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Where can I find screws for 99/4A console chassis?


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#1 jmazzy OFFLINE  

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Posted Tue Jan 22, 2019 4:00 PM

The chassis on both of my consoles are missing screws.  I've looked around at Home Depot and hardware stores, but I'm not finding anything exactly like the original.  I'm not a fastener expert, but these original screws seem to have an unusual dual-size coarse thread. 

 

I realize I could simply improvise with some type of similarly-sized sheet metal screw which would cut in and hold, but I'd much rather use a clean, exact match if possible.  Anyone know where I can find some?

 

 

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#2 HOME AUTOMATION OFFLINE  

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Posted Tue Jan 22, 2019 9:36 PM

Old carts! Where else?

 

 P.S. the release clips hold them closed quite well, all by themselves. :pirate:



#3 Airshack OFFLINE  

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Posted Tue Jan 22, 2019 11:07 PM

You can also consider getting an extra 99/4A for parts. They're going for as low as $9.99 on shopgoodwill.com in working order.


Edited by Airshack, Tue Jan 22, 2019 11:10 PM.


#4 ChildOfCv OFFLINE  

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Posted Wed Jan 23, 2019 12:58 AM

Perhaps it's a type B sheet metal screw?  Probably #6 or #8.

 

https://www.aircraft...?clickkey=11590



#5 cbmeeks OFFLINE  

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Posted Wed Jan 23, 2019 10:33 AM

You can also consider getting an extra 99/4A for parts. They're going for as low as $9.99 on shopgoodwill.com in working order.

 

 

I love the fact that the fleaBay scalpers haven't latched on to the TI yet.  I just bought my 7th TI-99/4A off eBay for $12 + $10.xx shipping.



#6 jmazzy OFFLINE  

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Posted Thu Jan 24, 2019 8:49 PM

Old carts! Where else?

 

 P.S. the release clips hold them closed quite well, all by themselves. :pirate:

 

You can also consider getting an extra 99/4A for parts. They're going for as low as $9.99 on shopgoodwill.com in working order.

 

Thanks.  I considered pulling screws from other equipment, but I'd prefer not to cannibalize any of my existing parts, and acquiring extra equipment for just for the screws wouldn't be worth it for me.  Besides, I don't really have the heart to cannibalize any TI equipment.  It hurts too much.

 

I'm still searching.  Slow-going, but it's a fun challenge, if nothing else.



#7 jmazzy OFFLINE  

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Posted Thu Jan 24, 2019 9:24 PM

Perhaps it's a type B sheet metal screw?  Probably #6 or #8.

 

https://www.aircraft...?clickkey=11590

 

Based on its thread type, the original chassis screws aren't conventional sheet metal screws.  My research to date revealed a few things about the original screws:

 

1)  They're what's knows as a "high low" thread.  See illustration below.  (Also, this PDF from Eisen describes the design in straightforward detail.)

 

2)   The "high low" thread design is better for low-density materials like plastic and wood because it's less likely to crack or strip those materials.  So it makes sense then that these screws fit into plastic holes in the TI console's chassis.  Seems a smart design choice by Texas Instruments.

 

3)  "High low" thread screws aren't very common in stores, except for large cement screws and anchoring screws which sometimes have a "high low" thread type, also.

 

I'm going to contact Customer Support at BoltDepot.com tomorrow.  Their website mentions they are a happy to help identify fasteners, and if they don't sell a particular fastener, they may know who does.

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#8 ChildOfCv OFFLINE  

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Posted Thu Jan 24, 2019 11:29 PM

Wow, I'd heard of type A (typical found in hardware stores and such) and type B (higher quality, denser thread pitch), but this is yet another type.  I guess there's always something new...



#9 cbmeeks OFFLINE  

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Posted Fri Jan 25, 2019 2:53 PM

If you manage to find them, I wonder if it would be worth buying a bunch and selling some batches?  Perhaps we could chip in and save on shipping.  I wouldn't mind having a few handfuls myself in case I need them.



#10 FarmerPotato OFFLINE  

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Posted Fri Jan 25, 2019 3:41 PM

Wow, I am glad to learn about these.  They look a bit like drywall screws.

