Out of my depth with part design and file type.

Hi everybody!

I'm a bit out of my depth. I have a job in the shop right now that requires a bunch of little round brackets to be cnc routed out of 3/8" MDF. They're dead simple - each is a circle with a couple through holes and some counterbores. The largest is 1.5" in diameter, the smaller size is 1.125" diameter. All the work can be performed from one side of the part. I need 40 of the smaller and 130 of the larger... but I digress. I don't have a CNC machine myself so I'm hoping to work with a local cnc shop. I've sent the drawing I was provided out to a few these shops ( which is a pdf), and they said they need a certain file type. I figured this would probably be the case. I'm a decent hand drafter, and I've used a few cad programs before but I'm far from "knowing what I'm doing". If a local shop wants the part as a dwg file, and would like the parts spaced an inch apart and an inch from the edges of the sheet, can I do that easily in google sketchup? If so, would somebody be so kind as to walk me through it? I know I can draw up the part itself, I just don't know how to duplicate it, place it in that grid pattern, and save it as a .dwg file.

thanks in advance to anyone who has any advice on this!

It might not be necessary to draw out the full number of parts in a sheet layout and might be better if you didn't try to guess their way of working.First of all,be aware that you are looking for very small parts and cutting all the way through the material will very likely lead to the part jumping around as the cut is completed,with likely damage to the edges.Some small holding tags may have to be left which you,or they, will need to clean off at a later stage.I would suggest you draw the parts using any program you have access to that can export a .dxf rather than a .dwg.The reason for this being that .dwg is an Autocad proprietary file type and from time to time they change the exact requirements so that an older CAD system won't read a newer .dwg.It helps their annual update sales if nothing else but .dxf usually works with anything.It helps enormously if the entities you draw are joined around the boundaries of any features that need cutting and while most CNC shops accepting customer files will check for this it does occupy a little time and the customer will end up paying.If you draw an example of each type of part you need and clearly state how many of each on the drawing the shop will have their own approach to leaving enough material around each part and allowing space for holding the workpiece in place.If your chosen shop is using vacuum hold down they will need a big enough workpiece to stay in place while the machining is carried out.You may need to discuss this with them and ask if you or they should do the nesting.

Find a different shop. It sounds like they don't know what they are doing.
If it's a simple as you say, they should be able to draw and program the machine in 5-10 minutes, and not need a drawing file from you.
When I do work like that, 99% of the time I don't want a drawing file. I prefer to do it myself, as I'll usually get much better results that way.