12V Motor for a Top Slide Drilling Attachment

I currently have a top slide drilling attachment driven by a small mains powered electric motor driving a spindle on which is mounted a 0-1/4" capacity Jacobs drill chuck.. It is fine for carrying out spotting and light drilling operations using small drill b its up to 1/8" diameter or so but the motor struggles and will stall when used for a job requiring a bit of grunt e.g. drilling 2.5mm diameter holes in a 3/32" thick phosphor bronze flange. I have fitted an electronic speed controller which does help but under any serious load conditions the motor will stall.

I have a 12V/5A PSU on hold but before commiting to buy I would interested to hear of any recommendations for a suitably small ( 2" dia say) DC motor which could be made to fit the bill. An ebay search will resuslt in many possibilities but further guidance would be much appreciated.

I have also wondered if a12V ex scooter motors might fit the bill although I have only seen 24v models listed. Any help and useful suggestions would be most welcomed

I'd think a 12V battery drill motor would be powerful enough if you had one you could re-purpose. Otherwise perhaps a 12V windscreen wiper motor?

Second hand battery drills are a dime a dozen these days, as soon as the latest model with more volts, more features, whatever, comes out. Make a bracket to mount the whole drill in the tooltpost?

Bit off course but...

DC brushless motors used by the radio flyers are very good for this, and quite inexpensive. A 500 KV motor ( that's 500rpm per applied volt) of 50/55 size - that's 50mm diameter, 50mm body length will comfortable deliver 200 to 300 watts RMS and close to 1KW for 15/20 seconds.

Easy to hook up - at the same model shop you can get the ESC ( the electronic speed controller) - give it 20 to 40VDC, hook up its 3 wires to the motors 3 wires, and also at the shop get a mini-servo tester - its has a rotary knob, a wire that connects to the ESC to which it sends the speed control signal , and from where it gets it's power.

Apply power, turn the knob and the motor runs. If you need more oomph in the low speed range ( sub 1000rpm) get a motor in the 100 to 300kv range.

I use these in toolpost grinders and my mini-T&C grinder, as well as a sensitive drill press..

Work very well.

some speed controllers - you would not need more than the 40A unit top, below

Joe

Here's my quick and dirty attempt:

a 500w ER11 spindle motor, clamp, power supply and collets from Ebay for about £90. There's a 10mm square bar screwed to the back of the clamp to fit a QCTP holder. It drops into place just like any other holder, and easily crossdrills, face drills off centre and mills slots like this fluted knob that I prefer to knurling

I also tapped my vertical slide for it, but that's such a faff to install that it's going to be more use for jobs like gear cutting if I ever get around to making the clock I've been considering for ages.

DC brushless 18v drills have amazing torque

Thanks to the gearbox, but very limited in top end speed for those small drill/mill bits..Most drills don't exceed 1800 rpm.

And very faffy to mount on the tool post as a complete unit..

Nicholas, your setup is neat - what is the lowest rpm that spindle is useful at?

Perko7 said:

I'd think a 12V battery drill motor would be powerful enough if you had one you could re-purpose. Otherwise perhaps a 12V windscreen wiper motor?

Not really - without the gearbox the available torque is poor - most DC drills are typically 4 to 8 amps under load @ 16 to 22volts - that's anything from 50watts to 200watts, the latter only at max volts/amps and RPM - which will easily be above 8 or 10K RPM, so not very useful...

Joe

Edited By Joseph Noci 1 on 18/03/2021 09:23:11

In order:

Joe, I've no idea what the actual RPM is, but I use a 6mm ball end mill for the knobs without any issues in steel. And ER11 is only good to 7mm so slow isn't really important. The disadvantage of this setup is that it's very long, which limits the work diameter. Cutting down some common drill bits is on my list. This is a tool that won't be used if it isn't deployable quickly. I used it last week to make a clamp-on nipple for a broken handbrake cable, and the whole job was done without removing the stock from the lathe. I've admired your grinders since you first showed them, and am very tempted to build one. But that's a bit more work than hacksawing a piece of stock, drilling four holes and tapping two of them.

A 12volt wiper motor is going to make a terrible drill, as it's nowhere near fast enough.

mine want to check out Steve Jorden's YT channel he plays around with this type of stuff quite a lot

H

I admire Joseph Noci's version of a toolpost drill, and think he is right about the power needed.

It takes the same power to drill a hole in the lathe as it does in a drill press, so many setups that are fine for small drills will be very under powered for larger drills or milling cutters. So if the need is to drill holes of (say) 6mm or greater, then a 1/2 HP motor would not be excessive.

