I was going to post this as a response to an earlier enquiry, but a number of others had responded to the message with similar remarks on getting parts and one off jobs fabricated. So I thought I make a new post out of it instead.
I work in sheetmetal and see this all to often, where someone comes in and needs a small job done or one off and be turned away or have to wait weeks, sometimes months just to get their job done and it costs a bomb for seemingly the small amount of work needed.
For anyone who is interested in getting something fabricated, here are some tips -
For more "complex" parts (things with lots of holes or irregular shapes and cut outs) - where possible, draw up the part(s) on a CAD program (such as AutoCAD or something similar) save the drawing as a .DXF file (most cad programs can read this type of file) and take it to someone that does CNC punch pressing or laser / water jet cutting. Punching and laser cutting only takes the fraction of the time it takes to mark out, hand cut and drill parts.
Not only does this make the drawing easier to read, but also eliminates the need for the draftsman / designer/ CNC programmer to redraw a hand sketch onto a cad program which takes time and costs money.
If taking in a hand sketch, make it clear and legible and ASK if they understand the drawing and if it has all the info they need to complete the job. Mark on the drawing which are the more important and critical dimensions, such as a battery tray for example that has to be a minimum of 320mm and 170mm internal dimensions, with tolerance of +10mm -0mm. This is so they can adjust their bend dimensions slightly if needed in order to get the right measurements so the battery will fit inside the tray.
Work out what type of material you would like and how much you need. Some
places may only use certain types of materials and up to a certain thickness. Where I work, we carry stock sheet metal of Zinc anneal mild steel, Black form (cold and hot rolled steel), Aluminium, Stainless steel, ranging from 1mm to 3mm thick, rarely do we buy anything under 1mm and over 3mm thick.
You may be able to source material yourself, but if its going to be CNC punched or laser /water jet cut, ask what size sheet will be needed as some jobs may need some "green" along 1 or 2 edges for clamping purposes.
Give all the information you possibly can, and make it clear. Every dimension (and if they are internal or external measurements), angle, type of material and thickness, if it needs to be painted or corrosion resistant or water tight, EVERYTHING you can possibly think of, hopefully this will sort out any confusion and mistakes and in the end will give you what your looking for.
If you have the material and do not require punching or laser cutting, do as much as the job as you possible can. Mark out, cut and notch with a grinder, drill holes and mark out fold lines and fold direction (such as bend up or down) where possible. Sometimes all you may need is for it to be folded and/or welded together.
Some
places simply do not want to do one off jobs because of the time involved, but would be more willing if they had a batch of 20 parts, or if you were going to be a repeat customer. So if you can, ask around, someone else might be interested in a particular part / bracket etc, and get as many as you can made at the same time. This should also work out cheaper in the end.
And last of all - BE PREPARED TO WAIT. Like most other businesses, they will put a $6000 job first before someone who wants a $100 job done, even if it is going to be paid cash.
Hope this helps some of you the next time you need something made up for your rig.
Cheers,
Darren. ( spotted_dog at iprimus.com.au )
PS. - I may be able to help out if someone is looking for small brackets, cover plates etc, let me know if you want something done and I'll see what I can do. Have access to CNC punching, presses etc. Nothing to big or time consuming as I just don't have the time.