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1. Motorbike Frame Tube Thickness Chart
2. Motorbike Frame Tube Thickness Size

People forget. They think it's a new thing, and last year on the Tube and buses was simply awful, but really, it was every bit as bad back then. I mean, they went after the Queen and the Prime Minister. A wide painting hangs above the sofa in an ornate golden frame, showing four large figures arranged in a landscape, coaxed from brooding. The term butted refers to the thickness of tube wall. If tubes have only one dimension along them, we refer to the frame as being butted, if it they have two dimensions (being thicker at the tube ends and thinner along the middle) then we are talking about double butted frames.

A motorcycle frame is a motorcycle's core structure. It supports the engine, provides a location for the steering and rear suspension, and supports the rider and any passenger or luggage. Also attached to the frame are the fuel tank and battery. At the front of the frame is found the steering head tube that holds the pivotingfront fork, while at the rear there is a pivot point for the swingarm suspension motion. Some motorcycles^[1] include the engine as a load-bearing stressed member; while some other bikes do not use a single frame, but instead have a front and a rear subframe attached to the engine.^[2]

• 1Materials
• 2Types
• 4Stiffness

Materials[edit]

In the early days, motorcycles were little more than motorised bicycles, and consequently frames were tubular steel. While the use of steel tubing is still common, in modern times other materials, such as titanium, aluminium, magnesium, and carbon-fibre, along with composites of these materials, are now used. As different motorcycles have varying design parameters (such as cost, complexity, weight distribution, stiffness, power output and speed), there is no single ideal frame design, and designers must make an informed decision of the optimum choice.^[3]

Steel[edit]

In Europe and the USA, steel tubing was the default material until recent times. All the major manufacturers (AJS, Ariel, BSA, Matchless, Norton, Sunbeam, Triumph, Velocette, BMW, DKW, Ducati, Moto-Guzzi, Harley-Davidson and Indian) used steel tubing.

Examples

• Most Ducati Motorcycles

Aluminium[edit]

Examples

Carbon fibre[edit]

Examples

Magnesium[edit]

Examples

• 1988Elf ROC-Honda Elf5-NSR500 500 cc Grand Prix^[4]

Titanium[edit]

Examples

• 1971 Titanium Husqvarna Inter-AMAMotocross^[5]

Composite[edit]

Examples

• Bimota SB8K, composed of two aluminium alloy beams and carbon fibre plates
• MV Agusta F4 750 Serie Oro, magnesium and aluminium
• Greeves 250DCX Sportsman, with cast alloy 'downtube', tubular steel rear subframe and semi-monocoque spine.

Types[edit]

Spine or backbone[edit]

The motorcycle engine is suspended from a single spine. Spine could be a solid structure.

Examples

Single cradle[edit]

The motorcycle engine is held in a single cradle with a single spine.

Examples

Half-duplex cradle[edit]

The motorcycle engine is held in a double cradle with asingle spine and single downtube.

Examples

Full duplex cradle[edit]

The motorcycle engine is held in place within a pair of separate cradles. The Norton Featherbed frame was the classic example, but many 'duplex' frames actually have a single spine beneath the tank.

Examples

Perimeter[edit]

Also called Beam or twin spar, two beams wrap around the engine to join the steering head and swing arm in the shortest distance possible for better rigidity. Beams are usually made of pressed metal (steel/aluminium). The trellis frame employs the same concept but uses welded members to form a trellis instead of pressed metal.

Examples

• 1885 Daimler Reitwagen

Pressed[edit]

The frame is pressed or stamped from sheet metal to form a car-type semi-monocoque. The frame may be entirely pressed (Ariel Arrow), or may have just a pressed aft section connected to the steering head by a conventional steel tubular spine (Honda Super Cub). Both the Super Cub and the Arrow also have pressed steel forks, instead of conventional telescopic forks.

Examples

• Ariel Arrow^[6]
• Honda Super Cub^[7]

Monocoque[edit]

More common in the car world, a monocoque frame comprises a structure where loads are supported through its external skin. On bikes they are used almost exclusively on racing motorcycles.

