IOTW CD 292 vs. CD 296 Discussion

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CD 292 vs. CD 296 Discussion

On 11/09/2009, Peter Persoff reported on ICON that Woody has assigned CD 296.2 to the insulator discussed below. This is the left most shadow profile as shown here PicturePoster #215029854, and the middle insulator as shown here PicturePoster #203551810

Current Discussion

John McDougald commented on Fri, 10 May 2008

I have been randomly asked to provide a question to ICON, so here's one that comes up every time the price guide is reissued.? Actually, it's a series of questions relating to the two CD's shown above.? The ultimate answer has to come from Woody, but what I am looking for is input.

1.? What insulators do you have that you call CD 292?

2.? How many different profiles are there?

3.? To whom to you attribute the manufacture of the unembossed ones?

4.? Can you provide pictures of each?

5.? Same set of questions (1 - 4) for CD 296.

6.? What do you believe are the distinguishing characteristics of each CD?

7.? If you were "in charge" for a day,?would you add CD numbers, combine them, or rearrange them in some way to more accurately reflect what is out there.

My ultimate objective is to gather a set of pieces, send them to Woody and let him make a judgment with all of them sitting in front of him.? Please contact me privately if you are willing to send pieces to me for this project.


John McDougald

Bill Meier commented on Sat, 11 May 2008

Here are the "three" CD 292's and CD 296's drawings that appear in the Price Guide. Used with permission. See PicturePoster #215029854

Look at John's reference email for the details he would like to see.


Dennis Stewart commented on Sat, 11 May 2008

The CD 292 outline drawing on the Grampa Mac Website of the online price guide shows the PRISM style which is like a CD 280 with a notch cut in the top for a wire groove. However if you choose PRISM for the primary embossing it says none found. The PATENT JUNE 17, 1890 embossing is on the totally different shape and style which is the one that needs the new CD assigned. The guide has the primary backwards on these two styles. The 1890 embossing doesn't appear on the PRISM style as pictured in the line drawing. Nor does the No Embossing variant come in the style that looks like a slashed top CD 280. It is the other one that needs the new CD. I don't recall ever seeing a true CD 296 with a Prism embossing. The confusion lies in the two so called variations of CD 292 and should be disassociated with the CD 296. CD 296's are Lockes and no name No. 20's and often rest on extended middle skirts. Neither of the other two styles do. If the true CD 292 matches the line drawing, then the Prism embossing needs to go with it instead of the 1890 and No Embossing and those should be assigned the new CD. It's tough to explain it any other way. Helps to have one of each sitting in front of you. As a side note, the term PRISM is a misnomer anyway since if you have ever seen a Knowles catalog you would know the logo symbol is actually an Emerald.

Paul Greaves commented on Sat, 11 May 2008

Well, since you asked...!

If you are ever going to sort out the CD numbers, you have to have some sort of basis to work from. What is the definition? What differences are "important" enough to merit a different number? Is there a definition of what merits a decimal number vs. a integer number?

I realize this is not how it works, so I won't go very far with this. If it was me, I think I would heavily weigh the intended use into the equation. As collectors, another practical side of it would be to ask the question, "does assigning a different number reduce the potential for confusion in identifying something"?

So anyway... I think I would call the ones with the narrow wire groove CD292. They come embossed with just the patent date, and they come unembossed. The narrow wire groove and unique crown design indicates that they were designed for a specific use with smaller gauge wire. I think the marked ones were made by the Elmer, NJ glass houses, and by Brookfield. Knowles listed them in their catalog, and even had a special name for them (the "Lachine triple petticoat"), The unmarked ones are a bit of a mystery, but could date to earlier Elmer production.

The ones marked with the Emerald (Prism) are also listed in the Knowles catalog, as the "Knowles triple petticoat", so apparently they saw merit in listing and selling both designs. It would seem that the essential difference is in the crown design, especially in the top groove diameter accommodating a larger wire on the "Prism" type. Interestingly the catalog lists them both as 4-1/2" diameter even though the actual specimens are a little smaller for the "Prism" type. So in any case, they should not be the same CD number.

