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How to make a "D" hole?

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EdT

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Your description is a little vague, but I assume you want to make a "D" hole in a piece of metal or plastic. It's not an easy thing to do. Perhaps the simplest way is to make a round hole and then fill up half of it with a piece of round stock cut in half. The separate piece can be welded, brazed, soldered, glued into the round hole and you'll have a "D" hole.
 
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no704

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Will be in plastic, likely UHMW. Bout 1/2" thick. I'll most likely just put a set screw or 2 on the d side. But it would be cool to make a D. I have heard of using a broach to do this, but can't imagine how that could stay on center?
 

bullnerd

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Hmmm..thats a good one!

1/4 dia, jigsaw might be a bit too big?

Homemade punch, Sharpen id of some 1/4 tube, smash the flat and flame harden it!

How many holes?
 

kazlx

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Missed the 1/4 diameter. I'd just drill a pilot hole and use a dremel with the drywall cone thing, basically a mini router.
 

bullnerd

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Missed the 1/4 diameter. I'd just drill a pilot hole and use a dremel with the drywall cone thing, basically a mini router.

Yeah, or make a template out of something thin and mini router it a little at a time?
 
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no704

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Wow, kind of expected abunch of answers. Guess it's a stumper.
 

MP&C

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Broach should be self-centering..


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This collet was made specifically for turning 3/4 square stock in making tooling for my Lennox Nibbler.

Picture%204814.jpg
 

oldironfarmer

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Wow !'stumprd the journal. Do I get a prize?

Ummm, no. You didn't "stump the journal" five hours. You even got some excellent answers but failed to notice.

The very first response was on target with your description: EDM

Later, when you mentioned plastic, you received the answer: Broaching

Broaching is the way to go but it is difficult to make a broach.

Depending on the plastic, you could make a few guided punches.

You failed to give the dimensions of the hole other than 1/4", so let's say the D will contain a 3/16" round hole. You drill a 3/16" hole, then machine a partial D shape, from a 13/64 round with more flat cut off than you want finished. You guide the tool through the hole and skim out part of the plastic. Then go to a 7/32, then 15/64, the 1/4 with the final shape.

You failed to say whether this mysterious hole was to be a blind hold. For a blind hole you do the same but relieve the inside of the tool to collect the waste material then manually clean out the bottom with a mini router.

Stump us with something hard.
 

dr_clyde

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If its not attached to anything, and is portable, I'd cut it on the waterjet. That's a pretty simple job, doesn't require any special broaches or anything.

The 2 waterjet shops I deal with would charge me maybe $50? I bet it would take 10 min to set up, 2 min to cut, barely even need to use garnet.
 
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oldironfarmer

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It occurred to me you are trying to make an appliance knob.

Two options: Search the internet and buy one.

Do like a lot of knob manufacturers do, drill a hole put a stub shaft into the hole with the flat on it, then press a small steel plate alongside the flat, embedding it in the plastic.
 

bullnerd

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Coping saw is a good one.

Filing UHMW kinda *****, especially a 1/2" thick small hole.

You never said how many holes? Quantity makes a huge difference in the process.

EDIT: just read Iron Farmers post. UHMW for a knob would be a bad choice IMO.
 

APEowner

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Rotary or conventional broach, water jet, press a heated pin into an undersized round bore, drill a round hole and insert a tube with a 'D' hole into it. You didn't give anywhere near enough information to get a real answer.
 
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no704

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Making an attachment for a rotary air cylinder to cycle test a knob.
 

ovrrdrive

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bend some sheet metal into the shape, heat it and burn through. Or use a rotozip and a few guides. It would be a lot easier to make the whole thing out of metal. At least with the tools I have available to me.
 

56Mark

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3D print. I make parts at work on 3D printer that should be strong enough for this. Resin material similar to ABS.
 
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no704

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:willy_nil
3D print. I make parts at work on 3D printer that should be strong enough for this. Resin material similar to ABS.

Might be the best reply yet. Have a diminsion sst and a maker bot. But want to use UHMW to not mar test samples. The first reply of edm is the best, but tring to keep procees in house.

Thanks all.
 
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