Examples

• 2000 Kawasaki Ninja ZX-12R
• 2006 Kawasaki Ninja ZX-14
• 2012 Ducati 1199

Semi-monocoque[edit]

If a 'monocoque' frame uses additional support, such as tubes or longerons, the frame is more properly called a 'semi-monocoque'. An example is Peter Williams' semi-monocoque Norton racer.

Trellis[edit]

A trellis frame connects the steering head to the swingarm pivot as directly as possible using metal tube arranged in triangulated reinforcement. Using lattice girder principles, a trellis frame is typically constructed of round or oval section metal tubular segments that are welded or brazed together. A well-designed trellis frame should provide a strong, lightweight structure that simplifies placement of engine & components, and gives good access for maintenance. Although construction of a trellis frame needs a more complicated process than, say, an alloy beam frame, it requires only a simple jig and a competent welder. No heavy capital outlay is required, so a trellis frame is ideal for a model that may be made in relatively small numbers. For this reason, the trellis frame has found favour with European manufacturers, and Ducati in particular.

Some motorcycles, such as the Yamaha TRX850, have hybrid frames that employ alloy castings at the swingarm pivot area. Another variation is to suspend the engine from a trellis frame, but have the swingarm pivot cast into the rear of the engine.

Examples

• Most modern Ducatis
• Suzuki Bandit 400 1989 Model

Engine as a stressed member[edit]

For rider comfort, a motorcycle's engine can be mounted on rubber bushings to isolate vibration from the rest of the machine. This strategy means the engine contributes little to frame stiffness, and absorbing rather than dissipating vibration can lead to stress damage to the frame, exhaust pipes, and other parts.^[3]

Instead, if the engine is rigidly mounted to the frame, vibrations pass to and are dissipated via the whole frame, and the rider. Rigid mounting allows the engine to contribute to the overall stiffness of the frame. It also becomes possible to mount the swingarm directly to the engine rather than the frame, avoiding the need for frame members extending downward to the swingarm pivot. By increasing the number of mounting points between the engine and frame, vibrations and stress can be better dissipated in the frame, typically creating a triangle between the swingarm in the rear, the cylinder head at the top and the lower crankcase area at the front. If a rigidly mounted engine not only contributes to, but is critical to, the stiffness of the frame, and is an integral part of closing the triangle or trellis structure that transfers force from the headstock to the swingarm, to the point that without the engine the frame would be deformed, the engine is called a stressed member, or a lifted engine. Sharing the load between the engine and frame reduces the overall weight of the motorcycle.^[3]

Stressed member engines were pioneered at least as early as the 1916 Harley-Davidson 8-valve racer, and incorporated in the production Harley-Davidson Model W by 1919.^[8] This was called a keystone, or diamond, frame.^[9][10] The 1946 Vincent Series B Rapide was designed with an advanced chassis, termed a 'tour de force for its day,'^[11] that included a stressed member engine. During early testing of the 1983 Kawasaki GPZ900R, twin downtubes were included, creating a full cradle, but the downtubes were found to carry little load, so they were removed, relying entirely on the combination of the steel backbone and engine for chassis rigidity.^[12]BMW's R1100 series twins of 1994 relieved the frame of stress entirely, with the engine carrying the total load from the front Telelever fork to the rear Monolever.^[13][14]

Stiffness[edit]

Frame stiffness is a problem for motorcycle designers, as it was for the bicycle frames that motorcycles are descendants of.^[15][16]

Modifying the stiffness of a factory-produced frame can be undertaken to improve handling characteristics. This is often done by triangulating the factory frame.^[15][17] Triangulation is a technique used in many engineering applications to stiffen structures.^[18] However doing so can also have undesirable effects if it overloads other parts of the frame, as a flexible frame acts as a spring to absorb some loads.^[19]

Lateral stiffness[edit]

