# CNC Milling Services?



## Mattaus (Aug 30, 2011)

Hi all,

I'm looking at making a light that is not of the usual form factor - something that you would'nt turn on a lathe really. Very simply put it's almost a box.

I approached someone here in Australia about the approximate cost and for a 2 part housing with total dimensions of roughly 100mm x 50mm x 60mm they indicated AU$500 or more using $90 an hour as their guide. I understand machine set up takes some time and I realise low volume runs (ie// one) are not cost effective; but that seems...expensive lol.

Or am I being very ignorant? Can any one suggest some cost effective solutions? Companies or businesses that would be good to look at?

I've already started looking at modifying my design to rely less on CNC machining and make more use of laser cutting (much cheaper from experience) but some CNC work will still be required.

A CNC mill is something I could use for many things so I even looked at purchasing my own small desktop CNC from a company but they seem to be unreliable and I'm not prepared to drop US$1300 on something I may not get.

For the record I want to make a one off light for my own needs but I am designing it so that should I like to take it further it is of 'commercial quality'.

Any comments or suggestions 

Cheers,

- Matt


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## precisionworks (Aug 30, 2011)

> they indicated AU$500 or more using $90 an hour as their guide.


That's $535 USD at today's exchange rate, which is dirt cheap. Make them commit to that in writing & get it done before they realize their mistake in pricing. 

My shop rate is $75 per hour but I'd figure 10-20 hours or more, somewhere around $750-$1500 USD.

For a one off, you don't need the additional expense of a CAD drawing & a CNC mill. All you need to provide the shop is a clear 2D drawing, and the only equipment they need is a Bridgeport type vertical mill. Once you finalize the design, then the CAD drawing & the CNC mill become essential for producing more than one item.


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## Mattaus (Aug 30, 2011)

precisionworks said:


> That's $535 USD at today's exchange rate, which is dirt cheap. Make them commit to that in writing & get it done before they realize their mistake in pricing.
> 
> My shop rate is $75 per hour but I'd figure 10-20 hours or more, somewhere around $750-$1500 USD.
> 
> For a one off, you don't need the additional expense of a CAD drawing & a CNC mill. All you need to provide the shop is a clear 2D drawing, and the only equipment they need is a Bridgeport type vertical mill. Once you finalize the design, then the CAD drawing & the CNC mill become essential for producing more than one item.



Thanks for the reply. Not the news I wanted to hear but not unexpected either. I'm definitely going to rework my design considerably - it won't look like the beautiful slab of metal I hand in mind but it'll be close. Then whatever CNC work needs to be done I will just have bear the cost of.

Ignorance is (was) bliss!


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## rmteo (Aug 31, 2011)

You can get an online quote from a place such as this http://www.firstcut.com/?s=PM&ls=PL


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## Mattaus (Aug 31, 2011)

rmteo said:


> You can get an online quote from a place such as this http://www.firstcut.com/?s=PM&ls=PL


 
Thanks. I'll check it out. I have talked to the guy that gave me the original cost estimate and he suggested some methods I could use in my design to reduce the setup and milling time as well as offereing some out of hours work as his own personal rates were cheaper. Not going to save me hundreds but it will help. I'll see how I go...time to fire up Blender for the first time in a long time!


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## precisionworks (Aug 31, 2011)

> some CNC work will still be required.


CNC becomes cost effective when the programming & setup costs can be spread out over at least a dozen lights. If a feature requires circular interpolation, tangential transitioning, or other complex moves the computer can generate those shapes quickly ... as long as enough lights are being made to spread the cost out.

The tool & die shop I work at has a CNC lathe & a manual mill. We run primarily 12-24 parts at a time, as under 12 gets really costly on a per part basis & over 24 doesn't work well for the simple equipment we have to work with. 

