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Metal work needed

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Here in San Francisco, none of the metal shops can be bothered with basic machinery, because the prima donna machinists are too busy pretending to be artists. But, I'm not bitter.

Anyone on this board want to offer their services as a machinist? I only need some holes bored in aluminum, in the style of the classic nearly-rectangular audio chassis. Here is an example part:
 

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By the way, the units in the above drawing are inches. This part seems uncomplicated no? And I just wanted it to be sanded in one direction and clear anodized. I don't know why no shop wold take the work. Maybe the five other sides were too complicated. Maybe the whole job is just too small.

Maybe one of you will take it!

:wrench:
 
Since I no longer work as a machinist I can't offer my services for after hours jobs, but I can make a few observations that are intended to be helpful.

Most of your dimensions are to 4 decimal places. This implies that you want this work done to one ten thousanth of an inch (commonly known in the trade as working to tenths). this is approximately +/- one twentieth the thickness of a piece of paper! These tolerances are not generally within the capabilities of a run of the mill machine shop.

Your post states " I only need some holes bored in aluminum" but your drawing shows a milled 1/8" relief in the top view, rounded corners, and a square (punched) hole. This is This is a minimum of seven setups on three different machines for just this one part.

I gather that you are very concerned about appearance i.e. "brushed in one direction and anodized". One thing you learn on the shop floor is the finished part is never as pretty as it looks on the computer monitor. What you are asking for is hundreds of dollars worth of work to be done to consumer grade finish while exhibiting little knowledge of process. I suspect the people you dealt with simply assumed the chances of ending up with a happy custumer were pretty slim.

Beyond that your dimensions imply something close to a standard rack mount size case. Why don't you buy an off the shelf case? (do a search here for cases) with blank front and back. You can then modify it using a cheap Home Depot tabletop drill press, a Unibit, home made disc sander and a file. The total cost for these tools is probably less than shipping and material costs let alone labor for full custom.

Please understand I'm not trying to dump on you. I just trying to educate and help you accomplish your goal.

"WORKING HARD IS VIRTUE, DOING WORK THE HARD WAY IS A VICE."
 
jwb said:
By the way, the units in the above drawing are inches. This part seems uncomplicated no? And I just wanted it to be sanded in one direction and clear anodized. I don't know why no shop wold take the work. Maybe the five other sides were too complicated. Maybe the whole job is just too small.

I can recommend some folks who'd be happy to do the job. Problem is, it won't be cheap. One offs never are. That's because all the set up costs are going into just the one piece.

So the question is, how much are you willing to pay for just this one piece? Unless you can find a friend willing to donate their time and just charge you the materials costs, you're looking at a faceplate that will cost you hundreds of dollars minimum. And for about the same price, you could have a dozen of them made.

But if price is no object, let me know and I'll hook you up.

se
 
Hi mltaunt! Thanks a lot for your input. It sounds like you are pretty familiar with the goings-on in the shop. Just so we understand each other, I studied mechanical engineering at university, although I never practiced outside of internships, so I'm more well versed in manufacturing than a random guy off the street. I realize the dimensions are all to .1mil, but I explained to the machinists, who were all working from paper-napkin sketches when I visited their shops, that this is just the default dimensioning style in AutoCad R13. The tightest actual tolerance on here is 4mils in six places, and 10 mils everywhere else.

Yeah there is a milled relief on the back panel. It is the only way to have the counterbored fasteners and still mount the connectors. The relief is on the inside so it doesn't need to be faced.

I know full custom is unusual, but I have particular taste, and this unit is a gift. My main problem isn't cost: I offered the first shop I approached a lot of money, but I got the "sorry I'm an artiste" brush off.

Thanks a lot for your input. Maybe I should redo the drawings to make them less scary.
 
jwb said:
Steve, I'd love to get hooked up with a shop, if only so they can finally tell me WHAT it would cost to make such a thing. And if they are in the Bay Area, so much the better.

Alas, they're not in the Bay Area. They're a bit east, up in the foothills in Shingle Springs (just east of Sacramento).

Carlton Metal Craft, Inc.
4191 Business Drive, Suite A
Shingle Springs, CA 95682
530 677-5729

Your existing drawing should be sufficient to get a quote, but they may ask you to fill in a few blanks. You can either FAX it to them or send it as a DXF file in an EMail attachment.

Good luck!

se
 
jwb said:
Yeah there is a milled relief on the back panel. It is the only way to have the counterbored fasteners and still mount the connectors. The relief is on the inside so it doesn't need to be faced.

That's what's going to be the bank breaker, regardless of whether it needs to be grained.

