Lathe drilling attachment

I could do with a small detachable drilling attachment for my lathe Steve Jordan type of thing. There are a few cylinder motors which would suit on ebay but I ve never heard the names before and dont know which,if any,are worth buying.( I ve heard of banggood!) Its for 1 to 5 mm holes in cast iron,mild steel or gm. Thank you ,.Jonathon

Something which I can put a small chuck or collets on.

Edited By Jonathon Bywater on 11/01/2022 22:38:27

That's what I use; an ER11 spindle motor, collets, clamp and power supply from Ebay. I bolted a piece of 10mm square bar to the clamp and fitted it into a quick change holder. took about ten minutes. It cross-drills, mills slots etc and will drill along the lathe axis too.

It is quite long, so won't work on large diameters.

Cost about £90 five years ago, but they're a bit more now.

..What's the lowest RPM that that will run at, Nicholas ?

Hi Jonathan herd is one i made a whikd ago with variable speed motor.

If you want the drawings i can email them to you.

David

Another option... a Potts spindle with an MT1 ER16 holder from China (with drawbar) and a belt drive. Traditionally these things were driven from a line shaft above I think but few people have those now. I made a sleeve from a bit of PVC drain pipe so that I could clamp my Unimat SL motor bracket onto it. Having the motor this way round helps with the overall length but is clearly not helpful with clearance/visibility around the job. It works though. In this pic I was using a small carbide milling cutter to higbee the start of an internal thread.

I've also used a cannibalised flexi drive to make a toolpost drilling attachment for my little Cowells lathe. The drive motor (drill) can then be well out of the way. The flexi drive bearings would not cope with milling though.

Have a look in No.308 (Oct 2021) of Model Engineers Workshop. Looks good for a lathe, mill or pillar drill.

I like that design by David George.

A most excellent re-boot of the classic milling / drilling spindle to bring it into the modern world of QC toolposts rather than the old style bolt to the slide unit. Be really nice to see a write up in MEW.

The article in MEW 208 linked to by Bo'son describes a very impressive tool but it is, I think, fundamentally for the "lathe only" shop needing milling / off axis drilling capabilities. It doesn't really translate to the sort of quick on / quick off device for a hole or three that the OP is looking for.

Having had the occasional need I'd seriously consider making Davids design if it were published with sufficient details to make a fast job. Despite using up the backs of a few envelopes over the years whenever the "that would be handy" need surfaced the effort involved in design, manufacture and component sourcing always seemed disproportionate.

Like everyone else here I'll not live long enough to get into the back half of my want-to-do list so things have to be prioritised.

One tiny gotcha to watch out for is arranging how to get the device in line with the lathe axis before applying the correct offset and starting work. I have a Coventry die-head in a QC tool carrier which has the same need to be accurately centred before starting work.

I turned the end of a blank end morse taper to fit the back end of the sleeve that carries the die head tube. Popping the taper in the tailstock and adjusting the slides so the die-head carrier sleeve can slide over the turned down end gets it true to better than half a thou with no drama.

Clive

No idea, but it's low enough for anything you can put in the 7mm collet to work well, like this 6mm ball end mill:

That's with it mounted to a vertical slide, which I did originally but it takes far too much setting up to be really useful. The QC holder means it drops straight into place. I didn't want to spend hours building something, but to have a tool that can save a considerable amount of time making another setup for a simple job like cross holes.

Another one based on an ER11 collet extension here:

One of the main limitations of mini lathes is their *very* restricted cross slide travel. My spindle has to be flipped over (which means swapping the motor mount to the opposite side of the body) between cross drilling and face drilling to give a reasonable working envelope.

Set up for cross drilling:

Set up for face drilling

The original 10mm diameter straight shank ER11 collet chuck. The only modification was to drill and tap the tail end of it M4.

The motor is from a child's ride-on toy and runs at ~3000 RPM on 12V. I have two sets of pulleys that can either gear that up or down to the spindle. Most (>99%) of the time I run it flat-out on the slowest gearing (so ~1800 RPM on the spindle).

The whole thing was made on the lathe - the spindle is mounted in a block of 38mm square aluminium bar that was trued up in the 4 jaw chuck - rough and ready cross-section:

The front bearing is a 3200 double row angular contact bearing and the rear bearing is a plain ball bearing. There was originally a spacer sleeve between the two bearings so that they could be clamped up tight with the outer race of the rear bearing floating in the housing. I though that it would be a good, solid bearing, but actually there was quite a bit of axial play in the double row A/C bearing (my fault - I didn't appreciate that this would be the case). To get around this, I just removed the spacer and used the clamping screw in the rear of the spindle to preload one half of the A/C bearing against the rear bearing. If making it again, I would replace both bearings with opposed A/C bearings with a proper preload adjustment.

It is quite capable of drilling 6mm holes in steel and some light milling.

Timelapse of milling steel (5mm HSS cutter):

Edited By Andy_G on 12/01/2022 09:59:50

Just curious, what stops the chuck from rotating when milling/drilling other than putting it in a low gear which presumably still allows some movement due to backlash?

I have added a plunger mechanism to the headstock that engages in indexing holes drilled the chuck backplate:

24 holes works OK for the common 2,3,4,6,8, etc... patterns. For anything else, I get all agricultural:

(Model jet engine that needed 15, 17 & 19 positions!)

Edited By Andy_G on 12/01/2022 11:10:42

With that point in mind, I made this spindle lock for my Willson lathe:

The cam action clamp will be familiar to cyclists.

Depends how important the hole is; cross drilling for a split pin, or cable for a nipple I just drill straight through as it's high speed and a light cut.

I use the attachment for fluting knobs(I think they look and work better than knurling, and is easier to do), and with brass and aluminium I rest a chuck jaw against a block on the bed ways. That also gives enough indexing for a looks good enough result.

For more important jobs, a stepper motor headstock dividing attachment is on my list of things to do.

Edited By Nicholas Wheeler 1 on 12/01/2022 11:40:17

That looks *much* more workmanlike. (I may steal the idea!)

Good question. On mine I have a couple of options - one is to add a washer to a thread cutting gear stud so that the gear won't turn. This does still allow some backlash. It also allows me to use, say a 60T gear on the spindle marked up with a piece of chalk to do dividing.

The other way is to put the drive belt onto the biggest pulley - then the lathe spindle has a mechanical disadvantage over the motor...

Neither way is perfect but usually get the job done...

...but for the higbee job I needed to turn the chuck by hand while milling so locking it would be counterproductive.

Wow.😄. Never expected all that. Interesting reading ,thank you.

Thanks chaps, now I know

I just love agricultural solutions. I can be too smartarse sometimes.