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Looking for someone who can burn an .008dia hole in a .025dia gage pin.

mark lavengood

Plastic
Joined
Feb 2, 2023
I'm looking for a vendor in or near northern Michigan, who can burn or drill an .008-.009 inch dia hole in an .025 inch dia gage pin. The gage pin will be 1in long and the hole needs to be 1/4in deep.
small quantity, just a few dozen parts.
Thanks!
 
Hi mark lavengood:
The depth to diameter ratio is going to kill you on this job.
If you have a thou per side overburn, your trode is now 0.005" to 0.006" depending on whether you intend to orbit to final size or not.
That is small enough that you will really struggle to find a trode with a flushing hole through it, and even if you could find a trode like that, good luck getting it to run dead nuts concentric without discharge dressing it first, and good luck forcing dielectric oil through it without a high pressure pump on your sinker.
The smallest tube trodes I can find with a quick search are 0.2mm so you'd need to discharge dress them down to 0.005"-0.006".

That's a 50:1 LD ratio...I very much doubt you can drop that down a quarter inch without internal flushing.
Certainly not on MY sinker.

Having said that, with a linear motor sinker like a Sodick, you might get away with it using a tungsten wire as your trode and jump flushing it but I wouldn't hold my breath.
Anyone who wants to try would be well advised to charge this job cost plus and expect the cost part to be steep just for the try...no guarantees.

I recently ran a job I posted on here that was a hair tearing experience and the features were a LOT bigger:


I only had to go through 0.200" of material.

So your project is a BIG ask, and I doubt any sinker EDM shop is going to view it as routine.

But who knows...there may be someone out there who sees this as easy...I'm not that guy and I do a fair amount of small stuff on my machine.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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Specialty work indeed.

I did some .022" holes earlier this year and thought that was tiny!

Try Stark Industrial in Ohio. No affiliation just offering a suggestion.
 
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Maybe try talking to the people who make coolant through drills and have them make this for you. They use powder metal and bake it around a preformed hole. Then they would just grind the OD to size. You could probably even finish the ID with a wire at that point if you had to.

I've drilled 1mm holes at over 50x aspect ratio using long drills, but I think .008" would be much harder to do.
 
I'll bet I could have done it in my Roders RFM600 mill. 42K RPM Mikron Crazydrill .0087 dia. Would be an expensive job though, those drills ain't cheap! Too bad I got rid of the machine last year or I'd give it a shot for you.
 
You might look at this outfit located in Western Maryland, Natl Jet Co, inc, that has quite the reputation for making small holes.

 
Maybe as Marcus said pump flush. Reverse polarity and attach workpiece to head so you get some gravity assistance. I also agree with cost plus it's going to be crazy difficult.

OT
I watched an episode of The professionals on NHK the Japanese network where they attempted to put a hole down the centre of a clutch pencil lead. One guy used his manual lathe and the other guy used a EDM. Lathe guy got it done. Obviously not applicable here.
 
I tried this once. 1mm brass with a hole flushing was more a dribble than a flow but it kind of worked. Problem was electrode burned fast so needed a pretty long length to go any depth it was difficult to get it centered without bending. This more see if it can be done job I would never try it for a customer. Maybe a hole popper would work better?
Bob
 
Hi bob:
A hole popper has some advantages but also some drawbacks:
It has high pressure flushing...that is good.
It relies on a ceramic guide bushing to keep the electrode running concentrically...that is normally good, but in this instance, it is bad.
I say so, because you need a custom size of electrode...the smallest stock tube electrode I can find commercially available is 0.2 mm.
That's just a twitch too big to allow overburn, so even though the trode is within the size range of the desired hole, the burned hole will end up oversized.

So the way to bring skinny electrodes like this to size is to discharge dress them...for those unfamiliar with the term, basically you burn them to correct diameter by bringing them close to a copper tungsten discharge dressing block and rotating them...burning them to size and concentricity with reverse polarity, so the sparks preferentially erode the electrode and not the block.
Now they're too small for the guide bushing and will rattle around in the bushing.