In the 21st century, advances like high power engines driving high traction tires,^[20] and better-performing suspension components, especially forks,^[21] led to a situation where designs with increased overall frame stiffness were made available to consumers. Analysts differ on whether infinite lateral stiffness is desirable,^[21] or whether a finite degree of built-in flex is preferable.^[22][23]

See also[edit]

Notes[edit]

1. ^ Note: ... such as the Ducati 900 SS
2. ^Note: An example is the Vincent HRD
3. ^ ^abcCocco 2004.
4. ^Cathcart, Alan (January 2008), 'ELF Racing - ELF Motorcycle Chassis Designs - Retrospective;Tracing A Decade Of Radical Racebike Experimentation', Motorcyclist, pp. 50(6), ISSN0027-2205, retrieved 2011-02-26
5. ^'1971 Titanium Husqvarna; A bike as trick as they got', American Motorcyclist, Westerville, Ohio: American Motorcyclist Association, vol. 60 no. 11, p. 75, November 2006, ISSN0277-9358, retrieved 2011-02-26
6. ^'1963 Ariel Leader'. Retrieved 2008-11-24.
7. ^Brown 1991.
8. ^Rafferty 2001.
9. ^Hunt et al. 2012.
10. ^Abdo 2012.
11. ^Field 2002.
12. ^Walker 2006.
13. ^Stermer 2006.
14. ^Coombs & Shoemark 2002.
15. ^ ^ab'Motorcycle frames explained–the frame game', Super Streetbike, September 18, 2009
16. ^Damon Rinard, Sheldon Brown (ed.), The Rinard Frame Deflection Test, Harris Cyclery, retrieved 2016-05-11
17. ^Foale 2006.
18. ^Enright 2015.
19. ^Tony Foale (November 1987), Frame mods, Tony Foale Designs, retrieved 2016-05-11
20. ^Kevin Cameron (June 2004), 'A short history of chassis flex', Cycle World, 43 (6), p. 18
21. ^ ^abJames Parker (August 3, 2011), 'Ducati Desmosedici RR: The 85 Percent Solution', Motorcyclist, Suspension components that allow less flex and uncontrolled wheel movement need fewer Band-Aids in the form of compensating motion in the chassis.
22. ^Parks 2015 '[M]otorcycle engineers design in a 'tuned' amount of chassis and tire flex. This is helpful because at maximum lean the frame and tire sidewalls are at a better angle to absorb bumps in the road than the suspension system.'
23. ^Kevin Cameron (July 2006), 'Rossi's woe', Cycle World, 45 (7), p. 18, [L]ateral flexibility must now be intentionally designed into chassis parts to supplement suspension action at high lean angle.

Sources[edit]

• Abdo, Edward (2012), Modern Motorcycle Technology, 2nd ed. (2nd ed.), Cengage Learning, p. 382, ISBN9781111640644
• Brown, Roland (1991), Honda: the complete story, Crowood, p. 22, ISBN1-85223-544-6
• Cocco, Gaetano (2004), Motorcycle Design and Technology, Saint Paul, Minnesota: Motorbooks Workshop/MBI, pp. 119–132, ISBN0-7603-1990-1, retrieved 2011-02-26
• Coombs, Matthew; Shoemark, Pete (2002), Motorcycle Basics Techbook (2nd ed.), Haynes Manuals, p. 9.6, ISBN978-1-85960-515-8
• Enright, Gráinne (2015), 'Structures', Technology for Leaving Certificate(PDF), Dublin: Golden Key, In the structural sense, triangulation refers to a technique used in frame structures to provide extra strength and support.
• Field, Greg (2002), Classic Harley-Davidson Big Twins: Knucklehead, Panhead, Shovelhead, Motorbooks International, ISBN9781610608817
• Foale, Tony (2006), 'Structural considerations: triangulation', Motorcycle frame and chassis design: the art and science, Tony Foale Designs, ISBN9788493328634
• Hunt, Phil; McKay, Malcolm; Wilson, Hugo; Robinson, James (2012), Duckworth, Mick (ed.), Motorcycle: The Definitive Visual History, DK Publishing, Penguin Group, p. 310, ISBN978-1-46540-088-8
• Parks, Lee (2015), 'Traction', Total Control: High Performance Street Riding Techniques (second ed.), Motorbooks, ISBN9780760343449
• Rafferty, Tod (2001), Illustrated Directory of Harley-Davidson Motorcycles, MotorBooks International, pp. 59, 64–67, ISBN0-7603-1126-9
• Stermer, Bill (2006), Streetbikes: Everything You Need to Know, Saint Paul, Minnesota: Motorbooks Workshop/MBI, p. 155, ISBN0-7603-2362-3, retrieved 2011-02-26
• Walker, Mick (2006), Motorcycle: Evolution, Design, Passion, Johns Hopkins University Press, pp. 174–175, ISBN0-8018-8530-2

