New toy arrived.

[tubegeek]

I will try at some point to model a loosely copied version of the pictured knob above just to see what happens. Would be great if there were a datasheet because then I could model a near-replica.

That would be amazing!

I don't know how far I'll get but I did get a very small start on the basics this morning. Keep in mind it's a work in progress but at least it is round.

So I guess I'm not the only dweebazoid around here who likes the ancient RCA knobs? I don't know if that makes me feel good or doubt my choice of hangouts.

[PRR]

> CA Broadcast News November 1937

THANK YOU!

More puff than geek-details. But a glimpse into the bygone times.

[tubegeek]

karbomusic:

Would you like me to try and take a side-view photo? I do have a few of these down in the basement.

[plexi12000]

wow!!!  killer.  mind if i ask what those things cost???   

[karbomusic]

karbomusic:

Would you like me to try and take a side-view photo? I do have a few of these down in the basement.

Can't hurt but if you do get a top and side.

[karbomusic]

I've been struggling with the RCA knob above but I haven't given up just yet. During the knob printing experiments I printed this little fella below, I wasn't that thrilled about it at first but then it grew on me because it has this weathered hard plastic type appearance which would go well with some designs I think...

[amptramp]

I've been struggling with the RCA knob above but I haven't given up just yet. During the knob printing experiments I printed this little fella below, I wasn't that thrilled about it at first but then it grew on me because it has this weathered hard plastic type appearance which would go well with some designs I think...

That is excellent!  There are a number of old radios that could use that exact knob.

[tubegeek]

During the knob printing experiments I printed this little fella below...

Excellent. A very nice small knob, should be perfect for stompboxes.

I'll hit the basement and take pics in a minute.

[karbomusic]

wow!!!  killer.  mind if i ask what those things cost???   

Depending on which one you get 400-3000. Mine was 1199.00 I think which is probably the best deal out there for features and overall value (It's basically a Makerbot with all the community driven upgrades and features at a better price, making it a better printer IMHO); hopefully I'll be using it for a long time. Also another "Honey Do List" item crossed off as of last night. New adjustable leg buttons for the dining room chairs that wobbled all the time:

Excellent. A very nice small knob, should be perfect for stompboxes.

Thanks, I'm going to try to print 8 of them at once soon. I just need to run a couple of tests to make sure the hole is just right for a snug fit since I don't happen to have any knurled pots. I'll get back to the RCA knobs soon, still not sure if I can pull those off. The overhang is a challenge unless I use a support structure and if I turn that feature on it's going to ruin the finish or at least add lots of labor cleaning it up post-print. Still some hope there though.

[tubegeek]

OK, well, here is a photobucket album with a few pics to take a look at. If there are any other views you need let me know. I measured the dimensions with a digital caliper too.

RCA Knobs Photobucket

If you could get anywhere close to these they'd be fantastic hardware, even if they weren't a perfect repro. So a win in any case!

I have a few larger ones too but this is the size you'd want for a stompbox, in fact, I think they would be terrific in a scaled down version also. That would give you a world premiere exclusive that might break the geekier portions of the internet!

Thank you for encouraging this mini-obsession BTW - it's not everyone that'd be so interested in 1930's knobs that they'd ask for a datasheet!

I did a little bit of Photoshopping on the side view to make the edge more contrasting, hope that helps. The original photo is there too in the album.

For the top view I placed a piece of white paper in the "waist" of the knob so you could see the profile of the nubbed top portion clearly.

FYI there is a brass insert in the bottom and a hex screw in the waist area that I didn't photograph, they are basically just like any other set-screw knob with a brass insert. The bottom has a slight depression in the middle down to the insert.

[tubegeek]

The overhang is a challenge unless I use a support structure and if I turn that feature on it's going to ruin the finish or at least add lots of labor cleaning it up post-print. Still some hope there though.

Question. (I don't know jack shit about this so forgive me if this is stupid.)

Could you print them in two sections, from the top down to the waist (printed upside down) and then from the waist down to the skirt (printed right side up? Then, how well does this material take to being glued? There would be a line deep inside the waist to clean up, but hopefully a 1/4" rod would align everything well enough while gluing to get a good result.

The only problem I see here is that the upside-down portion that includes the curved top would also overhang too due to the slight curve of the top surface.....

I realize this suggestion, too, is against the "magic" nature of the 3D printing process but it might be practical enough.

Sounds like either way there is some finishing work.

[PRR]

> FYI there is a brass insert

It might be an idea to *start* with a basic knob of high quality but too-small. Use the 3-D to fill around and above it in the RCA shape. Saves material, and gives you the brass insert (or other hole) pre-made no-sweat. I dunno if the 3-D glop will stick to cold plastic.

[karbomusic]

Question. (I don't know jack shit about this so forgive me if this is stupid.)

Could you print them in two sections, from the top down to the waist (printed upside down) and then from the waist down to the skirt (printed right side up?

That could be done, it's ABS you can glue it very well.

The only problem I see here is that the upside-down portion that includes the curved top would also overhang too due to the slight curve of the top surface.....

Right, however, I can print it with the overhang as-is and without support, it's just ugly. The ABS is still hot and there isn't enough support to keep the previous couple of layers from wiggling as the extruder is forming the current layer. This causes inconsistencies. I can probably make that better with careful tweaking of print speed, travel speed, and extruder temperature. That's where the current game and expertise lives.

Keep in mind that "in general" I can almost get away with up to a 45 degree overhang. This one is mostly problematic due to the small size of the knob, if it was larger, there would be more time for stabilization by the time the extruder makes its way back around to where it was if that makes sense.

I may try a solid print or at least a much higher infill (50-80%), that would help some but the biggest hurdle is the reduced size/travel etc. It ain't over just yet though; I may fail but don't give up that easily.

Also, I'm aware of the need for a brass insert but figured no need to cross that bridge until I had a printable knob.