Sensitive Drill Attachment

[JasonP]

After spending a productive weekend reading build logs for the MEM Corliss, I came across a discussion of a sensitive drill attachment. I'm new to the machining game and hadn't heard of this before, to my cost. When I was machining the engine block for my corliss I broke 3 drills trying to drill the steam ports, which caused no end of grief. It doesn't help that I'm using a bit of 1018 scrap that is quite "grabby".

So after a bit of research I hit ebay and found what I think is a nice tool, a Jacobs #0 chuck and #55 Drill attachment. It's now on it's way to me, but I'm a bit wary as it is used. Does anyone know how to evaluate how good this tool is? Where should I be concerned?  Any advise on this tool and it's use would be greatly appreciated.

Jason

[crueby]

I don't have much experience with a senstive drilling attachment, but have vowed to never again use 304 stainless steel, it also is very grabby and work-hardens quickly, destroyed a number of drills and taps on that. Some alloys are just not worth the trouble on models.


1018 steel is rated low for machining, though it is very popular for welding.  I much prefer using 303 stainless, it machines very well, does not work harden, drills and taps very well. Not available in as many shapes/sizes, but worth looking at if you can.

[steamer]

If its' not getting wet on a regular basis,  consider 1144SP.   It's a low alloy medium carbon steel, with excellent properties ( 100,000 psi yield ect) but is very nice to machine, drills, mills and taps very well, and is fine without heat treat, though you can case harden it very well.    good stuff!

Dave

[TerryWerm]

Can you tell us a bit more about the #55 drill attachment? 

Sensitive drills usually require a couple of things:
1. High speed. Spindle speed in the neighborhood of 10,000 RPM or even higher work the best for these tiny drill bits.
2. The ability to hold the bit nice and square to the work
3. The ability to advance the drill bit with light pressure. They often have a bearing mounted collar on the spindle that you hold with two fingers in place of a rack and pinion with a long handle. You don't need much pressure.

The reason a sensitive drill press has that name is because using your fingers to advance the spindle allows you to feel what the tiny bit is doing in a very sensitive fashion. If the flutes of a tiny bit are starting to fill up with chips, you will feel it in your fingers long before you hear it in your ears. With some of the very tiny bits the bit will break before you ever hear things binding up.

[steamer]

As Terry has described you need "feeeeel"    about 20 years ago, I made a sensitive drill attachment on my lathe.   It consisted of a MT3 blank arbor bored in the lathe it was going to be used in.   I bored it to fit (2)  1/2ID   x 3/4" long drill bushings.    I then got a straight shank drill chuck arbor with a jacobs taper to match a nice albrecht chuck that I had.     The shank fits very closely in the bushings.   I drilled a vent hole for the air to escape.    and you are done!

Later Joe PI published this video....and wouldn't you know it...

<a href="https://www.youtube.com/watch?v=PqU5wS0J4MU" target="_blank">http://www.youtube.com/watch?v=PqU5wS0J4MU</a>

I can't say i invented this, but I doubt Joe did either.    I will say it works awesome!   and as soon as you feel that drill do anything other than cut...just let go...stop the lathe ,and back the drill out.   works great!

Dave

[steamer]

Now if you want to drill REALLY small...   ( 0.0039" drill)    You need to control the feed of the drill   You're hand isn't good enough.  What happens is the drill grabs and tries to pull in and you break it immediately.   I built a rig that Jerry Kieffer described for my Levin.    And I want to say it worked awesome

To do this on a WW lathe, you make a new TS quill with a 40TPI thread on the back half.   Add to this a 3" diameter nut.   The way it works is you slowly screw the nut such that it lets the drill advance, but won't let it grab and pull it in.    It worked great!   

<a href="https://www.youtube.com/watch?v=4DFuSwGvX1A" target="_blank">http://www.youtube.com/watch?v=4DFuSwGvX1A</a>

and a picture of the rig below...with a big but very thin and delicate brass nut on a 3125 x 40 thread.

I use 1/8 shank PC drills     The part in the video is 5mm OD with a 0.1mm diameter drill.   The material is 12L14 steel.