• AxleAddict»

Building a Bike Is a Rewarding Experience

Building a motorcycle in your garage or in a small shop with minimal tools is no small feat. But it can be done and hobby bike builders are doing it successfully, even on their first attempt.

You can build a chopper frame on your own. The satisfaction you will get from building the frame alone is hard to put into words.

In the article I am going to cover a lot of subjects that cover in detail what is required to build a quality chopper frame. I will cover:

• jigs,
• tools,
• tubing,
• the fabrication processes,
• welding, and much more!

If you want to build a motorcycle from the ground up you will start with the frame (or chassis).

Some first time bike builders like to start with a pre-made from or rolling chassis and then piece the bike bit by bit from there. And that is a good idea because it will give you the experience you need when building from scratch.

But we want to build a chopper frame, so lets begin there...

Chopper Frame Jig

Assembly and Welding Jigs

Although it's possible to build a frame without a jig it's not a good idea. A jig is a massive help in the frame building process because it holds your frame together as you do your mock up and welding. Without a jig it's very difficult, time consuming, and it's much more likely you'll get a bent frame.

Commercial chopper frame jigs are very expensive. The beginning price could be anywhere from $5,000 upwards for an adjustable jig. The jig would have to be tailored to the bike design, or be infinitely variable. In either case, the cost would be prohibitive to the small shop or the individual builder.

To build a jig yourself, and I mean all the machining and other work yourself, you will have to invest anywhere from $200 to $700 in materials alone. If you tackle this job yourself, remember, it will always remain a 'work-in-progress' as you fabricate your frame. To the above right is an example of a builders Jig.
Notice the adjustments that are available for the steering neck, rear axle plates and seat post. There are four leveling adjustments on the feet extending out from the parallel rails. As long as the jig base (parallel rails) and the vertical assemblies are perpendicular to the parallel base rails, accuracy will be achieved in the frame. Many builders use actual major components such as engine, transmission, rear wheel and front forks to ensure accuracy of alignment.

Just because you have a jig to setup the tubing for welding, does not ensure that you will have a perfect frame. The tubing should be mitered and fitted such that the junction fits easily together. If you have to force it, you have done something wrong.

Tube Benders

These tools come in all shapes, sizes and prices. One supplier for tube bending and tube notchers is Pro-Tools from Tampa, Florida. The link to their site is located in the RESOURCE section of this document. Another supplier of tube benders is Williams Lowbuck Tools, Inc. in Norco, California. You will also find several other suppliers in the RESOURCE section.
A common question is whether or not a pipe bender can be used to bend tube. The answer is...not if the inside diameter (I.D.), and tubing is measured by the outside diameter (O.D.). Another difference is the wall thickness.

For our example projects, we are using tubing with a 1.25' diameter, and a 0.125' wall thickness. Some tube bending machine suppliers emphatically state that you absolutely cannot use a pipe-bending machine for tubing. Don't be fooled into thinking that you can use a pipe or conduit bender for bending tubing. Tubing is tubing, and pipe is pipe, and never the twain shall meet!

