New idea for rocker-pot assembly! Critique?

[H4T]

I've been trying to think up ways of making a pot assembly for a manual rocker wah for quite some time (as I'm sure some of you know, lol). Here's a little idea I came up with after stumbling upon something similar at GeoFex; using the shafts of two pots as the axis of a rocker....obviously the pots will each be housed in a sturdy box, with the shaft come out, so the the axis is sturdy.

I'm a little concerned about the strength of the shafts; I hope that the weight load will not be enough to snap the things before you can use it...just don't stand on the pedal, use your ankle to move it but don't stomp it, a seperate stomp box will be used for on/off.

Let me know what you think, and any problems you could see.



Obviously this assembly would really simplify the implementation of a wah pedal that doubles as an expression pedal, as well as the ability to select between two seperate sweep ranges!

[ninoman123]

Good idea and I have one to add on.

Instead of just leaving the shafts of the pot to support 100% of the weight of your foot, why dont you add some brackets or something underneath the shaft this would take some pressure off of the shaft and help distribute the weight of your foot. You could have a bracket with either a U or an O shape opening at the top then slide the shaft through that. One bracket on either side of the rocker and youve got it. Maybe some of our resident MEs could chime in.

[NaBo]

Nice work H4T!  Sorry to let a bit of the wind outta your sails... but someone beat you to it!  But still, you should feel pretty awesome to come up with it on your own.

I'm pretty sure the file detailing this type of project SOMEWHERE on geofex... but i cant find it.  I do however have the pdf saved locally... I'll email it if you want?  If you'd rather press on with your own genius, thats cool too, definitely understand :wink:

[ninoman123]

Post it NaBo. I would like to see it.

[petemoore]

On a two lug pot wiring, for a wah, I used a larger pot, ran the axis rod of the treadle 'hinge' out the side a bit, then, just used a neoprene hose section [short] to connect to the pot !!!
 Full sweep was had with a very small treadle range, I increased that by using a pot R Value reducing resistor [I just paralleled another pot till I liked it and then installed a fixed resistor in it's place]. Very Easy and quite reliable and 'ugly'. The ugly could have a box made to go over it [of course the pot is on an L bracket and on top of the box beside the pedal.
 Another way I've had good results is with a tape player or VCR's belt, a short belt drives the pot 'knob' [a drilled dowel rod...tricky], and that was relatively easy and works good. I carry a spare belt, but the belts are holding up really well so far, they are the thick 'square' kind...there's a little lag time as the spring of the short belt adjusts the pot, but on the phaser speed control this is more acceptable than on a wah`.
 I've pulled potshafts out just snipping extra length or prying knobs up, metal pots might stand it, I never risked the build and pots to find out.

[H4T]

@NaBo - I am hoping you are talking about the PDF I will link to below. If so, that is actually where I got the idea from. My idea reduces the work-load (of filing the pot shafts and such) as well as minimalizes the complexity of the rocker on the whole, hopefully lol.

@ninoman123 - this may be the what he was referring to, hopefully.

http://www.geofex.com/Article_Folders/wahrocker/wahrocker.pdf


I thought a little more and decided to reverse the pots, so that both shafts can be connected as ONE axle, and therefore supported better with the U shaped brackets proposed by ninoman123. Here's an updated picture of what I'm talking about. The striped bars would be simple blocks with a U shaped divot in the top that will cradle the common axle. The blue part you see is simply a sturdy metal covering that will slide of both pot shafts, connecting them as one.

As always, let me know what you think!

[ninoman123]

Excellent. Making the two shafts into one is a very good idea.  But there are still a few kinks. How will you get the pots and the shaft mounted together? You have to get the two pots mounted with the nuts and then somehow figure out how to get that axle connector in there.  You are probably better at mechanical stuff than me. I just cant think like that lol. But I'm sure there is a way.  Just keep the pots easily accessable for tweak/repairability.

[petemoore]

Looks to me like precision alignment of the shafts and shaft 'blocktops' would be paramount to the build.
 How about...put the pots BTB from the inside, shafts pointing out, under a wide enough pedal to run neoprene stress isolation tubes from each pot to the treadle axle.
 An A/B switch could control whether the 'right phase speed pot' or the 'left wah sweep pot' is in circuit at 'that' time....assign whatever parameter controller you want to right or left..perhaps both controlling a dual wah?
 If using analog taper pots of course one of them will be reversed taper...diddling with pot tapers could remedy this, use a linear on one side or something.

[Mark Hammer]

This is an interesting idea in principle, but I question the lifespan of the pots under this sort of stress.  They aren't really made to take on the sort of strain that a foot can directly apply.

At the very least, you'll want to use ultra-heavy duty pots.

[NaBo]

Ahh, yeah, sorry H4T!  I missed that sentence in your first post... silly me... carry on.  You're still awesome for thinking for yourself

Like Mark just said, you'll have to put some heavy thought into the pots you use.  For instance, the ones I use normally are from a local store in toronto, and they have a bit of MECHANICAL resistance as you turn them... whereas some heftier pots I ordered from Weber speakers have a smooth-as-butter travel.  You'll have to consider this because you want the pot to be "sticky" enough that the weight of the rocker piece (it has quite a bit of levrage due to where it's mounted) will not allow it to start er... "wilting"... when your foot's not on it :wink:.  But of course you wanna be able to get a quick enough sweep, and forcing a stickier pot would probably mess up the penolic wafer pretty quick...  Just fair warning- I'm sure you'll know you've found a good pair when it "feels" right.

