Lack of 4130 dimension info

[PoconoJohn]

Basically, what dimension should I use for a tube if no dimension is provided? What's the trick?

On page 12, I see the note there 'All tubing 3/4 X .035 unless noted' (is that for page 11 also?), but I'm confused; how do I know if they forgot to print or indicate a different dimension such as observed with the bottom center drawing where they obviously forgot to label the left vertical (common sense indicates it's the same as the others)? On page 12, the top right show 7/8 X .049 for the bottom horizontal and there's a note about the 3/4 angled piece on top, but what about the other pieces (page 11 is no help)? The bottom left has no measurements, so I guess those are 3/4 X .035.

On page 11 bottom, are all the cross members 7/8 X .049 (station 0.00 to 82.50)? What about the cross members in the center drawing? It's frustrating when the plans force me to guess.

[dougm]

Hi John,

I took the note on page 12 to apply to both pages 11 & 12 - i.e. all tubing 3/4 .035 unless noted. IF you spend some time cross checking the two pages this appears to be correct, but yes it is frustrating that you have to figure this out. There are a few other spots on the plans that you may have some challenges with as well, but those are well documented elsewhere in the forum. I've found a number of times that the answers to some of these sorts of questions ARE on the plans, but not always where you would think they should be. I've often had to cross check several pages to get all the answers.

Regarding the 7/8 x.049 pieces, if you check page 11 you'll see that they only appear on the bottom at stations 23.00 & 45.00. This is due to the landing gear attachment.



If you haven't already done so, I would strongly recommend you pick up an architects scale like this. You can find them at Staples, Office MAx, etc and are indespensible when determining length, width diameter, etc. on the plans and will help answer questions such as the 3/4 vs. 7/8 as you can measure this on the plans with a good scale.

[PoconoJohn]

Thanks Doug. I had tried using a ruler to measure the drawing, but I wasn't sure if it would be accurate, but I'll use that method and get at it again. BTW, I'm posting my project progress here: http://ImageEvent.com/hatz

[JBMoore]

What's the trick?
In nerd school drafting class, they teach you to put a general statement about dimensions in the information block... tolerance, size and what have you. That way they don't need to call out every single detail "unless noted".
As we all know, sometimes the prints lack this information for whatever reason and it will take a little time and experience to learn what to do. Remember these planes started out as chalk lines on the floor with no plans. You may need to cut and place a few things on your work table and measure the next piece yourself. My mentor told me that I would reach a point where I would start to visualize what I would need and not even use the plans any longer... and he was right. Once I laid out the centerlines on my build table, I didn't look at the plans until I was ready to weld the fittings on.
"Unless noted" I used 0.035" wall thickness. As you said, common sense will take over. The beefier tubes will be used in the high stress or load bearing areas.
Good luck.
Jeff Moore

[Nick]

John, this is the reason I was always happy to have a set of CB-1 plans handy. Great for cross-referencing. Not all dimensions are the same though, some common sense needs to be applied.

Nick

[PoconoJohn]

Thank you Jeff. Thank you Nick. I've been looking at the plans for almost a month and I'm ready to get my first order in for material. While I wait on that, I'll make the rib jig and various templates.

[PoconoJohn]

Here's what my (minimum) 4130 shopping list looks like so far (see anything weird?):

5/8 X .035...33 feet
3/4 X .049...31 feet
3/8 X .035...6 feet
5/8 X .049...2 feet
5/16 X .035...13 feet
1/4 X .035...3 feet
7/8 X .049...4 feet
1/2 X .035...35 feet
3/4 X .035...121 feet
1/2 X 1/2 X .063 squares...10 feet
3/4 X 3/4 X .032 formed angle...12 feet
1/2 X 1/2 square...2 feet

As far as wood (enough to get started):

