What's new
What's new

Hand drilling die cast zinc (and ruining the part)

Strostkovy

Titanium
Joined
Oct 29, 2017
So it's probably my fault but I'm making an electric control retrofit for a Clemco sand blast pot (I did this at my old job except I used huge solenoid valves for the pressure and purge directly, but this pot came with brand new pilot activated valves so I'm only adding a small valve to control pilot air) and wanted to drill out the hole for the hinge bolt that the control paddle pivots on so I could use a larger bolt and tighten up the slop in the mechanism before adding a switch to it. In the process the bit grabbed badly and snapped off a portion of the ear around the bolt hole, totalling the casting. figured I would rivet on a washer plate and drilled the through bore on the paddle. Just the weight of the hand drill made it want to dig and bind. I ended up drilling at around 60 rpm and running the drill backwards to smooth the burr if it got caught.

Anyway, I can make a new part but is die cast zinc that atrociously brittle and crunchy? I could have sworn it was typically soft and machineable, but this felt like pot metal without the telltale grain structure. This was made sometime in the 60s I think. What alloys are typically used for die cast parts?
 
So it's probably my fault but I'm making an electric control retrofit for a Clemco sand blast pot (I did this at my old job except I used huge solenoid valves for the pressure and purge directly, but this pot came with brand new pilot activated valves so I'm only adding a small valve to control pilot air) and wanted to drill out the hole for the hinge bolt that the control paddle pivots on so I could use a larger bolt and tighten up the slop in the mechanism before adding a switch to it. In the process the bit grabbed badly and snapped off a portion of the ear around the bolt hole, totalling the casting. figured I would rivet on a washer plate and drilled the through bore on the paddle. Just the weight of the hand drill made it want to dig and bind. I ended up drilling at around 60 rpm and running the drill backwards to smooth the burr if it got caught.

Anyway, I can make a new part but is die cast zinc that atrociously brittle and crunchy? I could have sworn it was typically soft and machineable, but this felt like pot metal without the telltale grain structure. This was made sometime in the 60s I think. What alloys are typically used for die cast parts?

Alloys ? "We don't need no stinkin' alloys" we just remelt the sprues, add some lead for make up,
and keep churning out parts.

I found idsblast.com sells copies of all those different valves, rather cheaply.
 
So it's probably my fault but I'm making an electric control retrofit for a Clemco sand blast pot (I did this at my old job except I used huge solenoid valves for the pressure and purge directly, but this pot came with brand new pilot activated valves so I'm only adding a small valve to control pilot air) and wanted to drill out the hole for the hinge bolt that the control paddle pivots on so I could use a larger bolt and tighten up the slop in the mechanism before adding a switch to it. In the process the bit grabbed badly and snapped off a portion of the ear around the bolt hole, totalling the casting. figured I would rivet on a washer plate and drilled the through bore on the paddle. Just the weight of the hand drill made it want to dig and bind. I ended up drilling at around 60 rpm and running the drill backwards to smooth the burr if it got caught.

Anyway, I can make a new part but is die cast zinc that atrociously brittle and crunchy? I could have sworn it was typically soft and machineable, but this felt like pot metal without the telltale grain structure. This was made sometime in the 60s I think. What alloys are typically used for die cast parts?

"Made some time in the 60's" is the actual issue.

ALL of that s**t ages REALLY badly over the long haul! The ZAMAK family, still in widespread use today had to address that very issue, did only "so so", even so.

If 'longevity" was on the dance card, Zinc was simply avoided.

See "WCFB" and "AFB" prefixes for carburettors, 1950's onward.

"White Cast Four Barrel" short-lifers. WCFB 2635S and WCFB 2636S side bowlers on Americas first production auto to deliver one HP per cubic inch. No, it wasn't a GMC product.

"Aluminum Four Barrel" was for premium priced longer-lifers.

60 year old whitemetal casting is just scrap that hasn't yet gotten the memo.
 