Speed was somewhere around 3000 rpm.   No you don't have to be spinning any faster than that....yes it does work.

Dave


Here's the article that Jerry wrote on the subject...

https://mb.nawcc.org/threads/safe-and-accurate-micro-drilling-on-a-watchmakers-lathe.150255/

[steamer]

I will be making an attachment for my Collet TS that is very similar, for the same reasons

[mklotz]

Micro drilling requires "feel", the mechanical feedback one gets when drilling.  Unless you're willing to spend big bucks, amateurs seldom have equipment that can supply that feel.  One approach is to build a very lightweight mechanism that can apply the work to a drill held stationary in whatever spins it - a sensitive table.

Adapting from an article in one of the mags, here's what I built...

https://www.homemadetools.net/forum/sensitive-drilling-platform-60287#post91042

[steamer]

I can only speak to what Jerry has done, and what I copied.    It worked fine Marv.

Dave

[steamer]

If you read the micro drill attachment description, it directly indicates that you need to control the feed, and not bottom out on the hole.    All of which Jerry describes in his article.

Dave

[steamer]

Love to talk to you Marv..

Dave

[JasonP]

Thanks All. Interesting points all.
I was just using a bit of steel I had on the shelf that was dimensionally close. Now I know how horrible it is it's getting tossed. I've used 12L14 - lovely stuff - if I can find it in the size I need, 4130, 4140 but that's a bit tough. I was trying to make a 4" adapter plate out of 4130 when I fried my lathe motor.... I'll take a look at the 1144SP and see if it's available.
10,000 RPM is a bit excessive for my machines! 2500RPM is my limit on the mill. This will be a learning curve.
I don't know anything about the #55. I assume it's a discontinued model, but I'll find out when I get my hands on it and report back.
I did see Joe Pie's video after I discovered the posts about the attachment. I would have made one and gone down that road, but I need it on the mill.
0.1mm is ridiculously small! I could barely see that without a microscope, let alone try to drill it!

[steamer]

Thanks All. Interesting points all.
I was just using a bit of steel I had on the shelf that was dimensionally close. Now I know how horrible it is it's getting tossed. I've used 12L14 - lovely stuff - if I can find it in the size I need, 4130, 4140 but that's a bit tough. I was trying to make a 4" adapter plate out of 4130 when I fried my lathe motor.... I'll take a look at the 1144SP and see if it's available.
10,000 RPM is a bit excessive for my machines! 2500RPM is my limit on the mill. This will be a learning curve.
I don't know anything about the #55. I assume it's a discontinued model, but I'll find out when I get my hands on it and report back.
I did see Joe Pie's video after I discovered the posts about the attachment. I would have made one and gone down that road, but I need it on the mill.
0.1mm is ridiculously small! I could barely see that without a microscope, let alone try to drill it!

That video was done under a USB microscope.   I can't see it any other way!!

Dave

[TerryWerm]

Sorry guys, the part where I said 10,000 RPM was meant to be 1,000 and up, and I failed to proofread it before I posted. Not sure if it was just a brain fart or what, as it has been an exceptionally rough day today.

I have a sensitive drill press with a stationary spindle. The table moves up and down and is spring loaded. The spring is adjusted so that it helps to lift the weight of the table, it acts as something of a counterbalance. It is easily adjusted to lift more or less as needed. It has a single speed spindle that runs in the neighborhood of 2500 RPM. The knob that lifts the table has better feel than one might think.

[steamer]

Nice drill press     Is that a home built?

Dave

[Mcgyver]

I have a sensitive drill press with a stationary spindle.

That created a mental image of drill press with a spinning head, column, work and table.

Jason, the key to small holes is a good drill, good material concentric drill and sensitivity.  As Dave points out, speed doesn't much matter.  (watchmakers make the smallest holes and rarely would go more than 1500-2000)  Those attachments are ok and hopefully JAcobs is still putting out high quality chucks (I've a 0 and it is very good), not as a good as a balance table like below, but certainly better than a large heavy quill and unless going really small, may be all you will need.

Dave, I've got one of the Levin drilling tailstocks, a mechanical marvel.



