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Thread: Drilling and tapping ar400
08-18-2009, 10:08 AM #1
Drilling and tapping ar400
hello guys, i am new to the forum and relatively new to metal working, al though i have some aspects under my belt i always have questions, so i have joined up to maybe get some different perspectives.
And my questions begin. I have one inch thick ar 400 plate that i have to drill and tap for a rock crusher i run in my pit. to put price in perspective, these plate a about 3 ft. by 2ft average, 6 pieces to a set, with 2 holes in 4 of them and 3 holes in the other two. To buy a manufactured set, it costs me around 6500 clams. I bought a 20 ft x 8 ft x 1 inch for the same price. I will get a lot more plates out of it.
Now i am drilling a hole to satisfy 1 inch standard bolt threads( proper thread term?). I have been drilling a 3/8 pilot hole, then drilling it with 7/8 for my final hole then threading it. Is this correct procedure do you think?
After my pilot hole is complete, i begin with a silver and deming bit (7/8) and drill through and have to redrill the hole again with a newer bit bc my first bit is always wear out and i am getting a little bit smaller hole than 7/8 the first time. I am using a magnetic drill press that has a reostat style speed adjuster on it. Big tool.
I thne tap with an extremely tapered tap (1") to begin with and then have to clean it up with a regular 1" tap.
I am doing these things without any big problems but my lack of experience is making me question having the right tools to cutting tools. I know the mag drill is the best drill to use as the plates are big and heavy and cant be fitted into any type of other drilling device despite spending 25 g's for a great big deal.
So i leave with some questions. Is my pilot hole correct size? Am i drilling the right size for taping one inch threads? What kind of drill bit should i use? What style? What piont? What degree? What material? ( all drill bit questions) Who manufactures these bits the best? Am i on the right track for taping procedure? Who manufactures the best taps?
I appreciate you interest and help.
08-18-2009, 11:52 AM #2
That abrasion resistant (AR) plate is sum pretty nasty stuff to drill or machine. That being said, plenty of Cutting Oil on your drill bit.
I'm guessing your hand drilling the plate?
Yes, for a 1" coarse -you use a 7/8 drill.
for a 1" fine- you use a 15/16 drill.
A mag base drill would be the ticket - you know that you can rent them Right?
08-18-2009, 11:53 AM #3
I won't go into your procedure here but I'll just make an observation.You're having to pay $6500 for a set of these plates with all the drilling and tapping already done.For the same price you're buying a 20'X8'X1" but you are having to do all the drilling and tapping,all be it,with some difficulty not to mention cutting the plates to size.This is all extra labor that "I" would have to tack on to the price of the original purchase.You get more plates out of the 20X8X1 but you still have to cut,drill and tap the holes which takes even more time.Unless,by some miracle,the plates you build outlast the predrilled and tapped IMHO you're work is counter productive.There's an old adage "Time is money".Unless your labor is free then I don't see where you're beating the price of a new set from the supplier.If your labor "IS" free then I'd like your shipping address so I can send you all the work I need done that I haven't been able to get caught up on.
08-18-2009, 01:32 PM #4
I actually do have a mag base drill i thought i mentioned that above but yeah that is what i am using. And for the guy who says time is money, i understand your statement about time is money and my time is worth more than the average yogie bear. I am the owner of this quarry, the ball and the rattle. i did not get this far by making random decisions and not taking into acount the price of materials and labor and inflation and time. I have a full understanding of my checks and balances, and i am only 22 years old. However, if i only got two sets of plates, which i will get at least 5, i will save enough money to make it well more worth my TIME to cut, drill, and tap them. Not even counting what shipping wiould end up costing me. And, just saying for two sets, there is no way 28 holes is going to cost me 6500. that would be better than 200 a hole. And i can do 8 holes in an hour as well. So at 5 sets of plates i have saved around 20 g's. at 8 holes an hour (70 holes total) that puts me at 8.75 hours of work, my time was worth 2285 dollars and hour. like i said, my time is worth a lot. anybody who can offer some help though to make me understand some more i would appreciate it.
08-18-2009, 01:43 PM #5
If you're using HSS, and wearing out a drill per hole, I'd be looking for something with a little more longevity, like a carbide drill.
I'd also try to make my pilot hole something closer to the dead-centre diameter of the 1" drill, whatever that may be, as it would vary on the manufacturer. With 3/8", you're most likely not using the full lip width of the 1" drill, which is just a waste as it's harder on that drill. To drill a smaller pilot hole would also be faster.
You've got through-spindle coolant on that mag-base?
Carbide for pilot and finish, and keep your feed high on the 1". How many taps are you going through per plate?
The term you were looking for in the original post in regards to the 1" threads is simply "coarse", being 8 threads per inch. The standard notation for such a thread would be 1" x 8NC, for National Coarse.
08-18-2009, 03:02 PM #6
Actually considering the material I think you are doing pretty well. If the hole are undersize it indicates that the clearance lips on the drill are wearing, no surprise in this material. Oil may help here. Experiment and find the maximum feed which means break a few shanks on the drills. The faster you feed the less work hardening you will have to deal with. The pilot hole by the book should equal the width of the drill's chisel point but drilling that much metal with a 1/2" shank will be very hard on the shank. Put a center or tap guide in the drill while still over the hole to start the tap. This will start it straight and save you the grief of a broken tap though this not usually a problem with taps this large.
This application seems a bit unusual to me. I have seen many liner plates and they are usually countersunk and keyed. This avoids having to machine the holes as you are having to do.
To avoid having to run another drill through to bring the hole to size use an oversize drill such as 57/64 or maybe even 17/32. This eliminate that step and make the tapping easier. There will be no significant loss of strength in the thread.
08-18-2009, 03:35 PM #7
I agree with the above statements. AR plate does suck to work with, but I don't have a lot of personal experience drilling and tapping it. I agree with HSS and plenty and coolant. Get some soluble oil and don't be stingy. I love this stuff and it goes a long way. I'm not sure how it would hold up, I've not used them much at all, but what about an annular cutter? Do any of you guys think a HSS annular with some coolant would hold up? No pilot hole, once thru and you're ready to tap.
Coondog if you're not familiar with an annular cutter, it's basically a hole saw on steroids with no pilot drill. It cuts the circumference of the hole and leaves a plug of material just like a hole saw. The amount of material actually cut is much less than using a drill but could be an expensive mistake to break them regularly or if you were to dull one on each hole. Just a thought.
Out of curiosity, what are these plates for? They sound kinda like cheek plates in a jaw crusher but the tapped holes are throwing me for a loop. I have several years of quarry experience under my belt, mostly in maintenance, some in operations but I'm drawing a blank.
08-18-2009, 03:47 PM #8
One reason you may be going through drill bits is your speed. I drill a lot of 3/4 AR 400 crap for wear plates for those mulch grinders. I use a sossner coated tap, and a split point cobalt drill at about 100 rpm. Drilled 44 holes and the drill still cuts. Broke the tap though. Plus no center or pilot drill. It's a 3/4 - 10 tap. Oh, by the way AR 400 sucks!
The more speed you have the more work hardening you'll get and in turn, less life out of the tooling.
Last edited by Ray Behner; 08-18-2009 at 03:51 PM. Reason: added stuff
08-18-2009, 04:40 PM #9
thanks for some real help
toolpost, this is the kind of advice i was hoping i would get. I had no idea on the pilot hole size. i appreciate the pionter there. i had never thought about it but that seems to make like perfect sense. so carbide would be like the pbvious choice huh? this is something else i did not know. ray behner backed that up behind you too. and sorry the mag base drill doesn't have the coolant thing, or at least not that i'm aware of. i had never heard of it and also never thought about it either. i am going to investigate manana but im sceptical. I still have the same tap i started with, although i have only done 23 holes so far. Like i said first, i have an extremely tapered tap i start with. i use some 1.5 foot cheater pipes on the handles of my t-wrench and its a good pull beginning out and i aint broke it yet. I then follow up with a regular tap. not sure about coating and stuff though. and thanks for the terminology as well.
tdmidget, when you say feed i am assuming your talking about putting as much pressure as possible on the drill bit. and when you talk about work hardening, i am also assuming you mean that when you just lolligag and dont put enough pressure on that drill bit you begin to sort of temper the plate and it becomes stronger so to speak. we all know what assuming does you us, but if i am correct in my conclusions the harder i push down the less tempering i will do, the quicker i will drill my hole and the less i will wear out my bit. i hope i haven't made an ass of myself. the center or tap giude you mentioned must be something in the sorts of a countersink bit or like a spear shaped bit the kind of ream out the hole so the tapp will start a little easier. let me know if i am still making an ass of myself. thanks for letting me know about the drill size. i could at least use this longer or until i wear it down to a bit less that 7/8. right? keep it coming guys thankyou
plantaionpete, i like the annular bit idea because the stress of the wear would be on the cutting face and not on the sides as much, but like you say, will it even cut it. i have seen these in the graingers cataloge, seems like an idea. maybe someone else could throw me a bone on this one. and you nailed the cheek plate. thats what they are, in a kpi 3052 jaw. and kpi is proud of they're wear plate. i get my jaw liners from rimtech and they come out of africa. 18 manganese seems to wear a whole lot longer than 21 manganese too, aint that something? these plates slide in beside the jaw plates on the cheeks and the bolts come in through the frame from the outside. i kind of inherited all this equipment and i do understand that this is the trash of jaw crushers, but there kind of wasn't a choice in the purchase. it was either all of it or none, now i just have to make it work for me.
and ray behner, you say you use a split piont cobalt drill bit, and a sossner coated tap. this is also the kind of info i was hoping to find. not knowing much about all this stuff, sometimes it is hard for me to distingiush between certain terms in meaning, like i understand that sossner is a coating on the tap bc of your wording, but sometimes ppl dont put things in context and i get lost in the idea of is it a manufacturer or a style or a coating. so this sossner is a coating, i also hear if TiCN or osmething like that. i would love for someone to tell me where and what to find, also the split piont thing seems good, but what angle on the tip should i get? theres 112, 118 132? i get so lost in this stuff and these things aren't cheap. as you guys probably noticed in my reply to ray french, i dont like to waste much, so i like to try and start from the beginning with the correct product.
this is kind of funny, but i was rummaging through some old army boxes of stuff my grandfather left behind on this earth. i found a larger drill bit in there that looked about right so i grabbed it and took it. later that week i was drilling some holes in this tough stuff, and the bit broke right off. well, hell. i live miles and miles from anything, like 120 miles from the nearest supplier and that is graingers at that. then i remembered that bit. i grabbed that rusted thing again and couldnt read a size on it. calipers, 7/8, ok where in business with a smile on my face thinking yeah right, no way this bit will ever drill a half in. to mys surprise that thing lasted longer than any of them. i guess granpa knew what he was doing. thanks for the help yall.
08-18-2009, 05:10 PM #10
Our jaw was a Lippman 4048 or something like that, can't remember exactly. Those cheek plates had square head bolts that went inside then nutted from the outside. I hated that crusher so much. It was good when it was good but it broke toggle bolts constantly, wore the seats in the swing die and toggle block like they were made from butter and not to mention the die bolts were always coming loose. Thanks to the oiler system it was always a nasty mess just to top it all off.
I did some of the ordering for awhile and most of our stuff came from Metso. The wear was always an issue, our rock was something on the order of 12,000 psi I think. We did whatever it took to keep the stuff moving. It's a hard business and I don't envy your position.
I think the annulars would be worth a try if you had the time and the dollars to give it a go. I would be sure to use lots of coolant and slow rpms. HSS is tough stuff and think it would take the AR okay with the proper approach but I would make sure to go with a quality cutter, not a cheap import.
08-18-2009, 06:18 PM #11
you guys had it easy at 12k psi, my rock is around 26k. it is called rhyalite. you never saw something so abrasive and also a 72 percent silica content in the blow sand. we get a max of 250 hours out of a set of liners and we are using some huge quarry tooth dies. its tough but thats why they want it. so i grit my teeth and do it. oh what fun. oh and 500 hours out of a set of grousers for the d10 too!!
08-18-2009, 06:34 PM #12
Where about are you in Texas?
There are several suppliers here in Texas that will ship overnight to you by CC if you are interested. The can supply you all of the items mentioned above and then some.
The cutting oil mentioned above is applied to the drill and or tap as they come intack with the plate you are cutting on using a "oil can". Nothing fancy here, just need to lubricate the drill and tap to help you out.
And if you get brave enough, power tap using the mag base drill, or at least start your tap this way. I've done hundreds of 1"-8 threaded holes in my past this way.
08-18-2009, 10:35 PM #13
If you have already made a hole and tapped it, in AR plate of any temper, with a Silver and Deming drill bit mounted in a mag drill, you are doing better than many already!
That said, if your mag drill would accept a morse taper shank drill, that would be a much more robust set up than the S&D version. But then you would be inclined to learn how to sharpen them with that split point so you wouldn't need a pilot hole. And that could lead to a much more contentious exchange here on the forum.
Also, I wouldn't be afraid to use a 57/64 tap drill to make the tapping easier. The recommended hole size for 1"-8 2B is allowed to be as large as .896. Granted, this is for a length of engagement of 1-1/2", but I really don't think that you risk any stripping of threads. It would make it conceivable that you could drive that tap with the mag drill, assuming you could come up with a lash up to drive it.
08-19-2009, 11:57 AM #14
I do NOT envy your operation at all. Our silica content was 3% max in St. Genevieve, not sure what our wear hours were but more than yours I know.
We dropped a slope mine underground in a seam of Salem stone with only 3kpsi. Wear life was unbelievable. They ran an HSI down there with no real depreciable wear running 10 hour shifts, 5 days a week for 5 years. Moisture content was around 15% so it was soft but very messy.
Good luck and I'll be sure not to apply at your outfit.