Alloys ? "We don't need no stinkin' alloys" we just remelt the sprues, add some lead for make up,
and keep churning out parts.

I found idsblast.com sells copies of all those different valves, rather cheaply.

Those are pretty reasonable prices. I'll definitely go that route and just maintain the diaphragms and seals as they wear. The solenoids I used at a previous job were similarly priced and had about the same wear issues.

I still prefer the electric controls switching a 3 way valve for the pilot to the big valves, as the "control valve" was just a paddle with a rubber bumper that plugged a leaking hole to allow pressure to build. Very finicky and otherwise annoying.
 
"Made some time in the 60's" is the actual issue.

ALL of that s**t ages REALLY badly over the long haul! The ZAMAK family, still in widespread use today had to address that very issue, did only "so so", even so.

If 'longevity" was on the dance card, Zinc was simply avoided.

See "WCFB" and "AFB" prefixes for carburettors, 1950's onward.

"White Cast Four Barrel" short-lifers. WCFB 2635S and WCFB 2636S side bowlers on Americas first production auto to deliver one HP per cubic inch. No, it wasn't a GMC product.

"Aluminum Four Barrel" was for premium priced longer-lifers.

60 year old whitemetal casting is just scrap that hasn't yet gotten the memo.

It got the memo now. Just instead of mounting a switch to the casting I get to build an entire new paddle switch to mount at the hose near the nozzle. So much for a half day today.
 
It got the memo now. Just instead of mounting a switch to the casting I get to build an entire new paddle switch to mount at the hose near the nozzle. So much for a half day today.

LOL! Well I may have an advantage in being older that your casting and having learnt it in the 1950's on castings already that old at the outset? Those carburettor SKU were on the DeSoto "Adventurer" mini-hemi MOPAR used as a low-volume production flagship in the early HP race. 375 CID 375 BHP IIRC. And I may not.

The OTHER part of the memo is that Zinc alloyed with COPPER AKA "brass" doesn't do all that much better, just takes longer to chemically go to Hell. Even have the stem of a gate valve snap-off in yer hand? Copper at the break looked red and worm-eaten. The Brass had lost its Zinc.

See the Atomic activity series and galvanic reaction relative potentials wherein Zinc sacrificially "protects" damned near every metal that can be utilized AS a metal, Sodium, Potassium & such making rather short-lived lawn furnishings...

And then the salts Zinc will form with damned near any other element. Chemically, Zinc is a promiscuous WHORE!

Bronze, Copper Alloyed with TIN, but not-only, OTOH, is a whole 'nuther story.

Bronze goods in the tombs of Egypt or Ancient China would not pass inspection for use today. But were still "there" and recognizeable - same as Bronze-Age weaponry in ancient graves, the whole world around, most any culture.

"Shiney wood?" The OXIDE is hell-for-stout.

The base under it is just high-grade "fuel" for a REDOX reaction. VERY high-grade!
See "thermite". For-real. Not as a PM "handle".

Or nastier, yet, since the loud noise departments of the tribes of mankind have LONG relied on it ... War Two, onward.

A-IX-2 Hexal

Around 50% more powerful than ignorant TNT.

... and keep seeking ways to get even more bang out of it:

Aluminum Iodate Hexahydrate (AIH)
 
"Shiney wood?" The OXIDE is hell-for-stout.

The base under it is just high-grade "fuel" for a REDOX reaction. VERY high-grade!
See "thermite". For-real. Not as a PM "handle".

We switch between cutting aluminum with nitrogen and steel with oxygen, and we seem to have gotten the ratio right because the flare ups in the table can last about 20 seconds after the cut has finished.

It's a bit of a concern when the dust collector fills up with 10 gallons of the stuff in fine powder form. We have decided to empty it frequently to avoid a huge fire, but it still has the capacity to self destruct in the filters alone.
 
We switch between cutting aluminum with nitrogen and steel with oxygen, and we seem to have gotten the ratio right because the flare ups in the table can last about 20 seconds after the cut has finished.

