advice on drilling a quantity of largish (1" ) holes in 1 - 1.5" steel

Mcgyver · Dec 11, 2013

I need to make around 1000 holes, varying diameters, but say 1 5/16" as a for instance in 1" and 1.5" plate. We'll be plasma cutting the 1" blanks out and probably torching the 1.5" blanks. Tolerance is 1/32 on diameter and location. Material is 44W, fairly run of the mill (literally) mild steel. In the 1" I can plasma cut the holes but at 1" can't hold the tolerance. There are four parts involved, each with several holes, parts are typically 8"x8". I'd make simply jigs for the drilling

Equipment for making holes (in addition to the plasma) is a radial drill, gear head drill press and a vertical knee mill. There's a good selection of large hss drills but if there was a silver bullet i'd consider buying it

I can make a hole, but I lack experience making volumes of them in plate this thick and in larger diameters so am unsure of what approach would be best. Cycles times start to matter with this volume. I'm interested to hear what approach you guys would take. Would you plasma cut then ream? drill the entire hole (no plasma), regular old hss? pilot hole? slugger drill? other crazy assed ideas?

thanks for any advice you can give

thanks

gmach10 · Dec 11, 2013

I used to use slugger or peripheral drills in a radial arm drill all the time. Jancy makes bits with up to 6" depth of cut. 1 5/16 is not a problem. Used 2 1/2" without any issues. Liked a product called Edge Cream for lubricant available at Grainger. Not sure of the sfm just played with speed till I got good results. As far as size goes usually held pretty close can't remember but never recall anything more than a couple thou over. The finish in the bore of the hole was as good as or better than reamed.

johnoder · Dec 11, 2013

thanks for any advice you can give

Water Jet complete, leave the drills turned off

kpotter · Dec 11, 2013

If you are going to drill them use an insert drill I drill about 100 1inch holes per month with one. No pilot hole no step drilling just one drill and one perfect hole.

Krovvax · Dec 11, 2013

or if you dont want to invest alot in a insert drill go with a spade drill so you just have to change the "insert" to do different hole size for futur job. I drill up to 1 3/4 with spade drill on ours radial drill so you might be good with this too. Stack the 4 plate together and drill the 4 plate in 1 shoot.

Mcgyver · Dec 11, 2013

kpotter said:
If you are going to drill them use an insert drill I drill about 100 1inch holes per month with one. No pilot hole no step drilling just one drill and one perfect hole.

sounds good

Water Jet complete, leave the drills turned off

problem with waterjets (at least that i've been exposed to) is they are sloooow. oh, and I don't have one. If we're allowed to dream, laser would be the way to go, but hey, If I had a 6kw laser this thread wouldn't have happened.

Limy Sami · Dec 12, 2013

You don't say which radial drill you have, but a decent sized radial with an ordinary HSS twist drill will eat those holes for breakfast, no pilot drilling, just one hit to diameter - job done.

adama · Dec 12, 2013

Im with sami, i have drilled that kinda number of holes on a radial and no pilot or anything else, just set some good stops on a vice or the table if the bits are too big and goto town. Its pretty quick too if the 1000 holes is spread across a bunch of different - small batches of parts.

I do know that at least over here gas - plasma and drill will end up a lot cheaper per part than water jet. That said, you only need a 4.5Kw laser to cut the inch thick parts.

DDoug · Dec 12, 2013

Neighbor shop did a similar job about 5 years ago, 5' long bars x 2" thick with similar holes (to yours)
spaced down the length.

He made a clamp on top drill jig, but he only had one operator (so jig rode along the whole time),
used a spade drill with coolant adapter,
fabbed up large tin tank around Cinicinnati box column drill (very much like radial drill).

He looked into the insert drills, but the low ridgity of his set-up kept him from
spending the money on the more expensive (but faster drilling) bit. did not
want to risk it.

