Are my nipples shrinking?

[Norton Commando]

Mako,

I love your comparator; it does a great job for measuring the external geometry of the cap. I remember quite distinctly when I saw my first comparator back in about 1974; it certainly seemed like magic to me back then and I'm still in awe of it.

But I missed how you measured the depth of the cap?

I found it tricky to determine this measurement using a depth mic, but that's what I used.  And as you know, depth is critical to how the cap fits the nipple.   

[Mako]

Mako,

I love your comparator; it does a great job for measuring the external geometry of the cap. I remember quite distinctly when I saw my first comparator back in about 1974; it certainly seemed like magic to me back then and I'm still in awe of it.

But I missed how you measured the depth of the cap?

I found it tricky to determine this measurement using a depth mic, but that's what I used.  And as you know, depth is critical to how the cap fits the nipple.  

I like the comparator as well, that one is a medium size table top model which works well for smaller things, it has quick change lenses on a slide for 5X, 10X, 20X and 50X  measurements.  I have some floor models that have optics for 200X and several that have automated inspection capability as well, you just program the inspection zones and it looks for the contrast changes.  It's much easier for the vision systems to detect the shadow line difference than for actual front lit camera systems.

I know a bit about vision systems  because for about nine years I was primarily doing equipment design and automation engineering.  I worked a lot with robotic manufacturing cells and a lot of vision and imaging systems.  I learned that what looks good to your or my eye is not always what looks "best" to the vision system.  Vision systems are all about lighting, I used a lot of back lights (when possible), infrared, strobing sources, polarized apertures and collimated light sources to make the vision algorithms "happy."  

The comparator in my lab has a edge finding capability but only in two axis.  Since the high point of the cap may be on a petal at the front or the rear of the cap the table has to be focused in and out to assure it is the highest point otherwise it will be fuzzy and the edge finder won't find it. They didn't use the edge finder since it takes longer to do the routine, they just put the part up, focused in and out using the cross stadia as a reference until they see the highest point then they place the stadia on that point and record the height.  Several other comparators we have also have focus and "best edge" capabilities and are very fast at finding the "high" edge within the thickness range of the part.  They use a "digital focus" to determine the area of interest and then the optical focus kicks in bring it in to the fine measurement focus.  Very automated and they generate a report in exactly the format you want or port it out to a spreadsheet if that's what you want.

To measure the inside height they used a digital drop gage like this:

For the caps they used a flat Ø2mm tip to drop into a cap after the height was zeroed on the granite plate the cap sits on.  This gives them a height to the bursting disk inside of the cap from the "top" of the cap cup.  All caps were measured in groups of 20 from each tin.  The caps are kept in individual tray compartments in a serialized order until all the dimensions are taken.  Then when filling out the spread sheet the cell formula reports the difference between the the drop gage height just described and the overall height giving the internal height dimensions.  A Ø2mm tip was chosen because the flat on the top of a Uberti or Pietta tube runs around Ø.120 to Ø.139 inches and the Treso tubes runs Ø.145 to Ø.150 inches on the seating flat diameter.

Does that make sense?

Regards,
Mako

[Norton Commando]

Mako,

Your setup for measuring the depth of the cap looks great!

Notably, this setup assumes the outside face and the rupture disc face are parallel, which they may not be. However, referencing from the bottom of the skirt would have similar errors, especially with the irregular-shaped petals on the Remington caps. I referenced from the bottom of the skirt using a depth gauge as shown in the photo. But obviously your technique is far superior to hand measurements as it removes, among other things, having to "feel" the surface that you're measuring. 

[Mako]

Commando,
A depth mike will work even for Remington caps if you hold it "up" in the orientation you show.  If you back light the tool with the cap you will see when a gap appears between the last point of contact with the cap skirt and the micrometer base.  It would be very tedious, but it would work.

In a few cases the differences in the contact points from side to side are slight but a lot of them have this kind of difference.


As you can see from that shot the petal on the right side of that cap is much lower than the other three petals.  You can see the differences on the other caps above too.

I've thought about the irregularities of the Remington skirt length and what would be the best way to determine where they grip on the cone.  I finally decided the longest length would be the best because they seat on the face of the cone which perhaps orients them with the longest petal extending the furthest down the cone.  I guess arguments could be made for averaging all four petals or even the two longest, but I've chosen the first contact point that provides "gripping" force.

