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 Post subject: AR400 steel and Drills
PostPosted: Wed Jan 23, 2013 7:17 pm 
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Joined: Tue Apr 13, 2010 7:31 pm
Posts: 132
Location: Palmer, Ma
Anyone have any experience will AR400 steel?

I had never heard of it but from what I can find with Google, its used for wear plates and cutting edges. A friend of mine approached me with a possible job that would require a lot of drilling. The steel suppliers that carry it say that it can be machined with HSS, but from searching the web, most people claim it to be forged in Hell with an appetite for drills.

Any recommendations for drills? Material is 3/8" thick. I'm still waiting to hear back from him on the hole diam but its looking like either 1/2" or 3/4" holes. The job should between 50 and 80 holes so I'd like to avoid using the wrong drill and burning them up to fast.

Thanks,
Griz


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PostPosted: Wed Jan 23, 2013 8:14 pm 
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Joined: Sat Oct 03, 2009 7:13 pm
Posts: 257
Location: Eureka, California
Griz,

I have worked with and drilled material known as AR steel..abrasion resistant, but am not sure it was a 400 designation. It has more carbon than a mild steel as well as additional alloying elements. It did drill with difficulty and if one lingered in one spot too long you would work harden the hole and be up the creek. We used traditional HSS bits, no coatings involved.

If your job was an in-house deal where the material could be drilled on the bench or on a machine I would think that with a proper bit and some good cutting fluid you could prevail in fine shape.

It is tougher than the average stuff...you will notice that immediately. :)

Stuart


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PostPosted: Wed Jan 23, 2013 8:18 pm 
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Joined: Thu Mar 18, 2010 2:05 pm
Posts: 1442
Location: Northern Nevada
I have built quite a few parts with AR360, AR400, and AR500, and some AR550-600. Mostly bucket parts, and some for crushers.

AR400 isn't that bad to work with. I use HSS bits, good quality ones. Cobalt helps, but not necessary with 400. I don't think Harbor Freight bits would hold up well. :)
I go a bit slower than A36, and KEEP IT COOL, and don't linger in the hole! If you star turnin' chips blue, it can harden up in a hurry.....hard enough you'll have to use carbide. The stuff will also work harden pretty quick if you have a dull bit, or don't keep the feed to 'er. (Don't ask me how I know)
3/8" plate, a squirt bottle would be fine. I usually work with 1" and above, and use mist.

Attachment:
Bucket Bosses.jpg
Bucket Bosses.jpg [ 264.66 KiB | Viewed 752 times ]


These bucket bosses are 2-1/2" thick AR400, and have M12-1.75 thru tapped holes. Drilled thru with a Hertel HSS bit,(no cobalt) and I used a Hertel spiral point tap, TiN coated.
There were 8 of them 2-1/2" thick, and 8 more that were 1" thick. I used one drill bit, sharpened once after I finished drilling the thick ones, and one tap threaded 'em all.....still sharp....after making a couple dozen more of these things later.
These things get welded into the bucket, and line-bored later.

I've drilled, and tapped holes in AR500 plate with HSS too..... not so pleasant as 400, you just have to slow down, and keep it COOLER.... but do-able. :)
AR600.....I used carbide & flood.

You might take a look here: http://www.hardox.com/en/Handling/Machining1/
Hardox is a popular brand of AR plate, and available locally, so I work with it a lot.

Bill

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PostPosted: Wed Jan 23, 2013 8:21 pm 
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Joined: Sun Jun 27, 2010 10:43 pm
Posts: 2513
Location: pendleton or
had to work some for a cutter wound up using a mag drill with annular cutters, cobalt and lots of cololant


http://www.zorotools.com/g/Annular%20Cu ... QgodDTkAcg


the previous description is accurate in my book pay attention to details and you will be ok


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PostPosted: Thu Jan 24, 2013 10:40 pm 
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Joined: Tue Apr 13, 2010 7:31 pm
Posts: 132
Location: Palmer, Ma
First off thank you all for the replies.

