I snug it down and if I need to move it some more, I take it out, chuck it into my drill press, turn it on, and trim the underside of the head a little bit with a 3 corned file.

[dannybb55]

European Rifles screw slots lined up, at least central European rifles did.There are several countersinks for sale in the antiques section on E Bay. While you are looking, bid on a couple of braces. I just used mine to countersink my butt plate for two stocks and they cut like the brass is butter.. They work nice on iron too.
                                  Danny

[whetrock]

Like Mark said, it's out of place on most longrifles. So if you are going for a historically correct look on an American-style longrifle, you might not need to worry about lining them up. When you look at old longrifles, the screws are (almost?) never lined up. (Note: You'll find an occasional screw lined up, but don't find the whole set of screws aligned. So that leaves you to wonder if even those the do line up were lined up intentionally. Of course, there may be exceptions...)

That said, if the build you are working on really calls for it, then you can use "gunmakers screws with extended heads" (Acer Saccharum's note above) to get them lined up the way you want. Or you can just make the screws yourself. The result is the same. To make this kind of screw, turn down (or file down) a rod to the size of screw you need, then thread it and fit it to the hole before you cut if off and finish making the head. Screw the threaded rod down snug in its proper hole, then mark on it where the slots should be oriented. Then pull it out, cut it off, file it to near finished shape, then saw the slot, then finish file it (or turn it, if you prefer).

When sawing the slots for that kind of build, you may want to grind the "set" off the teeth on a hacksaw blade. That way you get a fine, perfectly vertical slot without the rough edges left by the cross-cut set on the teeth.

But, again, if you are going for a historical look, it may not be necessary for your to approach the slots that way, either. It all depends on what you are trying to represent. The slots on some American rifles seem to have been filed by a very narrow triangular file, rather than sawed. So, all that is a reminder that it's helpful to study even those little fine details on any historical rifle that you hope to represent with a contemporary build.

Re your question about countersinks: "Also, how does one countersink so that the bevel is equal around the drilled hole?"

How many cutting edges are there on your countersink? In general, the more "teeth" it has, the less it chatters, and the smoother the cut. The smoother the cut, the easier it is to keep it smooth and even around the hole, and to get it matched up well to the screw head.

[QuanLoi]

Thanks for all of the excellent answers...

[David Rase]

I have been watching this thread evolve for the past couple of days all the while biting my tongue.  Reason being, QuanLoi posed the question on how to line up the screw slots on a long rifle project he is currently building.  I see that less than half the responses address the original question and the majority of the responses are the personal opinions of the poster.  I did not see where QuanLoi ask for opinions, he ask "how to judge the amount of countersink to drill in order to get the screw slots to line up a certain way".  The decision to "align or not to align" is irrelevant.  Just an observation.  Maybe I need to finish my first cup of coffee before posting.
David 

[Jim Kibler]

And as to the original question, keep adjusting countersink depth and have a number of screws you can try.  Not all the slots are cut in the same orientation relative to the threads.  As to the queston about alignment, the vast majority I'm cerntain weren't lined up, but there are a few that still have pretty much aligned screws today.  An Eister box comes to mind.

[mattdog]

"I have been watching this thread evolve for the past couple of days all the while biting my tongue.  Reason being, QuanLoi posed the question on how to line up the screw slots on a long rifle project he is currently building.  I see that less than half the responses address the original question and the majority of the responses are the personal opinions of the poster.  I did not see where QuanLoi ask for opinions, he ask "how to judge the amount of countersink to drill in order to get the screw slots to line up a certain way".  The decision to "align or not to align" is irrelevant.  Just an observation.  Maybe I need to finish my first cup of coffee before posting.
David

Well said and I think it needed to be said.  He only asked for techniques for lining up screw slots.  Personally I do like KL MOORS does.  It is simpler for me and I like to align the tang screw slot with the barrel.  It is a nice touch on any gun.

[Bob Roller]

I have taken the countersink tool and by using a hand vise which can
be a drill chuck with a handle and then turning the tool by hand in the
already established hole,an alignment can be achieved. It is basicially
"cut and try"but it works.

