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Not shopping today so

Initial startup with the cover on it indicated some interference. The rivets I put on the first gear were too long. So I ground the tails down and tried again.

At this point it's down to the finer things. I still want to get a pedal to control the speed, as it's a bit awkward taking your hands off the work to dial in the movement. Once I find that and get it jacked in I'll probably clean up the cover, make a little box over the power cord lugs and such, maybe paint it black.

OK so I've been using the bead roller and it works much better with the reinforcement and motor drive. But I started this whole thing trying to get a foot pedal control, and I'm not quitting until I have that.

With Gordon's help we determined that my pot is a 100k ohm model, not 50k like the sewing machine pedals. With no good way to know for sure what the commercially available cheap pedals were, I decided to make one. My first idea was to get a little gear and rack from McMaster Carr and rig that to turn my existing pot, relocated into a foot pedal housing of my own design.

But Gordon pointed out that 100k slide pots are easy to get, so I bought one of those thinking the housing and linkage would be easier.

It came the other day.

Tested good:

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I drew a + on the zero side ("this end down") and rooted about for a little metal box to put it in that will work with the EMPI gas pedal I bought for the Spyder and then didn't use.

Scrap bucket yielded treasure, as always.

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Slotted it with the grinder.

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Folded a little piece of .050 aluminum over the plastic slider to make it more rugged.

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Snipped another piece into the rough shape of a c-shaped pushrod.

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And that's all for now. I need to make a solid mount inside the box for the pot. There are little threaded screw holes in each end but I've no idea what screws fit it (tried eyeglass screws; too small). I'll probably use epoxy and some plastic bits to make a surround for it and snap it in place.

Ridiculous all around, I know.

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With no good idea what screws this little pot wants, I decided to make a bracket to hold it in place and use available (larger) fasteners to attach it to the pedal box.

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I grabbed a bit of sheet steel and wrapped it around an old number stamp that's close to the size of the switch. The fold is to space the switch out from the edge of the box and center it in the slot.

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I'll solder pigtails to the pot and then dab a little silicone or Liquid Nails on it to hold it in the bracket.

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Yeah, tiny is part of the problem.

The smaller the mass of the thing you're soldering, the quicker it heats up and the hotter it gets. So, almost as soon as the solder flows, the delicate bits attached to the lug get all incandescent on you, which is generally a bad thing.

A clip of fat metal of some kind between the lug and the delicate innards will (in theory) absorb the heat before it gets to the innards. And yeah, finding somewhere to attach the clip can be a creative challenge.

This is why they make those anemic little 7-watt soldering irons for electronics applications - they give you more time between solder starting to flow and total meltdown.

Maybe you've found the reason why normal people don't try to build a foot switch for the bead roller they build when they're fabricating a hard tonneau cover for their replica 550 Spyders.

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Here's a photo of a store-bought soldering heat sink clip being used to prevent the frying of a delicate electronic thing as the leads are soldered to connecting wires.

The heat sink goes between where the heat is coming from and the thing you're trying to protect.

This clip is marginally better than a plain ole alligator clip because it has (in theory) a little more contact area in its jaw than the alligator clip, but I think they sell them mostly to engineers who want to believe all that theory they paid a lot to study in engineering school.



SolderHeatSink

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I've soldered stuff since forever. Hemostats work really well for heat sinks. Bonus: they're stainless steel so rosin core lead solder doesn't stick.

Soldering tips: ONLY use rosin core electronic solder. Don't try to use plumbing solder and/or acid flux. NO NO NO on that.

I usually pre-tin wires, especially stranded. It cuts down the heating time before solder flows by a bunch. Less time heating is less heat-soak, and less chance of burning up semi-conductors.

Hemostats are your friend. And you can use them for other things, if you're so inclined.

Wait....

We're just ordinary folks!   (Most of us, anyway.)

Opus and friends

Lane is right, though...........    

Danny, too - Hemostats are your friends.  They even sell 'em in that big, red, tool vendor truck at Carlisle.  "Bill the Cat" uses them to hold his tongue out.

BTW, Leon had a typo in his post - The proper solder for ANY electronics is rosin core, not resin core (Damn you Spellcheck!).  The slight bit of rosin makes the solder lead stick to ferrous metals.  

The solder used for plumbing is Acid Core, which will attack the ferrous metals and quickly give you a poor electrical connection.

Bill the Cat knows this.  You should, too.

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Last edited by Gordon Nichols

All of the engineers I know (real or self-taught) seem to have three particular talents:  They keep an extensive junk box of spare parts (not to mention that they never throw anything away.....ever), the vision that things can go together for a purpose originally unintended and the ever-expanding skills to make that happen.  

Ed is the epitome of all of those.   Well done, sir!

back-to-the-future

Oh......   And there's a lot of perseverance in there, too!

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Last edited by Gordon Nichols

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