Each of those little lumps is a machined and knurled knob that keeps the fame together when in place
The bottom is the rear (I thought they were butterfly bolts)...
If I were (and probably will) to make a new one there are lots of changes I would make....
this has been mig welded together I would supect the originals were gas welded or most likely brazed... I would probably start by making it in stainless and get a mate to tig weld it and polish the joints...
The tubes slot over small steel bar inseted into the tubes and are secured using the knurled knobs, that screw onto what seems to be set screws that are screwed into the frame that also serves to prevent them coming off as they can#t come undone past the heads, they do not line up accurately as a result these tube eends open up, this is also made worse by the fact the tubes are not bent acurately so they line up correctly in the first place I would find a way to bend the tubes more accuratley and reinforce these tubes or make a hole in the tube rather than a slot so the tube does not open up and the knurled knob then becomes a screw in bolt...
It is no a days job to fabricate something like this, the main side tubes are hinged in 3 places so the frame folds up...
looking at it now, I would start by making the front and rear uprights and the attachments to the car...
then making a fully tack welded frame with front and rear tubes bent to shape and attached , the middle braces are neither here nor there and are easy to fabricate and fit at any time, this frame could then be removed and you could look athow to make it fold and slot together.
I have seen old spoft top frames from 1960s UK cars they are a combination of fold back and removeable spars, some used a D section tube as it provied a flat surface to weld brackets or hinges......
Not sure if this topic is of any use to anyone else as there are only 23-4 known Jollys, but there are many great mins on here that have years of experiance with odd thigs so input is always welcome...
