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"Ideas For ERB's Pellucidar Iron Mole "Prospector" For 15mm?" Topic


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1,285 hits since 25 Apr 2017
©1994-2017 Bill Armintrout
Comments or corrections?

Personal logo Cacique Caribe Supporting Member of TMP25 Apr 2017 10:35 a.m. PST

When I was a little kid and read the Edgar Rice Burroughs tales of Pellucidar, I became like this kid here, obsessed with making my way down to the Earth's core to see the prehistoric/fantastical wonders he described:

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NOTE:
Of course, in his novels Burroughs describes the "iron mole" (which was named The Prospector) as being much larger than that.

"Roughly, it is a steel cylinder a hundred feet long, and jointed so that it may turn and twist through solid rock if need be. At one end is a mighty revolving drill operated by an engine which Perry said generated more power to the cubic inch than any other engine did to the cubic foot."
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QUESTIONS:
A ) If one were to scratch build a surfacing one, as it burst through the ground and arrived on Pellucidar, what diameter would be appropriate for 15mm gaming? Would these proportions make sense?

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erbzine.com/mag57/5787.html

B) Also, any suggestions on what to use for the drill piece itself, aside from getting a large Lego drill tip?

auction

Thanks,

Dan
TMP link

Personal logo Cacique Caribe Supporting Member of TMP25 Apr 2017 11:03 a.m. PST

Here is some additional artwork to give you an idea of what I'm referring to:

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Also:

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erbzine.com/mag7/0741.html

By the way, this was the prop used in the 1976 Doug McClure movie "At The Earth's Core":

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PDF link
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YouTube link

Dan

TheBeast Supporting Member of TMP25 Apr 2017 11:22 a.m. PST

Have you seen the Ironclad Steam 15 and Steam 16? I know they're in the 28mm section, but consider them scale neutral.

I tore up several of GI Joe Mole Pod's to make a longer version, but never assembled same. I'm considering using it as part of my 'Shame of The Beast' thread of long doomed projects.

Doug

Edit: Sorry, could have SWORN I put a link in; scroll to bottom. link

Personal logo Cacique Caribe Supporting Member of TMP25 Apr 2017 11:30 a.m. PST

Ironclad? I must check them out.

Also, if we're gonna talk about a walk of shame of unfinished projects … most of what I've started these past years is still sitting there waiting for me to get back to:

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[sigh]

Dan

TheBeast Supporting Member of TMP25 Apr 2017 12:20 p.m. PST

Yeah, but even the greens are semi-usable… ;->=

Doug

mrinku25 Apr 2017 4:24 p.m. PST

There are some suitable drill parts on the 40K Ork Killa Kan sprue, as well as parts that should be convertible for a cylinder body:

NOT 100% sure about scale, but I think they may be okay for it. I have the bits, so I'll do a quick scale check when I get home tonight.

I know there was a mole drill for EPIC. That was a smaller scale, but was also meant to be a larger vehicle, so may work in 15mm as a small mole drill such as was used in ERB.

Alternatively, you may be able to find suitable spiral drill/plug parts at a hardware store.

Personal logo Cacique Caribe Supporting Member of TMP25 Apr 2017 4:54 p.m. PST

This is extremely interesting, though maybe not for this particular project:

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Dan

Doctor Merkury Inactive Member25 Apr 2017 11:26 p.m. PST
TheBeast Supporting Member of TMP26 Apr 2017 2:14 a.m. PST

Doctor, you should have also had the previous construction link, for the assembly of the screw. link

The Assembly of the Screw… definitely a title there.

Doug

SleepyDragon26 Apr 2017 3:25 a.m. PST

Is the Thunderbirds Mole an option?

Personal logo Cacique Caribe Supporting Member of TMP26 Apr 2017 7:19 a.m. PST

OMG, Doctor! That is absolutely stunning!!! I must make one.

