Bogen CHB-20A Rebuild

[physics]

Hi Guys

You cannot test your setup without using real cards.

Got it, so that confirms my suspicion.

The Cambion and any setup that requires a bottom holder is not the right approach for eyeleting a card - it may be okay when setting eyelets into floppy material, but not for a card.

Most arbor presses come with a flat thick steel bed which is preferably polished so the eyelet card can slide freely on it.

I see. I had thought it might be preferable for alignment to have the single point for the eyelet to rest against with the center guide pin. However it does get fairly inconvenient trying to keep the card balanced and level on the small support block I've been using while also operating the cambion press, and I assume that is why you don't recommended it. Using the Dake press which has a table like you mention, though not polished, is much nicer.

The arbor press will definitely work better bolted to a sturdy table even though you do not have to apply high force to install eyelets.

Yeah, keeping the cambion from tipping has been getting annoying and cumbersome.

Regarding the card layout: have you seen the inside of an old Fender? The layout is designed for the parts to be used, arranged in now classic shapes that make recognising the circuitry very easy. The point is really to use the space wisely with a minimum of jumpers on the card. Generic cards with two or three rows of eyelets or turrets makes tracing and repairs much more difficult later even though it looks neat.

Noted. I suppose that means the swiss-cheese practice card will only be suitable for breadboarding throw-away stuff.

Based on your above input, it sounds like the cambion isn't going to offer much advantage over just the Dake press, despite being made for terminal swaging, and it'd be a better idea to focus on getting things working with the Dake, which does have the nice big table and doesn't require precise vertical positioning of the work to perform at it's best. Magnet chuck here we come.

Thanks for the feedback! Also for you patience, I imagine it's probably a headache on your end watching this unfold.

[physics]

I spoke too soon. What I thought were good swages with just the tools and manual tapping were not, upon closer inspection. I found a way to get a good swage, but again it involves using a center punch before applying the staking tool.

Here is one of what I thought was a good swage obtained with just the tool and swiveling it around while tapping it with a small steel block:
   

Closer observation, and pausing during the swage process to check on the eyelet progress, revealed that it's not actually flaring outwards and instead is sort of folding itself in half as depicted below.
   

I was able to get a good swage that rolled outwards, but only after I first did the swiveling motion with a 1/4" center punch to get a nice even flare before following up with the staking tool. Comparison between the center punch + 1715 (left) and only the 1715 (right) in the picture below. The stuff sticking out of the left eyelet is just some debris that got caught inside while handling, and isn't an artifact of the swaging process.
   

So, back to the drawing board it seems. Current guess is that I'm leaning the 1715 too much while swiveling it, meaning that instead of the cone contacting the edge and flaring it the circular groove is smooshing the edge inwards so that it starts rolling in on itself as seen in the drawings. This whole thing feels like when you miss a negative sign early in a physics problem, but everything else checks out so you end up chasing your tail until you find where you flipped the sign. I wonder where I dropped the sign, metaphorically, in this problem... At least I've got a good puzzle to work through.

[physics]

New idea: tighter tolerance holes.

I was playing more with hand-tapping as well as the upside-down swaging setup, both outside of a card. I know Kevin's comments above that's not representative of the actual process and can't serve as a test, I just wanted to play with the eyelets and try to gather more observations about how they deform under pressure. Anyhow, I was moving the press down in tiny increments on one particular eyelet, stopping after each increment and observing the progress of the flare then resetting the eyelet on the tool and pressing it down a little more, and this one looked like it was going fine. There was the slightest hint of a flare all around the edge of the eyelet starting to develop, no defects in sight yet. I put it back on the press, and started to apply pressure. Things went well until they didn't, and the eyelet appeared to make the smallest tiny shift to one side with the edge there rolling under. From what I could see, this was before that part of the edge had contacted the circular groove in the tool. At the same time, the eyelet also went oblong, with the wall bulging out in the spot the defect happened. That sparked an idea: what if my eyelets are doing that in the holes I've drilled?

During some of my tests with a board to install the eyelets in, when I had tried positioning the eyelets under the punch I had noticed that I could move the board around a surprising amount while the eyelet was pinned between the tool and the bottom table or support the board rested against. Also, not all of the holes I've drilled can hold eyelets without dropping them, and the ones that do aren't that secure. The drill press I'm using is second-hand and not the best to begin with, so it's conceivable that it might have a hair more runout than is desirable even though visually the holes look fine to me. Circular, pretty clean, etc. My previous holes that were hand-drilled, well all bets are off with those given the wobbly setup and my poor drill technique (to make things cut better as the bit dulled I was swiveling the drill ). Kevin mentioned the importance of properly sized holes, and that in his experience the eyelets fit snugly enough to not fall out. So, based on that and my observations testingplaying with the eyelets, I'm starting to think that a properly sized hole does two things. 1) It keeps the eyelets from moving like I observed, and 2) it helps support the walls of the eyelet so that they can't deform in mysterious ways. I still need to measure them, but I think the holes I'm drilling might be a bit too loose and so aren't supporting the eyelet and are allowing it to shift around a little. I've been using a 1/8" (3.125mm) bit, so I just put in an order for a 3mm bit, and a 2.6mm bit. I'll be able to pick them up tomorrow and play with them a little to see if 1) I get tighter holes that still fit the eyelets and 2) I get good swages. Fingers crossed!