It's a bit of a concern when the dust collector fills up with 10 gallons of the stuff in fine powder form. We have decided to empty it frequently to avoid a huge fire, but it still has the capacity to self destruct in the filters alone.

Funny stuff, the light metals can be.

NIKE-HERCULES (IMPROVED) MIM-14B Battery Control vans were airmobile Magnalium alloy. The borderline-insanely accurate (12 foot CPE.. @ 90 Mike Foxtrot MILES OUT..) were bleeding edge build of a 1940's M42 "RADAR Gun Director" originally controlling 120 mm ACK-ACK cannon that had never fired a round in anger. Germany had no aircraft that could fly high enough to justify deploying them.

Dirt-simple Wheatstone bridge and servo amps implemented with push-pull-parallel 6L6 thermionic valves ate a lot of ergs.

I was 'elevation' operator, "A" Battery, 3rd of the 51st Arty, 52d Arty BDE, Old Bridge/Sayreville NJ. Our inventory of Whisky-31 nuke warshots was defending New York & the NJ to PA Chemical industry. We were not alone.

You'd have thought.. that more foresight wudda been applied to the selection of materials?

But we passed by a big photo of the remains of our deceased Brother.. "B" Battery, Holmdel, NJ ... each 6 hour shift swap.

Concrete slab. FRP external A/C duct. White powder on the slab. Period.

A/C duct was pointing at empty air ... over the layer of white powder that HAD been a Magnalium van full of Aluminium chassis, their cabinetry, racks, control panels ... and bus-bars...mere minutes before a bus-bar malfunction turned it into superheated dust.

Seems both of Nitrogen-pressurized and Carbon Dioxide, raw, fire extinguishers only added "variety" to the otherwise BORING, if rather blinding-rude and rapid REDOX reactions?

Crew had bailed-out safely. We had escape hatches. And superb training.
20 KT nukes as warshots to be lighted-up ... over our own soil .. sorta demanded that?

"Huge FIRE" of that dust you are holding won't be a lengthy one!

Trust your "cold" war tax dollars to have proved that much!
 
Funny stuff, the light metals can be.

NIKE-HERCULES (IMPROVED) MIM-14B Battery Control vans were airmobile Magnalium alloy. The borderline-insanely accurate (12 foot CPE.. @ 90 Mike Foxtrot MILES OUT..) were bleeding edge build of a 1940's M42 "RADAR Gun Director" originally controlling 120 mm ACK-ACK cannon that had never fired a round in anger. Germany had no aircraft that could fly high enough to justify deploying them.

Dirt-simple Wheatstone bridge and servo amps implemented with push-pull-parallel 6L6 thermionic valves ate a lot of ergs.

I was 'elevation' operator, "A" Battery, 3rd of the 51st Arty, 52d Arty BDE, Old Bridge/Sayreville NJ. Our inventory of Whisky-31 nuke warshots was defending New York & the NJ to PA Chemical industry. We were not alone.

You'd have thought.. that more foresight wudda been applied to the selection of materials?

But we passed by a big photo of the remains of our deceased Brother.. "B" Battery, Holmdel, NJ ... each 6 hour shift swap.

Concrete slab. FRP external A/C duct. White powder on the slab. Period.

A/C duct was pointing at empty air ... over the layer of white powder that HAD been a Magnalium van full of Aluminium chassis, their cabinetry, racks, control panels ... and bus-bars...mere minutes before a bus-bar malfunction turned it into superheated dust.

Seems both of Nitrogen-pressurized and Carbon Dioxide, raw, fire extinguishers only added "variety" to the otherwise BORING, if rather blinding-rude and rapid REDOX reactions?

Crew had bailed-out safely. We had escape hatches. And superb training.
20 KT nukes as warshots to be lighted-up ... over our own soil .. sorta demanded that?

"Huge FIRE" of that dust you are holding won't be a lengthy one!

