Sensitive drill

[Mr Ron]

I wanted to buy a sensitive drill that can go down to a #80 drill bit, but they cost around $300-$500. I was thinking I could use a pin vise and modify it to fit inside a tight fitting tube with a large thumb wheel and chuck it in the tail stock. Question is: do you think a good quality pin vise, like Starrett or Mitutoyo would have zero runout to be used for drilling small holes? I know the Albrecht chuck would work, but $$$$. I also want to use it in my vertical mill.

[Harold_V]

I suspect not. Any time a knurl gets involved, concentricity is suspect. When miniature drills are used, the slightest runout is reason for failure.

My recommendation? Bite the bullet. Pay the price of a chuck known to provide the needed precision. You'll be glad you did once the sting of the purchase price is paid.

I question if your tailstock would provide the needed concentricity. It is uncommon for them to be dead on center. You'll also struggle with the slow spindle speeds, typical of most engine lathes. Small drills benefit from high spindle speeds (often in excess of 10,000 rpm).

H

[armscor 1]

I used my Dremel drill stand which has a 1/8" Chuck, runs dead true, drilled a 20 thou hole in my lawn mower carby jet with good results.

[Mr Ron]

I just realized a sensitive drill won't work with a vertical mill, as the chuck has to turn via the small pin wheel.

[ernest_t]

The sensitive drill feed with the knurled wheel start about $38. US and go up, on eBay. One shank has a slot, the other a dowel. The knurled wheel has a ball bearing. The cheap ones are not very good quality. They're not hard to make and you can control the clearance etc.

[Mr Ron]

The sensitive drill feed with the knurled wheel start about $38. US and go up, on eBay. One shank has a slot, the other a dowel. The knurled wheel has a ball bearing. The cheap ones are not very good quality. They're not hard to make and you can control the clearance etc.

That's what I intended to make using a good quality pin vise fitted with a knurled wheel in a smooth fitting sleeve. The Albechet chuck is just too expensive.

[FKreider]

Yes you can do this - Joe Pi on youtube has a video on it:

https://youtu.be/PqU5wS0J4MU

[pete]

Albrecht isn't the only game in town. There were lots of sensitive drill presses around long before the Albrecht key less design was invented. Afaik Jacobs was just one of many with at least one model of keyed chucks that had jaws that could hold diameters that small. I've seen used Jacobs chucks with those capacity's many times on Ebay. Finding a NOS or very good condition one might take awhile, but they do show up for a whole lot less than those Albrecht prices. If Jacobs still makes them I still wouldn't buy anything new from them today given the average run out and quality I've seen mentioned numerous times on the PM forums. You might get lucky or you may not.

Lot's of the cnc guys will use an offset add on high speed motor attached to the mills main spindle to get the rpm. The Proxxon idea of a Dremel copy seems to be recommended for that use because of much better bearings though. Big bucks, but there's both electrically driven and air spindles meant to be mounted in a standard mill spindle to get well over 100k rpm. NSK http://www.nskamericacorp.com/?AspxAuto ... eSupport=1 is just one of them. Way too expensive for the average home shop. But there's also what are called spindle speeders that use gearing to mechanically multiply the available spindle speed. Those can be used in a lathe or mill spindle. There's also a kit to build your own, http://www.hemingwaykits.com/acatalog/S ... easer.html but it's maxed out at only 9k rpm. I've used tiny drills at well under there specified and ideal super high rpm so I know it can be done. Having that feel for how much pressure is being applied to the drill point is the most important part. That ultra high rpm is more for drilling efficiency than if the hole can be drilled or not with the available rpm.

[Mr Ron]

Thank you all for your response. I've ordered a set of pin vises and will see where I go after this.