[rjmmusic]

Hello, I'm an electronics manufacturer and am trying to find a cost effective way to get some front and rear panels made for a new line of products. The panels are quite simple - 1/16" aluminum, approximately 1.6" x 3.7", with a few holes in each.

I've looked into getting my own CNC setup to do these, but I don't think I have the time to tackle the learning curve at this time.

I've attached drawings of the first two panels I need done. Please quote for quantities of 10, 25, 50 and 100. (Please ignore the callouts on the drawings saying 20ga steel - aluminum is fine).

Need any other information? Please let me know!

[Donkey Hotey]

Your biggest problem getting a quote on those is the corners on those square holes. Mills can't make square corners; they can only make round corners. Most switches and other things that go into cutouts like that don't really need square corners so you have to change that to allow them to be made with a mill. 1/8" radius would be no problem. 1/16" would be do-able. Under that is still possible but it slows down the process and runs up your cost.

The fastest way would be to have them punched but then you're dealing with setup costs. In low quantities, milled is the way to go, though they will be more costly than punched items.

[Geof]

You should also toss in a few tolerances, particularly for the overall dimensions.

If the 3.676 by 1.597 is to fit in the end groove on a standard Hammond case these dimensions can vary by +/-0.01". This means that they can be cut to size using a shear so the holes can be finished at a single fixturing. Making these dimensions to a tolerance that requires milling adds two more fixturings and more or less triples the price.

[rjmmusic]

Good points, all. (You can tell I'm not a machinist!)

I'll do some math and figure out the allowable corner radius and tolerances.

The front panel screws to an extruded aluminum enclosure, so the tolerances on the outer perimeter don't have to be super tight.

I'll post with more information as soon as I can.

Thanks!
-Ron

[Geof]

...I'll do some math and figure out the allowable corner radius and tolerances.......

A 1/16" corner radius is made using a 1/8" cutter which is eminently doable, anfd I would be very surprised if you cannot accomodate that. Also I think you should be able to aceppt tolerances of nominal size plus 0.005" minus 0.000" which is trivial on a CNC. I have done many similar front plates for some products we make.

Don't be surprised if any quotes you get seem high for such a simple part; it is a bit fiddly and time consuming to make a little setup to do these type of low quantity jobs.

[Donkey Hotey]

My way of doing it would be to put full sheets in the machine, cut all the holes then go back and part out the individual pieces.

How I'll hold that large sheet as the pieces are 'parted' out of it is my trade secret.

The other way would be to make them yourself in a drill press. You could carefully lay out a couple of simple fixtures and do them yourself. You'll need square punches for those square holes though. They'd be time consuming but sometimes time is less expensive than expediency.

[Al_The_Man]

Without knowing all the details, I am guessing the the holes also appear in the extruded panel it is attached to, at least the fixing holes with a larger cut out maybe?
What I am getting at is if you do not requires the 1/8" Al. for structure, can you have these made from a different material such as Lamacoid? this would be very easy to have made at a very reasonable price, this would also allow engraving if you required it.
Also the Lamacoid can be mounted with double sided tape, eliminating the fixing screws, especially if the components can help secure it to the panel.
Al.

[rjmmusic]

Okay, here are two updated drawings with tolerances. I've also changed the rectangular holes to circles - I can make it work either way.

I also have uploaded a drawing of the extruded part that goes with the panels.

FYI, I'd like to stick to metal for these panels - some of these products will be handling audio signals, and I need some EMI shielding.

Thanks, and let me know what you think!

-Ron

[Donkey Hotey]

That looks much easier to make on a mill. Since you've changed the square holes to round ones, it looks easier than ever to make them on a drill press fixture.

I'm not necessarily going to bid this but maybe I can help you to make some other improvements in your product that having them cut in a mill could make possible.

Have you considered:

• Adding thickness to the plates for any reason? Like maybe a pocket into thicker material so an adjustment or switch can't be accidentally bumped? Or just to add some visual detail to the product over a plain flat plate?
• What about engraving? Once it's in a mill, they could be engraved with your nomenclature.
• Do you want these brushed finish? Polished? Tumbled? Are you going to get them anodized later? Or is supplying them 'as milled' good enough for you?

Stamping holds the advantage on inexpensive production when the units are in the 1000s. If you're low-production and having them milled anyway, another buck or two per part could make a huge difference in the visual details possible.

Everybody else: ignore my hijack. He asked for a bid on what's posted. I'm just trying to help him here.

[rjmmusic]

I'm probably going to get them anodized and then silkscreened, so I guess I'll only need the parts deburred somehow. No need for engraving or changing the thickness - we don't need to get too fancy.

Another possibility is having someone cut just the perimeter and the four outermost mounting holes - this is what will be common across all of the panels I'll need - and drilling the rest myself. Of course, that assumes I know how to make drill fixtures for something like this! Anyone have any tutorials?

Thanks again!
-Ron

[martinw]

Dear rjmmusic,

I have probably misunderstood, but here is my take..

You need front and back panels for an electronic enclosure. If you buy a standard enclosure, it may have blank panels anyway . Most enclosure manufacturers have in-house machining facilities.

We recently bought a bunch of polycarbonate enclosures that needed a whole load of tapped holes for cable glands etc and were really pleasantly surprised by the price that the enclosure suppliers gave for machining. The enclosures cost about $30 each, and they quoted an extra $5 for a total of 20 half inch tapped holes.

That was for a batch of twenty boxes.

Another thing that you might consider is that if the box supplier does all the work, you only have one outfit to deal with, pay, and complain to (alas).

I may have misread your query, if so, I apologise.

Best wishes,

Martin

[Donkey Hotey]

It looks like he's buying somebody's electronics heat-sink extrusion and this is for endplates to close it out. Yes, I agree with you though: if they sell the extrusion, they probably sell the blank endplates.

At that point, he could just make a drill plate and drill them himself. Or somebody could quote a tooling block with drill bushings precisely located so he could drill the prefab endplates.

[a5sniper1978]

Do you still need a quote on these?

[rjmmusic]

Thank you all for the quotes and the advice!

I've ended up going with a local shop that I've worked with before - their prices are competitive and they have the advantage of being nearby.

Thanks again,
-Ron