Determinig thickness of ticking.

[rogervan]

Hi,

I'm in the position of having to go and pick out 0.02 ticking. If I get a micrometer, won't it push in on the sides of the cloth, giving an unreliable test result? How about holding two microscope slides together and measure that. Then, cut one of them in half, putting one piece behind the cloth and the other on top of the cloth. Then measure the glass/cloth sandwich. That way I get the thickness of all three components. Then I use subtraction of the first from the second, getting a "good" measure of the ticking's thickness. This sounds good to me, but I'm a raw beginner and there might be fatal flaws in my proposed plan.

Any input on this subject?

Clffdvr

 

[BrownBear]

Your approach would certainly work, but seems like a lot of trouble unless you need to be really, really precise.

And you're right. With a dial caliber it's possible to compress the fabric quite a bit.

I standardized my method, which while it gives me consistent results, might give different results from anyone else.

I dial down while slowly pulling the fabric through the caliper, stopping when the fabric finally resists enough to just stop. I have to try pulling the fabric with the same force each time, but I bet I'm not too far off. I do this in three or four places on the fabric and compare results, and call the average my measurement. I could be a thousandth off from someone using different techniques, probably on the high side compared to someone who simply screws the caliper down till it won't screw any more. Of course, the thickness we worry about for patches is the compressed thickness, so the latter method might be more realistic. But I just hate screwing a caliper down till it won't screw any more. Seems like lots of that could eventually damage the caliper.

 

[twotoescharlie]

micrometer, most have a limiter so that you cannot over compress

TTC

 

[paulvallandigham]

You method will work, but you are making far more out of this than is necessary. When I measure cloth with a micrometer, or caliper, I tighten the device until I can just pull the cloth back and forth with some fricition. If you use a " Crush " fit with your instruments, you get a much wider range of sizings, simply because the cloth will try to move sideways as it is crushed. that is what happens inside the barrel of your gun when loading a PRB.

Since cloth thickness is not an exacting " science", and really is not a concern of the fabric manufacturers, you can go crazy trying to get " exact " thicknesses. If you find a fabric that is within .002" of your desired thickness, it will probably be good enough. Between the effect of the lube in the fabric fibers, and the squeezing of the patch down the barrel on lands and grooves, a bit of an " allowance " must be assumed. If sealing the gases is of prime importance, then use Over Powder Wads, or fillers, to do that job, and let the patch material simply grab and hold the ball to the rifling so that the ball is spun as it leaves the barrel. The lube protects the patching from burning in the barrel, and if you lube the barrel AFTER seating the PRB, the additional lube will both protect your barrel from rust, and provide extra lube to the patch to insure that the cloth does not burn. I also find I get about 20 fps MORE velocity with the same load, due to the reduction in friction between the PRB and the barrel because of the extra lube. I also achieve a lower SDV for a given load of powder, again, because there is much less variation in the friction coefficient when the barrel is lubed in front of the bore.

 

[rogervan]

Hi Paulvallandigham,

This will prove beyond any doubt that I'm a rank beginner. I need to ask what these terms mean: PRB and SDV.

It occurs to me from your response to my question, that I actually do want the crushed thickness. As you said, the patch cloth compresses a lot in the barrel.I just need to get a micrometer now. Very good, I'm almost ready to shoot this rifle.

One day I'll take photos of it and give the photo's URL on this forum, so you-all can get a look at it.

Clffdvr

 

[paulvallandigham]

PRB is Patched Round Ball. Shorthand on the computer.

SDV is Standard Deviation of Velocity. This is a mathematical computation, and not an Average velocity. The lower the SDV, the more consistent the load is, and the better accuracy you get.

 

[trent/OH]

If you can get ahold of this month's copy of Muzzle Blasts, you will find the Bevel Brothers have written an interesting article on this very topic. I won't synopsify it for you now, but if you can't find a copy let me know and I'll mail it to you.

 

[Bobcat]

IMHO the micrometer compressing the ticking is similar to the compression that occurs on loading so it should give an approximate "effective thickness". Although a tight patch and ball combination will compress the patch more than should be possible with a micrometer, the ratchet or friction thimble on the micrometer should not allow you to compress too much. I just bought some ticking today, washed and dried it and then checked the thickness. I was able to get readings from .016 to .021 just by manipulating the fabric by stretching. I've given up trying to get a really accurate measurement, when you find something that works well just buy all you can find/afford.

Bob

 

[paulvallandigham]

Expecting the patch material to compress is okay when discussing rifles, but with smoothbores, there is no place for the fabric to squeeze into, and you have to be more careful about the choice of patch fabric. While you can use a fairly thick patch in a rifle, by using a ball diameter that is .020" less than bore diameter, you are going to be restricted in how thick a fabric you can use when shooting Round Balls in a shotgun or fowler.

