Towers B/C

[Balsa Man]

AH I see, you want me to build three towers to test the BS and the building skills of the towers? Final one is the real deal.

It's more like three categories of towers, depending on what you're using them for. You'll probably end up making two or three of category 2, and probably not more than 1 or 2 of category 3 (Balsa Man?)

Yup, Unome, you've got it right-on.
Be patient - Remember how important a good, precise jig is; its the big time investment, but it really will pay off; both for ease and time for tower building, and the more precise it is, the closer you can push to the limits on wood (all forces evenly distributed, not one or two pieces getting disproportional loading)

[hearthstone224]

I feel like I've understood most of the basic concepts, now I just need to make a jig and start building, also finish up running all the numbers with my wood I currently have.

Wow this is so much harder than it looks

Do you have a good way of keeping track of sticks? I was thinking I would just number them but is there another better way?

[Balsa Man]

I feel like I've understood most of the basic concepts, now I just need to make a jig and start building, also finish up running all the numbers with my wood I currently have.

Wow this is so much harder than it looks

Do you have a good way of keeping track of sticks? I was thinking I would just number them but is there another better way?

Oh, yeah, forgot to mention that. Get a few felt tip markers. I use highlighters. Lay 5 sticks side by side, draw a line across all 5 near one end, remove one, draw a second line, etc. Then you have like green1, green2, 3, 4 , 5. pink, orange, green, blue = 25, for more, same thing but add a black dot, that gets you to 50... If you cut one down fm 36", re-mark. We always get kidded at competitions, "like why all the colored marks?..." But it works.

Yeah, doing tower well, it is harder than you'd think at first. But you've learned a lot.

[hearthstone224]

Ah, great idea. I'll see if I can go find myself some highlighters.

[hearthstone224]

Hey, does continually testing BS on the same stick of balsa wood make the BS decrease? Or should it never change?

Also, where can I get all this stuff?

"3/32nd plexi sheet for the panels, some ¼” plexi or other material for the base, the ¼” steel bar for the center, and small angle iron for holding/aligning the legs along the edges; also a GOOD square (I recommend a drafting triangle with the long side at least 12”, preferably 16-18”), and a plastic cutting tool".

You have a point Balsa Man, that I do need a jig. I'm not sure what I'm quite doing but I'd like to give it a whirl, therefore I probably need the materials. I don't have very much of an idea what your directions mean (and again thanks for being so patient with me, I'm not the best directions follower), so can we just talk about them piece by piece?

First part:

"Cut the base out of the ¼” material- a square ~40cm x 40cm
Mark the plate alignment on the base, where the 4 sides are precisely at 90 degrees to each other; glue down little ‘guide strips’ beside each plate alignment line; like 2-3” long pieces of 1/8” x 1/8” bass wood. The strips need to be parallel to the lines, and offset by 3/64th” (half the thickness of the plates, so that when the plate is put down on the base, the center of the plate runs along the alignment line); an hour at best, lets say 2? We’re up to 4hr…."

Okay so what I got:

1. Cut base out of the 1/4 plexi (Which I assume means plexiglass but then again, can you maybe send me the links to the materials I should buy?), 40cmx40cm using a plastic cutting tool I assume.

2. Okay I don't get the "mark the plate alignment" part. Do you mean I take the triangle and mark the 90 degree angles around the 40x40 plexiglass in case it isn't at 90?

3. What does Guide strips offset by 3/64th mean?

[Balsa Man]

Hey, does continually testing BS on the same stick of balsa wood make the BS decrease? Or should it never change?

Within reason, it doesn't change/degrade; it remains 'elastic'. If you bend it too far and fibers in the wood get broken, then it will degrade. 3-4-5 inches on a 36" stick will be well below the elastic limit.

Also, where can I get all this stuff?

"3/32nd plexi sheet for the panels, some ¼” plexi or other material for the base, the ¼” steel bar for the center, and small angle iron for holding/aligning the legs along the edges; also a GOOD square (I recommend a drafting triangle with the long side at least 12”, preferably 16-18”), and a plastic cutting tool".

Plexiglass (="plexi")- Home Depot (for the 3/32nd")- 1/4" plexi- a plastics store, or you could use a piece of plywood or shelf board, and cover it with (as in glue onto it) a piece of 3/32nds plexi (Home Depot). Steel bar, Home Depot. The triangle, an art or drafting supply store; the plastic angle iron- Hobbytown- they all have a display of plastic sheet and various cross-section....strips; rods, square, angle iron, etc. (Evergreen Scale Models - StripStyrene) The angle iron is Item #293; 4 14" strips for $3.99

You have a point Balsa Man, that I do need a jig. I'm not sure what I'm quite doing but I'd like to give it a whirl, therefore I probably need the materials. I don't have very much of an idea what your directions mean (and again thanks for being so patient with me, I'm not the best directions follower), so can we just talk about them piece by piece?

As you read through more times, and actually get to playing with stuff w/ your hands, and thinking about what you're trying to do, it will get clearer.

First part:

"Cut the base out of the ¼” material- a square ~40cm x 40cm
Mark the plate alignment on the base, where the 4 sides are precisely at 90 degrees to each other; glue down little ‘guide strips’ beside each plate alignment line; like 2-3” long pieces of 1/8” x 1/8” bass wood. The strips need to be parallel to the lines, and offset by 3/64th” (half the thickness of the plates, so that when the plate is put down on the base, the center of the plate runs along the alignment line); an hour at best, lets say 2? We’re up to 4hr…."

Okay so what I got:

1. Cut base out of the 1/4 plexi (Which I assume means plexiglass but then again, can you maybe send me the links to the materials I should buy?), 40cmx40cm using a plastic cutting tool I assume.

