Drilling 1inch hole in 1.5 inch thick A36

Sounds like the OP is hitting a lot of inclusions, etc, in the material. An inserted spade bit or a carbide toothed hole saw might be better.

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Usually I drill a 1/4 to 3/8 inch hole all the way through and then drill with the one inch bit and use lots of cutting oil at 60 or so RPM.
That is the technique I was taught. Pilot hole slightly larger than the web of the drill for finish size. Pilot hole, finish drill, no steps in between. The finish drill employs the majority of its cutting lip to get the job done. Going in small steps focuses the cutting forces on only the far outer edge of the cutting lip, and dulls it quickly.
 
Feed rate.
Not enough of it., use a minimum of .006" per revolution feed rate, such a hole would take less then 3 minutes each to drill in that material.
300 Rpms @ .006" per revolution = 1.8" per minute X 1.5 through = 2.7 minutes, this does not include starting at the chisel point and passing entirely through, a conservative 4 minute cycle is about right.
If you have the power do not drill a smaller pilot hole, just spot it and drill straight through in one shot to size.
Use flood coolant or flood cutting oil.

There is no reason that a 1" twist drill will not produce 50 such holes between sharpening or replacement.

I have posted this in the past.
How to drill.
1 5/16" hole through 3" of A36/1018 hot rolled steel rounds.

Place parts in chuck if a lathe or vice if using a mill
Place drill in spindle or turret, a plain old HSS twist drill is used here
Turn spindle on, engage feed and let it eat, no spotting required here as the finished bore is 1.75"
.008" feed per revolution at around 80 FPM cut speed or 250 Rpms
32 parts drilled at about 3 minutes each using one used bit.
 
Jesus I can tell all you old crotchety experts have never done any thing with a smithy any thing. Well I have used to and old 1220 XL smithy for years before I got my current, the op is not an apprentice of any thing he has what he has, no carbide indexable drills or end mills. Just a deasent drill set. The smithy realy was not really a versitile machine. It was an entery level, and not much better than a drill press. Just go slow and use small steps. If you want a set aaof MT 3 collects I have a set I used on my Smithy. Hardly used some not used at all. The smithy will do it just not at production speed.
CH
 
:grin: No , we all don't have 50 hp at the spindle , but what we try to give is advise . Good advise . We do understand that time is not of the issue in most instances to many of the questions , but the correct tooling is well worth the expense . You could drill that with a 18 volt hand drill and 1" bit faster than the progress being made here . Just saying , his rpms are too high .

Too many people are injured trying to do things half ashed . I see it at work everyday . I f you can't afford a 10 dollar drill to do it safely , I understand . And no , we all didn't start out as fully tooled machine shops . We learned the hard way and not on a computer . :)

Best advise I've ever gotten and passed on . " Work smart , not hard " .
 
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Does the mill head have a back-gear function? 315 is was too fast!!! Figure the surface feet at the edge of the bit. It's cooking ,ie getting very hot! I have a very old flat belt machine with #4 Morse Taper. This beast has a back gear and auto down feed. I drilled a hole 2 1/4" thru 1" A36. Very slow but a pretty hole. Not reamed quality but better than you would have thought. I watched it and applied cutting oil as needed. 1/4" pilot and then full size.
No backgear. Yeah it is smoking. I might try the drill press. It’s at 200RPM.
 
Jesus I can tell all you old crotchety experts have never done any thing with a smithy any thing. Well I have used to and old 1220 XL smithy for years before I got my current, the op is not an apprentice of any thing he has what he has, no carbide indexable drills or end mills. Just a deasent drill set. The smithy realy was not really a versitile machine. It was an entery level, and not much better than a drill press. Just go slow and use small steps. If you want a set aaof MT 3 collects I have a set I used on my Smithy. Hardly used some not used at all. The smithy will do it just not at production speed.
CH

I hate the Smithy. I really don’t use it for much. I made the mill slightly better by putting the xy table on it at the expense of the lathe. I have another lathe. Send me a note on the collets letting me know what you want for them. Thanks
 
As a hobby machinist, I do not have to run at production speeds. Manual feeding is the best choice on my mill for a part
that I can't turn in the lathe with feed . As long as I am making curls, I am advancing in the hole. I'm gonna watch the process
carefully and if she quits drilling, I will stop and put a new edge on the bit, maybe even take a coffee break, refill the oil can....... :)
 
Drilling at 006 feed is just eating up bits.,drilling an extra 1/8 at a time is wearing off the margin,and eating up bits...........for harder steels ,reduce the speed ,never the feed.......my Richmond radial drill isnt a powerhouse ,but will easily drill 1" holes thru wearplate.with ordinary HSS drills....and plenty of suds.......you got to keep the heat down,if the chip blues with suds,slow down a bit
 
Drilling at 006 feed is just eating up bits.,drilling an extra 1/8 at a time is wearing off the margin,and eating up bits...........for harder steels ,reduce the speed ,never the feed.......my Richmond radial drill isnt a powerhouse ,but will easily drill 1" holes thru wearplate.with ordinary HSS drills....and plenty of suds.......you got to keep the heat down,if the chip blues with suds,slow down a bit
I am seeing a lot of smoke/vapor..using a ton of tapomatic. I reduce speed but it is hard to keep the smoke away (manual feed). Is the smoke/vapor ok?
 
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