When measuring I.D.s I am particularly interested in the diameter at the mouth, I really don't care what it is deeper in.  The tapered shape of the cone doesn't contact the cap interior beyond where it is gripping the cone.  The diameter at the mouth is normally the tightest fit on the cone, but as the cap is pushed down the copper cup deforms and you get contact until the cone taper becomes smaller than the interior diameter.  One last thing to consider is whether the caps have any taper, unless the taper is greater than the taper of the cone then it really doesn't matter either.  Looking at the illustrations, your own tubes, pictures of tubes I have shown on other threads in the past and the pictures of the caps I have shown you can see the taper of caps is insignificant relative to the taper on the cones.

Like this:


The cone dimensions in that illustration above are this (taken with that Optical comparator you like so much   )


One of the reasons the Ø.1683 dimension provided by CCI make absolutely no sense is this:

That of course also applies to the Ø.170 dimension reported that is even greater than the ones attributed to CCI.

Looking at the dimensions on the Treso, the Ø.113 dimension fits the CCI #11 caps (that is if you believe 120 measurements from the chart way back in the thread).  If you put a cap with the Ø.1683 I.D. on a Treso tube (Treso tubes are designed for #11 caps) they would just fall off.  In fact CCI #11caps if they were at the reported dimensions wouldn't fit any of the tubes whether Italian factory or aftermarket.  I have measured both Uberti and Pietta tubes, and with an optical comparator.  With an external feature like the profile of a cone it is extremely easy to get very accurate dimensions using an Optical Comparator.

~Mako

[Crow Choker]

Hey-I love and appreciate all the info and pictures. Glad those of you who understand all the geomatics  and have access and knowledge to equipment and intruments that can measure such things as percussion cap demensions and can share all the information.  BUT, ya know what this is going to lead to??? There's goin to be a run on comparators(didn't know such a thing exhisted), depth guages, pin guages, mics, etc, etc as shooters will be measuring all their caps individually for the roundest, flatest, uniform seating depths, etc, etc just as some bullet casters measure and weigh bullets into groups. A whole new demension on cap an ball shooting!   KLACH-KLACH-KLACH (used to a local character in my home town that when he laughed, it had a KLACH sound to it, some of us still around still mimick him at times with the KLACH laugh)! (probably more information you need to know) (what do ya think Jubal Starbuck?)

[Lefty Dude]

All measurments and assumptions are based on clean cones. As my Treso cones approach the sixth stage of a match the #11 Remmy caps need more force for the seating.
For a Match like the Arizona State Championship in Tombstone last month, which was a two day 12 stage match. After the first day of six stages I removed the barrel for cleaning. The cylinder, I used a nylon brush and brushed the cone's.

I now carry a small brush and clean the cones after 3 or 4 stages.

[Mako]

All measurments and assumptions are based on clean cones. As my Treso cones approach the sixth stage of a match the #11 Remmy caps need more force for the seating.
For a Match like the Arizona State Championship in Tombstone last month, which was a two day 12 stage match. After the first day of six stages I removed the barrel for cleaning. The cylinder, I used a nylon brush and brushed the cone's.

I now carry a small brush and clean the cones after 3 or 4 stages.

Lefty,
That is very true and good advice.  I actually load off of the frame and I brush mine every time before even charging the chambers.  I have a stiff brush I use just for that purpose.  Since I started doing that I don't get misfires from unseated caps.  After every match or shooting session I clean the cones with a brass brush.  If I remove the tubes I use "brass wool" to clean the cones while spinning them on a rod I have tapped on one end to accept the tubes.

~Mako

[Lefty Dude]

FYI, Y'all;

For cleaning the inside of the cones. I use a dental small brush made by G U M they are go-between your teeth brushes. They come in three size's, narrow,medium & wide. The wide brush fits very nicely in the cones and gets them clean. They come eight to a pak. I buy them at Walgreens Drug Store.

With-out ignition you get no BANG-Boom ! 

[Deadeye Dick]

Lefty Dude,
Good idea, I'll have to try it next time. I normally use pipe cleaners.