where to make it?

[kv1521]

Hello all,

I need some parts for an optical instrument. I have few experiences in making parts. By search engine and forums I found some online machine shops such as emachineshop, quickparts, machinepier and ittmetalfab. Anybody here had experiences with them? emachineshop seems to be the most famous, but they don't accept my solidwork files. I had sent the design to the other 3 shops for quotation just now. Do I have to redesign my job with emachineshop's software if I want to work with them?

[ImanCarrot]

Any good engineering company should be able to make that from a printout.

One thing I would mention is tolerancing. It looks like you're sticking flat optics in the holes- tolerance your optics as +0.0/-0.1mm and the metal holes as +0.1/-0.0mm (for example). That way when you pot your optics in they'll definately fit without chipping. Usualy holes will be made to bottom tolerance and diameters to top tolerance so if you had +/-0.1 on both there's a good risk of chipping the optics.

Oh.. have you thought of black anodising it? (I take it that it's aluminium). This can greatly cut down on stray reflections and consequently reduce glare and increase contrast.

Good luck!

[kv1521]

Thanks carrot. The parts need to be black anodized. Even that it reflect too much light. There'll be light absorb materials stick in the hole.

[ImanCarrot]

Yep, anodising is too shiny.

We use a mat black paint on the edge of our optics which we spray on and seems to work quite well.

On ally, I don't bother with anodising, I just bead blast it to get a nice "grey" surface then spray lightly from a good distance so that the paint is effectively drying as it hits the surface- nice mat finish and no runs

[kv1521]

machinepier replyed with a rough quotation and some questions, pretty fast. The ask me questions about the finishing and anodizing. I'm totally confused. What is ball blaster? what's the different between soft and hard black anodizing? I have to pay some extra $$$ for them($10 for ball blaster and $10 for hard anodizing), do they worth the money? The price sounds not cheap for me. I'll be waiting for the quotations from the other 2 shops.

[DareBee]

A lot of us can work with SW files.
That looks to be about a $500 job (for one).

[kv1521]

$500 for one!
are you joking with me? The first quotation is already out of budget even it's much much lower than the price you mentioned. I'm still waiting for iitmetalfab and quickparts quotation. If there's no lower price I may have to change the design.

[ImanCarrot]

Might be cheaper to get it made of sheet steel or ally?

Wait till you see what your optics are gonna cost hehe.

[PixMan]

A rough estimate of what machinery, tooling and time would be needed to make that largely depends on the overall size cube and tolerances of the features.

How big is it, what specific material is it, and what's the tightest tolerance on which feature?

[kv1521]

I don't know what machinary to use. I guess some CNC is needed. the tightest feature is the angle. the tolerance must be within +-3'. Other dimensions are not very strict. The material is 6061 or other aluminium, not critical. machinepier's quotation is based on 6061.
Haven't got iitmetal's and quickparts reply yet. I hope they are cheaper.

[DareBee]

Please feel free to tell me how much time it will take too..

- Walk to the metal rack and select a suitable piece of material.
- walk to the saw, set up measure and cut the material.
- Clean chips out of saw.
- start the computer, download and interpret your supplied model
- use my vast years of machining knowledge cross referenced with my machines capabilities and my stock tooling to devise and notate order of operations and tooling required to do the job.

At this point we can go many ways with this part, judging by the size of the part the tolerance of the angle between machining faces and the fact that boring the holes takes too long for the required tolerance, I chose to do this in the CNC with 4th axis.

- import model into CAM (with reference to devised notes).
- program all required MOPS.
- it is break time get coffee.
- Set up the stock in the 4th axis fixture.
- inspect and set up the right tooling in the machine.
- mix coolant for the machine because tank is low.
- fill way luber on the machine.
- run each programmed mop clear of the part, in case you have some corrupt code, you can't afford to crash this expensive machine because people think machining isnt worth much and you can't afford to replace/repair it. Bad code happens, we are talking about a lot of complicated stuff going on between 3 different computers and millions of math calcs.
- cut the piece ( a quick process but for quote purposes in a 1-off situation it is proper to figure cutting 2, it is way too easy to make a mistake)
- inspect and deburr the piece.
- clean out the machine.
- put computer away.
- give part to QA guy to inspect and verify (customers bich if parts aren't right you know.
- Give to shipper to pack in a box and create shipping label and call courier for pick up.
- someone in the office enters all the job data, sets up new customer account, calcs and prints and mails an invoice.



I am sure I have missed a few things.
Tell me how long this takes exactly for 1 part?
The material is $6 and my labour is $56/hour.

Sorry about the rant
BTW this post just cost you $25

[kv1521]

I got quotation from iitmetalfab just now. The price is higher than the first, a little more than twice! but it's still less than $500/pcs. I'm confused, does lower price means poorer quality?