Need help making a 2 part housing (loft? derived?)

benj_fitzpatrick

I am trying to make a housing for a temperature readout (Omega CN32PT) and would like to have it split in half front to back to make it easy for setting up the power and T probe connections at the back of the readout (eventually this will be fabricated on a 3D printer). The front has a recess for the display and the back has a power entry module and an opening for the temperature probe (RTD). I used a loft to create parts that can hopefully mate, but the loft curves which is not ideal.

I would like to have these mate up with some means for screwing them together that does not stick out horribly. What thoughts do you have for how to create a better mate between the two parts?

nick_papageorge_dayjob

Is this what you want to enclose?

https://www.ebay.com/itm/374432590552?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=OHp8breNTem&sssrc=2349624&ssuid=5oWsg52nQJW&var=&widget_ver=artemis&media=COPY

Have you considered a clamshell design? That’s usually how electronics are enclosed, especially something as long as this. You could have a half-lap joint around the perimeter on the parting line. On the back side, you could have the parting line on the mid line of the connectors. Or, have a separate piece as a back panel for the connectors to pop through. 

benj_fitzpatrick

@nick_papageorge073, yup that is the temperature readout. The power feeds in on the top terminal block and the RTD would need to come through the case somewhere in the back third and wires into the bottom terminal block. The latter is small, only about 2 mm in diameter, so it is pretty easy just to feed through via a hole.

https://www.omega.com/en-us/temperature-measurement/temperature-wire-sensors/p/HSRTD

Here is a link to the power entry module:

https://www.newark.com/schurter/dd12-1111-111/power-entry-module-male-1a/dp/48M7021?gclid=EAIaIQobChMI1sKd7rbM_QIVG_3jBx19eQvYEAQYASABEgJQTfD_BwE&mckv=_dc|pcrid||plid||kword||match||slid||product|48M7021|pgrid||ptaid||&CMP=KNC-GUSA-GEN-PMAX-LOW-ROAS-Shopping

I did not go for a clamshell design b/c I figured the front display section and power entry module at the back would make it hard to close. Thoughts?

benj_fitzpatrick

For reference, here is my initial design. The CN32PT feeds in through the front (the rubber gaskets behind the display provide a rather snug fit in the front pocket) and the PEM screws into the back. My 2nd generation is meant to address one of the serious weak points b/c I have to remove the CN32PT every time I change T probes b/c the terminal block on the bottom is inaccessible. Hence my desire to have a design breaking it into front and back pieces.

nick_papageorge_dayjob

I'd probably make it like this, although there are a million way to skin a cat;)





https://cad.onshape.com/documents/1cb6823e7f9cd5a4abab5faa/v/b071110563b323ab063b8511/e/8b342e137c2a629dc11c85b5?explodedView=MmxDspVvE1k6gH09H&renderMode=0&rightPanel=explodedViewPanel&uiState=6408fdd9ba1cc50600d025c5

A few things of note:
-Clamshell design (means a bottom and a top, separated roughly in the middle). Most common design for injection molding an electronic enclosure.
-A half lap around the perimeter. Keeps the halves aligned.
-Omega electronics part represented as a rectangle. The box is built around it parametrically.
-Ribs to support the omega part (I did not see any screw holes in it on the pictures, but if there are, I'd probably use those instead).
-Ribs have .5mm of clearance to the part. You would fine tune their clearance in the CAD to get the right fit. In injection molding this is very important as you can't move the box walls once the mold is made, but you can make the ribs taller. In printing, you could alternatively just make the box bigger or smaller each print.
-The sides of the box are wider than the omega. This allows room to put 4 screw bosses. The head of the screw would be on the bottom, and the screw would thread into the top. (bosses not modeled).
-Openings in the front and the back for the LED, the PEM, and access to get to the screw for the wire.

nick_papageorge_personal

Edit: duplicate post.

nick_papageorge_dayjob

For your orignal question, here is one option from something similar I 3d printed a while back. Note the detents. One on each side:






You could also put a screw in instead of a detent (in the same direction as the detent). That will keep the design pretty on the outside. A snap finger could also work. I guess it depends how frequently you would want to access the internals.

benj_fitzpatrick

Thank you both, these are great ideas! I definitely like the idea of being able to access the power and T probe far more easily. Most of the time there is little need to change out the T probes, but it's always handy to have the capability. I'll let you know if I have any further questions after working through the above ideas.