Mahogany 1/16" plywood for gussets...2 sheets of 4X8
Spruce capstrip 1/4" for ribs...600 feet
Birch plywood 1/4" for nose block, trailing tip, center section bottom, center ribs...1 sheet 4X8
Birch plywood 1/8 for false nose...1 sheet 4X4
Spars for front...5" X 11'
Spars for rear...4" X 11'
Spars center section...4 1/2" X 5' and 5 1/2" X 5'
Spars (aileron)...4" X 5'
Spruce capstrip for the wing gussets...1/2" X 28'
Spruce capstrip for the wing gussets...3/8" X 12'
Mahogany plywood 1/4" for plywood rib #1 and center section ribs...1 sheet of 4X8

Still thinking about the leading edge components.

My plan is to build ribs then, if I have space (and I don't quit), build wings. Then I'll pursue the fuselage.

[dougm]

I'll rummage through my receipts this weekend and see how mine compare.

Is your steel tubing list supposed to represent all the tubing for the plane or just some portion? At first glance it doesn't look like it represents enough for the entire plane.

[PoconoJohn]

I forgot to type in the horizontal stab & elevator material. I know I'm going to make other orders and that I'll need to re-do some work. I did send in my first order; just wood for ribs. I won't order spars until I'm ready for that. When I make that order, I'll also order all the tubing I can think of.

I used tracing paper in order to reach the amount of material (to make sure I counted each piece and did not miss any or count any more than once). I had a sheet of paper with the various dimensions. As I drew over each piece on the tracing paper, I noted the dimension and wrote the inches I measured in the appropriate place. If I measured from a page with a different scale, that was noted. I then added it all up and converted it into inches and feet. I'm sure I messed up somewhere, but I think I'm in the neighborhood.

If you haven't seen my webpage, check it out; I think you'll like the size and clarity of my images. http://imageevent.com/hatz

[dougm]

OK, here's my steel list:
Feet...Dimensions (Round unless noted otherwise)
8.......1/4 x .035
41......5/16 x .035
8.......5/16 x .065
9.......3/8 x .035
8.......3/8 x .065
68......1/2 x .035
8.......7/16 x .065
55......5/8 x .035
8.......5/8 x .049
8.......5/8 x .065
199....3/4 x .035
171....3/4 x .049
8.......3/4 x .058
6.......3/4 x .095
18......7/8 x .049
8.......7/8 x .058
8.......1 x .049
8.......1 1/2 x .035
8.......1 1/2 x .065
8.......1 1/2 x 3/4 x .049 (Rectangle)
8.......3/4 x .035 (Square)
8.......3/4 x .049 (Square)
6.......1/2 x 1/2 x .035 (Square)

In addition to the list I also ordered my streamline tubing, but can't find the receipt at the moment. I'll go measure them later on. The list represents everything I could determine from the plans except for the engine mount. I still need to order for that.

I over ordered a bit on the 3/4 x .049 ( I probably needed more like 120 feet), but your list looks short on that one. Don't forget you have four longerons @ roughly 15.5 feet (you'll want them a bit long until you trim to final size) so that's ~62 feet right there.

A couple of comments on ordering the steel:
1. Plan for mistakes and order some extra. I've done pretty good so far until I got to the seats where I wasted a couple pieces. Fortunately, I can still cut them up for smaller pieces and make use of the tubing.
2. When you order you can get "full length" tubing which usually runs 18-20 feet. This is often easier because then you can decide how you want to cut it. It also give you some extra length to work with if there are any dents or scratches in the tubing. I had one arrive with a slight dent, but was able to plan around it and use most of the tube anyway.
3. Check on cutting charges and/or minimum sizes when you order. I bought all my tubing (except the streamline) from Dillsburg Aero (now out of business). He preferred to deal in longer lengths and would charge a cutting fee on anything shorter than 6 feet. This is why even for tubing where I may only need a foot or two I still ordered 6 or 8 feet. The savings on everything else more than made up for the extra couple feet.

FYI, I added your site to the Builder's Page.

Hope this helps.