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warren
human power expert

4269 Posts

Posted - 03/09/2010 : 18:03:38

So now we have a very pretty and fast looking tailbox plug, and we want to make some fairings. What's the next step? We have to build a female mold. Garrie Hill explained one methods of building the female mold, and is working on documenting it here:

http://www.recumbents.com/wisil/hill/femalemold/

-Warren.

sean costin
human power supergeek

Lesotho
1925 Posts

Posted - 03/09/2010 : 18:27:14

Thanks Garrie, It looks great. Please provide some tips to finding the equator of the plug and marking it. I was thinking about a rotating laser. What do you think.

Sean

Larry Lem
human power supergeek

South Sandwich Islands
1997 Posts

Posted - 03/09/2010 : 19:51:53

Sean is reminiscing about his nights at the disco.

I am anxious to see page 2.

Larry Lem

Garrie L Hill
human power supergeek

USA
1305 Posts

Posted - 03/10/2010 : 19:30:29

Sean;
With the plug laying on its side, sand bagged in to place, visually level the plug. When you do the scribing step, the square will lightly scuff a line around what is (hopefully) the equator. If it doesn't look right, just do over.
I just sent Warren some more steps. I'll have everything to Warren in the next 3-4 days.

Garrie "carbon based lifeform" Hill
HPRA Co-Dictator of the East
for pics of some of my time and money sucking projects
http://garriehill.winkflash.com/
and
http://s58.photobucket.com/albums/g277/cfbb/
and videos
http://vimeo.com/5513519

alevand
human power supergeek

USA
1651 Posts

Posted - 03/11/2010 : 04:44:35

In shipbuilding it's called a waterline, though you might have some marital problems if you try this in your bathtub. 6 weeks to Indy.

C:
Tony Levand

Edited by - alevand on 03/11/2010 04:48:36

Larry Lem
human power supergeek

South Sandwich Islands
1997 Posts

Posted - 03/11/2010 : 07:19:23

It would be the waterline if the boat were listing 90 degrees (to the side).

Larry Lem

raymondg
recumbent guru

829 Posts

Posted - 03/11/2010 : 11:48:22

Not just in shipbuilding, but in aircraft manufacturing as well. The standard three reference planes are called Waterline (horizontal plane, abbr. WL), Buttock (or Butt) line (vertical plane parallel to long axis, abbr. BL), and Station (vertical plane through cross sections, abbr. STA). Typically the the symmetry plane is called the "zero butt line" or labeled BL 0.00 (varies slightly from company to company). This is the reference plane you are trying to find. With the Orion, I have two symmetry planes, so I call the horizontal one WL 0.00, which is where I split the top half from the bottom.

I only bring this up because it helps to have a standard terminology for such things when communicating with others, and since I work in the aerospace industry, I am used to one that is already in common usage.

I'm looking forward to seeing those tailboxes. Happy Molding!

Raymond

LongJohn
recumbent guru

Netherlands
533 Posts

Posted - 03/12/2010 : 02:46:36

Raymond,

You make me proud!

Thomas (KLM)

Edited by - LongJohn on 03/12/2010 02:46:57

sean costin
human power supergeek

Lesotho
1925 Posts

Posted - 03/12/2010 : 03:36:15

Raymond, so in other words, we should make light skid marks on the zero butt line.

Warren, Let me know when you have that finished.

Sean

raymondg
recumbent guru

829 Posts

Posted - 03/12/2010 : 07:52:43

Sean.
Yes. For me personally, I would put a scribe line on the zero butt line with a sharpie held in a tool similar to what Garrie shows, only oriented so as to be a fixed distance off the reference plane (the mdf). Very similar to the tool you made to mark the wheel fairing tire cutouts on the Orion, if you recall, only much higher, obviously. Then I would mark the plug at multiple locations with small dots, where the geometry makes it easiest to know exactly where you want the mid plane to be, such as the trailing edge and the seat area. When you sand bag the plug, tap it into position until all those dots you made are at the same height from the reference plane, and then use your sharpie "scribe" to mark the whole centerplane.

This approach may seem overkill to simply locate the mold flange, and it is, but it serves another purpose. Down stream, when it comes time to cut holes in or mount brackets to your tail box, you now have a very precise reference plane to aid in their location. Simply put the tail box in the mold, and now you have a precise plane that you can easily measure from for any locating.

Raymond

Garrie L Hill
human power supergeek

USA
1305 Posts

Posted - 03/12/2010 : 08:55:53

Raymond;
Probably won't work in the case in point. You are assuming that this plug has bilateral symmetry. I can just about guarantee it doesn't. The plug has been done, redone, finished, and refinished. It WILL have lumps, bumps, waves, and wiggles. Therefore, eyeballing will produce a line that is as good as the plug. Trying for something better will just lead to frustration for these guys (Warren, Allen, Sean, Rick). Believe me, I took all of this in to account when I put these instructions together. Good enough really is good enough in this case. 't'ain't rocket science.

