using insert drill (u-drills) on a cnc plasma machine

cruz03 · Nov 12, 2020

Hi everyone,

i recently bought a cnc plasma table with a drill head.
i cut a decent amount of 20mm (little more than 3/4") steel plate, with the holes ranging between 14mm (9/16") and 25mm (1").
reason i bought the machine with a drillhead is so i could drill holes under a diameter of 1.5 of the thickness of the plate.

i'm looking at the option of using insert drill or U-drills.
my question is wether a drill head on a cnc plasma table can handle this
regarding RPM and rigidity.
it's a import machine from china, so not a super heavy duty 15 ton machine, but i believe also not the lightest machine.
i'll upload some pics of the machine.

- it's belt driven (not good i suppose)
- 450-3500 rpm
- don't know the horsepower yet

i'm not looking for speed like on a VMC, slow and steady will also do.
because now i drilling them afterwards on the drill press with a annular cutter

also if it's possible,
what is the best option for clamping the drill?
the machine will probably come with a drill chuck and a morse taper MK2 or MK3.
collect chucks a option?

thanks everybody

DDoug · Nov 12, 2020

cruz03 said:
Hi everyone,

i recently bought a cnc plasma table with a drill head.
i cut a decent amount of 20mm (little more than 3/4") steel plate, with the holes ranging between 14mm (9/16") and 25mm (1").
reason i bought the machine with a drillhead is so i could drill holes under a diameter of 1.5 of the thickness of the plate.

i'm looking at the option of using insert drill or U-drills.
my question is wether a drill head on a cnc plasma table can handle this
regarding RPM and rigidity.
it's a import machine from china, so not a super heavy duty 15 ton machine, but i believe also not the lightest machine.
i'll upload some pics of the machine.

- it's belt driven (not good i suppose)
- 450-3500 rpm
- don't know the horsepower yet

i'm not looking for speed like on a VMC, slow and steady will also do.
because now i drilling them afterwards on the drill press with a annular cutter

also if it's possible,
what is the best option for clamping the drill?
the machine will probably come with a drill chuck and a morse taper MK2 or MK3.
collect chucks a option?

thanks everybody
View attachment 304448 View attachment 304449 View attachment 304450 View attachment 304451

I always thought that drill head was for a starting hole on thick plate.

1/2" dia. (13mm for you) would be a stretch from what I am seeing on that machine.

cruz03 · Nov 12, 2020

digger doug said:
I always thought that drill head was for a starting hole on thick plate.

1/2" dia. (13mm for you) would be a stretch from what I am seeing on that machine.

yeah, 25mm is not going to happen but i cut 20mm baseplates with 6 holes of 14mm in each plate.
i would atleast wanna do that.
i think i read somewhere that insert drill require less downfeed pressure.
that's why i suggested that but any other way that would work is also good for.
i just wanna have most of the holes done on the machine wihtout the need to do it afterwards.

DDoug · Nov 12, 2020

cruz03 said:
yeah, 25mm is not going to happen but i cut 20mm baseplates with 6 holes of 14mm in each plate.
i would atleast wanna do that.
i think i read somewhere that insert drill require less downfeed pressure.
that's why i suggested that but any other way that would work is also good for.
i just wanna have most of the holes done on the machine wihtout the need to do it afterwards.

Not what I have experienced, insert drills take more thrust.

BTW your numbers, 25mm is that the thickness or dia ?

Thickness is not what takes the torque nor HP.

cruz03 · Nov 12, 2020

digger doug said:
Not what I have experienced, insert drills take more thrust.

BTW your numbers, 25mm is that the thickness or dia ?

Thickness is not what takes the torque nor HP.

the plate thickness 20mm
the other numbers are the hole diameter.

DDoug · Nov 12, 2020

cruz03 said:
the plate thickness 20mm
the other numbers are the hole diameter.

That's the way I read it the first time.

What if you used the machine to drill pilot holes (1/4" dia. or so) and then second op them on a drill press ?
This way, the machine does all the locating, picking up the existing holes on a drill press is easy.

ChipSplitter · Nov 12, 2020

Insert drills will NOT work for you, even 14 mm. Not only do they take a lot of thrust, they are also horrible at self-centering.

It would shake your machine to pieces. Or take a walk across the sheet. :eek:

The only drills that would maybe work would be a HSS twist drill or an Allied spade drill.

cruz03 · Nov 12, 2020

digger doug said:
That's the way I read it the first time.

What if you used the machine to drill pilot holes (1/4" dia. or so) and then second op them on a drill press ?
This way, the machine does all the locating, picking up the existing holes on a drill press is easy.

that would be the next option, if there's no other way.
but ChipSlitter said something about spade drills, maybe with those i can go up to 14mm-16mm diameter.

cruz03 · Nov 12, 2020

ChipSplitter said:
Insert drills will NOT work for you, even 14 mm. Not only do they take a lot of thrust, they are also horrible at self-centering.

It would shake your machine to pieces. Or take a walk across the sheet.

The only drills that would maybe work would be a HSS twist drill or an Allied spade drill.

okay, interesting.
looking at the machine and drillhead, do you think 16mm would be possible?