If you have more than one operator, jig can be lighter and simpler, first operator can
spot drill hole locations using jig.

country_boy · Dec 14, 2013

Milwaukee steel hawg cutters are available on ebay for a fraction of their new price. Buy a MT arbor ($150) which comes with a squirt bottle and tube that feed coolent through the center of the annular drill

I've done this all day. using a milwaukee mag drill press. Cutting depth is 2" only downside is you have to drill one piece at a time, as removing the slug before punching through sucks. Punch through and it is ejected. Far less HP is required to remove the 1/8" shell of meterial then the 1-5/16 complete hole. Never checked the tolerence, but it's got to better then plasma. Finish is reall nice

davethorik · Dec 14, 2013

Krovvax said:
or if you dont want to invest alot in a insert drill go with a spade drill so you just have to change the "insert" to do different hole size for futur job. I drill up to 1 3/4 with spade drill on ours radial drill so you might be good with this too. Stack the 4 plate together and drill the 4 plate in 1 shoot.

I have found this works unless the plates are out of flat. If there are gaps in the plate, no bueno. Drills will melt. I am not the biggest fan of spade drills.

wgnrr1 · Dec 14, 2013

I do this quite frequently. Build a fixture with bushings. Your choice of drill, but something good, not Chinese crap. Flood coolant. I run a hard feed also, my radial takes it very well with coolant. Holes are usually within .005.

I have a Carlton radial. Very heavy built. You need a stout machine to push like I do.

Another thing to consider is how close to the edge are these holes. Plasma and torching harden the material, a lot. I have some 1 3/4 plates I drill that are lasered. Edge of hole is about 1/2" from edge of part, and can be a real PITA because of hardness. If you can find someone to waterjet them, that's the best way.

Josh

IeliteENGINEER · Dec 14, 2013

would a laser cut anything over 1 inch thick, i never seen one that was able to cut any thicker. I would drill them with a twist drill

upnorth5axis · Dec 14, 2013

I would say if you can hold the tolerance with the plasma them do the holes with that. If you can't them just drill the holes from a fixture with the parts stacked. do not pre-plasma the holes this will cause more problems than it's worth

adama · Dec 15, 2013

IeliteENGINEER said:
would a laser cut anything over 1 inch thick, i never seen one that was able to cut any thicker. I would drill them with a twist drill

Modern lasers can go a fair bit thicker, but your talking very expensive machines and ones that need a serious amount of electrical supply. A 4.5Kw laser needs a 125 amps at 415V, a further 80 amps at 415v for the chiller and then about anouther 20Kw of rotory screw air compressor. 4.5kw maxes out at 25mm in mild steel. A 6Kw laser is going to bump thoes numbers by a 1/3rd! Can not remember the max it will cut though.

exkenna · Dec 15, 2013

Boring mill with an Ultra-Dex 1" indexable drill
Shameless copy of Komet drill.

$134.oo plus a pack of inserts for about $90.00

Will blow right through there.. no problems

http://www.ultradexusa.com/ULTRADEXUSA.2011.2.C.DRILLING.pdf

kpotter · Dec 15, 2013

I need inserts for an ultradex 1.5 inch drill do you carry them?

DDoug · Dec 16, 2013

exkenna said:
Boring mill with an Ultra-Dex 1" indexable drill
Shameless copy of Komet drill.

$134.oo plus a pack of inserts for about $90.00

Will blow right through there.. no problems

http://www.ultradexusa.com/ULTRADEXUSA.2011.2.C.DRILLING.pdf

Maybe....Curt, please give a bit more info on what they can and cannot do.

We still don't know what machine the OP intends on running these on. I suspect the
linked insert drill may not work on a manual drill, with a simple drill fixture clamped on top.

Piece clamped ridgidly to a milling machine table, yes, definitley.
OP inidcated "knee mill" assume a brdigyport style thing ? enough H.P. and feed ?

Geared head drill press, probably enough h.p. and feed, but enough ridgity ?

advice on drilling a quantity of largish (1" ) holes in 1 - 1.5" steel

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