Notes - Technical Tips and General Information

This is a "work in progress" document... it is not finished, but it is worth reading!

Technical Tips and General Information

by Ron Boudreau

1. Introduction
The intent of this information is to help others in the quest to build there dream.

I originally went to school to become an aircraft mechanic. I owned and operated a racing company in the early 70's designing and building formula cars using tubular space frames and monocoques. I have been working on cars for 39 years, restoring cars, building racing cars as a business, and now as a hobby.

I have been an engineer working in the computer industry for the last 30 years. I don't claim to be an expert on anything. Every person I have met that claimed to be an expert on a subject, usually was not, and the ones that were experts did not need to tell you they were. I have learned a lot over the years from other people gracious enough to share their wisdom and experience with me. In these pages I will attempt to share some of the information others have taught me. There will always be someone who knows more on each of these subjects and it is recommended to read and study the subjects in depth.

The adventure we are starting on is to reproduce a replica of one of the most powerful and highly refined vehicles in the world. Every aspect of the original car had teams of engineers working on its development. We are taking cars, parts and our own fabrications trying to the best of our ability to duplicate their effort. It should be our obligation to make sure our dream is safe for us and others we will be sharing the highway with. Our beautiful creation can turn into a heap of scrap in a second, if the suspension breaks going down the highway at 80 mph. Of course, the safety of others and ourselves is important. I hope that some of the information presented here will spawn some thought and consideration in the tasks involved.

2. Books to Build With
When I decided to build a Lambo replica I realized it was time to go back to the books to update myself on the latest information on design, hardware and fabrication. In life there is always something to learn. One of the meanings of the word technology is change. It seems as soon as you learn something and think you know what you are doing, some new information comes out and forces you to rethink every thing you held to be true and sacred.

Most of these books are available on Amazon.com, one exception is The Diablo book, which is out of print. I bought my copy on from a dealer in England through a web search.

