Anyone want to CNC a run of some small parts for me?

[gellfex]

I though some of you guys with homebrew CNC might be interested in knocking out these parts for me. I usually do them on my mill/drill, but time is tight right now.

https://drive.google.com/file/d/0BzdLZTw6DUZFbVFqX3l1WHhwNWc/edit?usp=sharing

There should be there 2 step files with 3 pieces total, 1 single and 1 pair. The holes are tapped 8-32. I would want a price for running 40 pcs of each, 120 total. I have more variations on these that I will need, but wanted to see what these would run. It's a clamp to hold wire with an L bend. The only tolerances that count is the distance between the holes and the width of the channel.

Thanks for reading!

[PJRitz]

What is a step file? how about a dwg or pdf

[George Bulliss]

What is a step file? how about a dwg or pdf

A step file is a 3d CAD file. Here is the pair of clamps. What's the material?

[Toolguy]

I may be able to help. Basic block size? How soon do you need them?

[gellfex]

Sorry about not stating the material, 6061 AL. The only other time I had to produce a file for CNC it HAD to be a STEP! I busted my brain learning FreeCAD to do it. I'd much rather work in Sketchup but it seemed that place could not use a SU file. What other format can CNC take as input? And that place (contracted by my client for that job) wanted a ridiculous amount for these. When I talked to them, they said "well, it's a 2 face job". Huh? It turned out they could not simply use 3/16 stock, but had to flycut down larger stock. What a waste.

Time frame? A few weeks.

[Toolguy]

I don't usually need files for anything besides 3D contouring. A 2D dimensioned drawing is fine or even a neatly done hand drawn shop sketch with legible numbers and letters. I have conversational programming so I can write the program right off the drawing. No need to make a computer drawing or run through a postprocessor.

[adatesman]

When I talked to them, they said "well, it's a 2 face job". Huh? It turned out they could not simply use 3/16 stock, but had to flycut down larger stock. What a waste.

Haven't opened the file you linked, but they're quite possibly right... No indication in the pic above whether the top or bottom have to be machined or can be left as extruded, and if as-extruded is fine there's precious little left to hold it with below the slot given that the corners of the extrusion are likely rounded. For knocking only 40 of each out, no sense in building a fixture; skim the top, machine the slot and holes, then cut the back off to thickness.

[gellfex]

Haven't opened the file you linked, but they're quite possibly right... No indication in the pic above whether the top or bottom have to be machined or can be left as extruded, and if as-extruded is fine there's precious little left to hold it with below the slot given that the corners of the extrusion are likely rounded. For knocking only 40 of each out, no sense in building a fixture; skim the top, machine the slot and holes, then cut the back off to thickness.

Funny, I just let the end hang out of the vise by 1/2" to mill the slot. Could be this is just too simple to take proper advantage of CNC. Maybe I should teach my 15 year old how to make these before he goes to Scout camp.

[adatesman]

Not a bad idea, teaching the kid. As for moving to CNC, the advantage to CNC is eliminating tool changes and part handling, which means multiple parts per clamping and wasting material if it's faster/cheaper. Tool changes and reclamping are slow and have a labor rate, and a possible loss in accuracy. These are just begging to be cut in multiples in the widest vise possible, with the top skimmed, slot milled and slotted to length, and then the bar flipped to cut it to thickness and part the pieces. I'd likely even go so far as profile the entire piece to ensure even clamping once fipped (pennies saved on material is dollars lost when a piece shifts and breaks your cutter). You'll end up with less handling, fewer tool changes, and less investment in time and fixturing that way. Which is not to say that someone here with nothing better to do won't do it slower/cheaper on a lark/learning experience, but that would be the typical approach a job shop would take.

(edit for grammar)

[garyhlucas]

Pop the pieces in the soft jaws and cut away.

[MikeHenry]

I only see a single step file with the two mirrored parts that George showed in post #3. Was there supposed to be a 3rd part?

The part looks easy to make, but you really should specify a numerical value for all tolerances even if they are loose. That way there are no surprises on either end. Something about the surface finish would be good too, especially on the top and bottom. Is mill finish OK, or do you need the parts to look better than that?

Mike

[Jaakko Fagerlund]

I only see a single step file with the two mirrored parts that George showed in post #3. Was there supposed to be a 3rd part?

The part looks easy to make, but you really should specify a numerical value for all tolerances even if they are loose. That way there are no surprises on either end. Something about the surface finish would be good too, especially on the top and bottom. Is mill finish OK, or do you need the parts to look better than that?

Mike

Kind of you get what you ask for, meaning that if not specified, everything is done to ISO 2768-mK in here and the surface finish is Ra 6.3, meaning basically a drill finish. Thhough usually parts come out way better than these and the general dimensioning tolerances are achieved on a CNC mill with nominal tooling diameters.