tardis roundel reference

[Theta Sigma]

One conclusion that I have come to is that we will never get 100% accurate measurements.  Fiberglass warps, and unless someone has the original plug that was used to make the molds, every cast roundel will be different in some way.  I am still convinced that the original plug was made of wood cut using chair rail and other trim router bits.  The profile is just too similar to be a coincidence.  Do a quick web search on chair rail profiles, and you'll see what I mean.

Having said all that, I hope this helps everyone.  

Here is a cross section I cut from a plaster plug pulled from a 3rd generation partial mold of a BBC roundel.



Overlay with my former pattern:



And the former pattern I intend to use printed at 33% scale using Microsoft Paint:



I intend to make more drawings showing the center locations of each arc, and other overall measurements, but I can't put it all on one drawing.  It gets too busy.  I just need to find the time to do it.

I also need to somehow find the time to actually finish the former and make a roundel.  I was finally able to obtain some lime putty to mix with the plaster, and I am hopeful that will be the trick to getting a smooth plug.

[galacticprobe]

One conclusion that I have come to is that we will never get 100% accurate measurements. Fiberglass warps, and unless someone has the original plug that was used to make the molds, every cast roundel will be different in some way.

You're right on all counts, and I believe that even the roundels used on the actual set walls (both the painted roundels and the "natural" ones that let light through) were all slightly different from each other. (So with all of those roundels in service back then, your replica will no doubt match at least one of them!)

I am still convinced that the original plug was made of wood cut using chair rail and other trim router bits. The profile is just too similar to be a coincidence. Do a quick web search on chair rail profiles, and you'll see what I mean.

Oh yeah... I've seen those bits! I also wonder if a special bit was made for this, and they had it welded to a lathe handle so they could turn out a plug on a lathe. At least that way they could turn out several plugs and make several moulds at once. It would have been cheaper in the long run doing it that way, rather than working with different chair rail and other router bits to make one plug. Pouring one mould at a time would have been time consuming, and with all of those roundels they must have had more than one mould. So my money is on the special lathe bit (or gouge, whichever you would call something like this).

Once they'd gotten a dozen or so moulds, which would have been enough to make up one wall panel, the plugs might have been thought of as throw-away items. If you could cast a dozen roundels at once, you could assemble one wall panel while the next dozen for the next wall were curing. Even if you lost one mould you'd still have 11 more - that is if they didn't make any extra moulds for replacements. So unless someone decided to keep one of those plugs as a souvenir, finding one would literally be like hitting the lottery!

I intend to make more drawings showing the center locations of each arc, and other overall measurements, but I can't put it all on one drawing. It gets too busy. I just need to find the time to do it.

You mean like the one Teletran posted here a while back? (http://tardisbuilders.com/index.php?topic=1032.15msg2738#msg2738) The image is right below his quote and it shows all of the "circles" for every contour of the roundel. Yeah... that's going to be a busy drawing! (Good luck... you'll need it. )

I also need to somehow find the time to actually finish the former and make a roundel.

Yes; yes, you do. (How long have you kept us in suspense? )

I was finally able to obtain some lime putty to mix with the plaster, and I am hopeful that will be the trick to getting a smooth plug.

Hopefully that will work. I can only imagine the frustration you've gone through trying to get that plug done without any blemishes in it. (I'd have put my head through a reinforced concrete wall by now!)

Dino.

[tony farrell]

Reading through this thread and looking at the casts which both Karsten and Theta Sigma have, it seems that my drawing of the mould for the roundels is very close to both these versions. It seems the only thing I've got wrong is the fact that the central flat disc and the flange do not lie in the same plane - the central disc is recessed when compared to the flange.

I worked out the dimensions from the Replica Prop Forum's photos of the roundel which - according to their site - was a screen-used roundel and which had come from the main Tardis (zig-zag) doors. I worked out the width of the moulded circular section as being 83 mm. Because I failed to realise that the central disc was deeper/more recessed than the flange, this means that I under-estimated the width of the moulded section and - allowing for the greater depth of the central disc - the figure of 84.4 to 84.5 mm makes sense. So, it looks as if all I need to amend is the dimension for the inner-most curve immediately adjacent to to central disc i.e., to make this inner-most curve slightly wider and deeper. I had thought I might have to completely 'go back to the drawing board'; I'm somewhat relieved that I don't. Phew!  

One conclusion that I have come to is that we will never get 100% accurate measurements. Fiberglass warps, and unless someone has the original plug that was used to make the molds, every cast roundel will be different in some way.

You're right on all counts, and I believe that even the roundels used on the actual set walls (both the painted roundels and the "natural" ones that let light through) were all slightly different from each other. (So with all of those roundels in service back then, your replica will no doubt match at least one of them!)