Garrie "carbon based lifeform" Hill
HPRA Co-Dictator of the East
for pics of some of my time and money sucking projects
http://garriehill.winkflash.com/
and
http://s58.photobucket.com/albums/g277/cfbb/
and videos
http://vimeo.com/5513519

warren
human power expert

4269 Posts

Posted - 03/12/2010 : 11:15:33

Ha I got it Sean.

Garrie L Hill
human power supergeek

USA
1305 Posts

Posted - 03/12/2010 : 13:37:32

Oh. Yes. Well, erm........ me too; but with a slow dawning of comprehension. Har-dee-harr!

Garrie "carbon based lifeform" Hill
HPRA Co-Dictator of the East
for pics of some of my time and money sucking projects
http://garriehill.winkflash.com/
and
http://s58.photobucket.com/albums/g277/cfbb/
and videos
http://vimeo.com/5513519

Larry Lem
human power supergeek

South Sandwich Islands
1997 Posts

Posted - 03/12/2010 : 15:45:32

I have a picture of James Schroeder from BM 09 with a "skidmark" from his chain rubbing on his shorts.

But it's not that funny.

Larry Lem

Jeff Wills
human power supergeek

USA
1141 Posts

Posted - 03/12/2010 : 17:05:32

quote:
Originally posted by sean costin

Raymond, so in other words, we should make light skid marks on the zero butt line.

And here's where things start going downhill... fast.

__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html

warren
human power expert

4269 Posts

Posted - 03/12/2010 : 17:21:26

Ok, Skreeeeeeeee.....Dragging thread back on topic....

Here's the latest update of Garrie's female mold page:
http://www.recumbents.com/wisil/hill/femalemold/

And, I bought a very heavy chunk of 3/4" MDF.

-Warren.

Jeff Wills
human power supergeek

USA
1141 Posts

Posted - 03/12/2010 : 17:23:25

Anyway... getting back on topic.

A question for those of you who have built plugs, molds, and other assorted composite thingamabobs:

I understand the process of building a plug, attaching a flange, making the first female mold off of that, making the other female mold off of the other side, and then making the parts in the molds.

But...

Is it possible to make the plug in such a way that you can split it apart after it's finished? That is, the interior structure would be a bunch of right-angle panels so that the plug separates into quarters, allowing easy attachment of flanges and subsequent mold-making.

I can see that it would be easy to damage the edges of the plug once apart, but since these sections are usually dressed up before the part is made I don't see it as much of an issue. Also, the parts are easier to remove from the mold, since the mold is split right in the middle.

Is this practical? Or is it too much work for a simple plug? Is everything dimensionally stable enough that the parts would line up after being pulled from molds made like this?

__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html

sean costin
human power supergeek

Lesotho
1925 Posts

Posted - 03/12/2010 : 20:28:36

You are all welcome for my brand of sophomoric comedy. To make up for my tasteless humor I have some constructive input. I have found that modeling clay can be easily and effectively warmed in the microwave oven without imparting smelliness to your food. It doesn't take too much, so don't overdo it. This is a really great service you are providing Garrie. I am learning new things.

Sean

LeeW
New Member

United Kingdom
56 Posts

Posted - 03/13/2010 : 01:26:19

Would it be possible to provide metric measurements for those of us who don't know what an oz is? Ok I tried converting 2oz to grams and got 56g which sounds horribly light for glass cloth, I don't think such light glass cloth even exists.
I have 300gsm glass cloth and 600gsm. Would they be suitable?

Garrie L Hill
human power supergeek

USA
1305 Posts

Posted - 03/13/2010 : 06:43:44

Lee;
16 ounces (0z)/pound.
.75 oz = .05 pounds
454 grams/pound
.05 * 454 = 21.28 grams per square yard
.836 meters squared per yard squared
17.73 grams per square meter

http://www.onlineconversion.com/

Yes, we start of with very fine, very light cloth. Yes, it is very, gossamer light. Imagine woven spider web!

Garrie "carbon based lifeform" Hill
HPRA Co-Dictator of the East
for pics of some of my time and money sucking projects
http://garriehill.winkflash.com/
and
http://s58.photobucket.com/albums/g277/cfbb/
and videos
http://vimeo.com/5513519

mikeatlbch
recumbent enthusiast

USA
191 Posts

Posted - 03/13/2010 : 08:03:09

Planes of reference. Wit the things we see and do maybe we should follow the anatomist.