	Lamborghini Countach, by Jean-Marc Borel ISBN 2-903652-01-5 (yea I know it's the wrong Model) It was published in 85 and more than likely is out of print. It is an outstanding narrative on every step in the building process of the Countach. I wish there was one as complete on the Diablo, it is the most comprehensive book on the building of a production car I have ever seen. It has pictures of the original concept unit body frame and the tubular frame they ended up with and a step-by-step study or every sequence in the building of a Countach. It even has the time each step takes at the factory. It almost has enough information to build one.
	Lamborghini Diablo, by Stefano Pasini ISBN 88-85880-36-3. I had hoped this book would be as comprehensive as the Countach book but I was greatly disappointed. It also may be out of print I got my copy from a dealer in England I don't remember how I found him but I got my book anyway. This is not a technical book by any means. It is the story of the design and building of the car and how it came into creation. It has very little technical information at all. It's got a few pictures of the frame, an excellent two-page cutaway of the Diablo and a specification page, but other than that it is void of useful information. The aforementioned items however make it worth the price.
	Lamborghini Workshop Manual and Parts Manual - I bought these items on Ebay. They are photocopies of the originals and cost $150 for the pair. They have scale drawings of the suspension and some frame dimensions. The parts manual shows every part on the car. When you see the parts manual it makes it look like a kit car. As a matter of fact, the Countach book brings this out vividly. The Countach and the Diablo are hand built. There are made with no heavy stamping equipment used like in a mass produced car. The Countach body panels are made on wooden bucks and English rolls. They are hammered and welded into shape by hand. The Diablo uses aluminum and carbon fiber panels presumably built the same way. Sounds like a kit operation to me. Of course one must disregard the fact that they also machine and build there own engines and transmissions and have craftsmen in every field. But the manuals are worth looking at and if you are building your own frame they provide a look at how it is done at the factory. There is no magic here; they weld steel tubes together just like we do.
	Prepare To Win, by Carrol Smith, is available on Amazon.com. If you only read one book in attempting this project, this is one you want to read. It could save your life. Smith is a fanatic, but a fanatic with the right knowledge about his subject. This book covers every thing from welding to suspension set up. He goes into plumbing, riveting, metal work, fuel cells, paint and plating. The drawing of how to fabricate struts and joints are priceless and follow aircraft standards. He is a nut about cleanliness in welding and preparation of things to be welded (me too). He shows rosett welds, which are mandatory on threaded inserts being placed into tubes.
	Metals, Fibers and Materials, by Forbs Aird ISBN 0-87938-916-8. This book is fairly in-depth on the metals and light on composites, but it is worth the effort. It is not an instructive book, but gives a good all around summary of the available alloys, their differences and their uses.
	Engineered to Win, by Carrol Smith, ISBN 0-87938-186-8. As you might have guessed Smith has written more than one book. In fact, he has a series of books each valuable in their own right. Engineered to Win probably has more information than you want to know. It goes into how steel is made and the metallurgical aspects of all the common material found in racing cars and cars in general, or anything else for that matter. It has examples fatigue analysis and their causes. It has a lot of great information, but is rather in depth and is more a materials book than a construction book.
	Nuts, Bolts and Fasteners and Plumbing Handbook, by Carrol Smith ISBN 0879384069. This is the bible of screwing things up in the right way. It is considered the best available book on the subject. As you might have guessed by now Smith is both a prolific writer and a true expert in the field. He has been the crew chief on Indy teams and managed several racing teams. He has forgotten more than most of us will ever know about racing cars and their construction. I highly recommend having these books on hand.
	Performance Welding, by Richard Finch ISBN 0-7606-0393-2 This book explains safety, equipment, fixturing, as well as the current methods and techniques. If you are going to weld anything your life will be depending on this book will give you information that your welding supplier won't tell you and most casual welders just can't keep up with. Carrol Smith actually shows more examples of the proper ways to construct and repair tube frames in Engineered to Win than in this book, but Performance Welding has more current information about the equipment and welding materials and the subject of welding.
	Chassis Engineering, by Herb Adams ISBN 1-55788-055-7. This is not as good as I hoped it would be, but it does have good explanations of suspension geometry, anti squat and such. It has some good shots of frame construction, mostly heavy stuff. There are some good explanations of torsional stiffness and the need for it. The examples of backbone frame construction are worth the price of this book. Since cutting the roof off a Fiero removes most of the torsional stiffness it would be worth the effort to put some back in by stiffening up the tunnel. It also illustrates the need to tie the front suspension loads into a torque tube on space frames.
	Street Rodder's Chassis and Suspension Handbook, by HP Books ISBN 1-55788-346-7. There are a lot of pretty pictures, but not much information pertaining to the effort of building a Diablo. It did have some interesting pictures of air bag springs, which is what I was looking for. Not worth the effort unless your building a duce coupe to tow your Diablo with.
	Race Car Chassis Design and Construction, by Forbes Aird ISBN 0-7603-0283-9. This book is a must read. It is more a "how come" than a "how to" book. It does a great job of explaining the reasons for things. It also has as many examples of bad designs as good ones. In one memorable section he explains how all the tubes in a properly designed space frame could be joined by ball joints and the frame would not bend or twist, because all the tubes would be in either tension or compression. He has an interesting chart showing the torsional stiffness of some past notable cars and some contemporary. Although it is not strictly a how to book from a fabrication point of view it is a how to from construction fundamentals point of view. For this aspect alone it is priceless.

3. Welding
Welding is defined as the art of sticking things together. It is simply taking multiple pieces of some materials and heating them up to their liquid state and combining them into one structure. If only it were that simple.

Safety
In heating metals up to their melting point, we are using either a flame from a torch or an electrical arc. No part of the welding process is beneficial to the human body. We are melting the steel or aluminum but we are vaporizing copper, oil and in some cases zinc and other substances. With electric arc we are generating high intensity UV light. In most cases we are the occasional operators and toxicity is usually harmful with repeated long term exposure.

There are however, a few things we should be aware of even as occasional users. Vapor: some people can have extreme sensitivity to the vaporization of copper, zinc, paint and oils, all of which, builders will be doing. The copper is a coating on most welding rods and spools of MIG wire. Most of us, myself included, thought the nice people who make the stuff were coating it so it wouldn't rust on us. But Performance Welding by Richard Finch states it is only there to lubricate the extrusion dies when making the rod or spools. The copper vaporizes at the temperatures we weld steel at, so at that point it's a gas we breathe. It is toxic to the human body. Most cars today, and I'm not sure if the Fiero falls into this category, are zinc plated (or galvanized). Vaporized zinc can have immediate respiratory complications for some people. If you, or someone in your family, has asthma or allergies be aware welding can aggravate their condition.

UV light: no part of the body should be exposed to UV light generated from a welder. This is easily accomplished with gloves and long sleeve shirts. Some light will still go through thin fabrics. There are readily available gloves and leather suits for this purpose. However, they are bulky and hot in the summer.

