drill and tap turbo hot side PITA!

[phillabaum03]

ok guys, ever since I've had my 98 gsx its been missing a bolt in the turbo and been leaking exhaust BAD so when I did my head swap/build I found out why theirs no bolt. The previous owner must have stripped the threads then kinda welded the hole like halfway close but never tappe it, just left it. So I welded the hole shut and started over but its like impossible to drill that cast. Im trying to find out about deharding? I believe its called. Anyone ever had to do this or drill cast this thick? I've tried brand new bits and everything and it barely puts a dent. I've been told to preheat the oven to like 600 and put the hot side in and every half hour or so decrese the oven temp like 100 degrees and when its done the cast will be softer and I might be able to drill and tap then...anyone got any advice? Thanks in advance

 

[Burnett03]

You need to get hardened drill bits.

 

[JWoodley]

What turbo are you running? Pickup a new hotside and save yourself alot of headache/heartache.

 

[blcknspo0ln]

I've tried and failed every single time. A machine shop can successfully do it for you, but you will of course have to pay. I also would second getting a used turbine housing.

 

[gorf]

ok guys, ever since I've had my 98 gsx its been missing a bolt in the turbo and been leaking exhaust BAD so when I did my head swap/build I found out why theirs no bolt. The previous owner must have stripped the threads then kinda welded the hole like halfway close but never tappe it, just left it. So I welded the hole shut and started over but its like impossible to drill that cast. Im trying to find out about deharding? I believe its called. Anyone ever had to do this or drill cast this thick? I've tried brand new bits and everything and it barely puts a dent. I've been told to preheat the oven to like 600 and put the hot side in and every half hour or so decrese the oven temp like 100 degrees and when its done the cast will be softer and I might be able to drill and tap then...anyone got any advice? Thanks in advance

The term is "annealing" which typically means heating metal red hot and then letting it cool SLOWLY. The opposite is heat treating for hardness where the hot metal is quenched very quickly.

Quick lesson in welding Cast Iron - WARNING! I am not an expert by a long shot - Cast iron has a tendency to crack if the heat from welding is concentrated.
1.) preheat the item with a torch, do a much larger area than you will be welding
2.) use welding rod for cast iron(heavy nickel I believe) do not go over one inch of weld length at a time
3.) use your torch again to heat around the metal away from the weld.
4.) continue to use the torch to let the iron cool down slowly.

You can try annealing with a torch, get it red hot and then back the torch off slowly. Not sure how much softer it will make the metal...

 

[phillabaum03]

Thats pretty much what my friends dad did for me today at work and supposedly got it. Thanks guys, always a help.

 

[JusMX141]

I've tried and failed every single time.

I've tried and succeeded every time.

I use a cutoff tool to make sure the broken bolt's surface is perfectly flat, then use a center punch to place a dimple right in the center of the broken bolt.

I start with a 1/8" drill bit, and work up from there using about 6 sizes along the way. I've never successfully drilled out a broken turbine housing bolt without repairing the threads with a HeliCoil.

I prefer to not use a Drill Press as I can never seem to get the drill bit to go straight due to the strange angles of the housings. I normally use my large bench vise and a giant Makita electric drill.

 

[blcknspo0ln]

I've tried and succeeded every time.

I use a cutoff tool to make sure the broken bolt's surface is perfectly flat, then use a center punch to place a dimple right in the center of the broken bolt.

I start with a 1/8" drill bit, and work up from there using about 6 sizes along the way. I've never successfully drilled out a broken turbine housing bolt without repairing the threads with a HeliCoil.

I prefer to not use a Drill Press as I can never seem to get the drill bit to go straight due to the strange angles of the housings. I normally use my large bench vise and a giant Makita electric drill.

AH! There's the trick

 

[JusMX141]

Haha yeah, I've found out the hard way the importance of using a center punch at starting with a nice, flat surface.

If you do alot of drilling, I STRONGLY recommend purchasing a Drill Doctor (Drill Bit Sharpener from Drill Doctor!). That one tool has saved me about $6000 in drill bits. When I'm drilling out a hardened Mitsubishi "11" manifold bolt, I'll have to sharpen even a hardened bit up to six times in order to keep it cutting.

 

[gorf]

Haha yeah, I've found out the hard way the importance of using a center punch at starting with a nice, flat surface.