I agree with Theta Sigma here: Even slight variations in the thickness of the fibre-glass matting used, if the matting isn't properly 'pushed' onto the original 'plug' during the moulding process, etc will result in slight variations between each cast which is made.

However Dino, if you refer to the set plans for the Season Fifteen Tardis interior, you will see that they contain an explicit instruction to cast the (semi) transparent roundels from the same 'plug' which was used to form the 'wood-painted' roundels from Season Fourteen's wooden control room. Indeed, the Season Fifteen Plans even specify where this 'master plug' is stored (B.B.C. Plastics Department or possibly the Bullens' Storage Facility - who stored the actual Season Fourteen Control Room).

I am still convinced that the original plug was made of wood cut using chair rail and other trim router bits. The profile is just too similar to be a coincidence. Do a quick web search on chair rail profiles, and you'll see what I mean.

Oh yeah... I've seen those bits! I also wonder if a special bit was made for this, and they had it welded to a lathe handle so they could turn out a plug on a lathe. At least that way they could turn out several plugs and make several moulds at once. It would have been cheaper in the long run doing it that way, rather than working with different chair rail and other router bits to make one plug. Pouring one mould at a time would have been time consuming, and with all of those roundels they must have had more than one mould. So my money is on the special lathe bit (or gouge, whichever you would call something like this).

Once they'd gotten a dozen or so moulds, which would have been enough to make up one wall panel, the plugs might have been thought of as throw-away items.

I think Theta Sigma makes a very valid point; on this side of 'the pond',"chair rails" are more commonly known as "dado rails" and often come in highly complex shapes. As to the exact methodology used for making the master 'plug' (or 'plugs'), well, you really only need to make one 'former' which could - itself - be cast from a short section of dado rail. You could then use the same method as was suggested in 1973's Radio Times Tenth Anniversary Special to make the Dalek's Dome:



On 23rd June, I had the absolute privilege of being invited to the Dr. Who Studios and spent the day being shown round not only the studios themselves but also behind-the-scenes areas such as the props stores. To say that I was like a kid in a sweet shop would be an under-statement!  

Whilst, for very sensible reasons (spoilers), I promised not to share any photos of my visit until after the Christmas Special is transmitted, I can say that (among all the other 'clutter' - Dalek Domes, costumes, masks, bits of control panels, etc) I did see the 'master plug' for the hexagonal roundels which appeared on the walls in the 'Gallery' scene with Tom Baker and Matt Smith from the 2013 50th Anniversary Special.

This was a simple hexagonal box made from MDF - the bottom of the box is a slightly bigger hexagon than the top i.e., its edges slope outwards (presumably to make it easier for the moulded plastic cast to be released). The top had a hexagonal recess around the inside of which six sections of timber quadrant were fixed. Beneath these quadrants was a circular recess at the bottom of which was another MDF disc which had four concentric grooves which had either been either routered or CNCd into it.

The point of this anecdote is that all the hexagonal roundels used in the 2013 Special were drawn from this one master 'plug'. Obviously today, the hexagonal roundels would be vacuum-formed which would speed the process up somewhat but - in principle - in the mid 1970s, there is no reason to think that there would be multiple master 'plugs' constructed. Fibre-glass sets within minutes (though it takes longer to fully cure). Once you have one 'plug', you can make as many casts from it as you like.

Anyway, my sojourn to Cardiff aside, I'll revise my diagram to take into account Karsten's and Theta Sigma's comments about the depth of the central recessed disc. I have a rather wonderful little computer program which allows you to convert millimeters into pixels. If anyone wants me to, this means that I could draw up an accurate PNG diagram at twice full-size. People could then print this out at half size and make their own 'formers' from that.

One last question for Karsten and Theta Sigma - excluding the flange, I make the diameter of the roundel 498 mm (19.6 inches). Does that tally with your casts?

T

[karsthotep]

 Tony,

Mine measured at 19.5 exactly,  i can take another look at it tonight when I get home, but looking at my picture and having measuref it a few times before I am pretty certain its 19.5.  Nothing wrong with me double checking for accuracy though. 

As for a former,  I personally would love to get one 3D printed with your updated dimensions, so i could make several "clean" versions so to speak,  I would rather not re-cast mine as the detail would be even less defined. 

[tony farrell]

Hi Karsten,

19.5" equals 495.3 millimeters so, that's only a discrepancy of 2.7 mm from my estimate of 498 mm (or 1.35 mm on the radius). I've not done too badly then!

Would it be possible to take several measurements of the diameter (just in case your cast isn't a perfect circle)? Thank you very muchly! 

T

[karsthotep]

I agree on your measurements they are in my opinion spot on, whats 1.35mm among friends ,

I can certainly spot check the radius dimms,  as you are right there could be warping and variations.