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Dan
PS. @Beast: "The Assembly of the Screw… definitely a title there."
That is indeed title-worthy! :)

Personal logo Cacique Caribe Supporting Member of TMP26 Apr 2017 10:07 a.m. PST

This cylinder gave me an idea for a good and easy starting point for the basic body, to which I could add all sorts of mechanical bits and rivets:

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TMP link

The various Burroughs sketches give the Prospector a diameter of 20ft or so. That would mean something around 60mm wide. Seems doable.

Dan

mrinku26 Apr 2017 11:09 p.m. PST

Hmm… just had a thought that you *should* be able to make the drill bit entirely from flat material (paper, card, plasticard etc).

1. Use a semi-circular piece to make a cone of the appropriate size and desired pitch.

2. Cut a circle of diameter equal to the circular base of the cone plus a bit more for the spiral.

3. Draw a smooth spiral from the circumference into the centre. Cut along that line.

4. Attach the spiral to the cone.

Probably would need a bit of fiddling around to get it just right, but you could mock up with paper or cardboard first, even if you plan to use more expenseive materials for the final product.

Found a picture that sort of shows what I mean, if it's not clear from the words:

As for drawing a smooth spiral, there are a few ways, but this might be the best one:

As an alternative, a long sausage of putty placed in a spiral along the cone and then pinched and smoothed would probably do the trick, especially if you were after a more robust looking spiral.

mrinku27 Apr 2017 2:08 a.m. PST

Following my previous post, I did some mucking around after I got home from work. Found a suitable spiral in the web and printed it out; drew a semicircle to suit a 60mm diameter:

Cut them out:

Assembled the cone:

Voila!

Took me all of twenty minutes to do the proof of concept. Attaching the spiral could be a little fiddly (in the above image it's just sitting in place) but a lot depends on materials and adhesive used.

Oh… and a pro tip – if you're right handed (like me) get a spiral that goes the *other* way, so that you're cutting counter-clockwise. It was bloody awkward cutting that one out!

Personal logo Cacique Caribe Supporting Member of TMP27 Apr 2017 4:07 a.m. PST

Wow! I had never seen this before. Very clever.

Dan

mrinku27 Apr 2017 7:56 p.m. PST

It's all just shapes :)

Which is really all that objects are anyway!

For the body of the mechanical mole, I think a soda can or three would be about right, especially for an piece where it's emerging from the earth. Although if you cleanly cut one in half, the uncut ends should neatly fit into the cut ends for a segmented look. You could probably make it poseable by running a taut string through the model from bow to stern.

CAPTAIN BEEFHEART27 Apr 2017 8:49 p.m. PST

OK Dan, Let's take it from the beginning. Is it a steam or an internal combustion engine? If steam, the lion's share of the machine is a water tank. Most vsf gamers take a WW1 tank and put smoke stacks on it are ignorant of the fact.

Your propulsion system is the key. Secondary is where the debris goes. You have been given some fabulous ideas on how to construct a drill bit but none on the motive system to push it through the earth.

You could build a tube with a spikey cone and say, this is an 'earth borer' and be done with it. I'd research mining devices to see how they do it. If you go with steam, have follow up support vehicles with coal and water,

,,,and leave the MSTK 3000 people out of it. ….except for the above posters as they are amazing!

Question#2 is the make up of your crew/team and their equipment and accommodations as that is the core of your game. How much X is needed to sustain Y?


JUst some thoughts…

TheBeast Supporting Member of TMP28 Apr 2017 11:46 a.m. PST

You have been given some fabulous ideas on how to construct a drill bit but none on the motive system to push it through the earth.

The assumption is that you push it behind you as you go. I know that's seldom shown. One could assume a central cavity of the borer to pull from the front.

The GI Joe mole has a small hole at the point of the drill, though I thought that it should be some flame to soften the rock. I'd started some 'tracks' to fit between the fins.

I think they were originally microscope slide racks.

