Fabrication tips and tech

[sabre2d]

Ive seen a thread for mechanical tips and id figure id start one for fabrication. a place where both new and vet fabricators discuss materials, planning ,layout, fitting, fastening and/or welding.i would like to start this with the fact of you ask 3 different fabricators how to do something they will give you 4 different answers. if it works for you it works. if there is already a post like this lemme know i was unable to find one.

 

on materials- choose the right material for the intended purpose. what stresses with the part take if any tensile, shear, cyclic load? find the right material using sources like a.s.t.m. can it be welded bent or machined? most common materials can be worked in any way but some are very difficult to machine such as tool steel some aluminum alloys cannot be welded or require special procedures. not all metals will readily bend, some metals even "soft metals" like certain aluminums require heat to be bent. Some materials are heat treated tempered, hardened, annealed keep in mind heating steel to open face temp. will change the grain structure of metals and its structural properties. factor in corrosion resistance. will the part be subjected to water, salt, heat, caustic or corrosive conditions? it may be worth it to use a non-ferrous metal in place of steel.

 

planning-i have a check list i go though in the beginning its helpful if you get your own together.some things i consider are mats. brackets fasteners make sure you have enough. do i have the tools to get the required results? will i have to clear moving parts? what are my realistic tolerances? if the part fails will it damage or break any other parts? will it have to be removed regularly? is weight a factor? are my mounting points strong enough? welded, bolted, brazed, soldered? come up with your own list to suit your project.

 

layout- measuring is critical you can avoid alot of issues by keeping tight tolerances and measuring constantly. have a nice clean work space it helps more than you think. have a level/flat surface to mock up parts. have the ability to jig up or clamp parts down to your flat/level workspace. use a thin writing device or scribe to mark, keep the marks clean and neat. if you use a thick writing utensil mark a side of the line to be your cut or fit up line most sharpies make a line about 1/8" wide. sqaure straight lines make the difference staight edges, sqaures, twine and the Pythagorean formula save troubles down the line. use a punch to make drill points this will help the drill bit from walking and cant be wiped or burned off by heat.

 

fit up- clamps clamps clamps, clamps make life easy you cant have enough r11 or sp 11 are a very nice c clamps can do pretty much anything and are relativity cheap.tack weld before full welds make sure everything fits right. brace where you can with a few strong tack welds. leave clamps and braces on until your welds cool, this will help minimize heat distortion. a good set of files can clean up cut edges and help fine tune your fit have flats and rounds/half rounds to start with. if you need help in the penetration department you can bevel joints in many ways any lay down multipass welds prep accordingly. tack weld fillet welds on the ends to keep them from being pulled one way or the other durring fit up. need to make uniform holes in several brackets or tabs?if you have a drill press lay out the hole pattern on one and tack weld the rest to it drill through and all your holes will have the same lay out.

 

welding-in the past decades welding has gone an arcane art to a sci i will share what i know and try to explain it scientifically. know your base metal ( see the materials section) match your filler metal accordingly. have a technique, different joints and positions require different methods and techniques such as C's the whip technique inverted T's christmas trees, ect ect. vfor your processertical up welds typically have higher penetration than vertical down (heat from the weld pool rises). clean weld is a happy weld clean off all contaminates mill scale, oxides, cleaners ect. ect. some cleaners are toxic when vaporized and welding through galvinized can make you very sick .if you use a welding process that produces slag cleaner metal make slag come off easier. make sure your using the right sheilding gas for the job. different gases have different shielding properties, penetration rates and arc stabilizers. know your capability as a fabricator i would never suggest a beginner tackle a project like a tow hitch. if it fails you can cause great damage to your rig and the rigs around you and you will be liable. have the proper ppe for what you are doing. you can never be safe enough safety glasses are a must even under a welding hood. face shields the proper gloves and welding leathers can mean the difference between losing a finger or eye and change a third degree burn into a first. have a proper fire extinguisher ones rated for oil and electrical fire will cover you pretty well. read your weld puddle dont stare at the arc with practice you can change your work angle, travel angle, arc length, stick out length, pedal input or even change your oscillation technique on the fly. use the right process for the job smaw (mig) will work well for most steel project but if you welding into greasy old dirty steel a flux with higher amount of scavengers may work better for you such as 6011 rod for a stick set up. If you use a stick set up you have a huge amount of versatility when it comes to electrode selection to fit the job they are coded for reference so get the right rod to suite your need. wire feeds have a smaller selection of filler material but is well suited for most common steels and aluminums. use the right polarity dcen, dcep and ac. gas, electrode, material all play a roll in polarity. welding ac has a cleaning cycle and a penetration cycle and can be adjusted on some machines to suit your needs. weld backing and heat sinks can help you from over penetration on help close a gap. you can use similar metals that will have to be cut off or dissimilar metals if they wont melt into your weld. use metals with high thermal conductivity for heat sinks such a copper or brass. i will continue to post more tips and tricks and feel free to post your own or ask about any specifics i will answer what i can and refer you for the rest.

 

sabre2d over