Rod

A DC scooter motor would be ok, preferably 24v

A "spindle motor" (the type used in diy cnc routers) might also be ok. Though they tend to be high speed rather than high torque.

Joseph - I like the look of your top slide drill attachment, it is just the sort of arrangement I have in mind. Could you please post the maker/details of the green coloured motor you have used in your box set. Details which would be useful include Voltage/Speed range/ Shaft dia etc.

Greensands..

The green motor is a Maytech ( www.maytech.cn) - MT063062-310-S

63mm OD, 62mm long, 310kv, 10mm shaft - max volts 60

The one below, in my PCB engraver, is also a Maytech - MT05040-800-S

50mm OD, 40 mm long, 800kv and 8mm shaft. 40Volts max

I removed the shaft, fitted a long shaft body ER11 collet chuck, which protrudes through down into 2 support bearings in the motor mount.

Maytech makes motors and speed controllers, all reasonably priced, and I find the quality very good - the PCB engraver motor runs permanently @ 22,000 RPM, and has about 80 running hours on it with no discernable bearing play at the motor end at all.

AXI ( East European) make top quality motors, 3 to 4 times Maytech price, but a total overkill for these applications.

This thread will, no doubt, wander on. Top and bottom of the problem is that the OP is over-loading his current motor. He simply needs a higher wattage motor.

The other issues - of speed, material, cutter type (material and grind) - are other things the OP needs to get his head around.

While there are tables out there, which are a guide, they are generally for commercial duty machining. The hobbyist needs to take this into account and sort out problems one at a time. Initially, just more wattage (and we don’t even know the current power) is required. Voltage is immaterial.

Edited By not done it yet on 18/03/2021 12:18:27

I do believe that is what most have been saying here???

Well the original post said the current set-up was struggling with larger drills. This tends to rule out high speed motors like the brushless DC. While power is important, the speed of the cutting edge and available torque are the crtical parameters. A 300W 30,000 RPM motor will not be much use for drilling a 6mm hole in steel.

We also don't know what the original motor is other than "mains" a "universal" motor will be much more use than a small induction motor.

Generally I think buying a used 18V (or higher) two speed gearbox battery drill and using the motor gearbox assembly will be the most practical and cost effective approach. You migh need a bigger power supply though.
The better drills have a separate module with motor and gears rather than using the casing.

Robert G8RPI

Edited By Robert Atkinson 2 on 18/03/2021 12:57:36

The two pics show the arrangement of my current top slide drilling attachment running from a mains operated motor fitted with a 5/16" dia o/p shaft via an electronic speed controller. It works well at the lower end but as said in the OP it struggles to drill 3/32" Dia in PB.

I am currentlyturning up a smaller diameter pulley wheel for the motor shaft in order to help improve the torque. In practice I would never wish to go much above 5/32" in drill size, anything larger being transferred to the milling machine.

The photos posted by the OP after your post suggest that he's already turning them too slow: an old, low power motor, and - at a guess - 3 to 1 speed reduction. The 300w, adjustable high-speed motor I showed works well for small drills(0.5mm for instance), 6mm drills and milling cutters. Actually attaching it to the machine is much easier too.

Thinking about this why not construct a belt and pulley arrangement?

You could use a slightly higher speed motor and use a 3 pulley arrangement to give you a range of speeds and torques. Maybe something like 1:1 ratio for small drills and maybe 4:1 ratio for bigger drills and cutters? It wouldn't be difficult to make.

I have a 12V motor from a child's ride-on toy (they eventually stopped crying )  that I think is well suited to this application.

It's about 105 mm long x 65 mm diameter and runs at ~3000 RPM on 12 volts. It's capable of drawing huge currents (10A+) but I have it running on a 3A speed controller which is sufficient to put a 6mm drill through mild steel quite easily and run small milling cutters.

It runs through a belt drive to an ER11 spindle (running in angular contact bearings) that gears this down slightly (~1.5:1) which I use mostly. I also have a larger motor pulley and a longer belt that fit the same centres that allow the motor speed to be geared up by 2.5:1 if needed. (I seldom use this though, as it isn't fast enough for a grinder, and the slower speed works fine with every size of drill that I've used (6mm down to 0.7mm).

The only drawback of the pulley arrangement is that I need to flip it to the opposite side when I change from cross drilling to face drilling as there isn't enough travel on the cross slide of the mini lathe to be able to accommodate both positions on the same side of the toolpost.

Edited By Andy_G on 18/03/2021 18:31:20