Author Topic: cnc milling (Read 6396 times)

oldschoolace · « **on:** August 20, 2011, 11:42 AM »

Does anyone have an idea as to costs for cnc milling work? Is it priced on a time basis and what sort of money would you be looking at to get something like a spider made up?

Cheers all

animal · « **Reply #1 on:** August 20, 2011, 12:13 PM »

Been 2 c somebody this morning along similar lines. Looking at shit loads 4 a 1 off

oldschoolace · « **Reply #2 on:** August 20, 2011, 12:19 PM »

Quote from: ANIMAL on August 20, 2011, 12:13 PM

Been 2 c somebody this morning along similar lines. Looking at shit loads 4 a 1 off

Damn it i knew that was going to be the answer

i did think about finding some oldtimer engineering type with milling gear but i think one element of what i want to do will need cnc'ing as its a bit fiddly

steve · « **Reply #3 on:** August 20, 2011, 12:24 PM »

where are you in the country?

if west london - heathrow
wellington engineering - opposite the hayes bmx track almost, 20 cnc machines I paid £300 for some custom aluminium car/van hubs

if in south west london
mollarts engineering - 20 plus cnc machines -specialist line boring drill manufacturer - i paid £440 for a pair of hubs
chessington

for one offs and the like look on here,

http://www.nsra.org.uk/newforum/forumdisplay.php's=0e8cebec76d352171f7ecc8dc3539c5e&f=6

there is a chap who laser cuts flat stuff forget his name - minimum charge for a small flat item is about 30 slaps

or east london
trevor dorrington - race car fab - no cnc, but milling machinery.
01268 777269

oldschoolace · « **Reply #4 on:** August 20, 2011, 12:34 PM »

Cheers Steve, in Manchester unfortunatly but the part i am looking to make isnt large so location isnt that important. It is nice to call in these places though and get to know peeps.

As general info for anyone northern there is a cracking place called general utilities in stockport who do laser, plasma and waterjet cutting. They are very reasonable and dont mind doing one off stuff. some of there waterjet samples through 2 inch steel are amazing. They had a bicycle around 5 inch long with spokes at around 1mm wide cut through the 2 inch stuff!

Hey we should have a thread for stuff like this!

Peter J · « **Reply #5 on:** August 20, 2011, 12:44 PM »

For a one off you’d be better off going to a local machinist who would make you one providing you have one he can copy or a set of drawings he can work from.

A CNC miller needs an “NC file” which is normally generated from either a 2D or 3D CAD file (DWG/DXF) if the company has to generate a CAD file there is sometimes an associated cost for a one off.

The main disadvantage with CNC machines for one off’s is the set up time and CAD file/model generation time and a skilled machinist using a conventional miller will be able to produce as good if not better and cheaper finished part.

We would charge £40 per hour + materials for “knife and fork” jobs

When we had an engineering company we’d do the “knife and fork” jobs on the conventional machines and anything that had tight tolerances/multiple/repetitive cuts would be CNC
If the spider is flat (Like a tuf neck power disc) laser cutting would be a better option normally there minimum charge would be £50 and you would get around 10-12 disc’s

I so miss making CAD models and playing with big boys tools

oldschoolace · « **Reply #6 on:** August 20, 2011, 12:48 PM »

I bet you do Peter, i would love to have a go at all that stuff. I'm a woodman myself so occasionally get to play with a cnc but metalworking could be ace!!

Am actually looking to get a stem made. I blame that american hotrod programme, it always looks so easy on there!

rooski · « **Reply #7 on:** August 20, 2011, 12:56 PM »

if you want a one off think £35 an hour for cad work,same for programming,same for set up and machining,plus material.

I think £200.00 could get you a one off spider

Lazer cutting a powerdisc and machining could be a lot cheaper.

oldschoolace · « **Reply #8 on:** August 20, 2011, 12:58 PM »

I'm pretty good on cad gear as i use it for work sometimes, just need a nice man with a machine

Peter J · « **Reply #9 on:** August 20, 2011, 01:30 PM »

A stem would take multiple passes and cuts plus you would also need someone with a lathe as well for the stem shaft

Material wise you'd need a good general grade like 6061 (T6) or if you can find an off cut go for 7075 better strength properties but more expensive and harder to find where as 6061 is cheap and every bugger stocks it

Also consider head treatment may be needed as well to relive the metal stresses associated with machining as well as help with tensile strength................I could get really boring and go into FEA (Finite Element Analysis) but to be fair even I fall asleep discussing that.....

As for the shaft Cromo all the way and this should be threaded into the stem head using a “force fit” I cannot remember the correct terminology for it

If I was making one I would also knurl the shaft along its length...........

I’d looked at making one (a one off of my design) and even with me generating the CAD model (which I still have) the costs would be in excess of £150 but then I suppose if I’d looked at making one to a normal specification with less cuts and cheaper materials I could get it down to £70 ish

If I ever get a spare Saturday I would love to go to my old place and make one I worked out it would take about three hours for me

oldschoolace · « **Reply #10 on:** August 20, 2011, 02:05 PM »

Sounds like you know your stuff Peter, i may have to pick your brains at some point

The stem idea i have is pretty straighforward apart from one piece so machining would be minimal hopefully. I did wonder about materials but from what little i do know about metals there are more grades than you can shake a stick at.
Would a plastic stem be madness? - in one of the harder plastics like tufnol

Peter J · « **Reply #11 on:** August 20, 2011, 02:39 PM »

Short answer is NO

Medium length answer is:

Although composites have, in some instances better liner strength than traditional materials you need to factor in “Product Life Cycle” this covers such aspects as stresses both cycled (pull/push) and twisting. Also these materials have a limited life....the first time its stressed it will retain 100% of its strength the next time it might me 95% etc etc until SNAP !!!