There are also some others to be concerned about. Little people and pets do not know what you are doing and will find it fascinating to watch the beautiful arc. It is our responsibility to look around before we weld and make sure people and critters are out of harm's way.

Heat and Splatter
Oxyacetylene, MIG and Plasma cutting generate a lot of sparks that make a mess and can cause a fire. It shouldn't even be necessary to say this, but sometimes when we are in a hurry we let caution slip and we get into trouble.

Sparks from MIG welders, plasma cutters, grinders and torches will implant little beads of molten metal into surface of glass. The windows for the kit should be taken far away or protected from sparks. Harbor Freight Tools has a welder's blanket for about $25 for this purpose. Welding can trash all our beautiful glass that we just paid a fortune for.

Burns
Anyone who has welded for a while will have burns to prove it. Things welded stay hot for a loooong time.

Theory
By an external source, we are melting a local area to create a pool of liquid metal and, most of the time, adding a filler rod of compatible material to fill or build up the welded area. Atmospheric oxygen is a major contaminant in the process and must be shielded from the pool during the operation. Done correctly the weld will be of greater strength that the parent metal. Otherwise, the parts will fail in their intended use. In all types of welding, oxidation is the enemy. At the melting temperatures of the metals, oxygen will readily combine with the metals making oxides of them. The oxides are extremely hard and brittle. When you buy sand paper you may see aluminum oxide printed on the back, this hard material is what would be in an unshielded weld. An oxidized weld will be as hard as glass and brittle with voids and inclusions in it. All the welding types accomplish their job by shielding the weld from outside oxygen in one way or another.

Types of welding
Oxyacetylene welding is the slowest and hardest to master. 99% of us will not use it for anything other than loosening rusted parts (normally found in New England). It accomplishes its goal by putting out massive amounts of heat to melt metal by the brute force of a flame. Large areas are heated up and the flame itself is a danger. Oxyacetylene welding has been around for a long time and has built airplanes in the 30's that are still flying today. It's an old process and a sound one. You can weld mild steel, chromoly, and aluminum (I can't) with it. The neutral flame shields the weld from oxidation. The flame puts so much heat into the surrounding areas that distortion and shrinkage become a problem.

MIG welding
MIG welding is by far the most popular type of welding on the planet. The reason is that the entry-level welders are cheap and the process is relatively easy to learn. These are also reasons it can be the most dangerous. A MIG welder works by feeding a wire from a spool located inside or in some cases outside the machine. As it hits the metal to be welded it strikes an arc, which melts the wire and deposits it where the tip is aimed and builds up a bead of metal. As long as you pull the trigger and hold it there, it will feed and melt metal. The process is varied by voltage amplitude, and wire speed. The proper setting of these two parameters will determine the penetration and buildup of the weld bead. Oxygen is shielded from the weld by flux or by an inert gas shield. The flux core MIG's are generally the entry-level welders because they do not require a bottle of gas and a solenoid to turn it on and off. The rub is that you have to deal with the flux after welding. Technically, you are supposed to clean the flux from weld every time you stop so you don't have voids in your weld. Since you start and stop continually with MIG welding, cleaning will become tiresome rather quickly. Afterward you need to clean all the flux off the parts before finishing. I have no first hand knowledge of these machines and I don't know how controllable they are, or the results that can be obtained with them. In Performance Welding, Richard Finch stated these machines should not be used because they lack feed and voltage control.

The gas machines use a mixture of CO2 and Argon. They should have adjustments for wire feed and voltage. The directions provided with the machines provide guidelines for the settings you should use for different gauges of metal. They are guides, but I find it takes some experimentation to get the right setting.

One drawback of MIG welding is that a weld made with a MIG welder will always have a cold start. The MIG starts putting down metal the instant the spark is established. At this point the metal is cold and you will not have full penetration until the process reaches a steady state temperature. The thicker the part, the longer this will take. So, if one section of your weld will be subjected to greater loads than another, start in the less critical area. Finch also states MIG welding is the hardest type of welding to master. "Easy to do, but hardest to master" (Performance Welding, Finch). Laying melted metal on top of another piece of metal is not welding. Proper rod, penetration and weld bead build up is the goal and it takes practice and understanding.

He also stated a machine capable of fine work will cost more than a new TIG welder, starting at $1500. In my opinion there should be a lot of new machines out there for less, but who has the time to try them all. My MIG cost $1100 fifteen years ago and I will not be using it on many Diablo part because MIG does not have the control I desire.

