Electronics > Mechanical & Automation Engineering

Recommend me a machine shop/machinist for this part (USA, China)

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Hi all,

Is this the right forum...? Worth a shot I guess.

I'm working on a blowby oil catch-can project for my car which has a GDI engine. I'm planning to use a Parker-Watts coalescing or particulate filter in line with the PCV line from crankcase to intake.

I got the idea from a post made by a guy named Dave who owns a small company called "Conceptual Polymers". He sent me the attached drawing of an extended tank for use with these Parker-Watts pnuematic air filters. He no longer makes it this part and recommended I find a machinist to make it. I need only 2 or 3 pieces.

Does anyone have a machine shop they can recommend? I live in New Jersey, so if anyone is in the area and has a recommendation, let me know. Otherwise, I'm thinking China or elsewhere may be a cheaper option. Anyone work with a Chinese supplier who was okay for really small one-off volumes like this?


For low volume pcbway has a CNC service, but my take is that they are only competitive for a few units. I asked for a quote of 100 plastic cnc parts and they quoted me more than double compared to a local machine shop

I really doubt you'll find a Chinese vendor interested in one-off custom runs from an overseas customer.  You'll probably need to talk to someone directly. I no longer own a machine shop, as is the case with most of the zillions of them that existed two decades ago.  I can however give you an idea as to how to proceed. 

First, don't make this out of a solid piece of aluminum, that would be a huge waste of effort.  I would get a few feet of 0.188 wall 1.50 O.D. 6061-T6 tube and a foot of 1.5 O.D. 6061-T6 round bar from onlinemetals.com. 

Then I would find someone that does manual lathe work (CNC is not always your friend) and show them the drawing and the metals I recommend.  They can make the tube section and a stepped end cap which can be TIG-welded on (my recommendation) or made with threads (if you don't like the appearance of the weld). 

Thanks to both of you.

Well, this sounds like a perfect time to jump down the M-CAD rabbit hole. I tried LibreCAD a few times over the years, but did not have the time or patience to figure it out. Maybe I'll give it another shot, maybe with Fusion 360 or something..

Per suggestion:  Go with 1.50" aluminum pipe. On one end, cap it off with a butt-welded cap or. a "stepped end cap". What do you mean by a stepped end cap? Is this a cap which has a ledge that "sits" on the end of the pipe? Example photo?

Then, the only real piece to make is the threaded "adapter" which adapts the pipe to the funky 1-7/16 - 18 UNF threads. This could be similarly butt-welded as the end cap. Maybe something vaguely like the attached? Is that an example of a "stepped end cap" by the way?

What do you think about brazing instead of TIG welding? I think, at most, the housing needs to handle ~10-15PSI. If brazing seems okay, I can probably do it myself with a Bernzomatic, and then all I need is the adapter piece by itself.


I don't know the function of the device, so I've no idea if the inside needs to be bored to that spec or not.  I chose metals that could be most easily machined to that spec.  "Stepped end cap" seems self-explanatory and indeed your photo (the top parts) resemble what I mean, just replace the threaded section with solid metal, not as long.

I don't think attaching a threaded adapter--if you can find one--to the tube is a good plan.  A skilled machinist could easily make that very neat and precise by machining the end of the tube as drawn.  I can't recommend brazing aluminum, especially with parts of different thicknesses.  This probably isn't a first-time DIY project unless you are aspiring to be Red Green.


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