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Internal turning small dia - deep

MartinH24

Plastic
Joined
Jun 28, 2023
Hello ,
I just want to ask if anybody have any idea how to approach the internal hole on the attached pic. ?
I have no idea how can this part be made .
Material C45 .
Thank you :)
 

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Me personally I would do the id first and use a micro boring bar to finish after spotting and drilling close to finish size as I could get. A lot is going to depend on your material and your tolerances.
 
That's a horrible part to make.

I don't think anyone makes a solid bar with that LxD ratio.

Micro bars are available with enough LxD to bore the profiled section only, but you would have to ream the inner parallel bore (and achieve 0.4 on the surface...) and get a concession from the engineers to omit the undercut at the bottom.

I also don't know how you might go about inspection... CMM is about the only option and I'm not sure how much confidence I'd have on the measurements taken given the profile geometry.
 
Looks like something you would want reamer for... Also looks like something that should be in a different section.
 
Hi MartinH24:
I'd make an electrode and burn it on the sinker using the C axis to rotate the trode, and orbiting it out to make the goofy undercut at the bottom of the hole.
You obviously can't ream that undercut, and you'll fight to single point bore it at that length to diameter ratio, but it's a simple shape to burn.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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I get details like that to sinker edm often enough.
Drill the center out as large as you are comfortable to save time.

How many you making?
 
To me that part begs to be drilled to rough size and then reamed using something like a custom chamber reamer. The small flare at the deep end would still need to be bored though.
 
Hi MartinH24:
I'd make an electrode and burn it on the sinker using the C axis to rotate the trode, and orbiting it out to make the goofy undercut at the bottom of the hole.
You obviously can't ream that undercut, and you'll fight to single point bore it at that length to diameter ratio, but it's a simple shape to burn.

Cheers

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

Could you get a 0.4μm RA with the sinker?
 
That's a horrible part to make.

I don't think anyone makes a solid bar with that LxD ratio.

Micro bars are available with enough LxD to bore the profiled section only, but you would have to ream the inner parallel bore (and achieve 0.4 on the surface...) and get a concession from the engineers to omit the undercut at the bottom.

I also don't know how you might go about inspection... CMM is about the only option and I'm not sure how much confidence I'd have on the measurements taken given the profile geometry.
I would probably split one down the middle. I could at least check all the locations, angles, finish and get some radial values on the diameters.
 
If your bidding the job, the obvious answer is to walk away in the opposite direction as fast as possible.

If you have to make the part then I would drill out as close as you feel comfortable, then finish the end with a flat bottom drill, and finish with a boring bar.

Then inspection just increases the fun your going to have with this part.

Good Luck ! (your going to need it)

--------------------------------------------------

There are some local shops who make servo valves/components for aerospace hydraulics who could likely make this part in their sleep. But the other 99% of shops, not so likely.
 
Hi Gregor:
Yeah, you can but you have to accept that it's going to cook for a bit to get there.
If you vacuum flush through the trode it'll make an awfully nice part and dead nuts accurate too providing the trode is accurate, but that's easy to do and to check.
All the features turn out perfectly concentric, there are no chatter marks no gouges and no tear marks from where a reamer picked up a chip.

I know, I know...firearms chambers have been reamed forever, and this part certainly looks kinda like it could be one, but with that blind end and undercut, I'm thinking maybe a resizing die for shell casings??
Now I know absolutely nothing about hand loading, but I do know that sure ain't no chamber for a gun...there's no place for the bullet to go.
If I recall correctly, chambering reamers also have a pilot on the front that goes in the bore to center the reamer relative to the bore...you'd have to cut that pilot off and butcher the reamer.
I don't know how much they cost but I'm thinking...not cheap.

Going back to your question though, the biggest drawback of a burned finish is that it's like a fine sandblast or glass bead.
If you forced a cartridge case in there to resize it, you might never get it back out.
So even though you can hit spec with a good modern sinker, you might still create an unworkable part, but I'm just speculating...I don't know what that part actually does, and it may well be completely unrelated to firearms.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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Everything to the left of the ~44.7 says Max 30. The way I interpret that is everything to the left of ~44.7 is optional, so the bore and the far left undercut is optional. Maybe the bore is to accept a reamer pilot. The undercut?

What the heck does the tilde ~ denote? Kuzelovitost translates to conicity.
 
Everything to the left of the ~44.7 says Max 30. The way I interpret that is everything to the left of ~44.7 is optional, so the bore and the far left undercut is optional. Maybe the bore is to accept a reamer pilot. The undercut?

What the heck does the tilde ~ denote? Kuzelovitost translates to conicity.
I'm guessing the tilde means a reference dimension or something similar to that - "~26.7" is already constrained by the diameters at both ends and the angle.

The "~44.7" appears to be a gauge length?
 
I'm guessing the tilde means a reference dimension or something similar to that - "~26.7" is already constrained by the diameters at both ends and the angle.

The "~44.7" appears to be a gauge length?
That's a fair guess. There is a double tilde at the far right on dia 11.33. If that also means reference then the left end location of that taper isn't defined.
 








 
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