TIG Welding
I might as well state this up front; I love this form of welding. TIG stands for tungsten inert gas, also known as Heliarc, named by the people who invented it. It also used helium as a gas when first brought out, thus, the name.

This form of welding melts metal by creating an electrical arc between the tungsten and the material you are welding. The tungsten does not get consumed and the atmosphere is kept away by an inert gas flowing out around the electrode. There are different nozzles and electrode material available to use with different metals. Different gases and gas combinations are also used for special purposes. Welding is done in DC and AC mode with a high frequency voltage superimposed over the AC during aluminum welding. DC is generally used for steels. There are many variations of all of the above for special purposes that are too complex for this article. The reason I am using TIG for my project is it is the most controllable and refined welding available. It takes longer than MIG but it gives a great deal more control, doesn't splatter, produces a clean looking weld and is considered the strongest. All of these forms of welding take practice. It is best learned at a night school under a qualified instructor.

Stick Arc Welding: I won't event go into this for in my opinion, it has no place on a racing car or on my replacar.

Cleanliness should be the norm in any type of welding. In welding, we are changing the state of the material from a solid to a liquid. Anything on the surface or behind it will mix in the pool of molten metal. Mill oxide, oil, dirt, sand and anything else will combine with the pool and make a new alloy. The trouble is that none of this is desirable. Sand blasting a part before welding should be avoided. The problem with this is that the sand or glass fractures and impinges itself into the surface of the steel or aluminum and when you weld over the surface all the sand or glass beads melt into the pool and cause voids in the weld. To prove this to my self I recently blasted a part and welded it. It had little black specks in different places. I ground them to see how far in they went, some were near the surface but a few went extremely deep. This would definitely have been an unacceptable weld.

In welding, it takes practice to become proficient. Don't be afraid to waste a tank of gas learning on scrap to get the hang of it. Take some test pieces and bend them 180º and see if the weld holds. A properly welded structure will not fail on the weld and the weld will be stronger than the parent pieces. Our final exam in aircraft welding class was to weld a small tank about the size of a large coffee can. The side seam and both ends were welded and then threaded fitting was welded on top. The tank was then filled with water and hydraulically pressurized until failure. If the tank broke on the welds you did not pass. A car is not a test item to be learning on.

4. Plating
To chrome or not to chrome that is the question, as Shakespeare said (At least I think it was Shakespeare). This is a religious question with some people so I'll just state some concerns and considerations in plating.

Chrome plating is banned by most if not all racing organizations on any critical part. It is helpful in deciding what a critical part is by considering if the part were to brake or fall off while driving, what the consequences would be.

In the process of chrome plating, hydrogen is entrapped and absorbed into the surface of the parent metal. The part must be post baked to rid the part of the hydrogen. If it isn't baked it will be subject to something called hydrogen embrittlement. Hydrogen embrittlement hardens the outside surface of the metal. The problem arises from having a ductile inner core and a hard outer core. Under flexing, the hard surface cracks causing a stress riser which leads to cracking and eventually to part failure. Yes I know just about every hot rod you see in every magazine is a toy land of chrome, but seldom does a hot rod get taxed to the limit or is used for anything but cruising at slow speeds.

Chrome is a very hard metal. When a lath or milling machine is purchased an option is to specify chrome ways. The ways are chromed to reduce friction and ware by adding hard chrome on the ways. A machine with chrome ways will out last many times a machine without them because of their hard surfaces. The hardness of chrome causes us a couple of problems. Because chrome is hard and usually polished it is extremely slippery. When we try to bolt two structures together that have been chrome plated it is like trying to bolt two pieces of ice together. In many structures we depend on the friction developed through clamping force to keep things in place. So we have a great deal of trouble trying to getting things to keep from moving with chromed parts. An alternator bracket with a slotted hole for adjusting the belt tightness is an example. I once built a Dune Buggy for a customer who put on chromed steel wheels. He could not keep the lug nuts tight. Chrome pieces bolted together will constantly move under load.

You can't use lock split or toothed lock washers on chrome. According to Carroll Smith they shouldn't be used anyway on anything except lawn equipment. But the principle of both these type washers is they have sharp edges that bite into the nut or bolt and the surface being bolted. Now chrome is harder than the material in the washer so what's going to happen. Well, the chrome being only 1/1000th of an inch think, or less, will crack at the impingement points and we now have a place for moisture to get in and causing corrosion defeating the original purpose of the chrome.