 

[CoyoteJoe]

Dutch Schultz does recommend cranking the micrometer down to measure the compressed thickness, you are quite correct that the compressed thickness is what really counts. However, after ruining a micrometer and a dial caliper by over tightening it I gave up that exercise. I employ the same method Paul and others have advised, slip the cloth through the mic and tighten until you feel a firm friction. Then you just have to keep in mind that some fabrics will compress more than others. A tight weave will compress less than a loose weave and linen will compress much less than cotton. I have some linen canvas which measures .020" which actually loads much tighter than some cotton canvas which measures .029". Your measurements will probably not be exactly the same as my measurements but both work for our own personal reference.

 

[Stumpkiller]

"Dutch Schultz does recommend cranking the micrometer down to measure the compressed thickness"

That's one reason I've questioned his measuring method. Crank down the same amount on an empty micrometer and you'll get into negative readings. "D'oh" comes to mind. The "C" bow distorts enough (at least on my trusty Starrett 230 to get a NEGATIVE 0.005" without much effort. The clutch is there for a purpose and you have to zero it with the same pressure you measure with to calibrate it consistantly.

I have also noticed a 0.002" variation depending on where you measure the same piece of cotton tick. I make two long folds to get three thicknesses in the jaws and measure (using the clutch) and then divide by three.

 

[fw707]

Paul, I don't really understand your thinking on how a patch "squeezing into" a rifle barrel is any different than it "squeezing into" a smoothbore barrel.
When you load a patched ball into a rifle barrel the tightness or resistance you feel is the patch against the lands. The patch material that goes into the grooves of the barrel has little or no resistance, so why is there more resistance against the barrel of the smoothbore than the lands of a rifled barrel would cause? I realize that the contact is on the full circumference of the smoothbore barrel, as opposed to 6 or 8 points on the rifled barrel, but how would that significantly change the force required to seat the ball?

I don't mean to insult anyone, but I've been shooting pillow ticking patching since the 70's and I haven't seen any difference in any of it that I've shot. If you spit on it real good and use the right size ball it'll shoot better than most of us will ever be able to shoot.
I don't have a mic, but I do have a set of calipers and every piece of ticking I've checked after reading the posts here measures out within a couple of thousandths.

 

[paulvallandigham]

In a rifle, the ball rides on the lands. That leaves side room for the cloth fabric to squeeze into, along with the fabric that is filling the grooves. In a smoothbore, there is no place to " squeeze ", and therefore, the only way to get a " too thick " patch down the bore is to deform the round ball a bit. That is one reason pure lead balls were used in smoothies. In the 17th and 18th centuries, the bores were not made to within a thousandth of an inch in diameter. Military muskets varied widely in diameter. A .70 caliber round ball might be put in a .69 caliber musket, or in a .75 caliber musket. Using pure lead allows both barrels to use the same ball. I understand that barrel standards accepted bores that range from .65 to .80 " !

 

[longcruise]

I don't measure patch material any more. Too many variables to change the measurement and besides, not all patching that measures the same will load or compress around the ball the same. Some patch material is denser or harder.

When I measure Joannes #40 drill, I come up with .017. Using the same technique, a piece of 10 oz artists canvas measures .022, yet the #40 actually is a bit tighter and harder to start. I guess because it is denser.

Nowadays I go by feel of the material. Most important, IMO, is once you find some good stuff, buy a bunch of it!! Some patch materials are soooo good that its worth going to a custom or hard to find ball size to get the right fit to the bore.

That's just my idea on it and I'm probably way over thinking and over doing!

 

[Elnathan]

In a rifle, the ball rides on the lands. That leaves side room for the cloth fabric to squeeze into, along with the fabric that is filling the grooves. In a smoothbore, there is no place to " squeeze ", and therefore, the only way to get a " too thick " patch down the bore is to deform the round ball a bit. That is one reason pure lead balls were used in smoothies. In the 17th and 18th centuries, the bores were not made to within a thousandth of an inch in diameter. Military muskets varied widely in diameter. A .70 caliber round ball might be put in a .69 caliber musket, or in a .75 caliber musket. Using pure lead allows both barrels to use the same ball. I understand that barrel standards accepted bores that range from .65 to .80 " !

Musket bores did range between those figures, but not among muskets of the same model. The Brown Bess was nominally .75 caliber (11 bore), typically ranged from .72 to .78 or .80 I believe, and fired a .69 caliber ball (14 bore). French and American muskets were nominally .69 and fired a .66 ball. One of the reasons that muskets were typically so inaccurate was that the ball was vastly undersized, so that even a larger than standard ball would fit down a narrow bore. Musket bullets were not tight, period - speed of fire was everything during the flintlck period, and the militaries took care to avoid the situation you describe.

 

[roundball]

All the talk about variances in material, variances in measuring techniques, consistency of a supply source, etc, is mainly what makes me just use the precut/prelubed patches under Oxyoke & TC labels...as a result of quality control they've always been consistent from one batch to the next.

And, buying them like I do, when I find a going out of business sale or a close out auction, I negotiate a rock bottom price if I buy all they have left...sometimes 2000-3000 patches at very, very low prices