[gez]

Without gearing you're going to need a flexible ankle!

[The Tone God]

The idea is not new. It was though of a long time ago and also discounted long ago.

1. All that shock from stomping and rocking is going directly into the pot and its mechnism. Pots are not very strong mechnically so I would look at a very limited life cycle.

2. Limited range. Pots typically have 318 degrees of sweep. A rocker pedal has maybe 60 degrees. You loose alot of range. How would you over come this ? Hmmm...maybe thats why they use a gear in rocker pedals.

3. Pot's rotational force required vary. What this means is some pots are stiff and some loose making adjusting the stiffness of the pedal impossible.

4. How do you plan on attaching the pot shaft to the pedal ? Set screws ? Threading ? Clamp ? Glue ? All offer poor reliabilty.

This is yet another case of if there was an easier way the industry would have already thought of it and be using it at this point.

Andrew

[H4T]

@gez - lol could be...which in turn would develop a unique technique, yay for uniquity lol.

@Mark & NaBo - in the first post the pots would definately have quite a bit of stress, but in the updated version, I believe there should be little to no stress on the pot shafts.

See, the treadle is connected to the blue axle shaft, which is held up / supported by the striped U shaped supports. If you took the pot shafts out, you'll still have the axle held up by the U shaped supports. So, most, if not all the weight will be placed upon the common axle, which in turn goes into the supports and the pedal as a whole. The pots just slide into the axle and spin with it, but they won't have to take any of the pressure.

I was thinking about the tapering last night and yeah, one will have to be reverse taper if you wanted two common sweeps, and I'll probably experiment with them both being log pots, to help increase the range a bit. But I think it would be really awesome to have both pots be different taper (I mean, no reverse taper, both standard log). This way, as the treadle turns, one pot's resistance increases, and the other decreases the same amount.

If you put a DPDT switch into your circuit to switch between the two pots, you can have a forward sweep OR a backwards sweep for fun, maybe even both if you wire them in parallel and/or actually knew what you were doing, lol.

@ToneGod - I can only answer #4, lol. The faded red areas of the diagrams are simple housing boxes in which the pot would sit in. Drill a hole in the side and the shaft would come out of a small box. Other than that, yeah, you win lol.

[NaBo]

well you've answered number 1 and 4... i'll try 2 and 3

I've heard several reports that just using a higher value pot will take care of the limited travel problem.

Pot stiffness, as I mentioned in my previous post is a little hit or miss... a matter of selection...  (and who knows how it might change over time and use) ... UNLESS...  you can devise a little adjustable "brake pad" of some sort.  I'm thinking of those little rolling rubber cylinders you see on exercise bikes for some reason

Naturally we cant expect a project like this to be as reliable or sturdy as a commercial wah... but it certainly makes the pedal a little less intimidating for the average diy-er.

[petemoore]

Still it's a fair amount of 'mechanicing', worth testing it I suppose..I'll opt for something I predict will  certainly be sturdier than necessary.

[H4T]

Maybe, but the idea was to make it a little easier to do, and less 'mechanized' than the file I got the inspiration from

http://www.geofex.com/Article_Folders/wahrocker/wahrocker.pdf

I was trying to make this easier to build, it seemed pretty complicated. But it does solve the problem that this construction idea does, and that is the sweep range...the PDF file shows how you can get much more range than this idea would have, so it'd probably be best to build that one, rather than mine. Oh well, worth a shot lol.

[C Bradley]

:idea: Related idea:

I'll be putting my opamp wah into a 4" drain cap. If I mount the pot vertical directly in the middle of the housing and put a 4" round plate on the pot for the knob, I've got a foot controller that I can spin or "scratch" like a turn-table for my wah effect!  :twisted:  I can mount small wooden blocks on the top of the box and under the plate for stops so that the pot isn't twisted too far, and also to adjust the sweep.

If the box is heavy enough, the DPDT switch for true bypass can be mounted on the side of the box; kick it with your toe and then step on the turntable. :wink:

:idea:  :!: You could mount the box sideways on a stand of some sort and have the switch on the top and the roller knob on the side! Just roll your foot forward or back on the knob.

EDIT: here's something I came up with last night (well, actually early this morning... :roll: )

http://img.photobucket.com/albums/v253/bluestrat28056/wah_controller.bmp

It's a pot with a long shaft mounted sideways just below the top surface of the enclosure. A wheel is attached to the shaft with a set screw. The two pieces of aluminum angle are there to secure the pot and provide support. I'm going to use wood for the wheel and mount stops on it so that the pot doesn't get over rotated and it doesn't go past the sweet spots. :wink:

[wui223]

I still cant get a suitable rocker,  i plan to make one like Marc did. He made 2 cool wah pedal from scratch