Yet there is a noted frame builder who states that if you are in near desperation and still need to have your frame tubing bent, you can use a 1' thick-walled conduit bender to do the job. The rigid electrical conduit is nearly the same as the outside diameter of ERW tubing. But don't plan showing the bike at some of the better shows. So there you have it. If you have a choice, your preference should be to use the right tool for the job at hand.

Other tools used for measuring include a decent tape measure, carpenter’s bubble level, a steel rule, a machinist’s square, and a nine-inch caliper.

Motorcycle Frame Tube Material

There are 3 types of tube used to build frames. They are Chromemoly, DOM, and ERW.

Motorbike Frame Tube Thickness Chart

1. ERW = Electric Resistance Welded. This type of tubing is created with mild steel. The tube is created from a sheet of mild steel, and then it's rolled up.
2. DOM = Drawn Over Mandrel. This type of tubing is basically the same as the Electric Resistance Welded tubing except that it has been put through an extra process to take out the imperfections which are supposed to give it more stability (strength).
3. Chromemoly is a type of alloy that has both Chromium & Molybdenum and has more strength than the other two types above. But it's a bit lighter.

The most common type of tubing used for chopper frames is DOM. But ERW is nothing to scoff at.

Chopper Frame Poll

Design & Fabrication Processes

Motorbike Frame Tube Thickness Size

Design Integrity
By definition, design integrity is the quality, or state of being complete or undivided. This includes a singleness of purpose in the fabrication of a motorcycle frame. If the frame fails, EVERYTHING fails! Everyone involved in the process must have the same goal as the designer. The materials must be of good, uniform quality.

The miter joints must be done properly and the welds must meet established minimum standards. Any compromise in frame integrity could result in premature failure and personal injury to the rider, or even death.

The designer should define the standards to which the frame is to be made, and demand that those standards be adhered to. Standards would include definitions of all materials used plus the definition of an acceptable weld and overall workmanship. In addition, all material standards that will be acceptable, and expectations of the overall design should be clearly outlined.

Before any successful project fabrication starts, the designer must have a goal in mind, as well as product expectations or there could be chaos. Imagine a motorcycle cruising down the highway at 70 mph, and the frame suddenly comes apart because of poor design or quality of workmanship or materials! The point to be made is simple! Make absolutely sure that every aspect of the project has been carefully considered in detail. You cannot allow for any compromise.

The standards do not necessarily have to be detailed data sheets, but should at least be considered and noted in writing. Hopefully you wouldn't build a house without a set of plans and specifications. The same should be true in most other projects undertaken.

Miter Junctions

Now comes the time to pull together the first union. Before you jump headlong into the project, you need to have a plan, or at least an idea of your finished product. A sketch will work if you dimension the drawing together with tubing angles.

Without at least this amount of detail, you will most likely have a misaligned and warped mess that you may as well schedule for the dumpster. Using your drawing as a reference, select the seat post where it joins the backbone.

Cut the seat post to length according to your drawing. Leave a little extra space just in case you need it for final fit. If the final piece is too short, you just start the seat post over again. Clamp the seat post tubing and make the rough cut with a notcher.

To finish the miter, use a half-round file to form the miter for a good fit to the adjoining tube. This is one of the reasons for leaving extra length whenever possible. Notice that the mouth does not come to a knife-edge. This would produce a poor penetration of the weld, and therefore a weak joint.

Seat Tube and Backbone

This image presents the near perfect fit of the seat tube to the backbone. The mouth fit is flattened or beveled to permit weld penetration into both tubes.

In this view, you can see the flat or bevel edge of the miter. All miter junctions are not so straightforward. For these, we use a paper template. There are many software programs out there that can help you with this.

Frame Bend Video

Frame Tube Bending

Now comes the fun part. Bending tubing! This guide is not intended for step-by-step procedural instructions on how to bend tubing. That generally is supplied in the manual that comes with your bender. If there is not a manual there, contact your vendor. You will find, however, the pitfalls you need to watch out for in tube bending.

