Aaron J. Cergol

Un-plugging a Pritchel hole

Recommended Posts

Ive got a 360# north German pattern double horn that I'm currently using. It's all torch gouged up, but has a flat face and tremendous rebound. The Pritchel hole is plugged with...metal? And is rustd solid. I've soaked the Pritchel in penetrating oil for weeks, moved it under the drill press and tried drilling it out. Three drill bits later, still nothing. I took some heat to it, but don't want to get it hot enough to ruin the temper. As a last resort, put a round punch in it, and struck it repeatedly with a sledge...didn't budge. Being that its a German pattern, I cannot access the hole easily from the bottom as the foot of the anvil would be in the way.

Any ideas?

Aaron

Share this post


Link to post
Share on other sites

Mix one part acetone and two parts auto trans fluid and dribble it in every litte while,,,,a day or three of that may work....And it is flammable so take care,

Share this post


Link to post
Share on other sites

If you couldn't drill it out that could mean that there is a piece of hardened tool steel broken off and jammed in there from some sort of tool like a punch or it's hardened weld material.  I don't know why anyone would put weld in a pritchel hole but I guess it's possible.  When you tried to drill it out what did you see in the hole afterwards?

Share this post


Link to post
Share on other sites

It seemed as if there were two pieces of metal wedged/rusted in. The first one was on the surface of the face and drilled out easily. The other seemed to be hardened and was deeper in. Looking in with a flashlight after drilling I barely see any shiney spot. Looking up from the bottom, its well rusted in. Being a German pattern, the pritchel hole goes through a solid 4.5" of material making this even more fun. :P

 

Thanks for the acetone mix-I will try this.

Share this post


Link to post
Share on other sites

Aaron - you burning the bits up or breaking them?  You should be able to drill it out, you just need the right bits.  And start small.  Possibly try a screw extractor?  If you can get it to bite you should be able to stick a wrench on it and get it to vibrating with a hammer.

Share this post


Link to post
Share on other sites

Aaron, do you have access to a Cole drill? Perhaps a Cole drill with cobalt bits? Might have to jerry rig a clamp setup but they do generate tremendous pressure without burning up bits, just takes a lot of elbow grease at least in my experience.Good luck,Bob.

Share this post


Link to post
Share on other sites

I have seen people drill hardened tool steel with carbide tipped bits. Slow drill speed, and I would think coolant would help. Some people have used the coal drill with a carbide bit to drill through leaf springs and I am sure they are very hard.

 

Maybe look into using a magnetic base drill with a carbide cutter in it. 

 

Can you heat some from the bottom so there is less chance of over heating the top?

 

Good luck, and some pictures could help us suggest more tips of removal.

Share this post


Link to post
Share on other sites

I've gotten things loose with this bad boy that I figgured were froze forever.......On an aplication like yours the bit would need to be unersized a little and hard. If it were to spread against the plug you'd be in worse shape......

post-15096-0-27982900-1358877373_thumb.j

Share this post


Link to post
Share on other sites

Tried cobalt, tried black oxide, tried carbide bits under the press going at a very slow RPM. nothing, no chips. Center punched it first and used copious amounts of oil. Cant get an EZ out or extractor in there with no pilot first though. I have often thought a mag drill might be the ticket. I have a freind who has one, that might be next.

A cole drill isn't a terrible idea! I think that might just work, and certainly in conjunction with some heat. Will have to figure a way to clamp it though...nothing to really get a firm grip on as everything that is available to grab is angled.

Macbruce-I don't have a compressor or air chisel, but I do have access to a jackhammer...hopefully it won't come to that. :P

Aaron

Share this post


Link to post
Share on other sites

I'd sure try to get a punch in there from the bottom. You could bend the punch to pass the foot or hammer on a second bar laid across the punch. If it's wedged in from the top, so some impact from the bottom might be just what it needs.

Share this post


Link to post
Share on other sites

Aaron:  Their is a diesel engine repair shop in Irwin, Il.(west of Kankakee, Il.) that has a machine that can vibrate/heat its way thru a broken headbolt or whatever without putting too much heat on what you want to save.  I can't remember the name of the machine however.  The point is their should be a repair/machine shop in your area that would have thise same machine that you could  take your vise to.  Maybe somebody on this site can put a proper name to this machine.  Meantime I will try to get more information tomorrow.   Armand

Share this post


Link to post
Share on other sites

If you can reach the bottom can you place a thin hydraulic jack there and press up with a round undersized punch ?

Share this post


Link to post
Share on other sites

EDM, electrical discharge machining.  Probably the same thing onetree is talking about.

 

Does the pritchel go all the way thru and is blocked, or did the original manufacturers hit a part of the casting that THEY couldn't drill?  

Share this post


Link to post
Share on other sites

Sounds like you have tried and been given alot of good suggestions. Last resort would be to heat the mass with a cutting torch and blow a hole through the center and then try to hammer and chisel out the remainder. It might loosen it up with the heat and by blowing out the center it will give it room to move. I know you are worried about ruining the temper but as long as your below 500 degrees you should be ok. You are heating up just the obstruction not the anvil. Good luck how ever you go.

Share this post


Link to post
Share on other sites

Fyi..most paper products start to discolor or char before they ignite. and most of them do this at 400f or below....so If you put some strips of masking tape on sides and top of the anvil you can monitor the heat if you try the cutting torch tip above.

Share this post


Link to post
Share on other sites

Hi Aaraon,

 

After all your attemps, let me make the silly question:

If you cann't drill that strange material, can you make a hole in another place of the anvil :)?

 

2c

AB

Share this post


Link to post
Share on other sites

A diamond coated/impregnated bit made for stone and ceramic might work but would take a while to grind its way through.

Share this post


Link to post
Share on other sites

The absolute LAST THING TO USE is an Eazy-out, like never!!!!!! Drill slow with water as cuttting fluid, oil is a lubricant, lubricates the cutting edge, WRONG thing to use!!!! If you can't punch it from the back-side, either drill VERY SLOW with a diamond bit (or ceramic) or cut it out with a torch and an oxygen lance. EDM would work well.

 

Maybe it is a candidate for shooting!!! gun powder might shake it free!!! :)

 

Neil

Share this post


Link to post
Share on other sites

Any chance a bolt and nit could be turned to push up. A jack might be too big for the clearances involved, but a nut and bolt would be smaller.

Share this post


Link to post
Share on other sites

A few small drips of nitric acid a few times a day for a few months.

or

solid Bronze rod a bit smaller than the hole wanted with course grit diamond dust (lapidary store or ebay) and water slurry on low setting under your drill press. Hang a weight or spring off the feed handle on the drill press and walk away. Clean out the hole every five minutes and add new dust/water. Be done in an afternoon.

 

Ric

Share this post


Link to post
Share on other sites

Do you have a plasma cutter.  You could probably get it out in 10 min with a plasma cutter.   One piercing cut down the center knock it out with a hand punch. 

Share this post


Link to post
Share on other sites

Hi    I dont know what a cole drill is but a cobolt Drill bit should bore through just about anything as long as its done slowly and cutting lubricant is used one of the water based emulsions are best,you say there is a lot of tourch guogeing evident so may be you are worrying about the temper a bit to much as its already been knocked about. good luck and let us know how you get on

Share this post


Link to post
Share on other sites

I was thinking the same thing about it being tapered and wedged in from the top. I believe your best bet would be to try to drive it out from the bottom. Though the gunpowder solution might be fun :P Tap the bottom of the pritchel and make a breech plug, with some black powder... (I'm not serious, depending on the weight of the plug, even a relatively slow speed like 500fps would send it through anything it wanted to, just about)

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.