Timing - Good Times?

[Bryan Perry]

I am interested in understanding more detail on timing. Clearly the "clocking" of the screw slot is consistent on the Parker Shotguns.

The few Parker fasteners I have worked with seem to "bottom out" (full torque) at an exact vertical or horizontal position.

A) Was this achieved in the original manufacture using a torque tool?

B) Was the head rotation planned to that level of detail for a given thickness of grip length?

B) Was the vertical or horizontal position achieved by backing off from a fully torqued position?

C) Other method?

Thanks for any insight, observations you guys can provide on fastener timing.

[Brian Dudley]

You may be severely overthinking the whole thing.

The alignment of the screws is completely intentional ans is simply a function of aesthetics and quality of workmanship in the end product.

[Mark Ray]

Brian, i think he is asking HOW the timing is accomplished?

[Tom Flanigan]

Aescetics aside, there is a functional reason to time screws. You can easily tell if a screw is coming loose and can tighten it down before the screw is lost. I think that is the primary reason for the practice with ascetics being icing on the cake.

[Daniel Carter]

Use the search function and you will find Mr. Dudley gives an explanation of how this is done.

[Bryan Perry]

Looks like there has been some constructive discussion on this topic in the past. The search engine works! See "Default Screw timing, and dings" from 10-28-2013, 12:28 PM:

"If it needs more of a turn to go home, chuck the screw up in a drill press and while spinning file material off the underside of the head. Do this a little at a time and keep checking until the screw times correctly."

I suspect several screws will require replacement on my Great Grandfathers 10 Gauge when it is restored so it would just be helpful to know more about what goes into a successful and correctly timed screw replacement.

Having worked with and engineered a variety of complex fasteners for aerospace applications, including very high strength fasteners used on the Space Shuttle and other advanced military and defense applications - I do find it interesting to learn more about the physical process of ensuring the proper torque is achieved when the screw is at a specific point in the rotation.

But really? "Severely overthinking the whole thing"?
Guilty as charged!

Here is a link to the 2013 discussion:
http://parkerguns.org/forums/showthread.php?t=11770&highlight=timing

My thanks go out to Daniel Carter for the search suggestion.

bryan



You may be severely overthinking the whole thing.

The alignment of the screws is completely intentional ans is simply a function of aesthetics and quality of workmanship in the end product.

[Brian Dudley]

What I mean about overthinking is when talk about torque specs come up and if the screws/threads are made specifically to line up slots when “torqued”.

The screws are installed to be tight. Not according to any specific measureable torque. And they are fitted also to have the slots aligned north/south when tight. This can be achieved a few different ways.

[Dean Romig]

Right, and after tightening the new screws into their respective place they are marked for alignment, removed, trimmed, polished and then the slots are cut according to how they were marked.





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[Brian Dudley]

However, at the factory the screws had their slots cut before installation and the alignment was gained by fitting under the head. I know this due to several new old stock screws that I own that are high headed with slots cut in them already.

I personally prefer to cut the slots after the screw has been installed and tightened. And anyone wondering how this is done can use the search function and find threads on it.

[William Davis]

Like Brian said more than one way to skin a cat. Lot depends on the fastener size and application.

Most times you time fasteners by removing material under the head. In a lathe you can just about get a screw timed by calculating how much it moves per turn and removing what’s needed to time. I like to get it close using a indicator then very light cuts to bring it into time. Best example I can give is installing a rifle barrel. It has to screw up tight and keep extractor cuts sight screws & dovetails properly alligned. How tight is more feel than measure with something like a torque wrench. Octagon barrels alignment is particularly critical. Round barrel often times not difficult, fitting the barrel and cutting for extractor and sights after. About the same idea as cutting the slot after the screw bottoms out.

It’s a important gunsmith skill.

Willam

[Jerry Harlow]

But it makes one wonder why the hammer screws go vertical (perpendicular) when every other action screw goes parallel to the barrels on a Parker. Just wanted to be different I guess.

[Scot Cardillo]

To expound on William’s explanation when he says you can calculate how much material to remove under a screw head.

The calculation is very simple. Divide one (as in one inch) by the pitch of the thread, that’s it. Knowing the pitch of a thread will tell you how far any given fastener will advance when it’s rotated exactly one full revolution.

For example, a pitch of 20 threads per inch (tpi) is calculated as follows: 1 ÷ 20 = .05. In other words, one full revolution of a 20 tpi screw will advance fifty-thousandths of an inch (.05).

