[SomeWhatLost]

I am obviously making a stupid mistake somewhere...
simple hole/drill op in 6061...
0.404" #Y standard off the shelf twist drill.... in tormach's medium TTS J chuck 30244 - Drill Chuck - 3/8" - JT2
~1.5" deep...
feed = 8.7
spindle RPM = 1702
G83: Peck drilling cycle (Full Retract) .101" peck

Problem:
towards the end of the hole, most of the way through, the drill gets 'caught' and starts spinning in the chuck... or stalling? not sure the proper term, but spindle is spinning fine, and drill isn't... as such, hole is not as happy as it could/should be... and drill gits auto extracted from chuck on the retract.... also, fwiw, the drill shank gets very hot when this happens...

I have tried cranking down on the chuck as much has possible, but I suspect the key will strip if I try much harder...
besides, it 'feels' like a feeds and speed issue to me... I tried dropping feed to 68% but that didn't help... just wondering if upping the RPM would help any?

I guess using a proper "CNC approved" drill would probably be better than your standard hardware grade twist drill... but I already have the twist drill,,, and I recently found myself gainfully unemployed, without the gain part... so not really looking to spend cash if I don't need to...

[SCzEngrgGroup]

The Tormach chucks are no better than "ok". You have to REALLY crank the snot out of them to make them secure on larger drills, and that is hard to do without the key slipping. I nearly always use ER chucks for drills - they never slip. Doing a 0.404 hole in one pass is also going to be tough. You'd be much better off drilling a 1/4" pilot hole first. Also, a hole that large, and that deep, will pretty much require lubrication, not just coolant. Very likely you're welding chips to the drill.

Regards,
Ray L.

[IMT]

Are you tightening all 3 positions on the chuck? Believe it or not it does matter.

[IMT]

Your feed and speed should work fine. In 6061 I can drill up to .500 without a pilot hole in high gear, have to watch the load meter and reduce the feed a little. If you tighten the Tormach drill chuck properly the spindle will stall before it slips. G83 is the right strategy, make sure your coolant nozzle is adjusted so it fills the hole with coolant when the drill retracts on each peck.
Anything larger than .500 I will drill a pilot hole and switch to low gear.

[popspipes]

I always had better luck drilling with some oil, coolant will keep it cool but not so good in the lube department.

Using coolant, once the drill gets a bit of aluminum color on it the drilling gets much worse, it seems to be a form of chip welding, and the chips do not slide as easily up the flutes as they should.

[Steve Seebold]

I would drill that hole at 2500 RPM 15 IPM put the drill in an ER20 collet holder and use flood coolant.

Spray or brush on coolant just won't work.

[LeeWay]

You can also buy drill bits with three flats on them. I get this type from McMaster Carr. They are excellent drills bits too, so win win.
I hate using a drill chuck in cnc machines. It's a necessary evil sometimes and may save your butt, but extra oomph needs to be applied to them over and above what you would normally do on a manual drill press.
Your feeds and speeds are still pretty relevant with drills.

[SomeWhatLost]

1st, thanks for all the suggestions....

the thing is, I have had far less issues drilling 1/2" holes than I am having with this stupid 0.404 hole and that is confusing me and sort of pissing me off at the same time...
actually, the only issue I have ever had with the 1/2" is that it is fairly easy to stall the spindle if you push it to hard/fast...

differences that I can see is that my 1/2 drill is a proper "cnc" style jobber drill, nothing special, fairly cheap black oxide which I cant imaging is of any benefit for aluminum... and my #Y is just your average "Titanium coated" (sure it is... looks like cheap gold paint/electroplating to me) came from a cheap set from a hardware store type drill..'
and the 1/2" is in Tormach's large chuck...
I do use flood coolant, haven't tried oil yet... but it isn't chip welding... at least not to the drill, it looks fine...
I think I will just a pre-drilling op to drill it out to 1/4" as suggested, and I will try tightening all three positions, even if that does seem odd...

[IMT]

Cheap tool are... cheap.
I have a set of Silver and Demming drills from HF that do just fine cutting wood. Use them for misc stuff around the house. I tried to use one for aluminum on my mill, ended up going to the tool supply and getting a quality drill (cost as much for 1 as the whole HF set).

[C*H*U*D]

I'm assuming this is on an 1100? I wouldn't attempt a hole like this in one shot on my 770...I'd center drill and pilot hole first. I had a run of parts that required a slightly smaller hole (.386") and I found the larger Tormach drill chuck worked better for me.

But like it was said before, these chucks work but are nothing to write home about.

[popspipes]

Cheap tool are... cheap.
I have a set of Silver and Demming drills from HF that do just fine cutting wood. Use them for misc stuff around the house. I tried to use one for aluminum on my mill, ended up going to the tool supply and getting a quality drill (cost as much for 1 as the whole HF set).

I have a set of Silver and Demming and they appear to be quality drills?? I also have a set of HF look alikes and they dont perform as well in steel. they are OK in wood ,plastic etc..

[Steve Seebold]

Cheap tool are... cheap.
I have a set of Silver and Demming drills from HF that do just fine cutting wood. Use them for misc stuff around the house. I tried to use one for aluminum on my mill, ended up going to the tool supply and getting a quality drill (cost as much for 1 as the whole HF set).