Also a few shots of a simple table that appeared in Home Shop Machinist magazine ages ago.  Its counter balanced and works very well. Highly recommended.

[steamer]

Sweeeeeet rig McGyver!    I would love to try that out and see what all the talk is about.'


Dave

[Krypto]

This isn't an equipment attachment, but here's a quick video of my Dumore sensitive drill press drilling a 0.3mm hole in a 3D printer nozzle.

<a href="https://www.youtube.com/watch?v=tCnfdj-l_yM" target="_blank">http://www.youtube.com/watch?v=tCnfdj-l_yM</a>

I also own a Cameron sensitive drill press.

Below should be a scope picture of a factory nozzle beside one I drilled (0.2mm->0.3mm).  Looks close and it worked great.

[Roger B]

At the more basic end of the scale this is a 0.3mm hole drilled in 2mm thick brass with my Proxxon TBM220. The chuck would not hold a 0.2mm drill.

https://www.proxxon.com/en/micromot/28128.php

[Admiral_dk]

All the smallest sizes I do ( so far 0.6mm ~24mil = 0.024") - is on the Table CNC @ Work. My experince here is that the higher the RPM the smaller the chance of a broken Drill-Bit (not that it happens very often anyway).
The slower the RPM or Feed -> the more the Bit wanders before starting the Hole (@ the surface).
But as mentioned - it is not required to be fast ....

Roger - I do not know how small you can get them (I see 0.1mm ~3.9mil=0.0039") - but have a look after 1/8" / 3.175mm shank VHM Drill-Bits for PCB manufacturing. The cheapest are from AliExpress, are ok - the Best are from a few German Manufactors (that I can't find right now) ....   

Per

[steamer]

All the smallest sizes I do ( so far 0.6mm ~24mil = 0.024") - is on the Table CNC @ Work. My experince here is that the higher the RPM the smaller the chance of a broken Drill-Bit (not that it happens very often anyway).
The slower the RPM or Feed -> the more the Bit wanders before starting the Hole (@ the surface).
But as mentioned - it is not required to be fast ....

Roger - I do not know how small you can get them (I see 0.1mm ~3.9mil=0.0039") - but have a look after 1/8" / 3.175mm shank VHM Drill-Bits for PCB manufacturing. The cheapest are from AliExpress, are ok - the Best are from a few German Manufactors (that I can't find right now) ....   

Per

Per    those are the style I run in the Levin    AS long as you don't mind the country of origin, they're cheap as chips...\

Dave

[Roger B]

I do have some reinforced shank 0.2mm drills that I used for the injection nozzles as standard 0.2mm drills were not rigid enough. These were used at 2000rpm with a lever feed tailstock on my Hobbymat.

[Admiral_dk]

Man - those are Very Long Shafts 

.... but other than that - that is the style I meant ....   

Per

[mikehinz]

Just a few comments to add to the information. 

Some time back I purchased a Royal sensitive drill attachment and put a Cushman 1/8" keyless chuck on it.  It turned out to be a very handy, very accurate device for the small holes that I drill. 

Most of the comments above are exactly correct, particularly when drilling really small holes, smaller than #80 / .0135".

My experience is only with drills #80 and larger.  What I've found is that down to #60 / .040" I can almost always successfully drill holes using my Bridgeport quill with a small Albrecht keyless chuck. And I use a small Albrecht chuck in my lathe (a 13" x 40" import) tail-stock and can successfully drill down to #60 without using the sensitive drill attachment.  I think the key(s) to the process are 1) high rpm, 2) new or perfectly sharp drills, 3) A small dimple made with a small center drill 4) backing out and clearing chips very often and 5) Use some good quality cutting fluid and apply it frequently.

Smaller than #60 I always use the sensitive drill attachment secured in a .50" collet and I recently drilled several .020" holes using the sensitive drill attachment.  All the above rules apply when using the attachment.  I find that drilling with the Bridgeport is extremely nice as work holding is easy with the vise, or with a fixture plate or with whatever jigs are necessary.  Accurate positioning of the hole is so much easier vs any other method I've tried.

