I have a gadget which I would like to modify. I need to check the available space inside the box and design the additional PCB/components to fit he available space. I thought of a soft putty like substance that I could put inside and then assemble and open it and measure the resulting putty. It would need to be fairly soft so as not to damage the existing circuitry, it would need to keep its shape when removed, and it should not stick to the eixting circuit board.

Does any such substance exist, or do you have any other suggestions how to do this?

 

Here is an iterative solution:

Take a piece of cardboard that is too large in both dimensions, the keep cutting it until it just fits. The lovely wife Morticia uses this method often for fitting things to odd shaped spaces. If you cut too far, tape it back.

When you are done, you have a nice template for the pcb.

 

These telescoping gaiges may not work in this case, but they're a handy thing to know about....

If you're trying to measure the inside height of an enclosure where you have some kind of access hole through the side (hole for a switch, battery door) these gaiges are simple to use. The legs on the top of the tee telescope, and lock into place when the vertical post of the tee is twisted. Press on legs to collapse them and turn the post to lock them in place. Insert the top of the tee through the opening and rotate the tee to orient the legs the direction to be measured. Loosen the post to allow the spring loaded legs to expand, then twist to lock the measurement in place.

Then disassemble the enclosure, and measure the length of the tee with a caliper

 

Certainly a telescoping gage could work, BUT you still need a measuring device.
My advice for determining the dimensions for a circuit board are to not plan on that close of a fit, because it will be inconveniently close when the board is fully loaded with components.
There does exist a material that is used for that sort of application. The intended use is producing accurate measurements of mechanical items. Unfortunately that observation was a while back, but it would give you a realm to look into. It was silicone based, I think, and rather flexible. It may also have been used for checking dies used for producing cast parts. So it would be a dis-checking material.

 

There is the compound used in the Electrical Distribution industry called Duct-Seal, it is pliable, non-hardening and non stick.
I have used this on occasion.
The only thing is you have to be careful removing it as it remains soft so take care if needed to retain the dimension.

 

Here is an iterative solution:

Take a piece of cardboard that is too large in both dimensions, the keep cutting it until it just fits. The lovely wife Morticia uses this method often for fitting things to odd shaped spaces. If you cut too far, tape it back.

When you are done, you have a nice template for the pcb.

Nice try but it is the height I really need to know.

 

These telescoping gaiges may not work in this case, but they're a handy thing to know about....

If you're trying to measure the inside height of an enclosure where you have some kind of access hole through the side (hole for a switch, battery door) these gaiges are simple to use. The legs on the top of the tee telescope, and lock into place when the vertical post of the tee is twisted. Press on legs to collapse them and turn the post to lock them in place. Insert the top of the tee through the opening and rotate the tee to orient the legs the direction to be measured. Loosen the post to allow the spring loaded legs to expand, then twist to lock the measurement in place.

Then disassemble the enclosure, and measure the length of the tee with a caliper

The problem is that there is no access with the case closed and it is the height inside that I need to know.

 

@AlbertHall Do you need to fill the void completely? Or just one side?

 

The problem is that there is no access with the case closed and it is the height inside that I need to know.

Okay, so measure the depth of the bottom and top separately and add them. I guess I still don’t understand your problem.

Pictures would help.

 

that is what the calipers are for:


https://www.amazon.ca/EZT-Electronic-Extra-Large-Millimeter-Conversion/dp/B08BXL9BFR/ref=sr_1_25?crid=NWLI7S7TFHB7&keywords=caliper&qid=1706981371&sprefix=calipe,aps,123&sr=8-25

https://www.amazon.ca/Digital-0-150...1&psc=1&mcid=5def73ef5c4b307393175e80bf23d4fa

https://www.amazon.com/Acrux7-Caliper-Calipers-Measuring-Projects/dp/B09KV7GJK9/ref=sr_1_18?crid=34E0BW7TLSSYO&keywords=caliper+set&qid=1706981507&sprefix=caliper+set,aps,103&sr=8-18

 

The problem is that there is no access with the case closed and it is the height inside that I need to know.

Yes, as I stated in the first sentence of my reply. I still thought it worth mentioning because people may not be aware of these measuring tools.

If there's a small clear area on the board, you might use spacers like 3mm fender washers and thin double-sided tape to create a spacer. Make a guesstimate on height, tape it to the board and see if the enclosure fits together. Add or remove a washer until the enclosure fits together and measure the stack.

Once you know the distance from board to enclosure cover, you can measure the height of components to determine clearance.

 

that is what calipers are for

How does that help measure the internal height of an enclosure with no access?

 

How does that help measure the internal height of an enclosure with no access?

The trouble is we do not know what this enclosure looks like.

 

why would you have to measure insides when the box is closed?
MAKE is accessible by opening it. then measure each side (box and cover).
distance can be added and subtracted.

ever saw mechanical drawings of something? all measurements are relative to some reference (datum), one need to derive the rest.

if the goal is to see inside closed box, use X-Ray

 

I have a gadget which I would like to modify. I need to check the available space inside the box and design the additional PCB/components to fit he available space. I thought of a soft putty like substance that I could put inside and then assemble and open it and measure the resulting putty. It would need to be fairly soft so as not to damage the existing circuitry, it would need to keep its shape when removed, and it should not stick to the eixting circuit board.

Does any such substance exist, or do you have any other suggestions how to do this?

Could you please elaborate with a photograph or two?

 

that is what the calipers are for:
View attachment 314300

https://www.amazon.ca/EZT-Electronic-Extra-Large-Millimeter-Conversion/dp/B08BXL9BFR/ref=sr_1_25?crid=NWLI7S7TFHB7&keywords=caliper&qid=1706981371&sprefix=calipe,aps,123&sr=8-25

https://www.amazon.ca/Digital-0-150...1&psc=1&mcid=5def73ef5c4b307393175e80bf23d4fa

https://www.amazon.com/Acrux7-Caliper-Calipers-Measuring-Projects/dp/B09KV7GJK9/ref=sr_1_18?crid=34E0BW7TLSSYO&keywords=caliper+set&qid=1706981507&sprefix=caliper+set,aps,103&sr=8-18

Nah, that's antique:



Twenty bucks, Amazon.

 

I played and used this a LOT as a kid in England, came in very handy, doesn't dry out and is firmer, stiffer in cold temperatures:

https://en.wikipedia.org/wiki/Plasticine

 

Nah, that's antique:

please do elaborate. what is antique about digital caliper?

 

i was also thinking about playdoh but without knowing what the board and parts it would be contacting, it may contaminate...
perhaps using suitable barrier may work (kitchen foil?)

https://www.walmart.ca/en/ip/play-d...VxSytBh2vPAsJEAQYBiABEgISEvD_BwE&gclsrc=aw.ds

https://livingwellmom.com/easy-homemade-playdough-recipe/

 

please do elaborate. what is antique about digital caliper?

Not the digital, this is what I was referring, in your post: