Power feed drilling

[Matt de HoestParticipant @mattdehoest99598]

Hi all, i wonder if you can help.

I was looking for a mill and had the opportunity to buy a biggish 6hp universal milling machine. It is awesome but downside is no quill on the vertical head. No problem i thought, it has powerfeeds and rapids in all direction so i can drill on on xaxis feed.

Unfortunately when it comes to actually doing it i have made more broken drills than i have holes!! First try was 6mm bit through a 3mm pilot. Drill decimated. I thought probably the result of too high spindle and speed (and maybe too dull a drill .. Maybe!!). Second try – lower feed, smaller drill – majoy snappage but very little hole making. Third try – higher spindle speed, same feed – got me a 4mm deep hole before the drill failed.

Ive found a twist drill speed and feed calculator (http://www.custompartnet.com/calculator/drilling-speed-and-feed) and looked at recommendation in machinerys handbook (and ill also sharpen the next drill!!). Is there any reason i cant drill on a quill-less mill by raised x-axis on power-feed and does anyone have any tips?? Regards matt.

[Matt de HoestParticipant @mattdehoest99598]

[roy entwistleParticipant @royentwistle24699]

A lot depends on what material you are drilling, personally I wouldn't consider power drilling anything. Feeding the drill by hand you can feel if it's cutting and apply pressure accordingly, but you can't do that on machine without a quill

Use the mill for milling and a drill for drilling

Roy

[John ReeseParticipant @johnreese12848]

Unlike drill press power feeds milling machine power feeds are independent of the spindle rotation. Once you determine what RPM you want to run multiply the RPM by the feed per revolution to get the feed rate in inches per minute or mm per minute. It is unlikely the machine speeds will correspond exactly to what you calculated so pick the speed just below what you calculated. Remember this: when you change the spindle speed you need to recalculate the feed rate.

I used to drill with the horizontal mill on occasion. It worked well except for the nuisance of calculating the feed rate.

You can also drill by hand feeding.

[HOWARDTParticipant @howardt]

How many flutes on your 6mm drill? You need to use three flute to allow the existing hole to guide the drill, two flute will snatch as one flute bites.

[Mark RandParticipant @markrand96270]

Try feeding the Z axis instead of the X axis.

[BikepeteParticipant @bikepete]

Posted by Matt de Hoest on 16/09/2017 19:27:26:

I was looking for a mill and had the opportunity to buy a biggish 6hp universal milling machine. It is awesome

Pictures of the mill please!

[HopperParticipant @hopper]

It can be done. I recently finished drilling 814 holes of 3/32" diameter through 1/4" steel plate under power feed without a breakage. This was with the drill bit mounted in a chuck in the lathe spindle and the job (dividing head index plates) mounted to the lathe cross slide. Power feed was by the usual leadscrew, at a rate of about .003" per revolution and spindle speed of about 950rpm. I used a short stub drill bit sticking out of the chuck only about half an inch or so.

What feed rate are you using on your milling machine feed? Can you slow it down?

How much slop is there on your Z axis ways? Are the gibs snugged up, or can the job move about laterally while being drilled, leading to broken bits? Do you have the X and Y axes locked to stop movement there?

Edited By Hopper on 17/09/2017 07:18:24

Edited By Hopper on 17/09/2017 07:21:02

[John HaineParticipant @johnhaine32865]

CNC mills drill with power feed all the time. I have only once had a problem, when the feed rate was completely wrong. Take it very slow to start with, and it may help to "peck" at the work, frequently withdrawing the drill to clear swarf. There should also not be a problem with picking up a pilot hole but do you really need one?

[Tony Pratt 1Participant @tonypratt1]

Sorry to rain on your parade but drilling on your mill is never going to be easy, most drilling operations require 'pecking' & that's what you cannot do.

Tony

[JasonBModerator @jasonb]

You can flick the feed from down to up and that will peck at the hole, as said above that is how a CNC machine does it so no difference between that and manually changing direction of feed.

This applies to using the table feed not a quill feed driven off the spindle

[RobinParticipant @robin]

Posted by Tony Pratt 1 on 17/09/2017 09:50:19:

most drilling operations require 'pecking' & that's what you cannot do.

It's a trap isn't it. You know perfectly well that G83 will peck and you are just waiting for a Newbie to say you are wrong so you can strike. Go on then, I'll bite…

"You're wrong"

[Tony Pratt 1Participant @tonypratt1]

Posted by Robin on 17/09/2017 10:16:53:

Posted by Tony Pratt 1 on 17/09/2017 09:50:19:

most drilling operations require 'pecking' & that's what you cannot do.