I have some parts quoted at the local Mazak shop, as they are better equipped to run in the 50-5000 range. Most of my runs are around 500, so a setup & program charge of $150 adds just $0.30 to each part. Every person who wants something machined in my all manual shop feels that CNC is the answer ... until the setup charge gets tacked onto the cost of the part. One customer had me build up a "standard" part using Devcon 10610 Aluminum Putty, then turn & mill the built up part to a print that he provided ... around ten hours total machining time plus $60 for the smallest container of Aluminum Putty. That made sense as he used the built up & machined part as a "master plug" to build a new injection mold, from which thousands of parts were made.

The key to economical CNC is quantity, and the minimum number depends on the shop that you use.


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## Mattaus (Aug 31, 2011)

Yeah I spoke to the guy today over the phone and a lot of it makes sense to me now that did not before. I'm slowly learning more than I thought I'd need to, but I have accepted the fact that the first one will cost me a lot but if the demand is there then a production run of sorts won;t actually be very bad at all.


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## Mattaus (Aug 31, 2011)

Yeah I spoke to the guy today over the phone and a lot of it makes sense to me now that did not before. I'm slowly learning more than I thought I'd need to, but I have accepted the fact that the first one will cost me a lot but if the demand is there then a production run of sorts won't actually be very bad at all.

It's just swallowing that first pill that's a little bitter...


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## precisionworks (Aug 31, 2011)

I feel your pain 

You do not want to know what I've spent on tooling for boring lights, or how much more it takes to do trit installations. Imagine 6 tiny end mills, each one the size of a match stick, at a cost of $240. Or a 1 ounce bottle of NOA61 at $42. I could go on and on but I think you get the idea. 

Every new project has a period of time during which you pour money in with the hope that your investment will be returned in the future. In machining you always have to spend money before you can make money.


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## 350xfire (Aug 31, 2011)

If it was cheap and easy, everyone would be doing it, right?


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## Mattaus (Aug 31, 2011)

350xfire said:


> If it was cheap and easy, everyone would be doing it, right?


 
I thought everyone was lol! But then again I keep forgetting people around here do lathe work....not CNC work. I'm such a nub sometimes :-S


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## precisionworks (Aug 31, 2011)

> people around here do lathe work....not CNC work.


Lathe work is CNC work IF done on a CNC lathe


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## Mattaus (Aug 31, 2011)

precisionworks said:


> Lathe work is CNC work IF done on a CNC lathe


 
I knew that....


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## unterhausen (Aug 31, 2011)

I used to think that CNC was the answer, and the truth is I can't stand to turn handles on a vertical mill any more. But it's not a slam dunk, unless you have a fancy tool changer/coolant, you still have to stand by the mill and supervise. I'm not sure what the difference is, but I really like turning handles on a lathe. I'd like to have a CNC lathe though.


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## PEU (Aug 31, 2011)

precisionworks said:


> I feel your pain
> 
> You do not want to know what I've spent on tooling for boring lights, or how much more it takes to do trit installations. Imagine 6 tiny end mills, each one the size of a match stick, at a cost of $240. Or a 1 ounce bottle of NOA61 at $42. I could go on and on but I think you get the idea.
> 
> Every new project has a period of time during which you pour money in with the hope that your investment will be returned in the future. In machining you always have to spend money before you can make money.


 
When I made the trit bezel run years ago, I purchased for the shop 25 1/16" and 3x 5/8" carbide endmills, at the end of the run not all survived the journey and most of them were dull thanks to the stainless steel.

When you design for CNC, it helps knowing how they will do your part and how to make the machinist work less, for example, if your piece of ALU needs to be milled to form a pocket, make the inner corners the biggest diameter your design allows, this way they use bigger diameter tools thus making more chips in less time, less time less money!


Pablo


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## Mattaus (Aug 31, 2011)

PEU, you've got me thinking. I did ask the guy for some advice to designing my housing to reduce costs. He gave me the following but maybe you can expand on them?