All this screwing around also demands control of the spark gap and the machine motion that hole poppers do not typically have...they are good for start holes and fluid passages, but not for an application like this one...you need a high end sinker EDM like a Makino EDAF series sinker, and a lot of patience to tune the process until it gives you what you want, consistently.

The OP wants "just a few dozen parts"
IMO, making even just ONE is a major undertaking at this scale...the budget for these is going to have to be huge to make it worthwhile to do all the fucking about necessary to get the process to work reliably enough to make those few dozen parts.

Gauge pins are also harder than a woodpeckers lips...probably 65RC or so.
That means that drilling them with a carbide drill is also a fair challenge.
It's a bit of a shit sandwich IMO no matter how you propose to tackle it...you couldn't GIVE me a job like this unless I had lots of time available to play until I got it right.
At the rate I charge, the OP would have to be made of money and not afraid to give a good chunk of it to me.
(But I don't have the equipment anyway, to pull this off)

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
You could look at the process used for making hypodermic needles, they drill a blank say 1” di with a 1/2” hole, fit a brass bar inside then draw the blank down to size and dissolve the brass out with acid.
 
Micro EDM. In Michigan another place offering such service.

Who ever suggest a coolant thru drill thanks for the laugh
 
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.250 deep and .001 total tolerance. Ouch.
Kiss the laser goodbye.
EDM is going to be watching the corn grow and the price for this time.
Micro drilling is not fun also.
You have a mess. Do you have many hundreds of dollars for this one simple hole?
 
Hi bob:
A hole popper has some advantages but also some drawbacks:
It has high pressure flushing...that is good.
It relies on a ceramic guide bushing to keep the electrode running concentrically...that is normally good, but in this instance, it is bad.
I say so, because you need a custom size of electrode...the smallest stock tube electrode I can find commercially available is 0.2 mm.
That's just a twitch too big to allow overburn, so even though the trode is within the size range of the desired hole, the burned hole will end up oversized.

So the way to bring skinny electrodes like this to size is to discharge dress them...for those unfamiliar with the term, basically you burn them to correct diameter by bringing them close to a copper tungsten discharge dressing block and rotating them...burning them to size and concentricity with reverse polarity, so the sparks preferentially erode the electrode and not the block.
Now they're too small for the guide bushing and will rattle around in the bushing.

All this screwing around also demands control of the spark gap and the machine motion that hole poppers do not typically have...they are good for start holes and fluid passages, but not for an application like this one...you need a high end sinker EDM like a Makino EDAF series sinker, and a lot of patience to tune the process until it gives you what you want, consistently.

The OP wants "just a few dozen parts"
IMO, making even just ONE is a major undertaking at this scale...the budget for these is going to have to be huge to make it worthwhile to do all the fucking about necessary to get the process to work reliably enough to make those few dozen parts.

Gauge pins are also harder than a woodpeckers lips...probably 65RC or so.
That means that drilling them with a carbide drill is also a fair challenge.
It's a bit of a shit sandwich IMO no matter how you propose to tackle it...you couldn't GIVE me a job like this unless I had lots of time available to play until I got it right.
At the rate I charge, the OP would have to be made of money and not afraid to give a good chunk of it to me.
(But I don't have the equipment anyway, to pull this off)

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

I think we've discussed EDM hole drilling a few times in the past. A lot of the 'Hole Poppers' use ceramic or carbide guides, that is correct. The companies that do a LOT of holes though, tend to not bother with those and just make the guides out of steel. Some of the guides we made used a piece of surgical tubing (stainless steel) in between 2 halves and the tubing was a replaceable part. You could unload the tool, take off the cover, replace all of the tubes and have the tool checked and back in the machine before you needed it for the next part. The other nice part about surgical steel tube guides is you can swage them to whatever size you want.

I think the bigger problem is a company with a nicer fast hole driller (or rows of them), won't ever want to stop a machine to setup a short run job like this.
 








 
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