Drilling 3.151 Hole in 4140 HT.

[Ron Branch @ Verisurf]

Guy wanted to share this. We have a part that is 21" long and needs a 3.201 hole thur it. In the past we would send this out for Gun drill. We have 60 parts to do and the company that was going to do it wanted $80 a part to do it. That sound reasonable right. Well I went against everyone and got a Comet Drill in here. The drill with everything was $2600. The idea was we need to send it out could not afford the machine time this would take and I have experience with these drills and felt we could do it in 20 minutes. At our shop rate with buying the drill we would come out at $4592. Well we are doing the hole in about 10 minutes. So it really came out to $3596 and we have the tool for 6 other jobs right behind that one. We have 50hp machine and it is pulling about 60% spindle load. Just wanted to put it out there encase others had something coming up like this.

 

We are drilling it at 450 sfm at .0064 per rev.

 

HTH

[peon]

I used those comet drills in the past with a former employer. They were AWESOME!!! It's hard getting owners to fork over that kinda money for one drill. They cannot fathom the reality!!

[Tom Dorgan from American Precision]

Great tools. Used Komet to core and bore large gate valve castings back in my 4 axis lathe days.

[shazam/TPP]

have a link for comet drill? i did a google search and not much there.

[specv]

Its Komet with a "K"

[Don M]

Excellent Ron.

Good job!!!

 

Thanks for sharing the info.

[Mic6]

C'mon Ron, quit hiding the video of that drilling op.

[Tony35]

ya lets see some chips

[Ron Branch @ Verisurf]

Here is the link: I will post up a video later. We ran the 1st part with a lose cartridge with no screw so waiting on the screw.

 

Here is a Link: Yeah sorry Komet with a K.

 

It is the KUB Centron Drill system.

 

 

Here is a picture:

HTH

[Joe788]

What kind of tolerance were you able to hold with the drill? Sounds like a pretty good setup!

[Ron Branch @ Verisurf]

We are holding +/-.005 with no problem. We are drilling 12" on the 1st side and then no the 2nd side we are drilling the rest. The biggest advantage to these drill are 2 key components. They have a Spot drill for the center and they have wipers that guide it like a gun drill. We did make our own adapter verses what they offered. Reason for that was we could time it like we wanted verse being limited to the timing they restricted us too.

[Mic6]

How much coolant pressure did you have goin thru it? and what machine is it on?

[Ron Branch @ Verisurf]

Standard pressure might be 150 psi if we are lucky. The machine is a Viper Lather. It has a 15in Chuck, 72" between centers.

[mike561h]

.005 TIR is awesome at 21 inches. Are you getting much mismatch in the center of the hole.

[Ron Branch @ Verisurf]

Almost none a couple thou this thing runs better than anything I have seen. Like I said it was a chunk of change, but as everyone can see know well worth the investment.

[Ron Branch @ Verisurf]

Here is some video of it buried inside the part and starting:

 

Link

 

Linky 2

 

Enjoy.

 

Oh and I went out there and kicked it up a little more and we are drilling 12" deep in 4 minutes.

[Tony35]

very nice

tooling is everything

do you think if you had more coolant psi you could push harder?

[Ron Branch @ Verisurf]

Coolant is not the issue. We are at 75% load on the spindle and Z axis and it only take 4 minutes I think that is pretty respectful and one of those be happy with what you got situations.

[Tony35]

you have 75% load on the z axis servo

you dont want the servo to kick out on ya

getting good insert life?

[Guest CNC Apps Guy 1]

Nice job Ron. Way to smack those penny pinchers around with facts.

[Ron Branch @ Verisurf]

Well after 10 parts inserts look untouched. If I had 100hp I would try .01 to .012 per rev and probably kick it up to 600 sfm. Think it would take about 2 minutes but I do not so have to deal with what we got.