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madman
05-04-2008, 07:56 PM
46 millimeter counterbores in two inch plus thick hot rolled flame outs. I was sitting her tonight musing over another Job Layoff , drinking some Beers. I received a Phone Call ,can you counterbore 46 millimeter holes in mild steel. I said sure no problem . Then later it was oh oh theyre huge. What would be the best way to do these? They are a18 inches long 8 inches wide and six holes per plate. Theres six plates of them to do. Thanx

moldmonkey
05-04-2008, 08:00 PM
If you have CNC capabilities, just mill circle it.

If not, a rotary table.

IOWOLF
05-04-2008, 08:51 PM
Or a boring head.

John Stevenson
05-04-2008, 08:59 PM
Madman,
What about this thread?

http://bbs.homeshopmachinist.net/showthread.php?t=5519&highlight=tool+cutter

The pic is missing, broken link but I'll see ifI can find it tomorrow.

Millbo
05-05-2008, 06:54 PM
Madman,

I've used these in my last shop with good luck. Multi-Tool is the defacto name of these I think. We had 2" plus sizes so I know their out there.

Hope this helps.

http://www.jtsmach.com/jtswebshop/Pr_CuttingTools/D337.asp

Tucker
05-05-2008, 07:35 PM
sounds to me like it all depends on what you have to work with and your hole locations and tolerance.

toastydeath
05-05-2008, 08:10 PM
What I want to know is who calls that damn thing a counterbore?

I have learned, through the mistakes of others, to treat any seemingly innocuous question as some sort of trick. "I need some counterbores" is a vastly different question than "Are you able to <insert simple task here>?" One implies work needs to be done; the other will require a gun drill and five axis VMC, no matter how simple it sounds.

oldtiffie
05-05-2008, 11:47 PM
What I want to know is who calls that damn thing a counterbore?

I have learned, through the mistakes of others, to treat any seemingly innocuous question as some sort of trick. "I need some counterbores" is a vastly different question than "Are you able to <insert simple task here>?" One implies work needs to be done; the other will require a gun drill and five axis VMC, no matter how simple it sounds.

Good call TD - again.

Seems that some-one either needs reaming-out or a good dose of cynicism or common dog ---- (fill your own 4-letter word to suit as a substitute for "sense").

Could also mean that the "Client" has been to another shop which either knocked the job back or quoted on it and the "client" just picked up the term and is "quote- (sucker??) shopping".

Accepting a job when not having concentrated on it or worse - "buying" the job or "under-cutting" is a sure way to win the "race to the bottom" and "going out back-wards".

drof34
05-05-2008, 11:58 PM
can you counterbore 46 millimeter holes in mild steel.
So what size does he want the counterbores?

Machtool
05-06-2008, 12:17 AM
46 millimeter counterbores in two inch plus thick hot rolled flame outs


They are a18 inches long 8 inches wide and six holes per plate

Where’s the rocket science going on here. Isn’t he saying he has some 18” x 6” rectangular plates, 2” thick. Surely that’s a Bridgeport sized job. Wont they be going through the 2” section. Probably M30 counterbores.

You could just drill them as normal, then sharpen your drill to a flat point to square out the seat. For 36 holes. Have you got a radial arm drill.

Phil.

jimmstruk
05-06-2008, 05:04 AM
When did a hole less than 2 inches diameter become huge?? Anyone with a 9x42 mill should do these holes easily. The owner of the plates will have to provide specs to work to. JIM

toastydeath
05-06-2008, 01:13 PM
Oh, I read that as an 18" deep, 8" wide counterbore.

I need to slow way, way down on the whole "reading" thing.

jimmstruk
05-07-2008, 10:00 AM
I owe Madman an apology for the remark about the hole size being no problem. After I wrote that I got to thinking, what if that guys shop is equiped with Sherline or some similar size equipment? My apologys are offered if that be the situation. My personal shop has larger tooling, so I would not have a problem with a job that size. JIM

jkilroy
05-07-2008, 10:18 AM
46mm is 1.811 inches, so can you find out if you can go 1.8125 (1 13/16)? Thats a counterbore you can probably buy. Check these guys out, they have a part listed.

http://www.supertoolinc.com/

camdigger
05-07-2008, 11:48 AM
Depending on how big the hole is that you need the counter bore for, this tool may be of use.
http://www.practool.com/super-drill.html

Being an experienced machinist, it wouldn't be too hard to duplicate. It's basically a fly cutter. The original design has a very slight angle on the cutter to cut a very slight cone to sever the outer rim before the inner to prevent snagging on through hole work. The relief behind the cutting edge is quite subtle to allow feed control and gives excellent durability.

Cam