SCREWS for SE & SE/30 Analog Board to Metal Chassis

[JDW]

Yesterday, a viewer of my Macintosh SE & SE/30 Analog Board Recapping Walkthrough video asked me about SCREWS which affix the SE or SE/30 Analog Board to the metal chassis. It was a good question because I too have some missing.

Here is a photo of the TWO TYPES which I have seen over the years...



The silver colored trio at left look almost like MACHINE SCREWS to me, in terms of the threads. The 3 at right I see more often, and despite the lack of a pointy tip, the threads look like a SELF-TAPPING screw to me.

MEASUREMENTS:

SELF-TAPPING
Shaft Length: 9.8mm
Shaft Width: 2.8mm
Head Width: 5.4mm (Phillips)

MACHINE SCREWS
Shaft Length: 9.7mm
Shaft Width: 2.7mm
Head Width: 5.4mm (Phillips)

As shown above, both types have a locking "tooth" washer near the head.

QUESTION: Those of you who have purchased replacements for these in the past, did you choose M3 machine screws, M3 self-tapping screws, or something else? The shaft length is pretty close to 1cm, so I would assume that length would be preferred.

EDIT: Colin very kindly educated me on the proper naming. What I referred to as "self-tapping" are in fact "thread-forming" screws. Thanks, Colin!

 

[Paolo B]

It’s an interesting one, my experience is that sourcing exact spares for our beloved vintage stuff may turn really difficult. Generally speaking, it‘s a mixed bag of metric and imperial screws. At that size, hard to tell one from the other by naked eye, at least for me. So I just check and confirm directly at the shop.

 

[JDW]

It’s an interesting one, my experience is that sourcing exact spares for our beloved vintage stuff may turn really difficult. Generally speaking, it‘s a mixed bag of metric and imperial screws. At that size, hard to tell one from the other by naked eye, at least for me. So I just check and confirm directly at the shop.

Does that mean you've never purchased the screws used to affix the SE Analog Board to the metal chassis?

No doubt there must be at least one person out there who has, and I'm just curious if they went with an M3 shaft width, and then would like to know which kind of threads (as per what is shown in my photo), and then would like to know how well that screw worked, or if it didn't. Because it if is a bit too large and you use force to screw it in, then that will become the only screw you can use, going forward, in that hole. Not a problem if it is a modern screw that is easily source for a low price, but something to note nevertheless.

 

[Trash80toG4]

Don't force fit a mismatch like that. For the bolts, go with drilling and tapping for a standard thread transplant. For the black sheet metal screws, they've always bothered me, but the metal may be too thin at those points for using a bolt in like manner?

 

[This Does Not Compute]

Here's a spreadsheet with all of the fasteners I purchased for my SE/30 Reloaded build, which includes every screw in the machine. Some of them are different than the originals but all have the same thread diameter and pitch.

SE and SE/30 Hardware

docs.google.com

 

[Paolo B]

Does that mean you've never purchased the screws used to affix the SE Analog Board to the metal chassis?

No, I don’t think so. Generally speaking, I prefer preservation to restoration, so if they get rusty I de-rust and re-use them.

 

[JDW]

@This Does Not Compute
Wow! Your compiled info is what everyone needs to know! Thank you!

More specifically, you name the Analog Board to Chassis screws as being MCMASTER 92525A205, which I Googled here:

#4 x 3/8" Type B Self-Tapping Screws / Phillips / Pan Head / 18-8 Stainless Steel

#4 x 3/8" Type B Self-Tapping Screws / Phillips / Pan Head / 18-8 Stainless Steel

www.fastenersuperstore.com

Pricing of more than $200 for 5,000 is impossibly expensive but the screw specifications shown there pretty much match the caliper measurements I presented in my opening post. Meaning, they are #4 screws that have fraction-of-an-inch measurements, rather than being metric “M3” screws.

Visual inspection of the photo on that site matches my opening post photo of what I called self-tapping based on the look of the threads:

I then Googled up the McMaster 95060A320 washer, which is sanely priced at $1.64 for 100pcs:

https://www.lily-bearing.com/products/jfagaadca/

 

[This Does Not Compute]

@This Does Not Compute
Wow! Your compiled info is what everyone needs to know! Thank you!

More specifically, you name the Analog Board to Chassis screws as being MCMASTER 92525A205, which I Googled here:

#4 x 3/8" Type B Self-Tapping Screws / Phillips / Pan Head / 18-8 Stainless Steel

#4 x 3/8" Type B Self-Tapping Screws / Phillips / Pan Head / 18-8 Stainless Steel

www.fastenersuperstore.com

Pricing of more than $200 for 5,000 is impossibly expensive but the screw specifications shown there pretty much match the caliper measurements I presented in my opening post. Meaning, they are #4 screws that have fraction-of-an-inch measurements, rather than being metric “M3” screws.

McMaster-Carr is both the manufacturer and retailer. Search for that part number on this page: https://www.mcmaster.com/catalog/131/3424/92525A205

Pricing is $5.30 for qty 100. If you don't care about them being stainless, mild steel screws would be much cheaper.

Note that there's a difference between "self-tapping" and "thread-forming" screws; these are the latter. (The case screws are thread-forming as well.)