Stuart- Thankfully I will be able to do this in house. They would be supplying the material, all i need to do is drill it so I will either be using my drill press or my mill if I can't get the rpms of the drill press to work out to the right sfpm. The math to figure that out may end up being another newbie post =]

Bill- Any recommendations for the drill tip angle? And would a collet of the right size have enough grip to use with a drill? I could use my chuck if I have to but its only a 1/2" so I would need to use a reduced shank if they go for the 3/4" holes.

Hammermill- Have you ever tried to use an annular with an adapter in a drill press or mill? I've never used a mag drill and probably wouldn't ever use it other than this job if I haven't needed one by now.

Sorry for all the questions but I really do appreciate the replies. I'll be honest, this is the first project I've been leery to take on. Thankfully drilling the AR400 is only a small part of it. The rest involves a bunch of parts made from 6061 and 1018 which shouldn't be a big deal other than being the largest project I've done. I just hate to pass it up.

Griz


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PostPosted: Thu Jan 24, 2013 11:21 pm 
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Joined: Sun Jun 27, 2010 10:43 pm
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Location: pendleton or
i have used them in a mill before. they are effective as you are only removing the outer 1/8 or so of the hole so its less material to cut. also they can be resharpened

a interesting aplication is redrilling a safe that had had ball bearings driven into the old hole. good luck


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PostPosted: Fri Jan 25, 2013 8:59 am 
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Joined: Thu Mar 18, 2010 2:05 pm
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Location: Northern Nevada
135 degree split points are the way to go, if you're buying. 118's will work though.
I've used collets on drills and never had a problem, although I don't know if it's a recommended practice. If it's not, someone here will scold me.... :oops:

I drilled some 1/2" AR400 plates for a teletram truck. A bunch of 1-1/8" holes. I drilled a 1/4" pilot, and then drilled to 1-1/8" with a 118 deg 1/2" shank S&D bit. All I had for my mill at the time was a 1/2" chuck. Worked fine.

Hammermill's idea of the annular cutter sounds good. They are time savers, especially for larger size holes. I've used them in A36, T1, and A572 with great success. Also did a bunch of rail at a mine once, as the client didn't want us burning the holes for the fish plates. Lot of crap in rail.....that job took some sharpening, and several new bits.

I've used an annular cutter in my mill once, for some 2" holes in 1" A36. It was before I got my 3/4" ball bearing chuck, so I used a collet to hold the cutter. Only 4 holes to drill, but no problems....and it was quick.

Bill

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PostPosted: Sat Jan 26, 2013 1:10 pm 
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Joined: Tue Apr 13, 2010 7:31 pm
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Location: Palmer, Ma
Thanks a lot you guys. You probably saved me a bunch of money and time if this job does materialize.

And maybe a few extra gray hairs =]

Griz


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PostPosted: Sat Jan 26, 2013 1:46 pm 
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Joined: Sun Jun 27, 2010 10:43 pm
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Location: pendleton or
you are most welcome


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PostPosted: Sat Jan 26, 2013 1:53 pm 
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Joined: Thu Mar 18, 2010 2:05 pm
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Location: Northern Nevada
You're welcome, and I hope you get the job!

No grey hair....light blond maybe....but no grey.

:D

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PostPosted: Sat Jan 26, 2013 3:14 pm 
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Location: Vancleave, Mississippi
Whatever hole diameter you end up with, you should start with a pilot hole. 1/4" should work.

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PostPosted: Sat Jan 26, 2013 4:39 pm 
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Location: Northern Nevada
Mr Ron wrote:
Whatever hole diameter you end up with, you should start with a pilot hole. 1/4" should work.

Regular point, I agree......

With a 135 degree split point, I'd skip the pilot. That's what I like about split points, and why I buy 'em and regrind 'em that way....one less operation.

242 1/2"-13 holes, so drilled 27/64" dia. I'd a been awful busy drillin' pilots.... :)
Attachment:
Lotta holes.jpg
Lotta holes.jpg [ 240.11 KiB | Viewed 628 times ]



And, of course, annular cutters don't need a pilot.

Bill

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