It's a trap isn't it. You know perfectly well that G83 will peck and you are just waiting for a Newbie to say you are wrong so you can strike. Go on then, I'll bite…

"You're wrong"

Robin,

I haven't got a firkin clue what you are on about ref ' it's a trap isn't it', the OP has a manual mill so what has G83 got to do with it?

Tony

[EmgeeParticipant @emgee]

If the drill chuck is mounted in the horizontal socket powered feed drilling could be carried out using the Y axis, but with such a large motor indicates an early machine that would not have high spindle speeds, especially on the horizontal spindle, hence much lower feed rates are required to avoid drill breakage.

The X axis could also be used for powered feed drilling if the head was turned 90 degrees, this may be the best method as usually on a universal mill vertical spindle speed is double that of the horizontal spindle.

Emgee

[RobinParticipant @robin]

I think this is all pie in the sky because we don't know what he is drilling in to, or did I miss something? Are we assuming quality bits just because he has bought a big power feed mill? In the words of Isaac Asimov, "Insufficient data for meaningful answer".

[Anonymous]

I suspect the reference to CNC arises from the comparison made by Jason to CNC canned cycles, although it doesn't deal with the complete story. For completeness:

G73 pecks by backing off a small amount (defined as a system parameter) every peck distance, specified in the command line. The intention is to break the chips but not clear them

G83 pecks and retracts clear of the hole on each peck distance, both breaking and clearing the chips

As to the original problem I suspect the answer will be in the feedrates. However, I wouldn't bother pilot drilling for a 6mm drill, I'd just go straight in. My vertical mill has quill feeds of 1.5, 3 and 6 thou per rev. But I don't use them for drilling as they're generally a bit slow and rather a faff to set up.

Andrew

[Ian PParticipant @ianp]

Posted by Robin on 17/09/2017 11:26:13:

I think this is all pie in the sky because we don't know what he is drilling in to, or did I miss something? Are we assuming quality bits just because he has bought a big power feed mill? In the words of Isaac Asimov, "Insufficient data for meaningful answer".

I think this applies to most of the questions posed on here.

Doesn't stop (sometimes pages) of replies discussing the minutiae of many techniques long after the OP has lost interest!

I see this is a first time poster too….

Ian P

[Ady1Participant @ady1]

IMO power feed drilling is only for mass production purposes

They figure out the best way of drilling a zillion holes automatically

But not practical for most hobby work which is mainly ad-hoc and bespoke work

[RobinParticipant @robin]

But, apart from that, what about the new shopping opportunity proposed by Howardt. I never knew 3 flute drills existed. A quick browse later and they are not impossibly expensive. Such fun, are they really self centering?

**LINK**

Now bookmarked and all I need is something that requires a lot of holes…

[jann westParticipant @jannwest71382]

so … the obvious answer is you need to peck the hole … but another thing to check is that the drill is truly perpendicular in X and Y to the workpiece and also the feed direction. Because only a slight misalignment will also cause the effect described.

[Martin ConnellyParticipant @martinconnelly55370]

I power feed on my CNC using manual data input (MDI). I set the drill to the correct rpm for the size of drill and feed at 30mm/min. I drive straight through for holes up to 3 times diameter. I only peck beyond this.

Martin C

[SaxalbyParticipant @saxalby]

A 6mm 3 flute drill is a real bargain at £34.40

[Matt de HoestParticipant @mattdehoest99598]

Awesome – thank you for all the replies.

Bikepete – tried to put pic on for you but am a bit rubbish with computers (hence no cnc for me!!). The mill is a Vernier VF3 with a swivelling bed – loads of pics on google. Is a beast – bit of overkill really but good for the tractor im restoring! Facing the parts for the stuart engine im making looks very funny. Love using the horizontal "mode".

What im getting is – pain in the proverbial but do-able with the right set-up.

Jann west – thanks ill try re- traming the head (takes a bit of doing it weighs half a tonne). Ill get some better drills and make sure speeds and feeds are right and give it another go. Easy to peck by reversing the feed but didnt seem to make any difference. Perhaps ill learn the difference between X,Y and Z as well well, ey?? Robin – big mill was cheaper than Bridgeport – felt like a good idea at the time!! Lots of versatility!! It will accept a bridgeport head to the overhead with a bit of fettling – this might be a way to go. Not sure how id explain this to the boss though!!

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