In medicine and anatomy:
http://en.wikipedia.org/wiki/File:Human_anatomy_planes.svg
Coronal Transverse Sagital Median Longitudinal
dorsal ventral caudal cephalad

On the otherhand, pictures can work.

Mike

Edited by - mikeatlbch on 03/13/2010 08:07:35

raymondg
recumbent guru

829 Posts

Posted - 03/13/2010 : 09:28:19

quote:
Originally posted by Jeff Wills

...
Is it possible to make the plug in such a way that you can split it apart after it's finished?
...

Yes. The bikes I worked on in college were all full plugs, and I didn't like putting the flanges on so every plug I have made since is split. You can see examples of symmetrical and non-symmetrical split plugs here:
http://www.recumbents.com/wisil/gage/orion_speedtrike2.htm

You can just drill holes through two plug halves and bolt them together if you like. Just use the wonderful non-hardening modeling clay everyone keeps on about to cover the hole when it comes time to lay up the fairing. It can also be used to cover blemishes like a chipped edge, rather than doing another fill and sand cycle.

Regards,
Raymond

Jeff Wills
human power supergeek

USA
1141 Posts

Posted - 03/13/2010 : 13:43:44

quote:
Originally posted by raymondg

quote:
Originally posted by Jeff Wills

...
Is it possible to make the plug in such a way that you can split it apart after it's finished?
...
Yes. The bikes I worked on in college were all full plugs, and I didn't like putting the flanges on so every plug I have made since is split. You can see examples of symmetrical and non-symmetrical split plugs here:
http://www.recumbents.com/wisil/gage/orion_speedtrike2.htm

OK- you used a half-plug to create a fairing that's symmetrical top-to-bottom. I was thinking of creating a full plug that would come apart along the waterline and butt planes (thanks for the terminology), add flanges, and take molds off of these "quarter plugs". By bolting pairs of molds together, you'd have a either top and bottom or left-side and right-side molds. (And, in the spirit of a couple Battle Mountain competitors, bolting them all together for a bombproof shipping container.)

As I said- would this work? Has anyone seen this done, much less attempted it themselves?

__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html

Edited by - Jeff Wills on 03/13/2010 13:44:21

raymondg
recumbent guru

829 Posts

Posted - 03/13/2010 : 14:59:48

quote:
Originally posted by Jeff Wills

OK- you used a half-plug to create a fairing that's symmetrical top-to-bottom. I was thinking of creating a full plug that would come apart along the waterline and butt planes (thanks for the terminology), add flanges, and take molds off of these "quarter plugs". By bolting pairs of molds together, you'd have a either top and bottom or left-side and right-side molds. (And, in the spirit of a couple Battle Mountain competitors, bolting them all together for a bombproof shipping container.)

As I said- would this work? Has anyone seen this done, much less attempted it themselves?

Jeff, the Orion and the Linear 95 were symmetrical vertically, but Great White was not. If you look closely at this pic, you will see both halves of the plug:

In this case it was split left and right at the zero butt line. If I understand you correctly though, you want to split yours into quarters, which I have not done, but would be little different in execution. IIRC some Varna molds split three ways: a bottom, and two top halves, with a non-planer split surface between the bottom and the two tops. Georgie is God and I think he just puts flanges wherever he thinks best and they turn out practically perfect, but the rest of us have to resort to other more time consuming methods.

Raymond

Edited by - raymondg on 03/14/2010 08:36:03

Dreamer
recumbent guru

USA
542 Posts

Posted - 03/13/2010 : 19:45:57

quote:
picture of James Schroeder from BM 09 with a "skidmark" from his chain rubbing on his shorts.

The new one piece molded seat fixes that problem. We used James as the plug and the short line transferred into the mold but we've got that fixed.

Jeff Wills
human power supergeek

USA
1141 Posts

Posted - 03/13/2010 : 21:27:52

quote:
Originally posted by raymondg
Jeff, the Orion and the Linear 95 were symmetrical vertically, but Great White was not. If you look closely at this pic, you will see both halves of the plug:
...
In this case it was split left and right at the zero butt line. If I understand you correctly though, you want to split yours into quarters, which I have not done, but would be little different in execution. IIRC some Varna molds split three ways: a bottom, and two top halves, with a non-planer split surface between the bottom and the two tops. Georgie is God and I think he just puts flanges wherever he thinks best and they turn out practically perfect, but the rest of us have to resort to other methods more time consuming methods.

Raymond

Yeah, I got up to my armpits building the OHPV Varna clones. It's as you describe: top is two halves, roughly 1 arm-length deep (which is why I got to squeegee the head section- I had the longest arms!) while the bottom pan is one piece. I was thinking that if the lower fairing got to be deeper and a more complicated shape, a vertically split mold would make extraction easier.

__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html

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