Limy Sami · Nov 12, 2020

cruz03 said:
okay, interesting.
looking at the machine and drillhead, do you think 16mm would be possible?

In wood possibly !!! FYI - drills take a lot of driving in steel, and the beigger they are, the more mumbo they need

cruz03 · Nov 12, 2020

i guess than my best option is to just pre drill them on the table with 6mm cobalt drill.
not what i was hoping for, i wanted to eliminate the second step (drilling on a drill press).

DDoug · Nov 12, 2020

cruz03 said:
i guess than my best option is to just pre drill them on the table with 6mm cobalt drill.
not what i was hoping for, i wanted to eliminate the second step (drilling on a drill press).

You could be drilling them while the machine is making the next part.
If these parts are too large for a standard sized drill press, a magnetic drill press might just
be right for this.

john.k · Nov 12, 2020

I think drilling 16mm/5/8" holes would be easily achieved......even more so if you were to use a small pilot hole,which would also solve any tendency for drill wander at start.Use sharp HSS bits,no problems.

CarbideBob · Nov 12, 2020

cruz03 said:
...
i think i read somewhere that insert drill require less downfeed pressure.

That would be weird.
Even 5/8ths in one shot with a good drill bit over many holes seems big for the posted machine.
One, two or five holes okay, 100 holes, I'm thinking things go bad.
You mention annular cutters. Here all that metal removed does not have to be made into chips.
Basically they are saws. Not cheap and sort of sensitive guys as to how they are used.
Saw, drill, turn, mill, grind.

I do see the not wanting a previous op. Here not so much the cutting time but the load/unload and staging of parts.
As machinist we all want to see chips fly but sometimes crazy slow and painful on one section works for parts out the door.
Bob

cruz03 · Nov 12, 2020

digger doug said:
You could be drilling them while the machine is making the next part.
If these parts are too large for a standard sized drill press, a magnetic drill press might just
be right for this.

yea, that's how i do it now, with my current plasma table.
but the annular cuttters get dull fast, and sharping them is not worth it.
maybe if i predrill it on the new plasma table i can use a normal cobalt drill bit.

gregormarwick · Nov 12, 2020

I'm going to go against the crowd and suggest that the drill head and machine can probably handle it, at least at the smaller sizes of hole.

In particular I'm going to disagree with ChipSplitter and suggest that an Allied style spade drill is probably the worst possible option.

Generally, insert (U) drills generate far less torque and far less feed force than about any other type of drill, but especially spade drills. Also, most modern insert drills are in fact self centreing.

For example, a 14mm Sandvik 880 in mild steel at 3.5k rpm and a reduced feedrate of 140mm/m generates only 5.44Nm of torque, and 648N of feed force.

The real challenges are going to be holding the plate secure during drilling, and mounting the drill to the spindle.

DDoug · Nov 12, 2020

cruz03 said:
yea, that's how i do it now, with my current plasma table.
but the annular cuttters get dull fast, and sharping them is not worth it.
maybe if i predrill it on the new plasma table i can use a normal cobalt drill bit.

"Mag drill" does not always equal "Annular cutter".... mine uses mt-3 drills.

I think if you put a 1/4" dia. hole all the way thru with the new table's drill head, when you get to the mag drill, using standard twist drills, you'll find
the drilling fast & easy.
As far as slag dulling the drills, twist drills are easy to re-sharpen.

Bill D · Nov 12, 2020

How about using a special made core drill. 1/4" tip 25mm long then the 20mm or what ever max diameter you need. This drills the pilot hole and full size hole in one operation.
Bill D.

DDoug · Nov 13, 2020

Bill D said:
How about using a special made core drill. 1/4" tip 25mm long then the 20mm or what ever max diameter you need. This drills the pilot hole and full size hole in one operation.
Bill D.

Why ?
Special drill will dull with the slag & scale just like any common twist drill.
But getting it sharpened will be much more expensive than simply walking over to a bench grinder
to sharpen a common twist drill.

ChipSplitter · Nov 13, 2020

gregormarwick said:
I'm going to go against the crowd and suggest that the drill head and machine can probably handle it, at least at the smaller sizes of hole.

In particular I'm going to disagree with ChipSplitter and suggest that an Allied style spade drill is probably the worst possible option.

Generally, insert (U) drills generate far less torque and far less feed force than about any other type of drill, but especially spade drills. Also, most modern insert drills are in fact self centreing.

For example, a 14mm Sandvik 880 in mild steel at 3.5k rpm and a reduced feedrate of 140mm/m generates only 5.44Nm of torque, and 648N of feed force.

The real challenges are going to be holding the plate secure during drilling, and mounting the drill to the spindle.

Have you ever tried using a U-drill and an Allied spade drill in a radial arm drill press (more rigid than the OP's plasma) ???? I have.............

The spade drill centers itself. The U-drill was a disaster. I wasn't joking when I said it might go for a stroll across the sheet.

using insert drill (u-drills) on a cnc plasma machine

Plastic

Diamond

Plastic

Diamond

Plastic

Diamond

Titanium

Plastic

Plastic

Diamond

Plastic

Diamond

Diamond

Diamond

Plastic

Diamond

Diamond

Diamond

Diamond

Titanium

Similar threads