I recently bought a "parts" SMT microscope for my new Electrical Engineering Workbench. This microscope has structural damage on a ~1/2" hinge feature at the rear of the scope where it attaches to the arm. The company (Vision Engineering) designed this scope so the hinge is part of the plastic housing of the scope - 1/2 of hinge is on left and the other is on right housing. I searched google images to try and find an example picture of the hinge; but they must know it has issues or no one has ever needed to take a picture of it. Emails with the local sales rep as only resulted in "you should send the scope in for service"... which when asked for a "ball park" repair cost... I got no response. I suspect the repair would probably cost near the amount of a new scope which defeats the purpose of buying a "for parts" scope to begin with.

I'll snap a picture tomorrow after work... after the latest JBWeld has cured.

I went thru a rather extensive "rebuild" of the hinge using some JBweld I had in the drawer. I basically re-enforced it by filling the hinge with JB weld and some #4-40 bolts to provide a clamping force. The repair worked ok for about 3-4weeks of very light usage; but came apart during use tonight. The jbweld basically didn't bond well to the hinge's plastic and couldn't handle the stress of the hinge (my guess). I've re-jbwelded the hinge tonight but honestly don't expect it to hold up very well for long.

I'd like to solicit the wisdom of my Pinball buddies ... to see what they might suggest as a rebuild advice.

At this point; JBWeld has failed me... mainly because it doesn't do a very good job of bonding the to plastic housing which I assume is made out of ABS or similar. Some people swear by JBWeld; but I haven't had a lot of success with it.

The only item turned up was a youtube video which seems to recommend 3M's EC2216 Epoxy... but that appears to be specific to the carbon fiber application.

I think some of the key limiting factors of this specific "application" are as follows:

1. Scope/Housing cannot be disassembled. No service manual exists; to returning the optics to proper alignment would likely be an issue.

2. Adhesive may need to bond to plastic housing
3. Epoxy should be flexible while maintaining strength to plastic bond.
4. May need to have fibers to aid in strength of hinge; ideally perpendicular to the hinge "crack".

My current thought was to try and do a carbon fiber re-enforcement type job on the hinge. Maybe cut some deep groves into the hinge and fill those groves with some fiber reinforced epoxy. But alas, I can't seem to find such a beast during a quick search on amazon or google. I could make a carbon fiber epoxy by mixing it into a 2 part epoxy; but wanted to see what real-world advice could be shared by our community.

Good info so far. I like the dryer sheet + epoxy idea.
Last night I ordered some 3M EC2216 Epoxy and some fiberglass sheet for two day delivery.
I should have it on Wed.

I still plan on grabbing some pictures tonight.

Thing is I don't know what type of Plastic the housing is made out of. I assume it's ABS; but its just that... an assumption.
I'll look into some AC77 to see how it works. Would be nice to get a small sample bottle for a reasonable cost somewhere.

Here's a picture of the hinge after an overnight JBWeld cure:
complete hinge - these two features hold all the weigth
P_20180611_192355 (resized).jpg
Basically; the hinge supports most of the weight of the scope head on this hinge.

The two "top" screws are my addition in order to aid in clamp force during the first repair. The #4-40 screws mate with some blind #4-40 nuts on the inside of the main hinge feature. The nuts are basically JBWelded to the plastic just below the crack which is now hidden by JBWeld.

?When?/IF the weld breaks again; I'll take some better pictures of the internal repair attempt.

I don't have an exploded BOM or diagram. I asked the sales rep for one so I could identify the parts I needed... and he responded that they don't have anything like that. :screw loose:

So; based upon my examination early on... as far as I can figure; the entire head is a single injected molded piece in two halves. IE and left and a right half. The hinge is part of that piece. It doesn't look like you can remove the hinge; 1/2 of it is on the right... the other half on the left.
To make matters worse; the lenses/optics appear to be either taped or screwed to the halves. My fear is that once it comes apart; it won't go back together properly without a major re-alignment.

That's what I sorta did with #4-40 screws. I stopped short of going into the void behind the parabolic mirror for several reasons.
1) I don't want to risk damaging that mirror.
2) I don't want to risk adding dust to the scope by drilling thru the housings.

I was thinking along the same lines.
I think when this JBWeld breaks... notice I said when. I'm going to try and do several different things.
1) Using a dremel; remove all traces of jbweld from the current repair.
2) Use AC77 or AC79 as suggested by terryb above to prime the plastic for epoxies.
3) Use 3M EC2216 Epoxy to repair the hinge structurally.
4) then use Fiberglass weave with 3M EC2216 to create a reinforced structure around the hinge.

JBWeld is strong; but I think I need flexible in this application. I think the JBWeld is "shattering" instead of flexing and it's also separating from the plastic of the housing. Hopefully the Primer will help the new flexible epoxy to adhere to the housing plastic.

Best I can do until it breaks again

1528851924394-1642079149 (resized).jpg

This is the arm I bought.
ebay.com link: itm
If you look at the listing; the third picture shows the arm's "mating" side.
Hinge w/o Head

Basically in my picture; the philips head screw is a screw I picked up at Lowes to resolve the missing screw. The philips screw basically provide a gravity hinge point to the curved part the head hinge. The bottom "stock" bolt secures the head to the arm. When both screws are installed; the plastic hinge is "secure" in the arm.

An interesting idea. Hopefully it won't get that complicated. I feel like changing to the new epoxy with primer will probably get me close enough.