So what to do? I guess I would lump the Prisms in with the CD296 if that is the only other choice. An argument could be made that they should have a unique number, perhaps CD296.x. Hmm... looking at the CD diagrams, I really don't see any essential difference between CD296 and CD295... I am sure they are just Hemingray and Brookfield/Locke examples of the same product (that is, electrically they were direct competing products). It is true that the Lockes are sometimes found with extended inner skirts, but that seems to be a function of production variance due to extra glass. The small difference in diameter is less than the variance found in other CD numbers (in fact, my Hemingray actually measures 4-5/8" which is very close to the Lockes).

I think there are some CD296 unembossed Brookfield products that are just like the Locke or "No 20" varieties. Perhaps they are unembossed due to a very worn mold.

Here is a radical idea... move all the Locke & No 20 (and the similar unembossed one) over to CD295. (Make the drawing indicate 4-1/2 since that is close to both.) Then the CD296 can be dedicated to the "Prism" type, with the drawing changed to indicate 4-1/4" like the actual examples. Leave the 1890 dated Lachine & it's unembossed counterpart as CD292. Since you asked... :-) -Paul Greaves

Bill Meier commented on Sun, 12 May 2008

If it was me, I think I would heavily weigh the intended use into the equation.

To me, that's the dangerous part... It's hard enough understanding the CD system, now you have to know what function the insulator was used for before you can look it up? Naw...

The CD system should be based on shape alone. Yes, some shapes had specific uses, but focus on the shape first... that should drive the CD number...


Bill Meier commented on Sun, 12 May 2008

The CD 292 outline drawing on the Grampa Mac Website of the online price guide shows the PRISM style ...

Look at PicturePoster #215029854

These show all three drawings... the middle drawing is not in the on line version. These are the 2007 drawings, although I don't think they have changed from 2003...

I also added the primary embossings as currently listed in the 2007 guide.

For reference the PG lists the following primary embossings for each:

CD 292 (I assume this includes CD 292 "alt" as well) - NO EMBOSSING and PATENT - OTHER (JUNE. 17 1890)



Paul Greaves commented on Sun, 12 May 2008

I am not recommending what you thought I said, I am just saying I would "heavily weigh it into the equation". The intended function will affect the shape, so in the end it is really the same thing. I am saying that I think it helps justify when differences in shape merit different CD assignments. That is, is the difference enough to be "significant".

I am not recommending CD assignments based on function! Based on shape similarities is clearly the best choice! -Paul Greaves

Ron Yuhas commented on Mon, 13 May 2008


Ahh..... the great CD 292 and 296 controversy. I guess I will throw in my 2 cents worth... or is that 3 cents with todays postal increase?

Under the CD 292 listing at the bottom of page 205 in the 2007 guide there is a diagram and it claims that it is the "No Embossing" style. I am fairly certain that there are no insulators without embossing that match that profile. The actual CD 292 insulator with no embossing matches the profile at the top of page 206 listed as the "Patent Other" style. I have this unembossed style that sits flat on its outer skirt and also with 3/8" extended inner skirts both in a blue color. The Patented June 17 1890 insulators and the unembossed style I have noted are virtually identical in molding characteristics. I consider the extended skirt insulator to be a CD 292 also. The CD 292 is distinctive for its narrow wire groove and the flared indented part that comes from the wire groove down to the neck of the insulator.

The CD 296 style includes the Locke No 20 styles and the No Name No 20 styles. They are distinctive with their wide wire groove and flat area between the groove and the neck of the insulator. The insulators may sit on their outer skirt or may sit on an extended inner skirt but I feel either style is still a CD 296 since the crown and body of the insulator are identical. There is a listing under the CD 296 for a Prism insulator. My biggest heartburn is where does this Prism listing belong. It does not match well with any of the profiles shown. It measures 4 1/4" at the base not 4 1/2". It has a wide wire groove but no flat area or indention below the wire groove.

Ok what do you do? Change the profile at the bottom of page 205 to be 4 1/4" and refer to it as the Prism style CD 292 and move the Prism listing under the CD 296 to the CD 292. Or move the profile at the bottom of page 205 to the CD 296 area and change the base size to 4 1/4" and refer to the profile as the Prism Style CD 296. Or create a new CD for the Prism Style. I am not a big fan of creating new CD numbers for existing insulators unless it can be shown that there is good reason. One thing if Woody did create a new CD it would not cause huge price changes since the Prism is not a rare item. If I were "in charge for a day" I would probably go with the first option listed.

