How to make a "D" hole?

[Kevin54]

1/4" od x maybe 1/2" deep?

First off, what do you mean a 1/4" diameter? Are you meaning 1/4" wide, or 1/4" tall? If you mean 1/4" tall, then the width of the "D" will only be 1/8". If you want the "D" 1/4" wide, then the height will be 1/2". And that is if you are using a full radius taking in consideration the height of the "D". As far as a diameter, you will only have a radius on one side.

Now if you can give either the width or the height, then I can tell you what diameter of drill to use, then you can either order a broach to take out the rest, or else file it in to size.

 

[ovrrdrive]

The first reply of edm is worthless since it's plastic.

I had to google EDM as I've never heard of it before but you're absolutely correct. Maybe he was referring to using a hot wire. Still not even Wire EDM but I can see where someone could get confused.

 

[Jim Johnstone]

I had to google EDM as I've never heard of it before but you're absolutely correct. Maybe he was referring to using a hot wire. Still not even Wire EDM but I can see where someone could get confused.

Fair enough, yeah i suppose a hot wire setup like they use for foam could do the trick. I'm not sure how those things would handle plastic.

I used to cut a ton of "D" holes with wire edm, and in something metal, there isn't a better process for precise holes.

 

[no704]

Needs to fit onto a 1/4" dia shaft with a flat on one side and 1/2" long.

 

[R.Anderson]

LOL!

set screw.

Your cycle testing a knob?

So why will this not work?


1/4" hole with a set screw is what bullnerd is saying and I will suggest it too.

Keep It Simple

Find a knob to modify, the size you are describing is very common for knobs for rotary switches and potentiometers.

 

[PugetDude]

Needs to fit onto a 1/4" dia shaft with a flat on one side and 1/2" long.

https://www.surplussales.com/ShaftHardware/Knobs-16.html

 

[er3456df]

Drill a 1/4" hole, then solvent weld a 2nd piece overlapping it partway?

 

[dontlifttoshift]

nvm, that won't work

 

[bobadame]

Uhmw is a thermo form plastic so you could mold it. You don't mention if it is a through hole or whether it has a flat bottom.

 

[APEowner]

I'd just machine a slot on the end of whatever coupler you have on the air cylinder that fits over the ridge on the knob.