Trust your "cold" war tax dollars to have proved that much!
As a kid in the 50s I was in awe of the Nike sites spread around Washington DC. Used to pass one often along RT 50 close to the Bay Bridge north of Annapolis Md.
Found several more as I traveled around the area.
Never knew they were Nukes though!
Joe
 
As a kid in the 50s I was in awe of the Nike sites spread around Washington DC. Used to pass one often along RT 50 close to the Bay Bridge north of Annapolis Md.
Found several more as I traveled around the area.
Never knew they were Nukes though!
Joe

I had the "release" authority seat over the NYADs inventory for about six months.

The only Army-Green uniform IN a room full of USAF blue, at the immediate right hand of the CO as "Deputy Battle Staff Commander."

Boss was a full bird, JUST medicalled out of his favorite chair.
McDonnell One-Oh-Wonder - one of Gabreski's senior pilots, and MOST unhappy to be flying a GSA swivel chair in a massive bunker instead of his beloved pee-bringer! Also nuke-armed, just teeny-tiny ones.

How many NIKE nuke Warshots and where? Part of what I shared with HIM. but *I* can't say!"

You could snoop the 'net?

Ed's Nike Missile Web Site

Extract:
Note: in the continental United States (CONUS) common deployment was only one T45 per pit, the other five where W31s.

Check the W31 yield? Close match to the Nagasaki strike.

Each.

Little hairs do NOT rise-up on the back of your neck, you ain't "normal".

Glad we never had to use them. Somebody wanted to court-martial me when I used them SIMULATED. One each to two of my own USAF fighters, gone in mere seconds. Simulated loss of IFF. Tough call, even simulated.

Fighter Commanders, Dover and Suffolk both said it was the RIGHT call, all part of the job as interceptor pilots, and the glorious bastards KNEW it when they mounted-up. That call was how a PFC ended up in a Field Grade Officer's slot!

I was actually kinda pissed to get orders to Belvoir OCS. I wanted Fort Sill.. hunkering after Command of a battery of 8-inch SP HOW we could actually FIRE, not just "simulate", even if only to clear jungle with beehive rounds!

No choice. Max score the test? Chief of Engineers owns your brain, ass along for the ride or otherwise! Artillery got second dibs. "back in the day".

It worked out OK..
 
Drilling potential and brass

So it's probably my fault but I'm making an electric control retrofit for a Clemco sand blast pot (I did this at my old job except I used huge solenoid valves for the pressure and purge directly, but this pot came with brand new pilot activated valves so I'm only adding a small valve to control pilot air) and wanted to drill out the hole for the hinge bolt that the control paddle pivots on so I could use a larger bolt and tighten up the slop in the mechanism before adding a switch to it. In the process the bit grabbed badly and snapped off a portion of the ear around the bolt hole, totalling the casting. figured I would rivet on a washer plate and drilled the through bore on the paddle. Just the weight of the hand drill made it want to dig and bind. I ended up drilling at around 60 rpm and running the drill backwards to smooth the burr if it got caught.

Anyway, I can make a new part but is die cast zinc that atrociously brittle and crunchy? I could have sworn it was typically soft and machineable, but this felt like pot metal without the telltale grain structure. This was made sometime in the 60s I think. What alloys are typically used for die cast parts?

Helps to knock off the positive hook on your drill bit with a diamond file on these soft metals.....also to work up in diameters to get where you want to go start small high rpms. ....works for me
 
...

Anyway, I can make a new part but is die cast zinc that atrociously brittle and crunchy? I could have sworn it was typically soft and machineable, but this felt like pot metal without the telltale grain structure. This was made sometime in the 60s I think. What alloys are typically used for die cast parts?

If you research 'zinc pest' you'll discover a lot more about what can happen to zinc alloy castings.

George B.
 
if you are drilling, especially by hand, a grabby material like brass or pot metal -- dub the drill by stoning a small neutral rake flat on the cutting edge and it won't grab.
 








 
Back
Top