I will try to post some photos in the morning.

Best regards, Ron Yuhas

Dennis Stewart commented on Wed, 14 May 2008

Therein lies the problem. It is the original 292 that has the prism embossing, not the "alt" or the 296. The original 292 has no listing for the prism embossing. To me, the 296 prism embossing listing is in error. Based on the three line drawings, the one on the left, the original 292, the reworked round top 280 design with the groove notched in, is the only one of the three I have seen in 35 years to be prism embossed. And all are embossed that way.

To me, the recent picture posted by Dan is a 292, not a 296. Because of what I believe is a price guide error, everyone is assuming their prism embossed pieces are 296 because of where the listing falls. The crown designs are the key and not the dimensions. I have three of the "alt" 292 pieces and no two are the same height. 296 examples are all over the board. Still would like to see a piece that looks like a Locke No. 20 with a prism embossing.

Andrew Gibson commented on Thu, 15 May 2008

After one of the discussions we had about the differences between CD 292 and CD 296, I put together a Picture showing the differences, and linked that to a bunch of other photos that had been posted to ICON. This picture

PicturePoster #203551810

shows the three insulator profiles in question -- unfortunately, it is in a slightly different order from Bill's posting PicturePoster #215029854 showing the scale drawings, but it does show the same profiles. And it captures a lot of the facts and I think has a good discussion of the details involved.

My personal feel is that the PRISM is a CD 292. Prior to 2003, there was a CD 292 PRISM in the price guide. The dimensions match the CD 292 more closely than the CD 296. And even today, the PRISM insulator in question is an exact match for the scale drawing that is shown as a CD 292 in the price guide. However, I'm in full agreement that the real way to settle the issue is to take all three of these insulators to Woody in person, and get a definitive answer.

I gathered together all the discussion that I can find on this topic, and put it in the wiki at [[1]]

Prior Discussion

Ron Jenkins commented on 18 November 2007

There is no such thing as a 296 prism in any color. I bet no one can prove me wrong if they read the price guide.

One more thing, If anyone can prove there is a 296 Prism in existence according to of the price guide size and demensions of a real CD 296 Locke please post a picture

Paul Greaves commented on 18 November 2007

There certainly seems to be something strange going on regarding CD292 and CD296 in the price guide. There are two CD292 drawing outlines shown, with one looking very much like CD296 in outline. That one is indicated as the "no embossing" style, yet I have never seen anything like this with no embossing! I have a no embossing that matches the other style shown on page 206 (it was in fact made in the exact same mold as one of my "Patent - Other" examples). I think that must be the CD292 "No Embossing".

My Knowles prism examples exactly match the CD292 drawing on page 205. Yet they are listed under CD 296 (actually, I have both SB examples and a {MLOB} example, both types with a Prism embossing). My guess is that the drawing on page 205 should be a variation of CD296. I guess the final answer would be up to N.R.Woodward to rule on. Paul Greaves

Andrew Gibson commented on 19 November 2007

I had a discussion with N.R. Woodward and John McDougald about the CD 292/296 Prism a fair while ago, probably shortly after the 2003 Price Guide came out and I noticed the change. Previous to 2003, the PRISM piece was listed as a CD 292. In 2003 and 2007, this piece is listed as a CD 296. I sent a photo (which I can't find at the moment) which compared all of these insulators side by side, as well as some others. Woody wasn't sure -- he wanted to see the pieces in question in person before he was willing to make a call as to what he thought. I forget what John stated as the rationale for moving this assignment -- John, do you happen to remember why this was moved?

Personally, I really feel that this PRISM is a CD 292. The dimensions match that for the 292, and as Paul Greaves points out, this piece exactly matches the CD 292 shadow drawing. Something definitely isn't right here.

