Cutting Pot Shafts with Dremel

[swinginguitar]

I used a dremel with cutoff wheel to trim some pots shafts. worked great, but now the pot shafts are loose vertically - they wiggle up and down. It only seemed to affect the performance of 1 out of four (it would short out unless you pulled it all the way up).

Did overheating cause this? Or vibration? Is the dremel a bad idea?

[defaced]

If you held the pot and cut the shaft, you probably put strain on the wiper to shaft connection or something else inside which is causing what you're seeing.  It would be best to hold on to the part of the pot shaft you don't want so the solid aluminum shaft is taking the load, not the pots innards. 

[iccaros]

I used some high voltage cutters, slice through the shafts like butter.  Like these

[sundgist]

Quite possibly heat.
I used to cut shafts with a dremel and they would loose their stiffness and turn quite loosely. Once cooled some would regain their feel others wouldn't.

Now I just clamp the shaft in a vice and use a hacksaw. I find it a lot quicker.

We're talking about metal shafts right? Do those snips do the job?

[Mark Hammer]

I'm a vice-and-hacksaw guy too.  Thinking about it, though, I probably need to come up with some sort of "bib" or apron to fit over the pot so that the little metal bits from the sawing don't end up inside the pot.  I suppose it is as simple as a piece of aluminum foil over the pot with the shaft poking through.

[swinginguitar]

I used some high voltage cutters, slice through the shafts like butter.  Like these

Not familiar with that tool - who makes them and where to get?

I actually cut them with the dremel in a "drill press" stand accessory with the pot mounted in an enclosure. I do imagine that stresses the shaft in the direction of the wheel's rotation...probably would help to hold the shaft tight mid-rotation while cutting.

[DavenPaget]

Just see a massive one and buy them , make sure it's truly hard , while testing it , go and cut something else in the shop  

Quite possibly heat.
I used to cut shafts with a dremel and they would loose their stiffness and turn quite loosely. Once cooled some would regain their feel others wouldn't.

Now I just clamp the shaft in a vice and use a hacksaw. I find it a lot quicker.

We're talking about metal shafts right? Do those snips do the job?

They do , pot shafts aren't terribly strong

I'm a vice-and-hacksaw guy too.  Thinking about it, though, I probably need to come up with some sort of "bib" or apron to fit over the pot so that the little metal bits from the sawing don't end up inside the pot.  I suppose it is as simple as a piece of aluminum foil over the pot with the shaft poking through.

I have a vice and it's a pretty small vice , will try the hacksaw thing out 

[iccaros]

They are lineman cutters. When I used to Install high power radio relay systems we used these to cut powerlines, nails, screws.. Anything that got in the way  

they are KNIPEX 9-1/4" Insulated 1000-Volt High Leverage, Side Cutting Linesman's Pliers

edit...
these are would be better
KNIPEX 9-1/4" High Leverage, Side Cutting Linesman's Pliers

[GGBB]

I did 5 pots that way last week without any problems.  I was careful to go very slowly with barely any pressure at the highest speed (my tool is a $10 store brand so I expect it is not as fast as a real Dremel).

[DavenPaget]

I did 5 pots that way last week without any problems.  I was careful to go very slowly with barely any pressure at the highest speed (my tool is a $10 store brand so I expect it is not as fast as a real Dremel).

I'm sensing the requirements for cutting off a pot shaft is a mini cut off saw , or a tool with very low torque compared to a dremel .

[CodeMonk]

Quite possibly heat.
I used to cut shafts with a dremel and they would loose their stiffness and turn quite loosely. Once cooled some would regain their feel others wouldn't.

Now I just clamp the shaft in a vice and use a hacksaw. I find it a lot quicker.

We're talking about metal shafts right? Do those snips do the job?

I've been doing it that way for ages.
When you are without internet and Radioshack is the only nearby parts source, you get creative.

[Mark Hammer]

Probably the most important part is measuring the amount of shaft you need to leave on in order to result in the knob being an appropriate height.  Too high and they're ugly. Too low and the knob rubs against the nut.

[iccaros]

Probably the most important part is measuring the amount of shaft you need to leave on in order to result in the knob being an appropriate height.  Too high and they're ugly. Too low and the knob rubs against the nut.