Doug

Personal logo Cacique Caribe Supporting Member of TMP28 Apr 2017 1:43 p.m. PST

The one in the film has the hatch near the back. I plan to have mine as close to the front as possible, so that they can still exit the contraption even if only the front third* has broken through the surface.

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Dan
* I don't plan to make the entire cylinder. I'm mainly interested in making the front protruding section of the craft, maybe at a 40-45 degree angle.

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CAPTAIN BEEFHEART28 Apr 2017 2:40 p.m. PST

I get it. Just the gaming piece. Just remember to leave a hatch or something above ground.

TheBeast Supporting Member of TMP28 Apr 2017 4:07 p.m. PST

Right-o. Mine, besides a rather long full train, was almost laid flat, but coming out of a hill side. More terrain than vehicle…

Doug

Dr Argent29 Apr 2017 5:10 a.m. PST
Personal logo capncarp Supporting Member of TMP29 Apr 2017 8:47 a.m. PST

Dan, rough gauging of the erbzine cutaway drawing gives me from 14'-18' diameter of the body. So, for 15mm, that mait from about 33mm to 45mm.

Personal logo Cacique Caribe Supporting Member of TMP29 Apr 2017 9:25 a.m. PST

Capncarp, that's perfect!

Thanks,

Dan

mrinku30 Apr 2017 2:16 a.m. PST

If you choose to scratch the drill bit, the erbzine one looks to be a bit pointier than mine. That's simply a matter of using a sector that's less than a semicircle. The spiral is one-size-fits-all… smaller diameter cone just uses less of it.

TheBeast Supporting Member of TMP30 Apr 2017 2:45 a.m. PST

Dr Argent: I think all your links are GMail, and we don't access to yours. ;->=

33mm to 45mm

Two to three times the height of a person, less if it's to 'eye level'? ;->=

The main cabin has two people sitting side-by-side, swivelling, plenty of room between and on both sides, and a fair structure to the beast itself.

Definitely on the high side of the estimate, I'd think.

The assumption is that you push it behind you as you go.

Actually, I think the image is more like a sub; the 'screw' pushes the medium around you. It is, after, scientific romance.

Doug

Personal logo Cacique Caribe Supporting Member of TMP30 Apr 2017 5:27 a.m. PST

@TheBeast: "the 'screw' pushes the medium around you. It is, after all, scientific romance"

LOL. Is that an euphemism or something, for what the iron mole is doing?

I must have a dirty mind this morning. Well, more than usual. :)

Dan

Dr Argent30 Apr 2017 7:24 a.m. PST

TheBeast, thank you. Let's try this.
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TheBeast Supporting Member of TMP30 Apr 2017 9:00 a.m. PST

Dan, it's ALL in your mind. Oh, wait, now mine as well.

It turns out that neither rock nor water is particularly 'compressible', so it has to slide around. Now, in the case of rock, it doesn't 'slide' so well unless molten.

I suspect the term 'mole' indicates the vision, but dirt IS surprisingly compressible.

"Scientific romance is an archaic term for the genre of fiction now commonly known as science fiction." Ergo, I use it descriptively for VSF.

Doctor: Much better! Oh, wait, I don't have an FB account…

;->= Still, much better, as so many do. Well done!

Doug

Personal logo Cacique Caribe Supporting Member of TMP05 May 2017 1:34 p.m. PST

Beast: "Dan, it's ALL in your mind. Oh, wait, now mine as well."

I'm happy I'm able to spread the madness! :)

Dan

mrinku07 May 2017 5:38 p.m. PST

Something else that might help with the look is the fluted kind of step drill bit, especially if you can source a cheap one:

A quick google search showed you might be able to get questionable quality ones for a few dollars on ebay.

mrinku07 May 2017 7:05 p.m. PST

Found another useful idea: garden/beach umbrella spikes. Some designs are spot on:

The classical conical thread ones seem to be older… good chance you may find a usable part in a junk or recycling shop.

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