08-19-2009, 04:14 PM #15
I would ike to get a couple of names of these suppliers bc i have been using ony graingers and i am afraid there might me some much better quality to be had for a much smaller price tag. that being said, i must clarify that i do not mind spending enough money to get the good stuff that can be sharpened and reused without being burned in the process. All i have on this mag drill is just the regular attachment that every drill has on it. THAT THREE LEGGED CHUCK DEALY. some more of my kick butt terminology. It is a milwaukee, the bigger or the 3 bigger ones they have. i bought the best most solid thing i could find in my area. i like it a lot. can be slowed way down if i turn the dial far enough. so anyhow, i will check on that power tap deal. that would be neat and i can see how it might work out with the drill size you guys are saying. hey, i have also heard the water is the best thing to use rather than oil or whatever, it doesn't seem like it to me but could this hold any truth? oh and plantation, i bet i am selling this rhyalite ballast for a whole more per ton than you guys sold yours for. I mean, there has to be a reason why i keep on doing it right????????
08-19-2009, 07:16 PM #16
Its tough to get enough feed pressure on a mag base drill to drill AR400 very well. Sounds like you're going to do this on an ongoing basis, and if so, you oughta think about getting yourself a radial drill. I've used one to drill a bunch of 1 1/2" holes in 2 1/2" AR400. Just engage the power feed and watch it work. For lube, I don't think you can beat the dark sulfurized cutting oil as is used for pipe threading. You can get that in gallons from any plumbing or piping supply house, marketed either by Ridgid or Hercules. Home Depot or Lowes may also keep it.
As long as you've got the space for one, big radial drills are dirt cheap. Something with a 15" column and a 5ft or 6ft arm can be bought in decent shape for $3000 or less, often way less. The smaller ones bring more money because there's more demand for them, but its hard to beat a big 'un for holes in stuff that's mean to drill. They take Morse taper shank drills and you can also get tap drivers with MT shanks for use in power tapping.
I agree making these parts is well worth the effort. Sounds like you bought the AR plate for about $1/lb and the factory wear plates are going for better than $4/lb. Lots of room in there to save some money. Based on the application, and having done some quarry maintenance parts in the past, I think you can safely go to a 57/64 drill for the tapped holes like someone mentioned above. That'll cut the torque required for tapping way down. You could likely use a spiral point tap, also called a gun tap, which works well for power tapping since it pushes the chips ahead of the tap instead of collecting them in the flutes.
Vulcan has a couple quarries here. One of them has an 8 ft Telesmith jaw. The jaw itself weighs over 100,000, toggle beam about 95,000, and the flywheel about 145,000. For times when something gets stuck or turned where the jaw won't break it, there's a hydraulic hammer with a 10" dia bit the operator can use to break the rock while he sits at his desk and wiggles a joystick. The jaw makes rip rap size stuff that's fed to a herd of cone crushers down the line.
They've been blasting in the same pit for over 30 years. Last time I rode to the bottom of it, it was 790 ft deep. Probably 3/8 of a mile across at the top. 3 or 4 years ago we got about 30" of rain in a week from the tail end of 2 gulf hurricanes. The creek that runs thru Vulcan's quarry got jammed up by a bunch of logs from a pallet plant upstream, and flooded the pit level full of water.
They brought in 2 floating pumps driven by 400hp diesels, and it took 3 months to pump the water back out of the pit. They were lucky that it had been raining for a few days before, because they'd walked an almost new Hitachi EX880 shovelfront and a couple more big pieces up out of the pit to do some maintenance on them. Had it not already been raining for a few days, those machines woulda been at the bottom of the pit over a normal weekend.
08-19-2009, 09:13 PM #17
If you aren't something is definitely wrong.
The power tapping they are referring to is putting the tap itself in your mag drill and running it slow and following the tap down with the drill, letting the drill motor do the turning for you. No attachments needed.
The taper they are talking about holds better than a drill chuck, but are more expensive per drill.
08-20-2009, 06:09 PM #18
so whoo can i get these things from? who has a reliable provider who can ship great cutting tools to me? i need good suppliers, if any of you have ever had anything to do with the great city of el paso, chihuahua, mexico( thats right, it belongs to them now, maybe not legally but they have taken it over) then you will know what i am talking about. the thread might be dieing, but someone please help me out with this last step. thanks a million for you alls help.
08-20-2009, 06:57 PM #19
www.mscdirect.com is where I would start.
They have anything and everything. They will ship you a catalog for free and it has around 4,000 pages with small print. If it exists they can get it and ship it to you. If you need something tool wise and they don't have it, it may not be made.
08-20-2009, 07:03 PM #20
Sounds like you are out there by El Paso. Not sure who is close to you for convience. There is a company called REX Supply that is out of Houston, they may have a branch office there. I know people laugh at Fastenall, but find their place out there. They can get you cutting tools as mentioned above. I'm sure there are industrial supply stores some where in El Paso you can deal with too, if not there New Mexico. Get the "Yellow Pages" out look!