Holding drills in ER collets

Towards the end of today's meet-up a number of members said they used their milling machines for general drilling. Some went on to say they would consider buying a drill press because of the bother of drawing bars and changing tool holders on the milling machine.

Although it is a fiddle to change holders on my machine (it does not use a simple draw bar) I rather like using it for drilling. I treat every drilled hole as a jig boring exercise.

Since I now have a range of ER25 collets from 1mm to 16mm in 1mm steps, bought for the lathe, I could use one with the milling machine's ER25 tool holder to hold a drill instead of a Jacobs chuck. I would save time and a bit of hassle. What is wrong with this?

JA

Not much, I do it all the time as the DRO is a lot more accurate than trying to pick up scribed and punched locations. Only thing I don't like too much is compressing my collets down too much but a few 0.5 increments and imperial size ones can help avoid that.

If you have a far eastern machine that needs the head winding up then invest in some stub drills in common sizes eg 0.5mm steps, tapping and reaming sizes then you don't have to wind the head up so far.

Nothing technically wrong, but I would find changing a collet most times for a different drill size to be a proverbial pain.

It's a perfectly sound idea. You will have to try out your drills for runout just in case some don't work so well. Collets can be bought in intermediate sizes and also inch sizes.

I use this method regularly for small diameter drills as I find using a drill chuck too heavy. I don't have a drill press so it's the mill and DRO with ER16 collets which gives a good level of accuracy.

Have to agree with all the above but would add that for very small drills I use a small drill chuck that fits in a 1/4" dia collet.

Brian

Possibly worth investing in a few spare nuts, so that if you are drilling several sizes in sequence the drills can stay in their collets and save time and fiddling about?

I have to do it because my chuck wont close down less than about 1/16 th and it's a real pain. Does anyone know where I can get a chuck with a taper for a startrite mercury? I think it's a j33 taper from memory and not easy to find.

Edited By Buffer on 06/01/2021 15:36:23

If you use very small drills, an er11 with a straight shank would be better, and hold that in the er25. The only downside of this is a possible increase in runout which may or may not be eliminated by re aligning the holders.

I too use my ER chuck for holding drills, especially for accurate work and if the drill has the same diameter as one of my collets so I don't have to compress the collet much. My cheap drill chuck has more run-out than the collet chuck.

Thor

Collets vs drill-chuck are mostly a time trade-off on my MT mill, though collets are also slightly more accurate.

Drill-chuck wins when many holes of different sizes can be drilled in a sequence because drill chucks can load a wide range of drill sizes in any order. Keyless chucks are best for this - keyed chucks are much slower.

Changing from a collet chuck to a drill chuck just to drill a few holes is a waste of time. With a drawbar system It's quicker to change collets than the whole chuck. (MT is not the fastest tool-holding system available!)

I prefer collets because they can both drill and mill, allowing a mix of operations to be done without changing the chuck. As it's unwise to mill with a drill chuck, they're unsuited to my normal mixed work-flow - jobs where I typically drill several holes of the same size (one collet), and mill with a relatively few cutter diameters. Every so often a job calls for many different drill diameters and that's the only time it's worth me changing to a drill chuck. But my once in a blue moon job might be the sort of work others do most of the time, in which case their preferred chuck is the other way round to mine.

Bet there are people who never fit a drill chuck to their mill, and others who never use collets.

Dave

I never use a drill chuck in my mill, only the lathe tail stock and even then for some jobs the ER collets are fitted (Ø19 shank on broach cutters for example).

Martin C

Dave's description is exactly how I do it:

ER32 chuck for milling, and any occasional drilling needed as part of a job.

If the job is mostly drilling, I fit the drill chuck.

I decide which to do on the basis of time against hassle.

To all, many thanks for the replies.

I can see the Jacobs chuck being relegated to the lathe.

JA

Edited By JA on 06/01/2021 17:09:44

If you use your drills in the ER collets then I hope you do not have 'scored' shanks that often happen with keyed Jacobs style chucks when a drill grabs. I am meticulous in always keeping my drills in their boxes and replace them immediately after use. I clean the flutes, examine the shanks for gouging, and also check the shoulders for blunting. Any drill that looks like it needs remedial action goes back into the drill box upside down - so that I can dress it, or resharpen as required at a later date. I am always saddened to see a half empty drill box because operators have failed to put the drill back straight after use. When I ran a small machine shop I was very specific that if anyone didn't replace the tools after use they would get marched off the premises.

Why didn't I think of that? I often use the collet chuck for drilling, and already have four nuts for the various ER tools I have. Using them will save quite a lot of time and hassle.

That rather depends on how you define 'very small drills', since ER11 has a minimum gripping size of 1mm.

For true 'very small drills' I have not found much past a 0-3mm or 0-2mm Albrecht keyless, but they are very expensive. I would be happy to learn of a more economical solution for sub-0.040" drills.

My couple of ARC drill chucks go down to 0.2mm though I've only used them down to 0.3mm as that's my smallest dia drill bit.

Not forgetting that a 1mm ER11 will close down to 0.5mm

Edited By JasonB on 06/01/2021 19:49:56

Not many people would want to hold less than 1mm drills, and an er11 would still be preferable than an er25 for them. I also have a straight shank er8 and a new British Jacobs 1/4" chuck. You are entering the realms of drilling machines running at up to 15000rpm when using small drills, I wouldn't much like to drill 1mm with only 3000rpm available.

You need to start making a few models Old Mart, I would say the majority of my engines have a couple of 0.8mm holes, usually cross drilled through MS, stainless or silver steel as it's a good size for 1/32" split pins. gas jets need smaller hence the 0.3mm I mentioned I've only got 2000rpm on the manual machines and have not had a need to go that small on the CNC yet.