- The more rounded your inner corners the better (so if you are using primarily a 6mm bit make your corners 3mm rounded). Sharp inner corners are a pain.
- Try not to make deep cuts more than 3 times the width of the cutting bit. So if you're using a 6mm bit, try not to cut grooves more than 18mm deep. They can be made deeper but require more passes.
- Parallel faces are easier for the machine to grip. I'm not really concerned about this because what I want to make is effectively a box. Doesn't get any easier to hold than that!
- Basically try to plan for as few cuts as possible, using as big a bit as possible. If you can design the whole thing to be cut with a single sized bit then you're onto a winner. Difficult to do depending on the design.

Anything else?


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## PEU (Aug 31, 2011)

aesthetic details are a b!tch, avoid them at least at the prototype, later if people like what you did, you can show renders of how the final product will look like. 
Less diameter for the tool needed means slower feed rate or more passes, both not a good option, as I said, design for the biggest radius you can, not that you need to think they only will use 1/4 or 5/8 but every operation adds up in time and money. This is important for production runs.
For making a single prototype your bigger cost will be CAM related and I'm assuming you'll provide them with fully detailed 3D CAD blueprints, so again, as Barry said, 500ish is not a bad number for a run of 1.


Pablo


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## 350xfire (Aug 31, 2011)

Mattaus said:


> PEU, you've got me thinking. I did ask the guy for some advice to designing my housing to reduce costs. He gave me the following but maybe you can expand on them?
> 
> - The more rounded your inner corners the better (so if you are using primarily a 6mm bit make your corners 3mm rounded). Sharp inner corners are a pain.
> - Try not to make deep cuts more than 3 times the width of the cutting bit. So if you're using a 6mm bit, try not to cut grooves more than 18mm deep. They can be made deeper but require more passes.
> ...


 
Yeap, the way it works it is based on number of "operations". The more complex the piece the more operations it needs, the more machine time and possibly more set up time.


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## Mattaus (Sep 1, 2011)

Yeah I'm supplying the 3D data, but I don't have access to any CAD to CAM software...otherwise I'd give them everything they need to shove in the computer and away they go.

I'll have to come to some sort of compromise because the 'run of one' is actually for my own personal needs. I don't want to build myself a crappy prototype that I can't get rid of! Plus I'm a perfectionist lol.

Thanks for the advice fellas. If only I could decide on my electronics setup then I'd be able to finalise the housing. Looooong road.


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## precisionworks (Sep 1, 2011)

> I don't have access to any CAD to CAM software


We run Alibre Design, one of the less costly CAD packages, but it is still $1000 USD. Some of the members may suggest a lower cost CAD package.


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## Mattaus (Sep 1, 2011)

precisionworks said:


> We run Alibre Design, one of the less costly CAD packages, but it is still $1000 USD. Some of the members may suggest a lower cost CAD package.


 
Yeah that's what I thought. It may be cheaper in this instance for me to take the hit on the added cost for them to convert to it to CAM code...or whatever the right term is. Probably help if my design is perfect the first time round to reduce the need for newer versions (and more conversions).


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## rmteo (Sep 1, 2011)

Mattaus said:


> Yeah that's what I thought. It may be cheaper in this instance for me to take the hit on the added cost for them to convert to it to CAM code...or whatever the right term is. Probably help if my design is perfect the first time round to reduce the need for newer versions (and more conversions).


 At places like the one I mentioned in post #4 above, you just send them CAD/Solid model and they quote you a price of the finished prototype part (inclusive of all programming and setup charges). For example, I got a quote for the item below a year ago (6061T6 alloy, approx 5.5x3.0x0.8in., just the housing, two piece - upper and lower) and it was way less $500.


