Early 80's Dumble Screw?

[amplifiednation]

Here's a long shot..

I'm doing a cab for a gentlemen in CA who has an early 80's ODS. He has long threaded screws that are starting to strip and asked if I could help identify them in order to buy new ones.

Here's a picture. I don't see how this is much different than a normal thread, maybe something more fine than a 32 count? I'm not sure, I also haven't seen many threaded screws with the point.

Any ideas?

Sorry I know this isn't as interesting as Gil's photos, but it's Dumble history nonetheless!!!!!

T

[M Fowler]

I just use the Fender pointed long chassis bolts #8 keep nut on it.

Mark

http://www.tubesandmore.com/products/P-H264-4

[mhartman]

The screw itself looks a bit like a Fender chassis screw, but the head looks different. Good luck!

[Max]

Here's a picture.

Is the owner of this 80ies ODS sure that both - the screw and the black plastic washer - are original? I ask, because judging by this picture the black plastic washer seems to be one for a countersunk head but the screw doesn't seem to be one with a countersunk head?

Cheers,

Max

[amplifiednation]

Max,
I didn't even notice that. I have an email to the owner to see what that washer is all about.

[Max]

early 80's ODS

AFAIR you'll meet (at least) three different versions of female screws in early eighties transition generation and 4th generation ODS amps. AFAIR the first version is exactly the same one as the one you'll meet in a 2nd generation chassis like #0040 e.g. The second version is the one documented in Gregor's pictures of #0094 e.g. The third version is the one documented in Gil's pictures of #0124. I've attached three pictures. So "early 80's ODS" might be not specified sufficiently to know exactly what kind of screw may be needed for an restoration in accord with the original specs or the original look (if this should be what the owner asks for).
picture source: http://www.roblivesey.com/dumble/ and https://tubeamparchive.com/viewtopic.ph ... 688#214688

Cheers,

Max

[ToneMerc]

Any ideas?

T

A thread pitch guage could at least identify the thread pattern.

TM

[vibratoking]

Interesting that you got 6 replies so far about a screw. Oh yeah, it's a Dumble screw. I thought a Dumble screw occured when you sent in your money and never recieved your amp?

[ToneMerc]

Screwed is right....how do you ruin a screw to that degree and when does one realize hmmm, I think something is the wrong here.

If you have a machine shop close by, stop by and offer someone a cold beverage of there choice to guage the screw threads. I'm assuming the other 3 holes are cut the same.


TM

[John_P_WI]

As an "old timer" in my machining experience etc here is a simple rule to follow: To find out if it is a #8, #10 or other # screw here is the general formula to find the outer diameter in inch based machine screws:

0.060+ (0.013 x #) So for a #10 screw we would have:

0.060 + (0.013 x 10)

or

0.060 + 0.130 = 0.190 inch OD of the threads.

Yes, a thread gauge helps, and if you know the general diameter and can identify IF you have an #8 or #10 screw you can easily count the threads in 1/4, 1/2, or 1 inch lengths and multiply by 4, 2, or 1 to figure out how many threads per inch there are. Look online for a thread tapping chart and you will see the combinations of OD and threads for the various size screws and it should be easy to cross reference.

BTW, IF you knew the exact line spacing of the paper in the pic you could generate a good guess.

[amplifiednation]

Well here is another thing I wasn't expecting. In the original Dumble cabinet, this screw not only passed through the chassis like a Fender chassis screw, but it actually passed through the chassis rail as well!

My first thoughts was the owner was looking for the thread count, but now I'm thinking it was set up so differently that he was nervous about setting it up the same way in a replacement cabinet.

[andyhardy]

I think we need the schematic

[amplifiednation]

I think we need the schematic

Ha, oh believe me, I've been pressing for pics. i don't have any info on the chassis...

To answer Max's question, that is a countersunk black washer...so i have no clue if it was original, the owner says it is, but I'm sure he got it second hand.

[brentm]

Wow, looks like it was cross threaded and force was used. Or the black paint that was used on the bolts accumulated and caused it to bind up. I wonder what the receiving threads look like on the chassis.

Once you figure out the thread count, I'd think you could find a suitable replacement at McMaster Carr.... Maybe just paint the top black instead of the whole screw.

[Max]

that is a countersunk black washer...so i have no clue if it was original, the owner says it is, but I'm sure he got it second hand.

If the pictured black plastic washer is original – and this is IMO possible - and at least the length of the pictured screw is more or less correct, too,
then the chassis of this original ODS will probably have the early fastening system of a 2nd generation ODS e. g. (see the picture of #0040 in my previous post).
Then AFAIR the four original screws might have been:

countersunk / flat head / slotted / N 10-24 UNC / 4" / steel / zinc plated.

Cheers,

Max