Bob Roller

[T*O*F]

I have taken the countersink tool and by using a hand vise which can
be a drill chuck with a handle and then turning the tool by hand in the
already established hole,an alignment can be achieved.

I do likewise, except I don't use the hand vise.  I just hold the countersink between my thumb and forefinger and turn it by hand.  If you have a slight mis-alignment between the screw head and the countersink, you can lean the countersink to correct it.

[Dphariss]

I agree with both Dave and Jim.
It is easier to achieve alignment with a number of screws. But they are usually only off by 3/8 to 1/4 turn anyway. So careful work with a countersink will fix the problem. But it only requires a few thousandths of an inch so work slow or you may end up with a too large countersunk hole.

Then with use or changes in the stock they may go out of time anyway. I live in an area where wood shrinkage is not uncommon and its best to set on one's hands when wood arrives to let it age some, maybe after cutting it out for example or ordering wood 2 years ahead of time. But I have a piece enroute now that I needed last month
Procrastination thy name is Dan.

If the screw already fits the hole perfectly for diameter, the best option is more screws or peaning the shaft slightly and carefully to stretch it.
Dan

[Roger Fisher]

trial and error.

Agree,, the one that gets me is the screw head in the sharply curved top of a Tennessee butt plate..

[whetrock]

I guess I don’t understand why some find the addition and discussions of “opinions” so offensive.

Many of us have little opportunity to study actual rifles, we only study photographs. And we use books and videos that are full to the brim with “opinions”. Some of those opinions are worth discussing.

For example, the famous book Recreating the American Longrifle by Buchele, Shumway, and Alexander (I have the 4th ed., 1983) says on page 75:

“The head of the [tang] screw may be finished flush with the top of the tang, or be slightly rounded. And the finished screw, when firmly tightened into place, should have its slot parallel with the axis of the barrel….”

That was Buchele’s opinion, and it has influence thousands of builders since the day it was first published. But at the same time, on page 46 of the book, Buchele showed photos of the tang area of 7 original rifles. Only one of them has the tang screw perfectly aligned. (Perhaps others had the screw aligned at the time of the original build, but if so they have since shifted.)  In a similar way, most sketches that Buchele included of hardware have the screws aligned in the sketch. Those sketches are instructional; they shape peoples’ ideas of how they are supposed to build. And yet the photos of original hardware that he included in his book (almost without exception) do not show the screw slots aligned. I think that kind of opinion and observation is worth discussing in a thread on how to align screw slots.

Nuff’ said on that. (For anyone actually interested… one obvious exception in same book is a photo of an outstanding rifle by Herman Rupp (date 1793, Lehigh Valley school) that did indeed have the three wood screws in the finial of the patch box aligned on the axis. (see p. 140)

[chuck-ia]

Seems to me once the stock and barrel have settled in a bit, taking the barrel out a time or two, the slot won't line up anymore? chuck

[whetrock]

Yes, that's right.   Your observation is esp important regarding the lock bolts and tang bolt (tang screw). Even if the smith took the time to align those screw slots at the point of build, the slots on those screws may not have stayed aligned very long. On many old rifles those screws slots show considerable wear from having been taken in and out.

In contrast, the wood screws that hold the patchbox, toe plate, butt plate, etc. were less frequently if ever removed. (Usually only removed if a repair was required.) And so observations of the screws on the hardware gives us a way of guess as to whether or not the original smith in question was or wasn't concerned about lining up screw slots.

[Dphariss]

Frankly when building a Kentucky rifle aligning the screws is way down the list of things the maker should worry about.
Worry about the lines and inletting, nobody is going to pay much attention to the screws. Aligning them is an option. Getting the lines and shaping right is not. These make or break a rifle.

Dan

[Jim Kibler]

Heck yes Dan.  I often hear people worry over small details, but then the work often lacks some of the very basics of what constitutes a fine longrifle.  Give it a foundation of of appeal and many small details become much less significant.