[GGBB]

I did 5 pots that way last week without any problems.  I was careful to go very slowly with barely any pressure at the highest speed (my tool is a $10 store brand so I expect it is not as fast as a real Dremel).

I'm sensing the requirements for cutting off a pot shaft is a mini cut off saw , or a tool with very low torque compared to a dremel .

I just used an ordinary cutoff wheel.  It was my first time doing this so I didn't know what to expect, but it turned out to be a piece of cake - the wheel cut through quite easily.  Max speed of my unit is 35000 RPM, motor is 1.2A.  It is low torque for sure as it slows down easily.  I have no idea if Dremels have higher torque - they have nearly identical specs.  The pots did get slightly hot but not that you couldn't touch them.  The pots on my tube amp get just as hot or hotter and they don't suffer so I'm not sure a moderate amount of heat would cause the problems you had.  Physical stress is more likely a problem, but a hacksaw is likely to be even worse in that regard if you don't clamp the shaft.  Did you push hard when cutting?  The cutters idea sounds like a good approach but I'd be worried about the shaft going out of round since aluminum is rather soft.

[amptramp]

The last time I had to cut some pot shafts (about two weeks ago), I put the shaft in the chuck of my drill press (pillar drill for the English) and rotated the shaft at the lowest speed.  I held a small coping/hack saw against the shaft until the shaft was cut was thin enough to stop the drill and snap the excess shaft length off.  The advantage over putting the shaft in a vise and using a hacksaw is the cut is always even although it may be conical if the saw is held at an angle.  These were relatively hard brass shafts with chrome plating on them, so if it does that, it can handle anything.  The trick is to mark the cut location with a piece of tape.

[deadastronaut]

yep vice n mini hacksaw...shaft held in vice...i have a marker on my vice to get same cut length...then file...

[DavenPaget]

I just used an ordinary cutoff wheel.  It was my first time doing this so I didn't know what to expect, but it turned out to be a piece of cake - the wheel cut through quite easily.  Max speed of my unit is 35000 RPM, motor is 1.2A.  It is low torque for sure as it slows down easily.  I have no idea if Dremels have higher torque - they have nearly identical specs.  The pots did get slightly hot but not that you couldn't touch them.  The pots on my tube amp get just as hot or hotter and they don't suffer so I'm not sure a moderate amount of heat would cause the problems you had.  Physical stress is more likely a problem, but a hacksaw is likely to be even worse in that regard if you don't clamp the shaft.  Did you push hard when cutting?  The cutters idea sounds like a good approach but I'd be worried about the shaft going out of round since aluminum is rather soft.

If it slows down when pushed that's when it's UNLIKE a dremel .
the manufacturer is probably lying .
anyway , i had been considering buying a small cut off saw 
http://www.jethobby.com.sg/cgi-bin/ezsite/prod/manager.cgi?action=show&pid=2129&cid=135&idx=1&gid=10

[birt]

The last time I had to cut some pot shafts (about two weeks ago), I put the shaft in the chuck of my drill press (pillar drill for the English) and rotated the shaft at the lowest speed.  I held a small coping/hack saw against the shaft until the shaft was cut was thin enough to stop the drill and snap the excess shaft length off.  The advantage over putting the shaft in a vise and using a hacksaw is the cut is always even although it may be conical if the saw is held at an angle.  These were relatively hard brass shafts with chrome plating on them, so if it does that, it can handle anything.  The trick is to mark the cut location with a piece of tape.

that is a very nice idea. should be a very clean cut!

[petemoore]

  Bolt cutters don't press on my fingers as bad as my wire cutters for potshaft cutting.
    When 'shearing' like this, starting with notch-scores [most of the way around the shaft, before the 'cut through] helps move some of the aluminum to the side...Ie when the shaft gets crushed a little bit...sometimes enough 'oval-ing' of the circular shaft to make requirement to sand/file it back down to the dimension which'll fit in a brass knob sleeve insert.
   Quick, no clamping [except the bolt cutters themselves] and no filing..and no need for ''preventative-avoidance'' to keep the wiper/wafer filing-free !
 

[GGBB]

If it slows down when pushed that's when it's UNLIKE a dremel .

I wasn't aware of that.  I thought all rotary tools were low torque.