Why not go with a 1/8" panel with a 1/16" counterbore and use some low profile socket head screws? That would give you virtually the same look as a fully inset, full height socket head while dramatically reducing the machining costs.

se
 

grataku

Member
2000-12-31 9:31 am
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jwb
comment about your drawing: it's going to be time consuming and hard to reduce the thickness of the plate in the way you are showing. Not to mention that you are going to lose alot of rigidity.
Do you really need that?
To do what you have drawn will probably take a machinist 4 hrs of work @ $60/hr unless they have highly specialized CNC machines. There has been some talk on this website about a place in EU were they do this type of panel work.
Some guy from south africa that build an aleph used them, I can't think of the name.
 
jwb said:
Thanks again for the advice folks. You see, this is exactly what I want the machinist to advise me on.

But machinists are in the business of machining, not designing. They typically operate from the assumption that the customer has already taken care of the design and their job is to turn that design into a finished piece.

Some machinists can be rather resentful of customers who expect them to assist in design, feeling that they're providing a service which they're not getting paid for.

Others are more helpful. It all depends on the individual. I've found that the smaller job shops tend give advise a bit more freely than the larger production shops (though that's not quite axiomatic). The job shops don't rely as much on repeat runs from their customers so they tend to be a bit hungrier for your business.

se
 
"But machinists are in the business of machining, not designing. They typically operate from the assumption that the customer has already taken care of the design and their job is to turn that design into a finished piece.

Some machinists can be rather resentful of customers who expect them to assist in design, feeling that they're providing a service which they're not getting paid for."


Ditto to both comments. I have done both design and machining for automotive assembly equipment. In a design shop when you are finished with a design it goes to a character called a checker, and if it comes back wwith only as much of his red on it as your black you consider yourself lucky. When a drawing goes out the door there is a reason for every damn drop of ink. The machinist, who likely has no idea what this thingy is for, better make it to print, in tolerance and quickly!

ps
By the way what kind of shops are you going to where they call themselves artists. You call somebody that in a shop here in Detroit and you better duck.

pps
You got a degree in engineering? You like to make custum, cost no object gifts? You like to meet my daughter?
:)

ppps
For fastening ideas try REID.com. Great catalouge and they deal in small orders!
 

Brett

Member
2002-01-07 6:02 pm
<b>who were all working from paper-napkin sketches when I visited their shops</b>

That's the sign of a good shop. I deliver all my designs to the local machine shop sketched on bits of paper (with accurate dimensions). CAD drawings seem to worry them, and take me longer to draw than it takes them to make it.

I call this the "Italian School of Engineering Design". Aren't all the very best designs worked out over lunch? The red bits on mine aren't from a checker, but usually splashes of pasta sauce. Very civilised way to work.
 
mltaunt said:
You got a degree in engineering? You like to make custum, cost no object gifts? You like to meet my daughter?
[/B]

Sure. Call my wife, we can all have lunch together.

I never thought I'd have a hard time finding a shop willing to take my money :scratch: I think of it this way: money is for spending, I don't mind throwing some money at an honest machine shop, and I certainly don't mind giving a unique gift. It's got to go around before it can come around, if you catch my drift.

So everyone is in agreement that if use a piece of uniform 0.125" thickness, it will be more manufacturable, and I can still counterbore 0.080" for low profile socket cap screws.

I just realize that if I make that change, I can make these panels myself with a jigsaw and drill press. Whee.
 
So everyone is in agreement that if use a piece of uniform 0.125" thickness, it will be more manufacturable, and I can still counterbore 0.080" for low profile socket cap screws.

I just realize that if I make that change, I can make these panels myself with a jigsaw and drill press. Whee.

Lets make it even easier. Drill your counterbore all the way thru the 1/8 plate. Drill the clearance hole thru a smaller plate and glue in back of faceplate. Round and grind (or sand) the corners and edges to match. Wouldn't hurt to glue some strips around the holes to stiffen things up. Glue you says. Sure I says. the last airplane you flew on probably had it's wings held on with glue. I would recommend a bandsaw or rotary file and a straightedge rather than jigsaw. Nothing like trying to cut straight lines and circular arcs with a tool intended for irregular curves.

ps
Lunch sounds great. You no fool around with my daughter, I no fool around with your wife. Deal?

pps
Hope your wife likes kids (my daughter is eight)
 
jwb said:
So everyone is in agreement that if use a piece of uniform 0.125" thickness, it will be more manufacturable, and I can still counterbore 0.080" for low profile socket cap screws.

No argument from me. :)

I just realize that if I make that change, I can make these panels myself with a jigsaw and drill press. Whee.

But a jigsaw and a drill press won't get you nice bead blasted edges, a well grained face and a good clear anodize. :)

se
 
mltaunt said:
Have you thought of using a wood overlay on the front panel. You may have more luck with a custom kitchen cabinet shop. It would solve a lot of problems although I don't think thats the look you are going for.

Or do the whole panel in wood for that matter. For considerably less than what he would have paid to have a machine shop do it up in aluminum, he could buy a nice router table and perhaps some other goodies and turn out a very nice looking panel.

Of course that may not be what he's going for. Personally I like the organic touch that wood can bring to audio electronics.

se
 
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