Seeed Studio Machining

Maybe these guys

What I've done is drop in on a local machine shop with a bottle of good wine.

How about a local plastic machine shop. In Buffalo we use Great lakes plastic.

George H.

Den fredag den 3. november 2017 kl. 18.22.25 UTC+1 skrev rickman:

lasercut sheets glued together? four layers should do it to make an end cap with a groove for an oring

Lasse Langwadt Christensen wrote on 11/3/2017 3:33 PM:

That's not a bad idea, but why four layers? One layer for the bulk covering the entire area and one layer to define the groove.

I am finding the Seeed studio web site to not be very clear. In the Fusion section under "More" they have a link for CNC machining. That page is a form to fill in for an estimate price. The instructions filling in the form are sparse like the rest of the web site. But I eventually figured out that the "Material grand/ID" is the letter code for the material type, in this case acrylic.

Doesn't matter much, no matter what else I fill in once I select Plastic Cutting Processing the cost goes to >=$300. I thought these guys could produce affordable prototypes?

I'm trying to build a clear plastic case that will consist of a round piece of tubing approximately 4 to 5 inches in diameter with a pair of plates to cap the ends. One plate will have a glued connection to the tube. The other plate is a removable lid which will need a groove cut in it to mount an O-ring to form a seal with the tube. The tube can be bought cut to length or I can get Seeed to cut it. But I am having trouble getting the plates made at a reasonable cost. Any suggestions?

Den fredag den 3. november 2017 kl. 20.47.21 UTC+1 skrev rickman:

one to cover the end, one to get the oring below any chamfer on the pipe edge, one to fit inside the oring, and one to hold the oring

Right I agree with all of that. just was thinking that Rick's $300 minimum is a reasonable number for setup. one costs $300, ten-$30 and 100 for $3 each*, It's similar with pcbs.

George H.

Use a stack of profile cut (2d) layers instead of a machined piece, weld flat surfaces with acetone: 2d cutting is cheap.

Use off-the-shelf plumbing parts?

Lasse Langwadt Christensen wrote on 11/3/2017 5:19 PM:

Yes, I see what you are doing. Here is what I was thinking.

I suppose my approach has a problem in that the o-ring can be over tightened, but it uses less material although your approach can use thinner material as it all stacks up. The over tightening can be prevented by adding spacer strips to the outside of the tube or it can be part of the assembly inside the tube.

I found a manufacturer's web site and o-ring usage is not at all simple. It requires pretty tight specs. Also, I don't see anyone recommending a configuration like I am thinking. Your configuration is called the "piston" configuration as the ring is supported by the rod. The degree of compression is determined by the dimensions of the parts rather than the degree of tightening by the user. My approach would have space for extrusion which would need to be tightly controlled. But then... I'm not looking for high pressure containment. I think I can be a bit lax as long as I prevent the user from crushing the o-ring.

I found plexi domes on ebay and aliexpress. I was thinking they weren't so cheap, but they are starting to look pretty good now. I can get one that is six inches in diameter which will remove nearly all dimensional constraints on the design. I just don't like the look of the dome, but for a first pass it will be fine. I'll still need a seal where the dome mounts to the baseplate, but that will be much simpler I think. I can use a simple rubber gasket.

What plumbing parts???? It needs to be clear.

rickman prodded the keyboard with:

Sounds like a simple turning job !

That arrangement will need a fair bit of force on the end cap to maintain the o ring seal.

Try it with the O ring sealing on its side.

The O ring cap would be:

End layer circle O ring layer - just slightly bigger than the O ring ID O ring retainer - just slightly smaller than the O ring OD

Once pushed into the housing it only needs a small force to retain it in place and the seal is better.

If the clear plastic requirement is just for the solar cell, there are plenty of IP rated rectangular polycarbonate enclosures with clear lids available.