Products are designed with in parameters for example certain F1 parts are designed to last a race because weight/performance is a more important design factor than longevity and therefore engineered/designed accordingly.

I’m not too good on composites but I would think that they would not react that well to this type of application because of the non standard loads this type of part would experience over its life span............not to mention crashed/bumps/scrapes etc etc

I know you can get MTB stems/bars made of carbon fibre but there are use/weight limitations

I have a 3D CAD package (Solidworks) with an FEA package (Solidworks Simulation) and I/we used to design some really cool stuff and it’s amazing how a little tweak here and there (not to mention material changes which then can impact on the design) and can make such a difference and to “Joe public” they would never notice a design change

http://en.wikipedia.org/wiki/Finite_element_method

oldschoolace · « **Reply #12 on:** August 20, 2011, 03:04 PM »

Dude do you stil work in this field? if not thats some wasted talent right there!

How about 3d printing a prototype then casting? I have just found an ace place literaly next door to my workshop that does laser cutting and 3d printing FOR FREE!!

Peter J · « **Reply #13 on:** August 20, 2011, 03:33 PM »

On I sold up a few years back but I still have a play with designing stuff plus I sometimes help out with the machining/assembly processes

Once you’ve made your 3D prototype then you could get it cast.....however the for a stem this would be a longer more expensive process:

Make 3D Model

Get a Foundry to modify Model with feeder necks/run offs

The model would have to be cast using sand/resin to make the mold (a die would cost £1000’s)

They would probably use LM25 as this has the best machining properties and is a good “general” alloy to die cast with

The part would then need to go though the machining process discussed before

The best option would be to machine a stem from “bar stock” because with gravity casting the crystals of the aluminium are not aligned as well as say extruded alloy

I’m not going to bore you with crystal alignment or mechanical properties of aluminium

One of the clients we had was a non-ferrous foundry in Sheffield and I did 100’s of designs/produce analysis for them

Designs are normally a trade off between cost/function

Example: Rolex Watches are function/feature over cost Casio Watches are cost over function/feature

Peter J · « **Reply #14 on:** August 20, 2011, 03:42 PM »

Oh and with any design/product you have to consider material/design harmonics

Classic example of bad design harmonics would be the Millennium Bridge (London)

oldschoolace · « **Reply #15 on:** August 20, 2011, 04:45 PM »

Quote from: Peter J on August 20, 2011, 03:42 PM

Oh and with any design/product you have to consider material/design harmonics

Classic example of bad design harmonics would be the Millennium Bridge (London)

Or the b of the bang

Hate the twunk who designed that and now they have give him the task of redesigning the routemaster bus

Thanks for the advice

griff · « **Reply #16 on:** August 20, 2011, 05:12 PM »

been reading this with interest (even though I don't understand a lot of it

)

but I think steve should show us his hubs...

Gary72 · « **Reply #17 on:** August 20, 2011, 07:30 PM »

If I ever win the lottery, Peter J is going to design me some Tuff style wheels that will take a cassette driver

Imagine tuff wheels polished to bling with a 9t driver and a 14mm axle

griff · « **Reply #18 on:** August 20, 2011, 07:38 PM »

Quote from: Gary72 on August 20, 2011, 07:30 PM

If I ever win the lottery, Peter J is going to design me some Tuff style wheels that will take a cassette driver
Imagine tuff wheels polished to bling with a 9t driver and a 14mm axle

I can imagine getting a hernia trying to do a bunny hop

oldschoolace · « **Reply #19 on:** August 20, 2011, 07:42 PM »

Quote from: Gary72 on August 20, 2011, 07:30 PM

If I ever win the lottery, Peter J is going to design me some Tuff style wheels that will take a cassette driver
Imagine tuff wheels polished to bling with a 9t driver and a 14mm axle

What like this

http://bmxmuseum.com/forums/viewtopic.php?id=348786

Peter J · « **Reply #20 on:** August 20, 2011, 07:51 PM »

I’ve worked on everything redesigning the torsion bar on the mk1 Audi TT............bloody Germans cannot design owt

!!!!!! to a mechanical “matrimonial aid” that pleasures the female of our species........you wouldn’t believe what they are will to pay for a bespoke piece to kit

And everything in between !!!

oldschoolace · « **Reply #21 on:** August 20, 2011, 07:56 PM »

Quote from: Peter J on August 20, 2011, 07:51 PM

I’ve worked on everything redesigning the torsion bar on the mk1 Audi TT............bloody Germans cannot design owt !!!!!! to a mechanical “matrimonial aid” that pleasures the female of our species........you wouldn’t believe what they are will to pay for a bespoke piece to kit

And everything in between !!!

we are not worthy

Gary72 · « **Reply #22 on:** August 20, 2011, 07:56 PM »

Quote from: oldschoolace on August 20, 2011, 07:42 PM

Quote from: Gary72 on August 20, 2011, 07:30 PM
If I ever win the lottery, Peter J is going to design me some Tuff style wheels that will take a cassette driver
Imagine tuff wheels polished to bling with a 9t driver and a 14mm axle

What like this

http://bmxmuseum.com/forums/viewtopic.php?id=348786

Like that but blinged, Complete ali wheel CNC machined and polished like on American Chopper

griff · « **Reply #23 on:** August 20, 2011, 08:01 PM »

like this?

Peter J · « **Reply #24 on:** August 20, 2011, 08:03 PM »

My first powerdisc..............I had the discs laser cut with the correct PCD to accept a Sugino chainwheel and I programmed the CNC to do the logo............Hummmm pies

Author Topic: cnc milling (Read 6396 times)

steve

griff

griff

griff