It's Such a Stud...plate (or, how to make Stud Plates for Rover assembly)
Original Author: Alan J. Richer
In the never-ending rebuild of my 109 I've often been forced to manufacture small components - most notable among these being the stud plates that are often used to join items with no easy back access. These originally were 1/4-28 threaded
studs pressed into pieces of thin sheet metal, with two or more studs to a plate.
Once placed through the holes joining two components, nuts and washers could be added and pieces fastened together without need to immobilize the bolt to screw things together.
Now, at least on my car, few of these original plates are still usable, as time and the elements have consipred to corrode them away. Because of this I've been forced to come up with a simple way to make them without access to welding gear or hydraulic press blocks for pressing studs.
The method I've worked out joins a piece of 3/4" hot-rolled flat steel and 1/4" fine-thread bolts using soft soldering - as is used to join copper piping in houses. It's not the strongest join, but for an item like this where all of the stress is tensional it's more than adequate.
Now, before you tell me you can't solder steel because it's a ferrous metal - think again. You can do so easily. It does require more heat and a good flux of the plumbing type, but it does work. The trick is to ensure that any plating or coating on the metal (other than galvanizing - that will actually help) is removed and that the steel is clean and bright. With the proper flux solder will take readily to non-copper items.
To make stud plates you will need the folllowing items:
Plumber's tin-lead solder
Plumber's acid soldering flux paste
3/4" x 1/8" Hot-rolled steel - note Typically, at Sears Hardware or the local hardware store this is called "Weldable" steel.
If all you can get is the shiny stuff, however, then be prepared to file the plating off of it before soldering.
1/4-28 x 3/4" bolts
Hand tools for measuring, shaping, cutting and drilling metal
OK, now how do you actually DO it?
Simple - I'll break it up into 3 steps.
1. Measuring and design
First things first - the design of the plate needs to be fixed before we can make it.
If you have the original plate all well and good - the stud spacing and length of the plate can be determined from that.
If not, measure the center-to-center distance between the holes on the items to be fastened, and allow 3/4" of steel at each end if clearance permits. Cut the 3/4 x 1/8" flat steel to length, mark out the center line and stud positions and drill the bar with 1/4" holes to allow the bolts to pass through.
Wirebrush the metal thoroughly to remove rolling scale and any debris or oil - you need a bright shiny surfgace. However, remember that no plating is allowable where the soldering is to take place - the solder simply won't stick to the typical thin zinc or cadmium plating on bright flat stock.
On a bench grinder or with a file, file the heads of the bolts till all plating is removed and the metal is bright. Neatness is important here only in that you need to get al of the plating off - the flats don't need to be straight or tidy for this purpose. If I'm doing multiples I will typically just chuck the bolts in my lathe and turn off the flats and the tops of the heads - but that's only because I'm lazy. A file and a bit of patience will do the job just as well.
Coat the surface of the steel bar where the bolt heads will sit with a thin but complete coat of acid plumber's flux. An acid brush or applicator is good for this, though oftentimes I'll use a thin stick or the like depending on what's to hand.
Coat the heads of the bolts all round with the plumber's flux and inert into the pre-drilled holes in the plate. Holding the bar horizontally with the bolt heads up (I clamp it in my vise, though a pair of locking pliers and a brick or two can be made to do) apply heat from a propane torch to the plate and bolt head join.
The flux will melt, then bubble and spread over the metal parts.
Apply solder to the join on the far side from the torch. The solder will melt and bead up, then as the temperature rises to the proper point will wick into and around the bolt head and plate joint. When this begins to happen, remove the torch and apply more solder till a fillet is built up arund the bolt head.
Now, move on and do the next one in the same manner. As the bar will already be hot, second and subsequent operations will be faster.
Lastly, let the bar sit undisturbed till it is only warm to the touch. The rest time will prevent creation of a "cold" solder joint which will have little structural strength.
Once cool, inspect the solder joints. Each should be clean, shiny and smooth and should have no open gaps.
Clean the bars thoroughly of all flux residue, then spray-paint them at least two or three coats with a good enamel. As this trick depends on unplated steel, we have to get something in between the metal and the atmosphere for them to really last.
If properly made these bars will easily perform any job that the original tin brackets LR supplies will do - and will last longer. The only things you need to be careful of are:
1. The total length of the plate - sometimes the space the plate goes into is restricted, so that the 3/4" to each end
needs to be modified. You can essentially set the end of the plate no longer than the outside of the bolt head, but if
you do make sure that the solder fillet is complete to all the other sides to ensure adequate adhesion.
2. The height of the plate as-described here is thicker than the original pressed stud and steel strip plate LR used. I've never run into a spotr where this is an issue, but it's something to remember. In that case, partially countersinking the bolt head, or using a slightly thicker strip and flathead bolts might also work.
Copyright 2005 - Alan J Richer
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