login   |    register
Scratchbuilders!
Built a model or part from your own materials lately?
Hosted by Mike Kirchoff
New to sbing
Lokis_Tyro
Visit this Community
Wisconsin, United States
Member Since: March 08, 2016
entire network: 128 Posts
KitMaker Network: 28 Posts
Posted: Monday, August 22, 2016 - 09:22 AM UTC
New to sbing, well versed in bsing! Couldn't let that one go lol

I'm working on and will be starting build that require scratch building. One of which will be a build of Crow T Robot for the sci-fi campaign. I'll be using evergreen sheet rod and tube. There a few complex curves and parts that will need to be made twice. Any general tips are welcome. For parts made from sheet that need to be cloned should I do this by stacking sheet with double sided tape?

My main question here is about making a set of hubcaps for a car build. I would like to do either baby moons or bonneville style hubcaps. I'd prefer the Bonneville style which are basically convex cones. Is the best way to make these a simple cut and splice to get the right shape/angle? To create the round baby moons would I create a form to heat and lay sheet styrene or would I be better off making a small vacuum form and using lexan?
turtle65
Visit this Community
Dunedin, New Zealand
Member Since: September 17, 2012
entire network: 266 Posts
KitMaker Network: 69 Posts
Posted: Thursday, August 25, 2016 - 12:23 PM UTC

sorry there hasn't been any responses as yet .
Anywho - re the Crow T Robot - if it was me I would definitely consider vac-forming things such as the "beak" and head.
What size are you looking at ?, as this can play a major part in how best to manipulate the plastic.
You don't need lexan to vac-form - common old styrene works just as well (cheaper).
Here's the link to my method of vac-forming:

http://automodeler.kitmaker.net/modules.php?op=modload&name=features&file=view&artid=1243

Re-baby moons - not being a car modeller however I know quite a few people have used the old style push pins/thumb tacks (brass) as these are a close fit size wise.
Bonny style - another option (if you have a dremel or similar) is just fill the original rims with putty and turn-down to the required curvature.
Hope this has been of some help. As always just ask way and I'm sure someone will provide an answer
turtle65
Visit this Community
Dunedin, New Zealand
Member Since: September 17, 2012
entire network: 266 Posts
KitMaker Network: 69 Posts
Posted: Thursday, August 25, 2016 - 12:31 PM UTC
Just found this on Pinterest that might help shed some light on how the Crow T Robot was made:

https://nz.pinterest.com/pin/321937073334597694/

turtle65
Visit this Community
Dunedin, New Zealand
Member Since: September 17, 2012
entire network: 266 Posts
KitMaker Network: 69 Posts
Posted: Thursday, August 25, 2016 - 12:35 PM UTC
Also:

http://www.botbuilders.info/index.php?topic=188.0

about halfway down the page
Lokis_Tyro
Visit this Community
Wisconsin, United States
Member Since: March 08, 2016
entire network: 128 Posts
KitMaker Network: 28 Posts
Posted: Thursday, August 25, 2016 - 09:21 PM UTC
Hi Roger. Thanks for the response(s).

The sci-fi campaign allows up to 1:6 scale so that will most likely be my choice as anything smaller will no doubtedly be pushing my skill boundaries too far. If I find a toy bowling pin that's an appropriate size that may dictate the exact scale I go with (no lathe to turn this). Nothing is in stone yet.

Thanks for the link to your article. It's a great sbs. You make it look easy. I think I'll have a tough time with the forms but that's half the point of doing this. I'll be setting up for another modelling related wood project so I'll finally build a forming box that will live a double life as a downdraft table. The size of your table is very practical. I was thinking much larger but seeing your pictures 12x12 looks to be just right. This may seem like a silly question, but is there such a thing as too much vacuum? Do I need an adjustable port to control pressure? I'm not concerned about the box collapsing but I wonder if the forming plastic might crack if not warm enough after a failed preheat. I'll be using a heat gun instead of an oven.

Regarding the hubcaps, I do have a dremel but it's stuck on high. I think the potentiometer, or whatever sorcery is in there, is foul (speed knob is broken).
My thinking for Bonnevilles was to make a disc, take a slice of pie out of it, then rejoin the disc ends together so it will form a cone and go from there. I'll need to experiment with paper to see if that even works. Hell, I might even laquer the paper and paint it if it works out. I'll see how thumbtacks fit too. Great idea.

I do have a link that shows how and what Crow was made up of. I didn't know there is more than one version of him though. Thanks for those links too. If it's of any interest here's the link I had.
http://www.mst3kbots.com/Crow.htm

Thanks for all the help, Roger.
RobinNilsson
Staff MemberDirector of Member Services
KITMAKER NETWORK
Visit this Community
Stockholm, Sweden
Member Since: November 29, 2006
entire network: 6,687 Posts
KitMaker Network: 1,042 Posts
Posted: Saturday, November 12, 2016 - 05:29 PM UTC
Suggestion for hubcaps: If you use a wood dowel it might be possible to use your (speeded) Dremel to turn a master for the hubcaps and then use it to press bowls into some softish sheet metal (food containers of aluminum maybe). The master should be made slightly, thickness of metal, undersize so that the outside of the pressed/stamped bowls get the correct size.

Trying to make cones with "the pie slice out of circle" method would probably result in cones with a visible seam or even an angle. If you use this method I suggest using thin aluminum and cutting the pie slice narrower than neede for the cone shape so that you leave enough metal to fold down (into the cone) as gluing surfaces. This would make it easier to shape the cone.

If you could consider casting you could press the master into modelling clay and cast with Araldite or epoxy glue.
This would result in solid hubcaps but if that isn't a problem ...

/ Robin