Is tension from the rack loosening the nut while riding? If so, maybe a second nut between the rack and clamp?
View attachment 241029
But it does look like it's just bending one side of the clamp rather than the whole clamp tightening evenly. Since it's welded, I assume on the front side, I'd try flipping the bolt and spacing it on the left rather than where my arrow is on the right where it's weak from bending. But it seems the same physics, I'm just guessing.
I'm sure you are correct about the rack playing into the seatpost clamp not staying tight enough. I should probably find the same hardware that Murray originally used to mount a rack to a seat post clamp like that, which in my (admittedly limited) experience has usually involved a nut with a shoulder like this that can't easily be found at your local hardware store:
I can remember being a kid and screwing up seat post clamps and bolts on cheap bikes like this on more than one occasion. It would go like this: the correct bolt and nut were missing, I'd find something in Dad's Magical Bolt Bucket that fit in the hole, and I'd wonder why the bolt bent in the middle and/or the nut rounded off when I tried to tighten it enough. (This also may have been attributed in part to using the wrong diameter seat post, but I digress.) Now I understand better what has to be clamped and how force has to be applied evenly. I just have to find appropriate hardware. I can't flip the bolt around as you suggest because one side of the clamp has a square hole and the bolt I'm using has a square shoulder under the head that just reaches through the rack into that square hole. Not exactly this setup, but similar:
If I'm going to use the existing clamp, I should probably get a regular bolt and space it away from the clamp so the head/washer isn't hitting it unevenly, if that makes sense. I even considered getting a length of threaded rod or a bolt like is used in some seat guts that threads at both ends, then using it to secure just the seat post clamp with two nuts, then putting the rack stays on the outside of those nuts and securing them with two more nuts. Or I may look into alternate clamps with divorced rack mounts as
@OddJob suggested above.
Is the wood panel and polystyrene experiment still in play? Looking forward to seeing how you design it.
Yes it absolutely is. I picked away at the wood panel this morning. It's not perfect, but I think I'm going with it the way it is. I tried to massage the upper curve and lower straight edge with a palm sander, which is the wrong tool, which is what happens every time I work with wood. I can envision the kind of table mounted sander I want to use to just barely skim away at the last couple of spots that aren't perfect, but I'm thinking I should quit while I'm close before I screw it up.
I have some stain downstairs that I'm going to use on the wood. I'm still deciding on a color for the polystyrene. I don't think I want it to be white; I'm envisioning the light tan wood color used for the edging on woodie wagons, whether the "wood" was actually wood or Di-Noc. I'm envisioning a color scheme something like one of these:
And since you asked, I've been trying to decide on a font for the name Beachcomber. I mocked up pictures in about a bajillion fonts, and I'm down to a couple I really like.
I have always liked this one, which is called Air Conditioner, but the problem is that it's VERY wide. If I want to keep the nameplate down to about half the length of the wood insert, the font will have to be about 1/2 inch tall.
My wife picked this one, which is called Donatello. It's growing on me. Kinda reminds me of the Coca-Cola font.
I can stretch Donatello to make it wider and fill the nameplate and it'll still look good, whereas if I squish Air Conditioner to make it narrower (so I can keep the height) it kinda loses something. I think a big part of the draw of Air Conditioner is the width. Side note: I have used it with a couple of modifications to make a reasonable facsimile of the old Schwinn font.
