Screw sizes on vintage tweeters (and where to buy them)?

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plastic_avatar
plastic_avatar Posts: 690
edited June 2022 in Vintage Speakers
I need to find the right size screws to order for my 3D printed Wuhan tweeter plate upgrade.

The stock screws that attached the magnet housing to the faceplate are a few mm too short (the face is a little thicker than stock because of the design and material used).

I am astonishingly ignorant of trying to figure out what size screw these are and where to order =(

It looks like the thread size is 4mm or 5/32 of an inch (if I measured correctly).

The length, from tip to cap is about 6.some-change-mm. BUT is length calculated by thread area or total length of screw?

Closest things I could find are:

4-mm 0.7 x 8-mm Phillips-Drive Machine Screws (12-Count) https://www.lowes.com/pd/Hillman-4mm-0-7-x-8mm-Phillips-Drive-Machine-Screws-12-Count/999994862

But!

I don't know how deep I can/should go into the magnet housing, and I really want a flat screw head (and hex if I can find it).

Am I on the right track? You guys have a better source than Lowes? Thoughts?

(I decided to model these, since routing the plates to fit is actually harder for me, to see if it would be a viable option. Draft plates are in leftover white filament and rough around the edges. Actual plates will be black and better quality.)

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The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • Gardenstater
    Gardenstater Posts: 4,186
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    You measure the pitch with your calipers bridging peak to peak on as many threads as you can and then divide that number by the number of complete threads and that gives you the single thread dimension. TPI (for english) = 1/single thread dimension. For metric they go by single thread dimension. Then take that number and look it up in screw dimensions charts, both metric and inch sizes. Do the same with the major diameter and you can figure out if it is metric or english and what size it is.

    The screw length is the total length for Flat Head Screws and for all others it is the length under the head.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
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  • Tony M
    Tony M Posts: 11,017
    edited June 2022
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    I bought my too long screws from Lowe's the first time. :o
    I bought the screws and they were just a smidgen too long and I popped the glue seal and smack! :s

    The pole and magnet kissed.

    I see you want to use countersink screw heads. I'll go out now and get my bag that the ones I used came in. I'll get the info and post it here in a minute.

    I'm sure all my screw experiences are in that thread on the Wuhan domes.

    So you're saying you want flat head screws for these plates? I'm going to read the above post thoroughly right now. Looks like countersink it is. :)

    WWW.AmericanintegratedSupply.com
    https://www.ebay.com/str/americanintegratedsupply?_trksid=p2047675.m3561.l2563

    American Integrated Supply
    4250 Grand River Ave.
    Detroit MI. 48208-2719

    I ordered 100 of the 8/32-1/4" button socket cap.
    I think these are the ones I used for the final fitting of the Wuhan's since these were ORDERED.

    I guess I knew these were the ones after previous experiments from buying the below ones from Lowe's.


    I also have 3 snack bags marked by me at;

    2...8/32 -3/16 button socket cap..........................one bag has Silver, the other Black screws.
    1...8/32 -5/16...countersink...hex head...Silver screws.

    I guess these were bought at Lowe's and were tried before, plus some are the ones (Black ones) taken out of the original SL2000's too.
    The LONGER 5/16" countersink screw was probably the length that popped the plate from the magnet. >:)

    I see your threads are apparently different and my screws might have nothing in common.

    But the Co. should have any size and make screw you will need. ;)
    Post edited by Tony M on
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • Gardenstater
    Gardenstater Posts: 4,186
    edited June 2022
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    It doesn't look to me like your magnet screw locations are countersunk. You will have to do that on a drill press to match your screw heads. You cannot really determine what screw lengths you need until you have done that. As Tony points out, you need to make sure they are a tad shorter than necessary, when they are fully torqued and your plastic material may compress? But you would measure untorqued extension below your plate and measure maximum penetration into the magnet assy. and determine from there.

    I hope your material is rigid enough that it works out for you, but it might not work out to be an improvement. :(
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • plastic_avatar
    plastic_avatar Posts: 690
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    Tony:

    Ha!

    I dunno if our screws are different. The 8/32 should be the plate-to-cabinet screws on mine.

    Garden:

    I want flathead, flat overhang. The countersunk heads were just what I found at Lowe's.

    I thought it would be easy to find the size screw Polk used, then order a slightly longer one (maybe with a flat head) from [insert diy PartsExpress or Lowe's equivalent here]. But no [laughs]...

    3D-printed Material

    I experimented a lot with this plastic and wall strength/rigidity for my other project; different wall thicknesses, fill patterns, layer heights... I think I can print a plate that'll work, that bridges the gap I need between chop's gorgeous end-game metal plates and modding existing plates.

    And you guys just gave me an idea to make the plate flush with extra strength! Damn, v5 is on my plate for tonight now =)
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • Gardenstater
    Gardenstater Posts: 4,186
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    "I want flathead, flat overhang. The countersunk heads were just what I found at Lowe's."

