Screws for 2470 Rear Cap

[blvdre]

I have a pair of 2470's in need of rear cap screws. It's an 8/32 x 1.5" screw, but the catch is, it has a tiny head (in order to fit into the recess). I tried calling JBL parts, but they no longer carry this oddball screw. I checked McMaster Carr until my eyes were bloodshot, but couldn't find what I was looking for (that doesn't mean it's not there though, their amount of screw stock is overwhelming). I even bought some hex head equivalents, but the head's a bit too big (not sure how successful grinding down the heads would be, doesn't sound like fun). Any suggestions?

[Mr. Widget]

The correct screw type is a fillister screw. Are you sure they are 8/32s and not 10/32s? Here are some fillisters, but no 8/32s:

http://www.fastener-express.com/index.asp?PageAction=VIEWCATS&Category=231

If you can't find them, you can turn the heads down on a lathe or drill out the back cap to take slightly larger screw heads.

If you are lucky, maybe someone here will have some extra screws?


Widget

[toddalin]

I have a pair of 2470's in need of rear cap screws. It's an 8/32 x 1.5" screw, but the catch is, it has a tiny head (in order to fit into the recess). I tried calling JBL parts, but they no longer carry this oddball screw. I checked McMaster Carr until my eyes were bloodshot, but couldn't find what I was looking for (that doesn't mean it's not there though, their amount of screw stock is overwhelming). I even bought some hex head equivalents, but the head's a bit too big (not sure how successful grinding down the heads would be, doesn't sound like fun). Any suggestions?

I was faced with EXACTLY the same problem the other day. I bought a 2420 off the 'bay and two screws were missing.

While we do have a specialty hardware store in the area that may have had these, I took a slightly different approach.

I used #8-32 x 1-1/2" "Cap Screw Sockets" that use an Allen key. These fit fine.

http://www.fastenermart.com/Merchant2/graphics/prod/S025300.gif

Mine are from Home Depot and stainless steel and are non-magnetic.

[Mr. Widget]

I even bought some hex head equivalents, but the head's a bit too big...
I used #8-32 x 1-1/2" "Cap Screw Sockets" that use an Allen key. These fit fine.

http://www.fastenermart.com/Merchant2/graphics/prod/S025300.gif

Mine are from Home Depot and stainless steel and are non-magnetic.Maybe the brand of allen cap screws that Home Despot uses have slightly smaller heads?


Widget

[blvdre]

I was faced with EXACTLY the same problem the other day. I bought a 2420 off the 'bay and two screws were missing.

While we do have a specialty hardware store in the area that may have had these, I took a slightly different approach.

I used #8-32 x 1-1/2" "Cap Screw Sockets" that use an Allen key. These fit fine.

http://www.fastenermart.com/Merchant2/graphics/prod/S025300.gif

Mine are from Home Depot and stainless steel and are non-magnetic.

Toddalin, that's what I bought from the hardware store the other day (we just call them hex heads), but found the head was too big for the tiny cap hole, just by a bit, though.

Thanks Widget, I can get some 8/32 x 1.5" stainless through McMaster, $8.75 for a pack of 50. If they work out, I'll offer up the extras, if anyone's interested.

I suppose if worse comes to worst, I can get one of the machine shop guys to modify the hex heads.

[toddalin]

Maybe the brand of allen cap screws that Home Despot uses have slightly smaller heads?


Widget

Mine are from Crown Bolt Inc. in stainless and fit the 2420 perfectly. They come in 2-packs so two packs replaced all four screws.

[blvdre]

Yeah, I don't doubt that head size varies between the different manufacturers. I'll have to take a trip out to the depot.

I also had one screw that wouldn't tension, so I'm going to run a tap through the threads to clean things up. Hopefully that will do the trick. On the plus side, the diaphragms appear to be in good shape. I blew out the screen/phase plug and the gaps, and cleaned out the gaps using post it note paper (masking tape makes me nervous). The dampener pads were rotten, so I'm going to make a close facsimile; at work we have some sticky back open cell foam pads (a bit thinner than the JBL) I can cut them to shape, add a felt backing and adhere them in place with double sided tape. I hope that will do.

[toddalin]

Yeah, I don't doubt that head size varies between the different manufacturers. I'll have to take a trip out to the depot.

I also had one screw that wouldn't tension, so I'm going to run a tap through the threads to clean things up. Hopefully that will do the trick. On the plus side, the diaphragms appear to be in good shape. I blew out the screen/phase plug and the gaps, and cleaned out the gaps using post it note paper (masking tape makes me nervous). The dampener pads were rotten, so I'm going to make a close facsimile; at work we have some sticky back open cell foam pads (a bit thinner than the JBL) I can cut them to shape, add a felt backing and adhere them in place with double sided tape. I hope that will do.

Also, perhaps the stainless screws have a slightly different head than the ferrous screws.

The bags have a UPC Code # 30699 71288 and note CAP SCREW SOCKET, #8-32 x 1-1/2", STAINLESS STEEL, AS-J / 31-J / 411

BTW, I was trying to get new JBL foams for my drivers and:

JBL never answered their phones and Harmon International never answered their e-mail. :(

[blvdre]

Thanks for the codes, I'll make a note of them. I did get the stainless hex heads, but depot's are probably from a different manufacturer.

Be persistent with the phone - I let it ring to the point of being annoying. Honestly, it must have rung about 20 times befor someone answered. I wouldn't usually do something like that, but I'd been trying to get through for days. I also went the e-mail route. My guess is that they're busy over there. No one I spoke with sounded too happy.

[subwoof]

I used longer than required fillister head screws and clamped ( the soon to be cut off ) end in a small drill and ran it against the vertical belt sander. This prevented flat spots and was very quick.

And yes nearly every driver's threads need to be cleaned out with a bottom tap and Qtip. Be sure to lube them well as it is raw iron.

Be careful with stainless as it is VERY soft and if it breaks off, a pain to remove.

sub

[blvdre]

Yes, it's always a good idea to lubricate the tap.

I like your idea for thinning the head, I may give that a go.

[SMKSoundPro]

Yes, that is the way. I have a 1" wide bench top Rockwell belt sander that gets a lot of use.

I replaced my 2470 screws that were chewed up and filled with wax bits with a pair of hex head cap screws and was able to chuck the screw into a drill motor and apply the rotating hex head against the belt sander to make a poor man's machine lathe. All worked fine!

That little bench sander gets alot of use!!!

[Woofer]

You can also just use a hand power/cordless drill and a hand file.
Secure the screw in the chuck, and place it against the file on a bench while pressing the trigger and before you know it, you'll have a nice smoothly turned head to whatever dimension you want.
:)

[blvdre]

That would work as well.

Hoping to reduce the "grind time" as much as possible, I went with the dual power tool solution (plus I get to use two power tools at one time). I installed a grinding wheel in my dremel, then secured the dremel in a vise. Since my screws were to length, I wrapped the threads in painters tape, and secured it in my hand drill chuck, taking care to go easy on the tension so as not to muck up the threads. Fired up the dremel and drill, and ground away. Worked like a charm, and now I have hex head screws instead of philips. It was difficult getting a #2 screwdriver in that tiny hole, but a hex driver has no problem at all. Thanks to all for your suggestions.