Are there alternatives? Yes! Zinc is used for surfaces that we need corrosion protection on. It also has the unique property of healing itself. If the plating is scratched the zinc will migrate into the scratch restoring its protection. There is also nickel and electroless nickel which give you the chrome look but have a slightly different color than chrome. Living in New England I will use zinc for its resistance to corrosion.

5. Materials - The stuff things are made from

Steels
First off, I am not talking about the zinc-plated stuff you can buy at your local hardware or home center. The stuff they sell as steel is in a different classification compared to anything resembling steel on this planet. Most of it is recycled whatever. It is made up from whatever was in the junkyard at the time the scrap truck pulled up. It resembles steel in only two aspects. A magnet will stick to it and it is gray-silver in color. Any other resemblance to steel is purely coincidental. Yes, I buy it all the time. I use it for fixtures, repairing my tractor and any bracket I might need around the house. This stuff does not belong on anything your or anyone else's life will depend. When I turn this in my lath it dulls the tool. A lath cutter is harder that a drill bit and it dulls it in a few cuts. It is almost impossible to get a good machined surface on it, because it is so full of impurities. When drilling a hole, the bit makes all kinds of strange noises like I'm drilling rocks. If you try to thread it, the threads rip, tear and dull your die. Enough said; it should not be on a car.

Cold vs Hot Rolled
An example of a hot rolled piece of steel is angle iron. Its skin is a rough gray-black. The gray black stuff is iron oxide, a substance as hard as a drill bit. Hot rolled steel is generally used in the construction business for industrial applications. The slag on the surface is usually incorporated into each weld made on these materials if it hasn't been meticulously cleaned off before welding.

Cold rolled material goes through more processing at the mill and is as the name implies, is continually rolled and sized until it is relatively cold. There is no hard slag on the surface and the color is the silver. There will always be oil and mill scale of a minute nature and all pieces should be degreased inside and out and sanded lightly before welding. As a general rule, if it isn't clean enough to eat off, it isn't clean enough to weld. Weld prep is fully explained in Performance Welding. This book should be read before attempting a project of this magnitude.

Chrome-moly steel
This gets religious again and you should never argue about ones religion. But for what it's worth, here are the two sides of the question. Some people think Chrome-moly is the latest magic steel around. Actually chrome-moly was developed in the 1920's or 30's mainly for the aircraft industry. Back then all of it was welded by oxyacetylene. It is the nicest steel I have ever TIG welded. Because of its purity it doesn't spit at you and it flows like butter.

Is it necessary for a kit car? Carrol Smith states he only uses it for suspension parts on racecars. He uses 1020 on every thing else. My opinion is in total agreement with his. On my car, I am also using 1020 DOM for the suspension pieces. I don't believe it is necessary for a streetcar considering the complexity of dealing with it.

Carrol is of the opinion that chrome-moly should be heat-treated after welding. Richard Finch is of the other philosophy that it isn't necessary. Carrol's point is that chrome-moly doesn't come up to strength until you heat treat it and untreated isn't much better then mild steel. This is absolutely true. It also has to be purchased in the correct state of heat treat before fabrication and welding. Finch on the other hand cites the fact that many planes that were welded with a torch and not heat treated in any way, have been flying over us since the thirties and are still airworthy.

Chrome-moly welded with anything other than rod made for the purpose will be no better than the strength of the rod you use. If you weld it with mild steel rod the weld will not be heat treatable. Finch specifies in Performance Welding, the proper rods to use and he is adamant about using non-copper coated rods to prevent alloying and toxicity.

In my humble opinion, chrome-moly is not necessary because on a road car you can just increase the metal gage to insure the proper load capacity and not have to deal with any of this. My book on the Countach says the frame is made of 1mm (.039 in.). If I were building a structure of tubing that thin I would agree chrome-moly would be warranted. I don't intend to test the limits of engineering and be on the hairy edge of design. I will use heavier gauge materials and I will not tax the limits of the metal on a highway. This is just my opinion and as many people will disagree with it as will agree.

In Engineered To Win, Carrol Smith gives an extensive explanation of steels. Metals, Fibers and Materials also covers the field. These books will help you make an educated choice based on practical needs.

Aluminum
This will be short because aluminum is a much more complex subject because of all the heat treatments and alloys it comes in and the scope is far too deep for this article. Also most of us will only be using Al (aluminum) for panels that close structures to weather and not load bearing panels.