    I think you are saying a screw that doesn't seat in a countersunk, conical shaped seat (82deg english, 90deg metric)? That's not a flathead. I guess you are talking about socket head (or torx preferably) buttonhead screws. I got mine on eBay.

    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • Gardenstater
    Gardenstater Posts: 4,186
    edited June 2022
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    M4x0.7 and #8-32 are very close in nominal diameter (0.1575" vs 0.164") but the other way you can find out which you have is by measuring the thread pitch. The metric would be about 36.3 tpi equivalent and of course the english is 32 tpi.

    #8-36 is a fine threaded screw and does exist but I'll be darned if I've ever come across it being used in my *travels*.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • plastic_avatar
    plastic_avatar Posts: 690
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    Right.

    Flathead connected to flatheaded engine in my brain, not screw(driver). Sorry. I did say I was screw uneducated ;)

    You think ordering a torx screw that's listed as 4mm or 5/32 in diameter and about 8mm long (since the stock is a little over 6) is what I need to find?
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • Gardenstater
    Gardenstater Posts: 4,186
    edited June 2022
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    Do you have a dial or digital caliper? That's the tool you need to do everything I said above, short of buying a couple M4x0.7 and #8-32 and finding which is the correct thread size and then trying different lengths by trial and error. As Tony said, error can be costly though.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • xschop
    xschop Posts: 4,702
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    Double check SL2000 Hack thread. IIRC all SL2OOOs were 8-32's. RDOs were metric.
    Don't take experimental gene therapies from known eugenicists.
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  • VR3
    VR3 Posts: 28,040
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    What 3d printer you using
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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  • plastic_avatar
    plastic_avatar Posts: 690
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    VR3 wrote: »
    What 3d printer you using

    Just ye olde Ender 3 Pro.

    I just got it... 2 months ago?

    Crash course.

    Bought a second used one, but can't get it to print worth a damn =( So, at least I have parts for the second one =P

    On the screws:

    I see where I need new glasses...

    I kinda wasted a thread on it, but I still need to get some the right length, and all this helped me rediscover some obvious things.

    Long Rona and brain fog is a thing.
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • plastic_avatar
    plastic_avatar Posts: 690
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    Of course, some places say 'overall length' and some say 'thread length', but some list head and thread length separately but don't say whether the length listed is overall or thread... and I'm not sure if either is accurate =[

    - The little ones I have are 4.25 to 4.5 in thread length, with an overall length of about 6.25mm. So, pretty much 1/4 inch overall.

    - The depth to the plate/seal inside the magnet housing at the bottom of the screw holes is about 2.5 to 3mm.

    - Tony, I'm guessing a 5/16, if measured in total length, will get me what I need at a total mm of right under 8. The added thickness of the face should keep me at least 1mm away from the seal.

    Now to wait a week on delivery to see if I'm right =\
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • Gardenstater
    Gardenstater Posts: 4,186
    edited June 2022
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    If they are too long you can use a cutoff wheel in a rotary tool to cut them without making burrs usually. Screw a couple nuts on before cutting and clamp in vice. Then when you unscrew the first nut it will expose any burrs so you can nick them away with the cutoff wheel before removing the last nut.

    Length given never includes the head unless it is a flat head or oval head. It is understood that it is the minimum material thickness you can use it on without it extending on the other side.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • plastic_avatar
    plastic_avatar Posts: 690
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    BAH!

    Sites and their words!

    I ordered the 1/4 version just now, too.

    If it's just threaded length, that will work.

    I hates having extra screws, but I also hate cutting things down.

    Lame, I know.
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • plastic_avatar
    plastic_avatar Posts: 690
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    I think the 1/4 will be the size I need.

    Plate draft #8:

    3upidyl7lyev.jpeg
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • Tony M
    Tony M Posts: 11,017
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    How long does it take to "print" a face plate?
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • plastic_avatar
    plastic_avatar Posts: 690
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    Tony M wrote: »
    How long does it take to "print" a face plate?

    I think 3.5 hours at the .16mm setting on my Ender 3 Pro at default settings.

    Sorry took so long to answer!

    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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  • Tony M
    Tony M Posts: 11,017
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    That's ok. I'm a very patient man. ;)

    I'm not looking to buy a plastic printer asap.

    I think they're cool as can be and a modern marvel too.

    I've seen some very nice printed chess pieces sets I wouldn't mind owning.
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • plastic_avatar
    plastic_avatar Posts: 690
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    Tony M wrote: »
    That's ok. I'm a very patient man. ;)

    As well you must be, for plastic printing is a'waitin game, see?

    And I need to reprint mah plates!

    The coating didn't dry smooth =(

    I never thought I'd buy a 3D printer, but I had a need, and it's a damned marvel.

    Between my big project and the plates, money well spent =)

    Anker has a Kickstarter'd model due out in the Fall. Looks amazing. Expensive, but cuts out the shadetree mechanic'ing of the others.

    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * Ye Olde college stereo in the garage
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