Drilled holes too large for potentiometer mounting...

[jimladladlooklike]

Sooooo I messed up.

I drilled 8mm holes instead of 7mm for 3 of the MANY pots to be mounted to my latest project. I'm just wondering if anyone has ever done this before and whether or not it caused problems. I'd rather get another enclosure and start again if it's going to give me grief when it comes to assembly!

Thanks all

[Kevin Mitchell]

It probably won't be as bad after some primer and paint.

In the past I've messed up drilling so bad that I covered the holes with epoxy and flipped the box over. - all hidden with a thick coat of primer. Nowadays this is a total waste of time as my enclosures aren't as precious - been in the game long enough to know when to call it a loss.

The nut should cover the extra space you've drilled.
If you're using wired pots just fit them on and get them nice and even before you torque the nuts on.
If you're using right angled PCB mounted pots you don't have to worry as much since they'll already be positioned right, just make sure they don't slip too much before you torque.

[ElectricDruid]

I drilled 8mm holes instead of 7mm for 3 of the MANY pots to be mounted to my latest project.

I thought that's what the pot washers are for - covering that little gap! That's what mine always get used for, anyway!

1mm wrong should be fine. "Wrong" can be much wronger than that!

[stallik]

When I first started drilling enclosures, I deliberately opened up the holes 1mm too large. It allowed me some wiggle room to align a long row of pots. Tightened correctly, they haven't moved though I'm sure an engineer would cringe at my methodology. I'd say that you didn't screw up but weren't aware of the benefit of your design choice

Now, I prefer to drill a smaller hole (in the right place) then open it out with a reamer. I find that more accurate especially for larger footswitch and 9v holes

[Ben N]

You know those guide tabs on the pots that we always just snip off? This might be the place to use them. If there is still room for a guide hole (and it will be covered by your knobs), that might help prevent excessive play in the oversize hole.

[PRR]

> 8mm holes instead of 7mm

So 1mm?

I don't mm. I would leave a good 0.030 inch clearance though.

0.030" * 25.4mm/in = 0.762mm, which is same-as 1mm to a caveman like me.

This isn't precision race car engines. (Actually they do use 0.030" clearance, at least on rotating parts.)

[anotherjim]

There are step drills in odd mm step sizes. They seem rare but I have seen them online bundled with the usual even step ones. I don't think there are any that go in 1mm increments due to not enough meat on the cutting edge.
We have both metric & imperial sizes in the UK. I often find there's an imperial drill that's a better fit for a metric part. Digital or vernier callipers are a friend for choosing drill sizes - no need to work out any conversion math just use the jaws as a go/no-go gauge.
As to fixing undersize slop, you might find a pipe to slice a sleeve ring off. If it's undersize, cut it so it springs on like a C-clip.

[amptramp]

You might be able to cut a flat plate with the correct holes and mount it on the inside of the chassis where it doesn't show and fix it to the chassis.  At least the positioning would be right.  It would be sort of like the brass ground plane used on some Fender amplifiers where there is a right-angle section piece of brass stock with all the holes drilled and it is used as a local ground plane for pots and input jacks.

And I endorse the idea of using the pot anti-rotation tabs on any build - the stresses from hitting either end of pot rotation will unscrew a pot in no time if they are not used.

[Phend]

Don't do anything until you test mount the pot with washer and nut and knob. Tighten it up.. See a gap ?. The hole size is meaning less if when tight the pot dosn't move and there is no gap. Gotta gap ? Get bigger washer. In the shop we used to say if the clearance is over the drawing tolerance and it works leave it be.

[davent]

You know those guide tabs on the pots that we always just snip off? This might be the place to use them. If there is still room for a guide hole (and it will be covered by your knobs), that might help prevent excessive play in the oversize hole.

With the Hammond diecasts i've always used i found if you file down the anti-turn nub a bit, you don't have to drlll the hole for it all the way through the enclosure. The pot will sit flat and still be prevented from turning while tightening the outside nut.

[jimladladlooklike]

Alrighty then! I have sone options it seems. Thanks all!

[slashandburn]

Nobody mentioned lock (or anti-shake) washers yet? Maybe I've skimmed over and missed it.

I'd just put those on the underside, out of sight. Tighten the nut from the front with them all aligned in a way that meets the eye-test and forget about it.

[deadastronaut]

spider washer underneath. done.

when you tighten it up, its not going anywhere...

however as someone else said, by the time you tighten it with just a 1mm difference it will likely be ok as it is

so dont sweat .

[Phend]

Last resort,  arc welder.

[Ben N]

There are step drills in odd mm step sizes. They seem rare but I have seen them online bundled with the usual even step ones. I don't think there are any that go in 1mm increments due to not enough meat on the cutting edge.

This was a clutch find for me, and it's cheap enough to replace regularly.
https://www.aliexpress.com/item/32652016475.html?spm=a2g0o.order_list.order_list_main.15.21ef1802oZR9OX

[jimladladlooklike]

Nobody mentioned lock (or anti-shake) washers yet? Maybe I've skimmed over and missed it.

I'd just put those on the underside, out of sight. Tighten the nut from the front with them all aligned in a way that meets the eye-test and forget about it.

Nice pic slashandburn!

[anotherjim]

There are step drills in odd mm step sizes. They seem rare but I have seen them online bundled with the usual even step ones. I don't think there are any that go in 1mm increments due to not enough meat on the cutting edge.

This was a clutch find for me, and it's cheap enough to replace regularly.
https://www.aliexpress.com/item/32652016475.html?spm=a2g0o.order_list.order_list_main.15.21ef1802oZR9OX

That's brilliant. And it starts at 3mm which is the most common screw size I use. Downside is that you can't part drill the next step up to form a countersink which can be done with the ones that skip a size.

[antonis]

Downside is that you can't part drill the next step up to form a countersink which can be done with the ones that skip a size.

Also, it isn't suitable for drilling depth more than 4-5 mm (distance between 2 consecutive step sizes..)

[davent]

There are step drills in odd mm step sizes. They seem rare but I have seen them online bundled with the usual even step ones. I don't think there are any that go in 1mm increments due to not enough meat on the cutting edge.

This was a clutch find for me, and it's cheap enough to replace regularly.
https://www.aliexpress.com/item/32652016475.html?spm=a2g0o.order_list.order_list_main.15.21ef1802oZR9OX

As a new customer the website says for me cost of the bit is 'one cent' Canadian. Been ten years now that the penny has been out of circulation here. No idea if i'd get free shipping.

[FSFX]

There are step drills in odd mm step sizes. ... We have both metric & imperial sizes in the UK.

I also have both metric and imperial sizes of step drills that allow a bit more choice of size.
Stores like Lidl and Aldi in UK and Europe often sell low cost packs of step drills although they are just the metric ones.