ODD'L ROCKETS

Turned the triangle over and wicked thin CA into the joint. After the CA was dry, the masking tape could be peeled back without a problem. Belive it or not!

A template is supplied for sanding in the correct angle for miterd joints from the base to the tip of the pyramid. And the correct angle would be 60 degrees. I'm sure it works just fine, but I choose to use a differant approach.


www.oddlrockets.com

bradycros said:

A template is supplied for sanding in the correct angle for miterd joints from the base to the tip of the pyramid. And the correct angle would be 60 degrees.

Click to expand...

A triangle's inside angles add up to 180 degrees. So, each of the three corners meet at a 60 degree angle. You're mitering two sides that meet at each corner, so the miters should be 30 degrees.

-- Roger

I am going to build my own sanding jig outta cardboard.

jadebox said:

A triangle's inside angles add up to 180 degrees. So, each of the three corners meet at a 60 degree angle. You're mitering two sides that meet at each corner, so the miters should be 30 degrees.

-- Roger

Click to expand...

Nah ah...

First and second pictures, 30 degrees. Crap-ola

Third picture, 60 degrees. Hmm... much better.


The sides of the pyramid are free standing, nothing has been glue together yet.

There's a story as to why there are pictures of the wrong 30 degree angles. :cyclops:

the sum of the angles of a triangle are indeed 180 degrees...however for
pyramids(3 sided) like this that only applies to the base. the sides join at 120 degrees.
rex

Rex R said:

the sum of the angles of a triangle are indeed 180 degrees...however for
pyramids(3 sided) like this that only applies to the base. the sides join at 120 degrees.
rex

Click to expand...

I like the way you think.

After cutting the card board pieces at 30 degrees and attatching them to a flat surface, I ended up with this jig.

A Side Wall piece is laid on the flat surface of the jig, which has a tilt of 30 degrees. The edge of the Side Wall piece is allowed to slide down to the table top. It's not pictured, but masking tape was used on the edge of the Side Wall piece still on the jig, fixing the Side Wall piece in place and maintaining its position on the jig. Everything is slid over to the side edge of the table top, which is at a 90 degree angle from the table top (aka a corner).

The outside corner of the Side Wall piece (the edge lying on the table top, which is the edge you'll see when the Pyramid is assembled) is alined with the 90 degree intersection of the table top and side edges. The inside corner of the Side Wall piece is sanded down/off until the sanding block is flat aginst the edge of the table tops side edge.

The sanding block is kept at a 90 deree angle by the tables side edge. The Side Wall piece is kept at 30 degrees by the jig. The Side Wall piece now has a 30 degree angle on it (or what ever angle you build the jig to hold, like,I don't know, lets say 60 derees).
Repeat for the other five edges, taking care to only sand the inside edges of the Side Wall pieces.

Rex R said:

the sum of the angles of a triangle are indeed 180 degrees...however for
pyramids(3 sided) like this that only applies to the base. the sides join at 120 degrees.

Click to expand...

Sort of ...

Like a famous Star Trek villian I was thinking in two dimensions ....

Anyway, at any point in the pyramid parallel to the base, the inside of the pyramid forms a triange, so all the corners are 60 degrees - in the horizontal plane.

But ... the sides of the pyramid also need to be mitered/joined to form vertical triangle. So, you're really mitering the edges in two directions at once - horizontally for the small triangle and vertically for a larger triangle.

The math is really simple*. See:

https://www.josephfusco.org/Articles/Dihedral/Dihedral1.html


-- Roger

*for Stephen Hawking

bradycros said:

A side piece is laid on the flat surface of the jig, which has a tilt of 30 degrees. The side piece is allowed to slide down to the top of the jig saw table top. Everything is slid over to the edge of the table top, which is a 90 degree angle.

The outside edge of the side piece is alined with the edge of the table and the inside edge is sanded off.
The side piece now has a 30 degree angle on it.
Repeat five more times.

Click to expand...

With a mock assembly it became painfully appearent 30 degrees would not physically work.

Regrouped, crunched differant numbers of my own and got 60 degrees for the miters. Cut 60 degree angled pieces from card board and glued them onto the 30 degree jig pieces that are already in place.

Repeated sanding of the edges at 60 degrees and obtained very good results.

30 degrees.

This whole thing about 30 degrees got started when I looked at the SIDE WALL SANDING GUIDE (see photo one below). You can see it says the angle is 30 degrees.

The sanding jig I built for 30 degrees didn't work (the jig works fine, it's the 30 degrees that doesn't work) so I modifyed the the jig to 60 degrees, which did work out well.

A kick to the head comes when step 16 is read, it says:

"Find the SIDE WALL SANDING GUIDE on the Pattern Sheet. Set the flat bottom of a finished Side Wall Assembly on the shaded area at the bottom of the Guide.
Notice the 60 degree sanding angles for the left and right sides."
See photo two below.