The biggest problem is inaccurate measurement, or selection of incorrectly sized tools for your bender. This could result in several problems such as overall length error, bend angle error due to failure to consider springback, bend deduction distance error for a given O.D. of the tubing, etc. Another problem could be the measurement of the bend angle, or rotation of the frame tube in compound bends. Any of these issues could hamper the assembly of the frame.
Bending tube comes with a unique set of problems that could cost a good sum of money in scrap material. If the bend measurements are grossly incorrect, resulting in overall dimensional error, you have just created a piece of scrap. Now if the angles are correct and the final length is too long, you are probably okay, so just trim the excess.

Flat and Tube Welding

Material Preparation:

Material should be thoroughly cleaned to remove all scale, grease or oil residue. Parts to be welded should be properly fitted to each other, aligned and maintained in position during the welding process. To maintain alignment and position, clamps, bars, tack welds or other means may be used during the welding process.
Flat Welding:

Flat welding is just as the name implies. Welding of horizontal or vertical planes can generally be termed as 'flat welding'. Preparation is the key to any welding, but more so in flat welding. Butt-welding requires that the two pieces of metal be prepared with a recess or angle to permit better penetration of both ends being joined. Butt-welding generally refers to flat stock or pipe, but can also refer to tubing as well. However, butt-welding of tubing for aerospace and medical applications is usually accomplished by use of computer-controlled
orbital welding machines.
Tube Welding:

Since the focus of this report is the fabrication of Chopper Frames, we will concentrate mostly on manual tube welding as opposed to orbital welding. In our process, we can choose to use MIG, TIG or Stick welding. Some people insist that the 'wire feed' arc welders are better than the conventional 'stick' method.

TIG, Stick, or MIG Welding?

The argument for and against TIG, Stick, and MIG welding is almost as old as the first motorcycles ever built.

The preferred method is TIG because it is a very smooth and strong weld. But then again, you can get similar results from MIG welding. And Stick welding is nothing to scoff at! I know welders in their sixties who have fabricated some works of art with an old 'buzz box' welder (an old stick welder).

In truth, there is no difference in characteristics or quality of weld. The 'wire feed' systems are faster than 'stick' welding, but when using one of the 'wire feed' methods for welding tube, the advantage of the speed is lost. So, which one is really better? The opinions out there are as many and varied as the welders that use them. Whichever system fits you and your application, then that's the one for you.

So if you were to twist my arm I would say TIG weld your frame. But TIG welding requires skill and practice. It's not easy, and TIG welders are quite expensive.

MIG welding and Stick welding is easy. MIG being is the easiest of the three.

So if you are not experienced or your funds are limited, go with a good stick welder. You can buy excellent ones for under $400, and good ones under $200. Buy a name brand like Lincoln or Hobart. Norther Tools and Eastwood make pretty decent ones as well.

Welding Takes Practice

Welding is an acquired skill that borders on being an 'art form'. It takes practice to produce a good weld. Don't think that a 'pretty' weld is necessarily a good weld! You see only the surface and not the depth of penetration.

Don't be afraid to take a few pieces of scrap and weld them together.

After the weld has cooled down, use a band saw or suitable type of saw to cut across the weld. You can then see the degree of penetration (or lack of), which will let you know real soon just how your welding is! Below is an example of what I am talking about.

The picture here is a TIG weld. Notice in the first photograph how the bead blends well into the metal without a lot of buildup of metal. But you can't tell about the penetration between the tubes without an x-ray of the junction or cut the junction in two.

Look close at the photo on the right, and you can see the penetration between the lower tube and the upper tube. Generally you would not cut your frame in half to see how good your weld is! This is a practice piece.