Here is a CD 292: [2] Here is a CD 296: [3] And here's the CD 292/296 PRISM: [4]

Bill Kemp commented on 19 November 2007

I posted this back in 2003 also after talking to Ron Yuhas. There is no CD 296 prism which we both agreed on.. Comparisons are at PicturePoster #56486990 and PicturePoster #56486817

In Fact the Prism is neither a CD 292 or a CD 296 and deserves a different CD number. Size is different as is the top.

Andrew Gibson commented on 19 November 2007

Bill Kemp said:

>In Fact the Prism is neither a CD 292 or a CD 296 and deserves > a different CD number. Size is different as is the top.

I'm not Woody, so I can't say for sure whether it "deserves" a different CD number. Elton had a similar feel with the CD 287.2 variants, thinking that they shouldn't be the same CD same when they currently are. Elton said that he has pointed out the 287.2 variants to Woody, and Woody didn't think that they were different enough to justify a new CD. Woody has a number of criteria for determining whether something should get a different CD number or not -- I do know that there have been some cases where he has said that a difference in crown detail was not sufficient to justify a new CD. And a 1/4" difference in size certainly isn't so much that in and of itself it justifies a new CD number.

"Consolidated" is a key word -- there are plenty of insulators that are similar but different and still grouped under one CD (though I will also readily admit that there are many that are very similar and yet have different CD numbers). If you want a definitive answer, someone needs to show Woody these insulators and get the "correct" answer. In person -- as I said, I showed him these insulators in photos already, and he did not reach any conclusion.

My personal feel is that this insulator is definitely not a CD 296, in spite of being listed in the Price Guide that way. I'm comfortable with it being a CD 292, though I would agree that it is definitely different than the PATENT - OTHER 292. Different enough for a different CD? That I don't know.

Ron Jenkins commented on 19 November 2007

The price guide suggests that a CD 296 Prism embossed insulator exists in the same size and demension and in all the good colors as a 296 Locke insulator but in reality does not. They list the CD 292 no embossing variant as only coming in blue and aqua but in reality comes in lime green and yellow green also and they all are prism embossed so in reality there is no unembossed variant of a CD 292. the only thing it has in common with a CD 292 Locke version is the demensions. Now I don`t care if they call it a 296 or a 292 call it a 292 point whatever but it really needs to be addressed in future price guides so collectors don`t beat thier head against a wall looking for these insulators that don`t exist. I have seen them called 292 in some auctions and 296 in others and on icon for sale list as both 292 and 296 and it can`t be both so it is as confusing as hell. Hope we get this right sometime. Ron Jenkins nia 3491

Ron Jenkins commented on 20 November 2007

Actually the prism don`t match the demensions as a 292 since it is 4& = 11/8 inches across the base rather than 41/2 inches just the same highth = as a real 292

Paul Greaves commented on 21 November 2007

Yes, my specimens (with the Prism embossing) are just like you say... = being about 4 1/8" diameter. I guess it shows that the manufacturer = wasn't very good at meeting their own specifications! Paul Greaves

Ron Yuhas commented on 25 November 2007

I would like to throw another log on the fire on the CD 292 - 296 controversy. The 2007 price guide shows a CD 292 drawing on page 205 that is listed as a no embossing style. I have never seen a no embossing style that looks like that diagram. The Prisms that I have look identical to that diagram except they are 4 1/4" wide at the base rather than the listed 4 1/2". I have never seen a Prism that looks like or has the measurements of the CD 296 where they are listed now. Prior to the printing of the 2007 guide I had sent John McDougald a letter on numerous items and one of them was that the CD 296 Prism listing should be moved to the CD 292 This did not happen so John have had a reason. I still feel that if you go by the current diagrams in the 2007 guide that the Prisms are CD 292's.

Daryl Richardson commented on 26 November 2007

When dealing with Prisms, and the two CD's 292 an 296, there is only one thing you need to know. On 292's, the area where the saddle meets the wiregroove is recessed. On the 296, there is a ridge, such that the base of the ears along with the ridge form a complete circle above the wiregroove. Measurements vary greately inside of any given CD due to mold variations and you can often expect up to 1/4" of variance in any given dimension. The skirt of a 292 also has a smaller radius as it curves from the base up to the wiregroove where the 296 is more gradual.

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