 

I can find Hi-Lo and Plastite #6 and #8 online in bulk for 3-5 cents apiece. Where bulk is 10,000. Whoa.



#11 helocast OFFLINE  

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Posted Fri Jan 25, 2019 3:46 PM

If you manage to find them, I wonder if it would be worth buying a bunch and selling some batches?  Perhaps we could chip in and save on shipping.  I wouldn't mind having a few handfuls myself in case I need them.

I don't see prices for anything less than 5K/10K bulk even on fastener sites assuming a low-tensile, #6/#8 1/2 inch.

https://www.amazon.c... Forming Screws

 

These are about the best shots I can get:

 

Attached Files


Edited by helocast, Fri Jan 25, 2019 4:04 PM.


#12 Ksarul OFFLINE  

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Posted Fri Jan 25, 2019 5:12 PM

I just ordered 250 that might work. If they do, I'll pass the data on, as I don't want to lead anyone astray. . .



#13 jmazzy OFFLINE  

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Posted Fri Jan 25, 2019 8:16 PM

Yes, I was thinking the same:  I suspected other folks might need/want these screws, too, so if or when I actually found the right size, I was considering proposing some kind of group buy.  As a few of you indicated, high low screws of this approximate size seem to be sold by wholesalers who require a minimum purchase of hundreds or thousands of pieces.

 

Ksarul:  I'd be very interested to see what you receive and how well they fit.  Do you mind if I ask what the cost was for 250 pieces?  

 

I'll continue to dig around also.  BTW, I did contact BoltDepot.com today, but they don't carry high low.



#14 jmazzy OFFLINE  

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Posted Fri Jan 25, 2019 8:24 PM

I don't see prices for anything less than 5K/10K bulk even on fastener sites assuming a low-tensile, #6/#8 1/2 inch.

https://www.amazon.c... Forming Screws

 

These are about the best shots I can get:

 

 

It's been challenging for me to get good photos that indicate proper size, but yours are great shots.  Thanks for sharing them.

 

I also decided to take this a step further and bought a digital caliper on Amazon today.  Should help me to get precision measurements of the original screws.



#15 Ksarul OFFLINE  

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Posted Fri Jan 25, 2019 9:39 PM

The ones I bought were $35, including shipping. They also require a Torx bit. . .


Edited by Ksarul, Fri Jan 25, 2019 9:39 PM.


#16 jmazzy OFFLINE  

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Posted Tue Mar 5, 2019 7:19 PM

So I did substantial additional research on screw measurements and lingo.  I also finally measured the TI's original chassis screws using my new digital caliper. 

 

IMG 5876
IMG 5875
IMG 5874
 

These are my findings on the original chassis screws:

 

    -pan head, phillips, high-low thread
    -head diameter: 5.3mm (or .209” aka #4)
    -head height: 1.95mm
    -thread (major) diameter: 3mm (or 15/128” or .118” aka #5)
    -root (minor) diameter: 1.6mm
    -length: 12mm or .47” (~1/2”)

    -thread pitch (distance between adjacent threads): ~1mm
    -threads per inch (TPI):  20
 

I also found a wholesaler with a detailed fastener product website.  I called them, and the salesperson was kind enough to send me 2 dozen screws for testing.  I believe I've found a near-perfect match!  (See photo.)  Just for good measure, I've reached out to a couple of other folks to have them test these, too, but I'm about 99% sure they match just fine.

 

chassisscrew Old New comparison

 

Assuming these new screws are confirmed a match, I'm happy to share some with anyone who might need or want them.  (The cost would simply be 5 cents per screw + USPS shipping.  Note I'm not looking to make any profit here.  I'd simply like to make these easily available to other TI enthusiasts, since it was so challenging to accurately identify the size and then subsequently find a good wholesale source.)

 

To gauge interest, feel free to share your thoughts on whether you would like some and what quantities might make sense.



#17 Ksarul OFFLINE  

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Posted Tue Mar 5, 2019 8:26 PM

Those definitely look like they will fit the need. The ones I bought are a bit too thin for the purpose--but they look like they might be perfect for the three screws needed in one of the Guidry 3D-prinited cartridge cases, so my funds weren't wasted on the project.  :)

 

I could definitely use at least 100 of the right console screws though, as I never know when I'll need some of them.






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