[Theta Sigma]

I will take measurements as well.  Stand by.

However, in my opinion, the central disc and the mounting flange were in the same plane on the original plug/mold. The casts warp and draw up causing the outside flange to rise above the central disc.  When I made my plaster cast, I did my best to force them back into the same plane while casting.  If our goal is to produce an accurate plug, then we have to take the warping into account.  That way, when actual fiberglass roundels are cast, they will warp during cure and the flange will rise up.

[Theta Sigma]

It's very difficult to delineate exactly where the flat center ends and the detailed section begins because there is no sharp boundary/transition.  My best measurement of the detailed section is 84 mm and the center being 330mm.  That makes 498mm, exactly what Tony got. 

Assume some shrinkage of the fiberglass /mold and round that up to 50cm, which I believe is the standard assumption of the overall diameter of these roundels. 

I will be aiming for 50cm overall when making my plug, if that ever happens before my end of days.  At the rate I am going, I'll be 65 before I get anything done.  My life is just so crazy I never can find the time.

[Theta Sigma]

Dino, I believe this video nicely illustrates the concept of how I think the original plug was made.  If I had the money, I'd buy a router table and a set of bits to attempt this.  I think it would be even easier with a full circle because you could have wheel guides on the inside and out side to keep it where it needed to be on the table.


Skip to about 1:31 in the video.

[warmcanofcoke]

So if we had a turn table / lazy susan, wood, router, router bits, and some sort of pivoting adjustment bracket, we could make one, and then Vac form as many as we needed.

[Rassilons Rod]

That is some BEAUTIFUL carpentry in that video

[omarvance]

That's amazing! I need to find someone who knows how to do this lol.  

Dino, I believe this video nicely illustrates the concept of how I think the original plug was made.  If I had the money, I'd buy a router table and a set of bits to attempt this.  I think it would be even easier with a full circle because you could have wheel guides on the inside and out side to keep it where it needed to be on the table.


Skip to about 1:31 in the video.

[galacticprobe]

Skip to about 1:31 in the video.

I actually watched the entire video. I found it fascinating! (It made my brain hurt) but I found it extremely fascinating. It also made me wish I had the money, tools, and the knowhow to do this. It also reminded me of something I'd seen on an episode of 'This Old House' some years ago when they needed to replace a pieces of moulding that were too rotted to save. They used one of those pin contour thingies to get the shape of the surviving moulding, and then took it to a toolmaker where they had a router bit custom-made specifically to route out some new moulding.

If you've got the money to play with (which I guess these guys had), then you could have a special router bit made to the contours of the roundel's "ridges" and cut out plugs as you need them. (It could also serve well for some ceiling corner moulding... and I wonder if that was placed around the edges of a room, how many people would look up at it and think "Now where have I seen that pattern before?")

Dino.

[karsthotep]

  a couple of years go I looked into getting a plaster master copy made from a manufacturer that makes those ornamental chandelier medallions, based on a cad drawing that Theta had put together with cleaned up measurements at the time.  For them to get the tooling made up it would have been 1,235 US dollars, After that each plaster cast would have been 190 dollars. Its always the tooling that gets you especially if you only want one. I don't know if wood would be any cheaper, but somehow I doubt it.  The cheapest would be getting your own modeling clay, making the former and as Tony posted for the Dalek dome, take the time and make one yourself. 

Tony,  checking on the measurements of the roundel, in several sections and your 19.6 is the closest. some spots on mine were 19.5, some 19.6 and some a little bit more than that depending on the area,  so not a perfect circle by any means due to warping as well as the thickness of the fiberglass in any one area. 

I laid it on the counter top as I was curious how much further the inner circle protruded down past the outside flange,  Again, taking into consideration warping and its not perfectly flat,  the inner circle sat about 5/8's of an inch further than the flange of the roundel.

[Theta Sigma]

Skip to about 1:31 in the video.

... and I wonder if that was placed around the edges of a room, how many people would look up at it and think "Now where have I seen that pattern before?")

Dino.

That is exactly what happened with me.  I was sitting in my kitchen mindlessly staring at the chair rail, and said "holy cow, that so reminds me of the outer section of a roundel."

Some more examples of "roundelesque" chair rail:

http://www.homedepot.com/p/Alexandria-Moulding-AMH-300-1-1-16-in-x-3-in-x-96-in-Primed-Finger-Jointed-Pine-Chair-Rail-Moulding-WM300-93096C/205902098

http://www.homedepot.com/p/Woodgrain-Millwork-WG-1001-11-16-in-x-2-3-4-in-x-96-in-Primed-Finger-Jointed-Chail-Rail-Moulding-PFP1001-08/203209385