If you do alot of drilling, I STRONGLY recommend purchasing a Drill Doctor (Drill Bit Sharpener from Drill Doctor!). That one tool has saved me about $6000 in drill bits. When I'm drilling out a hardened Mitsubishi "11" manifold bolt, I'll have to sharpen even a hardened bit up to six times in order to keep it cutting.

I've always had good luck sharpening my drill bits by hand. Of course I was a machinist for a while and someone showed me the correct way to do it.....

 

[JusMX141]

I got the Drill Doctor as a Christmas gift from my father some years back. I had seen the infomercial, but I was skeptical as always at how well it would work....nothing works like they show you on the infomercial, right?

This tool is freakin' unbelieveable. It works so fast....it literally takes longer to get the bit out of the drill chuck (old-style with key) than it does to sharpen it. You can sharpen the bits until there's practically nothing left- in fact, some of my bits are only 2" long, but still cut as the day they were new.

I'm impressed, and I'd recommend it to anyone who doesn't have the ability to sharpen their own bits.

 

[turboglenn]

I'd love to learn about sharpening bits by hand, i never have quite got the hang of it and the sharpener i had was junk, hence why i "had" one.

The advice on flattening and punching the bolt are crucial for getting a good hole started in the center of the bolt. Start with the smaller bits and work your way to the size you need. I will usually keep stepping up one or 2 sizes at a time while doing something like this until i can start to see some of the OEM threads, then i'll back off the drill and try and pick the pieces out with picks, screwdrivers etc or see if a bolt extractor will work.... ( i really don't like using "easy outs" or bolt extractors because they can break off leaving you with an even harder piece to drill out than you began with) That's why i will just drill and drill until there's hardly any bolt material left and try getting it all out with picks.. or if you get the bolt where you can see the threads all the way around and still can't get the pieces out of them, run a tap through the hole.... I haven't used an easy out in over 5 years now and i've haven't had to drill a broken one out since then

ONe thing that will make a HUGE difference is to buy Cobalt drill bits..Not the brand name cobalt, but the material use to make them. I can only get good cobalt bits at one place here in town and they aren't too cheap, but really not bad when you think of how many TiNi (titanium nitride) coated bits you burned up before buying a cobalt one.

I make some grill burners for a company here in town that does large outdoor brick/stone fire structures and i usually have to drill 288 holes in each burner, the holes are 1/16 diameter put into 1/16th thick stainless steel (T304) SS eats drill bits and when i first started making these for the grill place, i went through 12 TINi bits just getting the first 40 or so holes drilled. I switched to cobalt, I broke a few cobalts even before i learned to cut them down so they chuck up really short (only as long as needed) but after that i did about 900 more holes on 3 more bits and one of those only broke because the guide holding my material let one side raise up and break the bit when i was pulling out of the hole i just made. The other 2 i actually dulled, one from not enough cutting oil, the other from trying to move too fast.

So, slow down, get cobalt bits, flatten & punch the place to be drilled and go slowly from smaller to bigger bits until you're there. Good luck! (if your friends dad didn't get it done' for you already) I have one of these jobs coming up on a friends car, both turbo bolts on the driver's side are broken off :EEK:

EDIT: And it's not the cast that you're needing to soften/aneal, it's the weld bead that you're drilling into that's so hard. I've been a welder for years and have never bothered to find out why cutting, drilling, machining and sanding the weld is so much harder than the parent metal. The only "easy" material i've worked with that was a metal filler was aluminum and the high nickel rod used in cast iron (#'s 55 and 99 repectively)

 

[estoyaqui30]

Actually the best bits to use are "solid carbide" they are harder than the cast or the factory turbo bolts, which are stainless steel.

 

[estoyaqui30]

not meaning to post such a short answer. I was told by my brother who is a machinist/MSEE that the way to go is using "solid carbide" drill bits , but that they need to be used in a drill press or milling machine. They do break easily if you use them in a hand drill. I will find out at some point soon as I have one broken turbo bolt and I know that when I remove the turbo, the other three WILL break! the Mitsu bolts are some grade of SS and I am running a Forced Performance FP-3052 turbo. The hotside is also SS so the bolts are stuck. I was thinking about getting a new hot side housing, but they only list it for sale with the center cartridge. The will cost almost as much as a whole now turbo. So I guess I will have to try to drill them out. A nice assortment of bits can be purchased from Industrial Supply Equipment from MSC Industrial Supply the sell machining tools.

Jason