Batteries
What does this have to do with Al you ask? Well put Al next to steel uncoated and with the presents of moisture you have a battery. The way a battery works is the metal from the anode migrates to the cathode in the presents of an electrolyte. The electrolyte can be acid rain with sulfur or in New England where I live salt from the roads or ocean air, if you live near the coast. The point here is if not properly coated to build up a barrier between the two metals, you will create a battery that will corrode the Al faster than you can believe or desire.

Most of the strongest Al alloys are not weldable. The weldable alloys make great tanks, trunk boxes and the like. They are generally riveted to steel frames and must be primed with a zinc primer before final assembly in order to prevent corrosion.

Welding aluminum can be accomplished by oxyacetylene, MIG, or TIG. I have never tried MIG on aluminum. TIG welding aluminum is a delight because it looks so nice when done properly. The surfaces close to the welded area should be cleaned of oxides and dirt. I use an aluminum etch brushed on the surface to render a chemically clean surface.

Composites
These include fiberglass, carbon fiber, and Kevlar.

The basic theory of a composite is combining two or more different materials into a substance possessing characteristics different than the individual materials possess on their own. In our case, the composite (fiberglass) is used because by combining resin with glass fibers, a strong light weight structure can easily be made by forming and mixing the two in a reverse image mold to render the shape we want.

For most of our purposes there are three basic materials that concern us. These are the gel-coat, resin and glass fiber material.

Gel-coat
The main purpose of the gel-coat is to conform to the surface of the mold and setting up or hardening just enough to keep the texture of the glass mat or cloth from creating a surface pattern. If the gel-coat is too thin or not hard enough during fabrication, the texture of the cloth or mat will show through on the surface of the finished part.

There are several types of gel coats for different purposes. They're tooling coats made for the punishment of making several parts from the mold.

(To be continued)

6. Fabrication

Mounting Bolt Pattern Measurement

The need to build a transmission adapter presents many problems. One problem is how to measure the bolt pattern on the engine. My engine has covers and protrusions to get around so I could not just transfer the holes to a plate. This is a solution I came up with for measuring my engine.

1/2" tube   Crank bore less .001-.002

To measure the angle of the bolts I machined a round piece of aluminum to fit the crankshaft bore. This should be a close tolerance fit. I made it so close I have to turn it to release the air from the blind hole. .001 to .002 less than the bore should do. Then drill a hole perpendicular to the center line of the plug to allow a rod to slip through. This should also be as close as possible. I drilled it under and then used an expanding reamer to make it a slip fit. Then put a 90º notch at 45º from a surface at the end of a square piece. I used .75x.75 aluminum. Then drill close tolerance hole to allow it to be pressed on the end of the ½ in. tube.

Turn a piece with a clearance hole to mount and center a cam degree wheel.

Next drill and tap a hole in the center of the first round part to allow mounting a cam degree wheel. From the back it will look like this.

Place the assembly into the bore of the flywheel.

Make up a suitable pointer and mount it to any convenient hole.

To find top physical center of the engine find two bolts that are symmetrical about the center. Place long bolts onto the mounting holes hand tight but fully seated with no play. Firmly push the square piece with the 45º notch onto the diameter of either bolt. Zero out the cam wheel and then move the notched piece to the next bolt. The physical center is half way between this measurement. Move the wheel back and forth between the bolts to check. They should be the same number of degrees from either side of 0º on the cam wheel.

Now by placing long bolts in all the mounting holes you should be able to work your way around the engine and end up with a map of the holes. Slide the arm in and out to compensate for the different distances and when measuring be sure the fixture is pushed all the way into the crank bore and the 90º notch is square and tight against the bolt. The notch will center the rod on the bolt for each measurement.
The next thing you will have to know is the distance from the crank center. This is done by machining another round piece to fit into the crank bore.

Turn this diameter to 1.00in for convienence since you will need to subtract ½ its diameter over and over

Turn a second diameter to 1". In finding the bolt locations you will need to subtract half its diameter with every measurement to adjust to its center dimension. I got lazy and milled a flat ½ its diameter to give me a true reading to start with.
Now with this fixture placed into the crank bore you are ready to measure the distance of each mounting hole from the crank center.

Place a vernier face on the flat or diameter of the fixture.

Place the other face on one of the mounting bolts.

It takes a little finesse to get the measurement. You will need to move the vernier up and down on the bolt to get the furthest measurement. Since you have not parallel line between the blot ad the fixture you need to play with this a while to get the correct measurement.

(To be continued)

7. Frame Design Intent

(To be continued)

8. Hardware

(To be continued)