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## rmteo (Sep 1, 2011)

BTW, getting a quote is free and you get it in about an hour. Here is a sample quote ($129, qty 1, *note the lead time*) http://www.firstcut.com/FirstQuote.aspx

Quote #: *117607* 
Quote date: *5/10/2011* 
Part #: *Firstcut Demo Quote Part* 
File name: *ThreadTestPart beefed up boss(2).SLDPRT* 
Extents: *1.75 in x 0.35 in x 3 in*
Material: *ABS - Black*
Lead Time: *1-3 business days*






Within reasonable limits, size (and material) does not affect the price significantly as most of the cost is in programming/setup for short runs. Multiple units (>1) will lower the unit price significantly.


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## Mattaus (Sep 1, 2011)

Hmmm rmteo - I did look at the site but clearly not hard enough. That price is pretty damn good considering what I am looking at right now. In regards to lead time I'm not sure if those days are good or bad - seems good to me lol.

Seen as the quote is free I wonder if it's automated? If that is the case then they may not mind me submitting several. What's shipping like as I am in Australia. Then again a quote may help me figure that part out on my own.

Thanks!


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## rmteo (Sep 1, 2011)

They are very good at keeping up with lead times. I have used them for prototypes and they have never exceeded their quoted lead times. I have also used their service for injected molded parts (which can be done in as little as one day) http://www.protomold.com/

The quotes are automated and you can submit as many as you want (you need to set up an account first). Shipping in the US (3-5 days) is about $8. I don't know if they will ship directly to Oz. Shipping your parts via International Priority Mail is $US$13.95 (have done this on numerous occasions) - I can do it for you if you want.


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## Mattaus (Sep 1, 2011)

rmteo said:


> Shipping in the US (3-5 days) is about $8. I don't know if they will ship directly to Oz. Shipping your parts via International Priority Mail is $US$13.95 (have done this on numerous occasions) - I can do it for you if you want.


 
Well I'm a fair way off even getting to a quote stage. I'm still doodling in Visio trying to come up with simple 2D drawings. Once I am happy with them I will transfer them to Blender but I'll probably make changes at that stage as well. Then I'l get a quote and probably make changes again depending how that comes out. I've upped the output power of my light which in turn requires more cooling and thus makes a larger part to CNC. More $$$ in other words. I might do a few different designs of varying size.

Long way to go.


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## rmteo (Sep 1, 2011)

Is it anything like this 2x26650 concept I was working on a couple of years ago?


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## Mattaus (Sep 1, 2011)

That looks very familiar to those flashlights that go for thousands on these forums. I was never a fan of them so I can't even recall the name...

But no - I'm building a 4WD light bar for my own ute. 9 XM-Ls driven at 3A each off the car battery (3s3p). I plan to use a selection of Ledil lenses to achieve good throw with some side spill and local flood....so everything lol. As it stands the housing is roughly 230mm wide, 100mm tall and approximately 60mm deep - heatsink fins included. Current market lightbars with a similar output fetch $1200+ at about 8 times the physical size and a vastly increased number of emitters (failure points). The way I see it if I can develop something smaller, cheaper, more power efficient but at the same time more powerful then why not see if anyone else wants some? Plus the design in my mind is fairly eye catching. I know a lot of people here in Australia that would love the look on their 'mini trucks'.

This of course all started with a simple 100mm x 80mm x 60mm 3 emitter design and just exploded. Typical.


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## rmteo (Sep 1, 2011)

Actually that flashlight could be made and sold for $195 complete with an AC/DC charger for in-light charging.

At about the same time, I was working on something similar to what you are doing. It is a modular lighting system for both AC (110/240V) and 12V DC operation with optional RF remote control. It can be configured with 1-4 light bars in both vertical and horizontal configurations.


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## Mattaus (Sep 1, 2011)

I'll have to get a render going soon so I can share it/get opinions on improvements. Really the only thing I'm a little worried about is that my design at this stage is more form over function which could limit the ability of the case to pull the heat away from the LEDs - especially XM-Ls. I'm also going for fully weather resistant which obviously requires rubber sealing to be included, something I have not started looking at yet.