Having already sanded 60 degree angles into the Side Wall Assembly, I set the flat bottom of a finished Side Wall Assembly on the shaded area at the bottom of the Guide.

And ya know what? It fit like a glove.

All this run around because the 30 degrees is a typo.

Conclusion: The correct information was available in step 16. I saw the 30 degrees in the SIDE WALL SANDING GUIDE first and ran with it. A note should be included with the instructions that the 30 degrees in the SIDE WALL SANDING GUIDE is a typo and needs to be amended to 60 degrees.

Whew! Glad that's over with.

The next step calls for glueing the 60 degree miters together.

With that task in mind, pieces of balsa were glued to the Pattern Sheet to facilitate the process. The balsa pieces will prevent the Side Wall Assemblys from slipping away from each other while performing the task (that's not in the instructions, but should be).


Visit www.oddlrockets.com

Works well.


Available at www.jonrocket.com

Rare photo op. The reclusive Flying Three Sided Pyramid. Also refered to as a Wedgie. Available at www.jonrocket.com

Warning: This photo contains explicit 60 degree miters. Warning

Hi Todd,
Sorry about the confusion. The build looks great so far and your building jigs look to be very helpful.

I did a simple overlay on your picture so you can see where I was coming from when I drew up the instructions.

Set a protractor on the instruction picture to see the 30 degree angle.
I agree, I believe you probably need to sand more than the 30 degrees to be sure the sides butt up against each other.
One corner of the triangle is 60 degrees total, (a combination of two 30 degree angled sides).
Three sixty degree corners is the 180 degrees for the complete triangle.

This is how I had it explained to me anyway, geometry was never my strong suit!

Thanks, I'll correct the instructions for the next run of kits!

Chris

hcmbanjo said:

This is how I had it explained to me anyway, geometry was never my strong suit!

Click to expand...

You didn't do bad ... for a banjo player.

As to myself ... there's no excuse.

BTW, I ran the size of the Wedgie through the online calculator at:

https://www.josephfusco.org/Calculators/Advanced_Box_Cutter.html

and it returned a "blade tilt (bevel) setting" of 58.69 degrees.

-- Roger

Is pay me time, yes? I am liking to have every moneys I am owning.

Photo op II. The motor mount has a very good fit.


See Hans "Chris" Michielssen's building rockets and read his build tips at:

www.modelrocketbuilding.blogspot.com
www.howtobuildmodelrockets.20m.com

The czech is in the mail ....

BTW, the photo in post #52 must be from your earlier days. You have a beard in the one in post #53.

-- Roger

jadebox said:

The czech is in the mail .....

-- Roger

Click to expand...

Speaking of mail...

I got Apogee's Rocketry E-zine Newsletter, March 1st 2011, Issue #281 in my e-mail and guess who's got an article in it? TRF's very own Chris Michielssen, what a guy! He doesn't just have a article in this months issue, his article is this months issue. Go to www.apogeerocketry.com/education/download/Newsletter281.pdf and read the free pages of great information he has to share.

For more free pages of great information from Chris go to:
www.modelrocketbuilding.blogspot.com
www.howtobuildmodelrockets.20m.com

And visit Chris's:
www.oddlrockets.com

Chris's rockets are available at:
www.jonrocket.com

This template is called the Launch Lug Cutout Pattern, I don't know why. The launch lug is mounted on the motor tube. The template is attached to the Side wall and you cut out a rectangular hole for the launch rod to pass thru. So, I'm calling it the Launch Rod Cutout Pattern. Six of one, half a dozen of the other I guess, as it makes no difference.

Because of the steep slope of the Side Wall, the Launch Rod Cutout slot has some length to it.

I rounded the corners of the Launch Rod Cutout slot. The template corners are square. I like the look the rounded (bull nose) corners give better.

A rotory tool and a Dremel bit were used to grind out the Launch Rod Cutout slot.

The bit got away from me for a split second and took off a little more material in one spot then I wanted, but it's fixable.

The last two steps in construction call for making and attatching the shock cord anchor.

The Glue Application Stick supplied with the kit pulls double duty and now will become the shock cord anchore.

The Glue Application Stick has ample leftover material to allow for the building up of both ends on the shock cord anchor stick.

So, again I deveated from the step in the instructions as posted below.

Another method for achieving the notch (slot) on the 3" piece of the Glue Application Stick is to cut two 1 & 3/8" pieces from the remaining glue stick material and then glue one piece to each end of the 3" piece. This will leave a 1/4" notch (slot) at the center for the shock cord to pass thru.

The shock cord sub assembly.

The last construction step. I'll wait until filler, primer and paint are completed to attatch the anchore to the side wall. A strip of masking tape will be laid down to keep the adhesion area clean until ready for the glue up.

Filling...

Before

&

After.

Some times I worry about your perfectionism, T.

Now let's have a flight report and launch photo!

I've never seen such a smooth, polished Wedgie. Nice work!

Are you going to use the available skins or paint the outside walls?