Tail post size

[ultra]

I seem to have used a 3/4 inch x .035 wall tube as the tail post to my frame instead of a 7/8 tube.

There is a page in the plans that specifies the 7/8 is optional and that I could use 3/4 inch tubing, will I run into any problems later on in my build?

[Tom XL-7]

Look at page 25 on your XL plans 
Shows a little bit of 7/8 added to act as a socket to receive the 3/4 alum tail.
The 7/8 option would be heavier but simpler.
Tom XL-7

[ultra]

Look at page 25 on your XL plans
Shows a little bit of 7/8 added to act as a socket to receive the 3/4 alum tail.
The 7/8 option would be heavier but simpler.
Tom XL-7

Thanks, I think I'll just keep the 3/4 inch post for now.

On another note I have about $40 worth of off cuts of chromemoly tubing. Is it structurally safe for me to weld them end to end to make a longer piece to use in the frame?

[scottiniowa]

On another note I have about $40 worth of off cuts of chromemoly tubing. Is it structurally safe for me to weld them end to end to make a longer piece to use in the frame?

Ultra- I think this was your question and not Tom’s

first, you never weld tubing end to end for a structural piece.  Look up scarf joint, for a much better explanation. but in the end, if your labor is anything at all, you wouldn’t earn $1-2.00 per hour in savings.  Hardly worth it.

Now for #2,  This takes time, but using a XL spread sheet really makes this work.  
     from your plans, you take all the longest pieces and write them down..   This might be one cut per length to get this piece, but you have on your spread sheet, what you have left (remainder of the length)
      Then you take the next longest required part,  either this comes out of a new length or one of the remainders from above.
       Pretty soon you have shorter and shorter lengths required for frame, but are taking these out of the remainders from above.

      This works for each tubing size…  it really works out well, of course what makes a mess, is if you cut a piece to full required  length and either have your measurement wrong, or  cut the piece wrong.  Either way, you soon learn to NOT DO THAT again.  ;-)  

      This works for any size of aircraft frame.  The pile of scrap left over is very small.

    Preplanning is your friend here for both time and dollars.

Best of success.

[scottiniowa]

On another note I have about $40 worth of off cuts of chromemoly tubing. Is it structurally safe for me to weld them end to end to make a longer piece to use in the frame?

Ultra- I think this was your question and not Tom’s

first, you never weld tubing end to end for a structural piece.  Look up scarf joint, for a much better explanation. but in the end, if your labor is anything at all, you wouldn’t earn $1-2.00 per hour in savings.  Hardly worth it.

Now for #2,  This takes time, but using a XL spread sheet really makes this work.  
    from your plans, you take all the longest pieces and write them down..   This might be one cut per length to get this piece, but you have on your spread sheet, what you have left (remainder of the length)
     Then you take the next longest required part,  either this comes out of a new length or one of the remainders from above.
      Pretty soon you have shorter and shorter lengths required for frame, but are taking these out of the remainders from above.

     This works for each tubing size…  it really works out well, of course what makes a mess, is if you cut a piece to full required  length and either have your measurement wrong, or  cut the piece wrong.  Either way, you soon learn to NOT DO THAT again.  ;-)  

     This works for any size of aircraft frame.  The pile of scrap left over is very small.

   Preplanning is your friend here for both time and dollars.

Best of success.

Thought a bit more on how I do this….if say I have 101” piece, left and I had three piece that added up to 100” I would most likely take advantage of the only one inch waste… but would go over all the parts, to see.  

The beauty of this, is that you can mix and match cut lengths to leave the least waste.

that’s all folks!
Scott

[John Reinking]

Thanks, Scott.  We novice builders put great regard to your more technical posts, they are very helpful.

[ultra]

Thanks, Scott.  We novice builders put great regard to your more technical posts, they are very helpful.

I found his CAD drawing especially helpful too.