Hopefully this is information is useful.  If I ever have to drill anything smaller than #80 I think I'd look seriously at the various watchmaker techniques mentioned above.

Mike

[Chipswitheverything]

The Pillar Tool sensitive drilling attachment, as per my example here, has been made by many, of course, and it works extremely well.  When Geo. H. Thomas designed it, he opted for speeds of 1200 and 2200, not that fast, but he states that the very high theoretical speeds for tiny drills are not really achievable in such a machine made in the home workshop, nor very necessary. 
 I have used my drill to make many hundreds of holes at 10 thou diameter ,0.25 mm., for drilling pitot holes in stainless steel and cupro nickel hypodermic tube , which was laid under the carbon fibre top skin of small propellor blades ( made by an aerospace company ) used for research into high speed airflow at my place of work.   A CO2 cylinder was coupled to the tubes as the drilling was done, and the swarf ejected by a burst of positive pressure as the hole was drilled.   I have also used the drill head rigged up with a temporary scheme of bracket and motor, attached to the fixed spindle of a very large radial arm drilling machine, to work over the surface of much larger aerofoil test wings.   The sensitivity of the action on the GHT drilling head is a very great help in controlling the feed of these small drills.  Dave

[JasonP]

The drill attachment arrived. The Chuck is a Jacobs #0, made in the USA, and very nice quality. The drill attachment itself doesn't have any markings on it. The vendor claimed it was a Jacobs #55, but I can't find any reference to it on the internet. The tool seems to be very well made, with a round edge plastic disk that may have been knurled at some point but is now mostly smooth. There is a brass coloured end cap as seen in the pic, and the mechanism is a very precise fit with no play. The bearing tiny bit rough in the hand, but I'll stick in on the mill today and see how it feels. I'm trying to resist the temptation to disassemble, clean and lube, 'cos that's another rabbit hole.
Oh, and it didn't come with a chuck key, so it's a trip to Grainger on Monday to pick one up 

[Admiral_dk]

Looks good and as long as you can get another Key -> All is Well     

Per

[JasonP]

Well, not so good. I put it in a collet on the mill and clocked it to make sure it's concentric. Nope. TIR is 0.01, which on this is horrible. I popped the chuck off the taper and took a series of measurements and the shaft that engages with the chuck is bent. The 1/2 shaft in the collet has less than 2 tenths runout, the end of the morse taper shaft has 10 thou runout. With the chuck installed this is magnified the further from the chuck the drill bit is, the worse it gets.

The vendor has "no returns" on the ebay listing, so I may end up doomed. I think the chuck is good, so now I'll have to buy one of the Chinese SDA's. 

 <a href="https://www.youtube.com/watch?v=2xECLshgRQ4" target="_blank">http://www.youtube.com/watch?v=2xECLshgRQ4</a>

[steamer]

I'd take a shot at making a new shaft.   I suspect you can do better

Dave

[steamer]

Scored some German made  ( Gunter?) 0.1mm 1/8 shank drills.....

I might burn one to play  ( I have 6 in a ity bity plastic box)

Dave

[TerryWerm]

Nice drill press     Is that a home built?

Dave

Sorry for the delay in responding, it has been beyond hectic around here. To answer your question, no it is not. It is a commercially built unit, and the name tag says "Micro Balancing Inc."

Some of you may have noticed the numbers on the table, and they reference degrees from a zero point. That 'drum' is not a part of the standard table for this drill, but it also has a table insert on the top which locks into place. It has a couple of holes in it that allow a part of some sort to lock into the table. I suspect that armatures or whatever might need balancing are tested and marked for a needed change at a certain degree reference point. The part can be locked into the table which can be rotated to a degree to match what is needed, and then balancing holes could be drilled.  I hope this makes sense, but it is not easy to explain.

I purchased this drill press from an eBay seller and so far, I am quite happy with it. It has not disappointed me yet. I thought about removing the rotating drum from the table but have not yet seen a reason to do so. I don't see a reason to keep it either, but it does make a neat point of conversation and makes the device appear to be more complex than it really is, thus impressing those persons that haven't got a clue.