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## wquiles (Sep 1, 2011)

Mattaus said:


> I'll have to get a render going soon so I can share it/get opinions on improvements. Really the only thing I'm a little worried about is that my design at this stage is more form over function which could limit the ability of the case to pull the heat away from the LEDs - especially XM-Ls. I'm also going for fully weather resistant which obviously requires rubber sealing to be included, something I have not started looking at yet.


 
Unless you have active cooling (electric fans), you really have to plan for the worst case scenario: standing still, on a very hot night (90+F). Here in this older thread, in post #12, I list the math equations to figure out what size/efficiency for a heatsink you need given a particular goal for steady state temp, given your particular thermal load:
http://www.candlepowerforums.com/vb/showthread.php?240896-how-to-find-out-what-size-heatsink-you-need&highlight=heatsink

IN that thread we agreed that a good number to use for the amount of heat being created by the LED (vs. turning into useful light) was about 80%. So if you have 9 XM-L's, each at 3 Amps:

9 * 3.65 volts * 3 amps * 0.80 = 78.84 = lets say about 80 watts that need to be dissipated as heat (assuming a vf of about 3.65 volts at 3 amps).

So assuming your worst case scenario:
Tr - Temperature rise
Ta - 32°C (90F)
Th - 49°C (about 120F, max. temp to prevent getting burned by touching heatsink with bared hands)
Ph - Power applied to heatsink = 80 watts
Rth - Thermal resistance (in °C/W)

Tr = Th - Ta = 49 - 32 = 17°C
Rth = Tr / Ph = 17 / 80 = 0.213°C/W

Now that you have a goal, you can now find an available heatsink that has 0.213 °C/W or lower. Note in a link in that thread, various CPU heatsinks were being evaluated for a similar load as what you are contemplating, and the passive (no fans) heatsinks only scored about 2.67 °C/W, and in fact, even the units with fans, did not achieved as low as you need in your particular case - which means that based on this quick, high-level analysis, you need something "significantly" larger than a good CPU heatsink. Maybe you need to look at larger heatsinks such as those used in bench power supplies.

Here is one, where "if" anodized or painted with a thin coat of matte black paint, the thermal resistance is about 0.3 °C/W (still not good enough), but gives you an idea of the size you would need:
http://sound.westhost.com/pcb/heatsink.htm

Will


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## Mattaus (Sep 2, 2011)

Holy...

Right so I totally ignored doing any maths. I did think about the cooling requirements but as usual I managed to skip over them in the typical Aussie "she'll be right mate" way of doing things.

The example heat sink you provided is narrower height wise than my intended design by 20% but longer by roughly 33%.

My design is also intended to be CNC'd from a single block of aluminium 6061 - so the case itself plus the fins on the back (which are of the same length as your example but much more numerous) would help transfer the heat. If the case is black anodized I believe that a housing of the dimensions and design I am working on *should* be big enough dissipate 80W of heat.

:duh2:


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## precisionworks (Sep 2, 2011)

> the case itself plus the fins on the back (which are of the same length as your example but much more numerous) would help transfer the heat.


An air-to-air heat spreader like that will benefit from a small internal scrubber fan (or fans). The scrubber fan/s keep air moving inside the sealed case to prevent the localized heating that happens with a scrubber. Lots of sealed devices like VFD's commonly use these.


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## Mattaus (Sep 3, 2011)

precisionworks said:


> An air-to-air heat spreader like that will benefit from a small internal scrubber fan (or fans). The scrubber fan/s keep air moving inside the sealed case to prevent the localized heating that happens with a scrubber. Lots of sealed devices like VFD's commonly use these.


 
Could you elaborate on this a little more? Are you saying have a fan running inside the sealed section where the LEDs and Driver are housed? Or on the back to force air over the fins?


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## precisionworks (Sep 3, 2011)

Mattaus said:


> Could you elaborate on this a little more? Are you saying have a fan running inside the sealed section where the LEDs and Driver are housed? Or on the back to force air over the fins?


 Inside the housing to eliminate localized hot spots.


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