[K O'Connor]

Hi Guys

I actually logged in here to post that fact regarding the support of the eyelet shank by the wall of the snug-fitting hole, but you beat me to it - hehe.

With a proper size hole, the eyelet is snug and does not fall out. This means the hole is the correct size and its roundness is very good.

With the eyelet pushed fully into the hole and then the card turned over so the factory roll is fully supported on the table of the arbor press, the eyelet is most likely going to form a proper roll when the staking toll is applied correctly. With the arbor press, there is no off-axis motion of the tool - alignment and light force in one motion provides the desired result.

Even without the arbor press, the correct hole tightness and roundness and a solid table surface to rest the factory roll against sets you up to make good crimps with the tool and a hammer.

The support of the eyelet shank wall is crucial to attained a proper crimp.

The bulk of hobbyists do not have an arbor press and many do not have even a cheap drill press. Anything you can do to assure that the holes are round and tight is a good thing. You really do not want to see splits in the roll you make as that means the eyelet is going to loosen over time. Of course, almost immediately you will be inserting component leads and wires then soldering the connection, which ultimately keeps things in place.

[physics]

Hi Guys

I actually logged in here to post that fact regarding the support of the eyelet shank by the wall of the snug-fitting hole, but you beat me to it - hehe.

With a proper size hole, the eyelet is snug and does not fall out. This means the hole is the correct size and its roundness is very good.

With the eyelet pushed fully into the hole and then the card turned over so the factory roll is fully supported on the table of the arbor press, the eyelet is most likely going to form a proper roll when the staking toll is applied correctly. With the arbor press, there is no off-axis motion of the tool - alignment and light force in one motion provides the desired result.

Even without the arbor press, the correct hole tightness and roundness and a solid table surface to rest the factory roll against sets you up to make good crimps with the tool and a hammer.

The support of the eyelet shank wall is crucial to attained a proper crimp.

Thanks for the confirmation! Today I got several drill bits from McMaster-Carr: 2.6mm, 3mm, 3.048mm, and 3.1mm. 3mm was too small for me to get the eyelets in without using the arbor press to shove 'em in, 3.048mm was almost there but things got hung-up near the factory roll and required the press again, 3.1mm was just right. The eyelets fit snugly enough that if the factory roll has a little asymmetry so that one edge of it touches the board before the rest of the circumference, the eyelet won't go any deeper than that since the hole leaves no room to wiggle. 3.1mm is 0.122", one thousandth of an inch larger than the eyelet shank, and 3.048mm is 0.120", one-thousandth smaller. Seems I didn't give the drill press enough credit, it's apparently precise enough for one thousandth of an inch to matter. Nice.

Anyhow, with the 3.1mm bit I drilled a bunch of holes and did some test runs installing eyelets. With the cambion the results were tantalizingly close to perfect, there were still small defects but most of the time you needed to scrutinize the roll to see that part of its circumference was folded over on itself. If I squinted I don't think I'd notice it, but still not there yet. Using the cambion, I brought the tool all the way down to the eyelet and then tried to move it with my hand, and it appears there is still some wiggle possible at that point in the tool's travel. I assume that remnant wiggle source is the cause of the issue. I also tried using the Dake arbor press while just holding the keystone tool in place over the eyelet, with predictably poor results. The magnet chuck from earlier is in the mail, which should make it possible to securely mount the keystone 1715 on the arbor press without drilling into the ram. Hopefully that's the final key to the puzzle.

I also tried hand-swaging, but still ended up with parts of the eyelet walls folding in on themselves. Maybe that'll take some practice, but I was hoping that once the hole was properly snug it'd be a cinch to get a nice roll. We'll see how things go. I'll probably end up trying again several times while I wait for the magnet chuck.

The bulk of hobbyists do not have an arbor press and many do not have even a cheap drill press. Anything you can do to assure that the holes are round and tight is a good thing. You really do not want to see splits in the roll you make as that means the eyelet is going to loosen over time. Of course, almost immediately you will be inserting component leads and wires then soldering the connection, which ultimately keeps things in place.

I've gotten lucky so far with almost no splits, just the darn walls folding inwards. I assume the results of the folded-in walls is the same as the splits, but with the added aspect of trapping solder 'n flux in the fold and possibly resulting in blow-outs?

Thanks for your input and confirmation of my guess. I think I'm one step closer now.