Don't EVER buy cutting tools at Home Depot or Lowe's. Spend the time and a little money and buy your tools at a local industrial supplier. You won't regret it.

[IMT]

Don't EVER buy cutting tools at Home Depot or Lowe's. Spend the time Cora money and buy your tools at a local industrial supplier. You won't regret it.

Absolutely! For machining buy good machining tools, for general purpose stuff around the shop use hardware store tools. My high quality drills don't get used in a hand drill and the hardware store drills don't get used in the mill or lathe (in a pinch I've done it but the results were usually not good).

[CadRhino]

I don't have a problem drilling up to 5/8" on my 1100 but I always pilot drill first.

[Steve Seebold]

I don't have a problem drilling up to 5/8" on my 1100 but I always pilot drill first.

That's cheatin'. But that's what we need to do on the low powered machines.

[mountaindew]

Don't EVER buy cutting tools at Home Depot or Lowe's. Spend the time Cora money and buy your tools at a local industrial supplier. You won't regret it.

Absolutely! For machining buy good machining tools, for general purpose stuff around the shop use hardware store tools. My high quality drills don't get used in a hand drill and the hardware store drills don't get used in the mill or lathe (in a pinch I've done it but the results were usually not good).

I have no problem with Dewalt black oxide drill bits going thu anything you put under them. So far they outperform my YG bits by a long shot! Only problem with Home depot dewalt drill bits is they dont have full sets or range of sizes. Try One and you wont be disappointed. While back with a Dewalt 1/2 b.o. bit I put a 1/2" hole thru 2" thick alum. square at full rapid speed by accident! Would have went into mill table if the holder did not crash on the 2" block. Was amazed a drill could do that. e-stopped the machine, reset, and backed the head and tool out and the hole had a decent finish even That bit is still in the same Tormach half inch chuck and still in use to this day! Also I recently I used a 1/4 b.o. to drill 300 holes in some 3/8" cold roll and it looks like it did when I took it out of index. It replaced a coated YG that I was using before that I couldn't get tight enough in the chuck. The Dewalt bit had indexed flats that held better in the marginal quality TTS chucks. Was surprised at same speeds and feeds it made cool long curl chips that didn't bird-nest, just fell to side like flat springs.

In case people wonder well how many projects call for 1/2" holes anyway! Because of Steve quoted above my large drills are among the most used tools on my Tormach. While back he mentioned he always plunge drilled large areas that I had been milling before. From then on I start most big parts with large arrays of drill holes that take material out at 5x faster speed then any end mill. I now draw circles in my cad models to aid in positioning the holes in cam software, makes it simple and mmr goes up and my mill using high speed tool paths that go round and round go down . Then send the end mill in to clean up and finish the model design.

[IMT]

I put a 1/2" hole thru 2" thick alum. square at full rapid speed by accident! Would have went into mill table if the holder did not crash on the 2" block. Was amazed a drill could do that.

I suppose you don't have a video of that. Would like to see it.

...I start most big parts with large arrays of drill holes that take material out at 5x faster speed then any end mill...

5X the MMR?!! How fast do you feed the drill? I can pocket in 6061 at around 2 in^3/min with an end mill. For a .5 drill to remove 10 in^3/min it has to feed at 51 in/min!
I don't doubt the benefits of plunge roughing because of the increased rigidity in the Z direction but 5X seems exaggerated.

[mountaindew]

I suppose you don't have a video of that. Would like to see it.



5X the MMR?!! How fast do you feed the drill? I can pocket in 6061 at around 2 in^3/min with an end mill. For a .5 drill to remove 10 in^3/min it has to feed at 51 in/min!
I don't doubt the benefits of plunge roughing because of the increased rigidity in the Z direction but 5X seems exaggerated.

I was lucky the 2x2 stock was hanging over the vise 2" and the bit went thru and did not hit the vice at that speed otherwise I would have experienced a real tool crash. I admit itt did have a 0.120 hole as deep as that short bit would go. All my drill ops start with that over used drill bit size


Your right on over stating. It just looks faster and sounds more aggressive then an endmill also drill bits are cheaper and easy to sharpen if needed for rough work. I also developed this habit because it saves endmill life! Some of Sprutcam operations look for holes larger then end mill and automatically use that as a plunge point and avoids ramping into pockets. Sprutcam drill ops are among the fastest to setup also. Then you can go back and clean up with more precise tool paths

[spumco]

Just a thought, but your chuck is a 3/8 and you are trying to hold a .404 drill. Ive noticed that the jaws on chucks may hold a drill thats larger than capacity, but they dont have much engagement on the shank. Maybe just going up to a 1/2 inch chuck will hold it better as there will be more jaw in contact with the shank.

[Steve Seebold]

Just a thought, but your chuck is a 3/8 and you are trying to hold a .404 drill. Ive noticed that the jaws on chucks may hold a drill thats larger than capacity, but they dont have much engagement on the shank. Maybe just going up to a 1/2 inch chuck will hold it better as there will be more jaw in contact with the shank.

Put your 1/2 inch drill in an ER20 collet. I don't even own a drill chuck for my PCNC1100