A screw thread with a pitch of 48 tpi will advance .0208 per full revolution. (1 ÷ 48 = .0208)

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To expound even further on the subject of threads, for those who are interested; a fine thread is generally stronger then a coarse thread (mechanically). The trouble with a fine thread in some cases is how many turns the hardware requires to drive the fastener home. This is resolved by machining multi-lead threads. For example, a 20 tpi double lead thread will advance twice the distance as a single lead thread or, one hundred thousandths per revolution. (.1). That’s achieved by chasing two separate threads with a pitch of 10 tpi that begin (and end) exactly 180 degrees from one another on the workpiece. A triple lead thread - same thing only now the workpiece has three individual threads that begin, and end, exactly 120 degrees from one another. From an engineering and manufacturing perspective, the number of leads is basically unlimited, especially since the advent of CNC that greatly benefits set-up time in comparison to setting up an engine or tool room lathe to achieve the same thing. On a CNC lathe, or mill using thread mills, it’s literally a few additional lines of code and you’re all set.

[Dean Romig]

Interesting stuff Scott - you must do that as a profession.





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[William Davis]

Threads and threading is a fascinating study. To go into detail get a copy of Machinerys Handbook. The big thick one, they come out with new editions often & the most current is expensive. Older editions inexpensive used and for a topic like threading just as good.

I am a hobby machinist and always impressed what a true machinist can do. Sadly it’s becoming a lost art.

William

[Tom Flanigan]

The level of knowledge on this board always amazes me.

[Kevin McCormack]

The level of knowledge on this board always amazes me.

The level of anality also amazes me!

[Kevin McCormack]

For the umpteenth time, INTERNAL COMBUSTION ENGINES ARE 'TIMED'; SCREWS A 'QUALIFIED'!!!!!!!

[Tom Flanigan]

OMG Kevin. I'll try not to make that mistake again. Fall is coming. If you make it to Millbrook this year, let me know. Maybe we can round up a few grouse and woodcock.

[Dean Romig]

For the umpteenth time, INTERNAL COMBUSTION ENGINES ARE 'TIMED'; SCREWS A 'QUALIFIED'!!!!!!!


HA! Gotcha Kevin! You made reference in Russ Jackson’s For Sale thread to the screw in the stock head not being “TIMED” with no cross-reference...:bigbye:







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[Daryl Corona]

[QUOTE=Dean Romig;250422]HA! Gotcha Kevin! You made reference in Russ Jackson’s For Sale thread to the screw in the stock head not being “TIMED” with no cross-reference...:bigbye:


I knew exactly what Kevin meant as we chuckle about "timed" screws quite often. There also is the debate over water table vs. action flat. Please don't let either keep you up at night:rolleyes:

[Dean Romig]

Yup, tomatoes - tomahtoes...

Breech balls and fences too.






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[Mark Ray]

My Grandad was a master cabinet maker, and often used the term “timed” or “clock faced” to describe common orientation of screwheads. I have a chest of drawers and a desk I have had since I was a little kid that he made. The screws holding the drawer pulls, although hidden from view are all perfectly vertical in orientation.

[Dean Romig]

Aligning screwheads on any given product lends a ‘finished’ appearance to the work and serves to give the buyer confidence in the care and attention, and pride, given by the craftsmen.





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[Scot Cardillo]

I never came close to becoming a master but, before stepping foot into a machine shop, I apprenticed in a cabinet shop for a couple yrs. "time the screws" was the nomenclature always used for the task that is the subject of this thread. Later, once I made my way into a machine shop, the "proper" term was indeed, "qualify" but really, it's all in the context of the objective at hand. In other words, if adjusting a bleed screw to get the timing right on a machine peripheral to assure a proper sequence of events..you TIME the screws. If machining a screw that has divisions on its face designed to line up against a mating parts fixed division, you set the TIMING in order to QUALIFY the assembly.

My Grandad was a master cabinet maker, and often used the term “timed” or “clock faced” to describe common orientation of screwheads. I have a chest of drawers and a desk I have had since I was a little kid that he made. The screws holding the drawer pulls, although hidden from view are all perfectly vertical in orientation.

[Brian Dudley]

Oh... the grouse don’t care what direction the screws are pointing. So I have been told before about these details as well as others.

[Michael Meeks]

Oh... the grouse don’t care what direction the screws are pointing. So I have been told before about these details as well as others.

PM sent

[Scot Cardillo]

There are likely a great many pirates rolling in their graves every time they hear a MarLINE knife referred to as a Marlin knife..wonder how many poor souls had to walk the plank for that one..:rotf: