Seating knobs closer to enclosure

[armdnrdy]

I made a little discovery yesterday while working on a present for a friend.

Now most of us already go through the trouble of cutting down the pot shafts so that the knobs aren't sticking ten feet off of the face of the enclosure. I found something else that can be done to get even closer.

I was working with the Davies 1510 clone knobs from Tayda. I cut down the shafts, fitted a knob, and the clearance was still too high. It turns out that the knob hole was bottoming out on the threaded bushing keeping the knob from riding low to the enclosure face.

The fix:
I used a Lenex VB11 step drill bit by hand to "carve" out a 1/8" cavity that would clear the bushing. I believe that I took it down to the second step of the bit. Make sure you back off the set screw on the knob before creating the cavity.

I was able to get a good, clean looking 1/8" clearance from the bottom of the knob to the face of the enclosure.

[rousejeremy]

I HATE dealing with longer pot shafts. I will try your trick out though.
In the past I used different size knobs with the different shaft lengths with good results aesthetically.

[amptramp]

There is a rather simple way of getting pot shaft lengths right.  Start with a solid-shaft pot that has a longer shaft than necessary - the longer, the better.  Hold the pot in a drill press chuck and wrap tape around the shaft at the cut length.  Spin the pot shaft (and of course, the entire pot) at the lowest speed on the drill press.  Hold a hacksaw at the tape mark (the mark can be over or under the cut line) and push it in.  You will probably get a conical cut, but that is OK for most knobs.  I did this with a couple of 4 inch pot shafts and they turned (no pun intended) out perfectly.

[John Lyons]

Two things I'll do here.
Drill out the knob if possible. A lot of times you can get another bit of depth from the knob.
I do this with one knob type I use a LOT.

Use an internal tooth lock washer between the pot and the inside of the box. This locks the
pot down well and shortens the threaded bushing on the top of the box.
For tiny knobs I'll cut down the shaft if I'm trying to fit in a knob in a small space to the lowest
profile.

[armdnrdy]

Use an internal tooth lock washer between the pot and the inside of the box. This locks the
pot down well and shortens the threaded bushing on the top of the box.

I've used these as well. I purchased a few standard size lock washers from a US hardware store chain.
That reminds me....I should source some washers that actually fit the pot shafts. It looks like about 7mm inside dimension.

Does anyone know what size internal tooth lock washer fits an Alpha 16mm  pot bushing off hand?

[Unlikekurt]

I too am sort of obsessed with getting the knob very close to the enclosure.  I generally use a nut on the inside of enclosure AND cut down the pot shaft on the outside in order to get the length appropriate.  With many of my builds I also then encounter an issue where the pot nut on the outside of the enclosure is too large to fit into the recess in the bottom of the knob ( i generally use 24mm PEC pots with 3/8 inch bushings, so the nut is much larger than that of the alpha pots).  What I do in these cases is rather extreme, but I fixture the nut onto a lathe and very gently and gradually take down the angles until it will be able to fit into the recess of the knob.  Trick is to get it so it's not so round it can no longer be tightened.  I then use two guitar picks, one on each side of the knob, as standoffs when screwing the setscrew in; this maintains a minimal height off the enclosure so nothing ends up rubbing.

[seedlings]

I aspire to one day have one of the most frustrating build problems to be knobs too far from the enclosure!    What a fantastic problem to be concerned with, when you think about it.  See, I'm still stuck in the learning phase.  If I get something working on the very fourth try, then I could care less what the knobs look like.

But, that's not entirely honest... I do look at the knobs and wish they were lower.  Then I cut one too short, or break off half of the split shaft, which brings me right back to enjoying the tone.

Great ideas though - I have a stepped bit, and will be employing that tip.

CHAD

[GGBB]

Does anyone know what size internal tooth lock washer fits an Alpha 16mm  pot bushing off hand?

Taiwan Alpha 16mm are M7 washers which have an inner diameter of 7.1mm.  I've looked for M7 lock washers nearly everywhere and they are virtually non-existent.  It seems that commercially available metric sizes are typically even numbered (M6, M8, ...) with the odd numbers being specialized.  There isn't even a close fitting SAE alternative as far as I could find.

http://www.taiwanalpha.com.tw/english/p_e_78-1.htm

[armdnrdy]

Thanks for the info Gord.

I found M7 internal lock washers here:

http://www.fastenermart.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=H&Product_Code=MWS113-3612&Product_Count=&Category_Code=

Low minimum order $15.00......no handling fee.....but ships UPS which can be a bit pricy!

I can't remember if Aron allows group buys.  

I think I'll look around on the site to see if they have metal (stainless, nickel) top washers for footswitches.

[estch71]

I'm a bit rough on the pots.  I used a bolt cutter a few times to snip off the excess and then used a file to level the top of the the shaft.

[davent]

I use 5/16" SS internal toothed washers that were sourced at McMaster-Carr. In metric they have M6 & M8 but not the M7.

Regarding the original picture, does the mismatch in size between the splined shaft and set-screw knob not skew the knob off kilter so it rubs against the top of the enclosure while turning if mounted so close to the top? (My big issue with those pots.)

dave

[armdnrdy]

There is a couple of "fixes" for that issue in this thread in case you missed it.

http://www.diystompboxes.com/smfforum/index.php?topic=103750.0

Tayda is starting to stock solid shaft Alpha pots for 50 cents.....so our troubles (wobbles) are almost over.

[davent]

Yup, did post in that one... have never been at all satisfied with any of the fixes so just stick with the solid shafts from Small Bear which i have a pile of for now, by the time i need more Tayda will hopefully have an expanded selection of values.

Thanks
dave

[John Lyons]

Dave. I've found 5/16 to be too sloppy (big) on Alpha 16mm pots.
On 24mm they are just right though.

I've searched high and low for the right internal toothed washers
and I've settled on 1/4" washers that have been split (by me of course).
Just take a washer and split it with a pair of angle cutters (NOT your wire strippers!)
Make sure it splits all the way (it will click) and it will tightly slide over the pot threads.
This works perfectly for me and 1/4" internal toothed washers are everywhere.
I usually get them for 5 cents each in 500 or more quantity.

[GGBB]

Dave. I've found 5/16 to be too sloppy (big) on Alpha 16mm pots.
On 24mm they are just right though.

I've searched high and low for the right internal toothed washers
and I've settled on 1/4" washers that have been split (by me of course).
Just take a washer and split it with a pair of angle cutters (NOT your wire strippers!)
Make sure it splits all the way (it will click) and it will tightly slide over the pot threads.
This works perfectly for me and 1/4" internal toothed washers are everywhere.
I usually get them for 5 cents each in 500 or more quantity.

Great idea!  Thanks John.

[duck_arse]

never the same pot twice, coupled with never the same knob twice, means I do every knob-job (?) custom.

I've got a date with a hacksaw and a splined shaft tomorrow, just to fit a 1965 vintage plastic sato knob. it has a metal insert around the top.

the hardware-store washers I can ever get are something like mudguard washers, massive thick buggers, never like the thin ones we want and like.

[tubegeek]

and I've settled on 1/4" washers that have been split (by me of course).
Just take a washer and split it with a pair of angle cutters (NOT your wire strippers!)

oh snap!

Nice! Thanks!

[davent]

Hi John, Thanks for the tip on splitting the washers, forever finding washer ever so slightly too small for the bushing i need them to go over, this will come in very handy.

The 5/16" washer are definitely a sloppy fit on the 16mm Alphas however i've found that the shoulder at the base of the bushing is sufficient that no matter how off-centre the washer is relative to the shaft, all teeth are engaged with the shoulder so you get proper bite and the pot is flat to the washer/enclosure, nothing coc­keyed.

The issue i am finding sometimes when using them is there isn't enough thread coming through the enclosure for the nut to grab onto,( i haven't tried flattening the washer some but that might work.) As a result have been using the tabs more often, drill from the inside just deep enough that the drillbit taper is passed and the straight of the bit is into the enclosure, then stop drilling (drillpress depth stop) before marring the top of the enclosure, never break though.  Have to grind the tab down a bit to get the pot to sit flat, all about compromises and adapting.

dave