Thread subject: Homeroasters.org :: Frame Design and Construction
Posted by Alchemist on 07/13/2008 08:29
Now, in a good shop, they have a tool to mark the metal so the drill bit does not wander. I don't have one, but I do have nails.
Get a nail and rap the metal where you want the hole to be. Even a drill press mounted drill can wander, so don't skip this step.
Go ahead and drill both holes (BUT ONLY IN THE OUTER PIECE).
Posted by Alchemist on 07/13/2008 08:31
OK, you have both holes drilled. Great. Now dry fit them again.
Mark through ONE (1) of the holes to the support underneath.
Posted by Alchemist on 07/13/2008 08:36
Now drill out that one hole (don't for get to tap it with the nail to align the bit).
Since you are 'field aligning' the fit should be perfect.
Fasten the parts together.
At this point you drill straight through the angle part's hole to the support below and be assured of perfect alignment (and don't have to nail tap it this time).
Posted by Alchemist on 07/13/2008 08:46
Set that other fastener and you are done with that part.
As with most detailed instructions, it took me probably 10-20 times the time to explain it and you to read it than it does to do it.
Finally, take note of the rounded edge, and how obvious it is that the piece would have fit better if I had had more of a gap in the original speed square laid out piece. Even so, this would fit just fine once all the pieces were together.
One final note I laid out rough dimensions (with exact numbers, I know) but they did not take into account those bend radii. At some point you asked me for the the exact dimensions we would need for the sheet metal skin and I told you I could not answer that. This is exactly why. I didn't (and don't) know how much to allow for bends, and way more importantly the fasteners. The skin will go over those, and you can see how much they are going to add. What we will do is field measure those lengths with some extra, bend the pieces up, fit them, note the overlap (because of the extra), then mark and cut the skin for a perfect fit.
Posted by David on 07/20/2008 19:32
I started practicing some of the metal work fundamentals that you suggested.
On two spare 8" strips of 3/4" angle aluminum I marked off the "V" for the 90 degree bend and drilled the hole at the bottom, as suggested by Dan.
Except for scoring the metal somewhat when drilling the Dan Hole, the cutting on the lines went fairly easily.
Well, the angle wasn't quite right, as will be seen, but that didn't keep it from being easy!
Posted by David on 07/20/2008 19:38
Bending it accurately turned out to be much harder.
I decided to hold the short strips to the board with screws and bend it around the corner.
Posted by David on 07/20/2008 19:39
I did not know where to attach it exactly. My first guess gave too little distance from the "fulcrum."
The angle is too shallow to let the corner close, and the corner bend is off center a bit. Workable for sure, but still off the mark.
Here's another view of the same corner:
Posted by David on 07/20/2008 19:43
I attached the second piece of metal, adjusting as shown in the picture.
I went a bit too far in the other direction with this second bend, leaving too much space before the bend point.
Posted by David on 07/20/2008 19:44
Again the corner doesn't quite line up, but in the opposite way.
Posted by David on 07/20/2008 19:49
Lesson learned. I'm sure I could get it right the next time.
Yes, I realize that I don't have to actually attach the metal to bend it, and I get it that doing it freehand will allow me to adjust the bend as I go.
And, even though the folded corners would be stronger, I think I'd like to skip the bending at this point.
I think I'd prefer to just trim the metal off at 45 degree angles and make simple joins at the corners. We could just attach them to the vertical braces.
Are you OK with that?
Posted by Alchemist on 07/21/2008 09:56
Yes, you hit the same conclusion I did. I will design around making the corners three separate pieces and holding them together with the support.
The only real change is that I want to hold each piece in place with two fasteners (rivets) since we won't have the added support of the bent corner.
We will keep the bends to less than 90 degrees. 45 at most.
Edited by Alchemist on 07/21/2008 09:57