Chopper Frame Assembly Procedures - Jig Versus Non-Jig Assembly

Jig vs. Non-Jig Assembly

To be clear...it is possible to build a motorcycle frame without a jig. Various tools, crutches, and other 'insider' methods can be used, but unless the issue is one of cost, it would be very difficult to imagine anyone wanting to build a bike 'free-handed' when a jig makes the process so much easier. However, if you are intent on NOT using a jig or have no ther choice, lets get at it!
Non-Jig Assembly

As mentioned earlier, you need to have a plan, or at least an idea of your finished product before getting to started. A sketch will work if you dimension the drawing, together with tubing angles. Without at least this amount of
detail, you will most likely have a misaligned and warped mess that you may as well schedule for the dumpster.
Frame Drawings

There are several good sources for drawings if you don't already have a set. The main one that comes to mind is Custom-Choppers-Guide.com. They also carry plans created by BCC Orlando and offer extra stuff for ordering them.

Motorcycle Frame Building Video:

On to the Motorcycle Frame Assembly Process

Okay, now that you have drawings in hand, lets work on getting the necessary tubing and other miscellaneous steel parts gathered together
The tubing we're going to use is 1.125' x 0.120' ERW, unless otherwise specified in your drawings. If you don't have a source for tubing, you can find several under the topic of RESOURCES in this document. Next you miter the various components of the frame and check for good fit. After you finish with this process, you can begin piecing the frame parts together as depicted in the example below.
This section is somewhat akin to a jigsaw puzzle. After you have bent and mitered the tubing, you need some way of temporarily holding things together. Lets assume that you have perfect measurements, angles and orientation. Since we're not using a jig, we need to get to as level a spot as possible in order to start the assembly process. The next figure show one method of holding the pieces together for tack welding.

Frame Alignment:

To align the frame during the assembly process, use the motor (engine), rear wheel and front forks to verify fit and alignment. As you can see from all of this, you need four arms or two people to work together. You can imagine how the frustration can potentially build up.
Place major assemblies into the frame to verify alignment. Of course if they fail to line up properly, you have some adjustments to do. This is why the frame components are only tack welded. You still have a chance to salvage the hard work you have done on the frame.
After you are satisfied with the parts placement, you can begin welding the frame together. Of course there are many other ways to assemble your frame without a welding jig. This is only one way to accomplish the task at hand. You can see from the examples that there has to be a better way to get your frame together correctly and that is why we recommend a welding jig. If you want to build your own jig, there are numerous sources for the plans, including Custom-Choppers-Guide.com.
You probably already noticed that these are the same sources for frame plans. Buy them both at the same time and you just might get a discount.

Using a Jig

The welding jig must be mounted with all four corners level. The leveling platform should be elevated to knee height.

This could be a series of blocks or a welded frame upon which you place the leveling platform. Any suitable arrangement will work, just as long as the jig is level. After the platform is level, you can then place and mount the verticals to the platform.
Picture 1: Frame with engine and transmission mockup is located in the jig for alignment adjustments and tack welding.
After alignments are satisfied, the frame can be welded together.
Picture 2: This frame has already been tack welded together, using the jig.

The Beginning

This is by no means an exhaustive guide on the building of Chopper frames. It does however give you a frame of reference for what must be done to build a Chopper frame.

The skill level required is alluded to throughout this article. Familiarity with basic hand tools is a definite requirement, as is the use of welders and tube bending tools.

It's up to you now to take the first steps. Get your equipment, plans, and start building!

If you need any more help, resources, or encouragement please comment below :-)

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Where Are You In The Chopper or Bobber Build Process?

• Still in the dream stage it will be a chopper i like the old school look like a1200 Still in the dream stage it will be a chopper i like the old school look like a1200 with some rake not a lot but a chopper, sissy bar good brakes and lights comfortable seat something I can ride on the long roads in northeastern Arizona nott looking for a whole lot of comfort but a good weekend rider and would like to put it all together for $2000 or less is it possible

• I took a hartail frame from Craigslist chopped it from the hardtail forward, took it from a bobber look to a 26' over long chopper

• I want to build a Captain America style Ridge frame with a Softail suspension for the 50th anniversary of Easy Rider what would a frame like that cost 242 to 60 yd in the back and a white Wide Tire in the front

• Looking to start real soon .I want to prove to my self and others I can do it