Yes- but see above for alternative

2. Okay I don't get the "mark the plate alignment" part. Do you mean I take the triangle and mark the 90 degree angles around the 40x40 plexiglass in case it isn't at 90?

The plate alignment is the four plates at 90 degrees to each other. The plate alignment marks are a 90 degree cross, where the bottom of the plates contact the base. Where they cross is the tower centerline- so,scribe/mark one line, running diagonally. Then scribe another at 90 degrees to it, crossing the first near the center of your base square.

3. What does Guide strips offset by 3/64th mean?

Since you want your 3/32nds" thick plates to sit exactly on your plate alignment marks (with the 1/4 x 1/4" bar sitting on the centerline), that means if a plate was lined up perfectly (as in center of edge running exactly along the line), each edge would 3/64" out from that line (3/64 + 3/64 = 3/32). So, if you carefully place guide strip exactly parallel to the line, 3/64" away from it (and glue it down), then when you put plate against it, the center of the edge of the plate will be running exactly along the mark.

[hearthstone224]

Oh, that makes a lot more sense.

What d'yall think of this?

https://www.amazon.com/Red-Devil-1170-P ... B000BZZ1D0

Looks pretty sweet. But then again, that might be just because its 5 dollars so I don't need to get a mean look when I ask my teacher to buy it off amazon.

So Balsa Man does this seem adequate enough for a plexiglass cutter or do I need something better than it

Another problem: Is plexiglass supposed to be around 200 bucks? That is expensive :O

The cheapest one I found on Home Depot Website was 48 in. x 96 in. x 1/4 in. Clear Acrylic Sheet which was 179 bucks.

Is that what we want, or is home depot not showing everything it has in the store? There wasn't a trace of 3/32 plexi or 1/4 plexi online.


Also- The center of the base runs along the alignment line, meaning the whole base of the 3/32 plexi doesn't rest on top of the 1/4 plexi?


Looking ahead, do I need to buy this special "120 grit sandpaper" or can I just use pieces of sandpaper found in the classroom?

If you don't mind tomorrow I will probably make a post asking about the part where we cut the plexiglass.

[Balsa Man]

Oh, that makes a lot more sense.

What d'yall think of this?

https://www.amazon.com/Red-Devil-1170-P ... B000BZZ1D0

Looks pretty sweet. But then again, that might be just because its 5 dollars so I don't need to get a mean look when I ask my teacher to buy it off amazon.


So Balsa Man does this seem adequate enough for a plexiglass cutter or do I need something better than it

That looks fine.

Another problem: Is plexiglass supposed to be around 200 bucks? That is expensive :O

The cheapest one I found on Home Depot Website was 48 in. x 96 in. x 1/4 in. Clear Acrylic Sheet which was 179 bucks.

Is that what we want, or is home depot not showing everything it has in the store? There wasn't a trace of 3/32 plexi or 1/4 plexi online.

This more like it? $15.73
http://www.homedepot.com/p/OPTIX-20-in- ... /202038049

I used "plexiglass" as a sort of generic term- sheet plastic- acrylic is fine. 0.093 is 3/32 (within less than 1/1000"- 0.09375)


Also- The center of the base runs along the alignment line, meaning the whole base of the 3/32 plexi doesn't rest on top of the 1/4 plexi?

I'm not following your confusion here. The center of the bottom edges of the plates sit on the alignment lines. Just like the picture that got posted earlier. The plates rest on/are glued onto the base. Be sure to get some glue for plastic, too.

Looking ahead, do I need to buy this special "120 grit sandpaper" or can I just use pieces of sandpaper found in the classroom?

Sandpaper comes in a range of grits. I recommended 120 because it's about right for getting a nice smooth edge on plastic. Too coarse, and the edges are rough/chewed up. Too fine and it will take forever to sand down. 120 is medium- very common, nothing special.

If you don't mind tomorrow I will probably make a post asking about the part where we cut the plexiglass.

In my description, I recommended trying the technique out on a couple of pieces of scrap before tackling the plates. Do that, and you should understand how to do it.

Looking at all the words can be intimidating. There are lots of words so the correct/complete info is there. You need to get your head around ...the big picture; what you're trying to do/make. When you've done that, the details make sense, and help you. Try cutting 4 panels like out of poster board- tape them together; see/understand what its going to look like. Then make it strong and precise, using the plastic

[kinghong1970]

tbh, unless you have a lot of tools and experience at your disposal, cutting plexi or any form of plastic is a massive pain in the rear.

to get accurate and dead flat cuts, table saw would be nice, or those new track saws... but with the speed these work at, it will melt the plexi and you will not have accurate cuts.

[Balsa Man]

tbh, unless you have a lot of tools and experience at your disposal, cutting plexi or any form of plastic is a massive pain in the rear.

to get accurate and dead flat cuts, table saw would be nice, or those new track saws... but with the speed these work at, it will melt the plexi and you will not have accurate cuts.

I absolutely agree, table saw is preferable; that's how I would do it (though I have done the hand cutting, and with patience and some practice, for sure, it can be done very accurately). I described the hand cutting approach for hearthstone because it sounds like he has neither access to, nor experience with table saws, and wanted him to know there is a workable way to do it without them.

Key is good steel straightedge, and firmly taping it in position, and not trying to cut/get too much depth w/ each pass of the cutting tool. You don't have to cut all the way through to get a clean break; if you get around half way through, put the piece with the cut line on a counter top/work bench top with a good sharp edge to it, with the cut line like 1/8" beyond the counter top edge, and good heavy pressure on the straight edge, snapping the piece beyond the cut line off is actually.....pretty easy/reliable.

From discussions with one of the coaches I'm working with this year, there may be an even better way than (old school) table saw- if you can get access to a laser cutter- program in the dimensions..... also, with access to a big enough 3-D printer, you could do it... ain't technology wonderful