A Hi-Speed Sensitive drill press

[Joseph Noci 1Participant @josephnoci1]

A short intro to a small Hi-Speed sensitive drill press I made, based, as for a number of my other DIY machines on some Aluminium extrusions.

The drive motor is a RC Brushless motor, giving about 900 RPM/Volt, and in this application driven up to around 25,000 RPM max, fed from a DC supply via a Brushless speed controller. The motor is capable of delivering nearly 800watts (!) in a flying aircraft, with cooling, for short periods. On the drill press I see a max of 2 amps at around 30volts/26,000 RPM.

The Motor is attached to a spindle mount, containing an end bearing at the ER11 Collet end. The collet chuck is an ER11 with a straight shank of 10mm diameter, 100mm long. That was turned and then ground down to 5mm diameter for 60mm at the motor end, and then fitted into the motor itself, replacing the original motor shaft.

The vertical slide is a standard 20mm slide rail, with a standard ball bearing slide block – the rail scrapers have been trimmed to eliminate any stiction, aiding the sensitivity of movement.

The plunge lever has a number of lever arm holes, allowing a range of movement – a small hand movement giving a large drill movement, through to the opposite. The magnified movement is useful when drilling PCB's for example. The arm is counterbalanced for fine movement, and can be adjusted to be just in balance.

The table sits on a 90 degree angle block, part of the extrusion meccano set stuff..and can be raised and lowered.

The motor and spindle were Dynamically balanced using the Miklos Balancing Software which works very well.

 

 

 

 

 

 

The slide rail and block

 

 

Balancing – white ring is OPTO RPM Sensor

Red arrow isbalance weight

 

Balancing – white ring is Accelerometer superglued to beam

 

 

Edited By Joseph Noci 1 on 02/12/2016 13:49:16

[Joseph Noci 1Participant @josephnoci1]

Hi-speed Sensitive drill press based on RC brushless motor

[SpurryParticipant @spurry]

That's another excellent bit of work, well done.

Pete

[Rod AshtonParticipant @rodashton53132]

Could you show some detail of the collet chuck connection to the spindle please.

[Les Jones 1Participant @lesjones1]

Hi Joseph,
I think it would make a very good article for MEW.

Les.

[Joseph Noci 1Participant @josephnoci1]

Thanks Spurry! I do enjoy making these things..

Les Jones , the problem with living on the edge of no-where, is that one is very much alone in doing this stuff, so I sort of go into the workshop after breakfast, and come out for dinner with a whole lot done, and…no photos…So the darn construction is not documented, only the end result! A pity, but that's how i have always worked..Will try to do better on future projects!

Rod, as I wrote above, I have no photos of the motor/spindle construction, and am reluctant to strip as it means I would have to rebalance again!

However, I drew up a quick sketch of the basic idea –

I used a HACKER brushless motor, 900kv, Outrunner type, with 5mm shaft.

I removed the shaft. I used an ER11 collet chuck, with a straight 8mm shank, 100mm long, machined and ground at the non-collet end to 5mm to fit the motor bearings and the outer motor (rotating) case boss. The other various bosses, tubes, etc are seen in the picture below. The collet end is supported by a 10mm ID bearing recessed into the Ali tube. The whole thing is pressed together lightly, thereby applying pre-load to the bearings ( A Little!) and the the grub screws in the end of the motor outer are tightened, with a touch of loctite.

Does this help?

[Rod AshtonParticipant @rodashton53132]

Aha! Thanks Joseph. My previous purchases of larger collet chucks have all had a deep back counterbores through the shaft and this has caused my specific design problems. A solid shank negates my enquiry.

Appreciate you sharing the sketch.

[Ian PParticipant @ianp]

Joseph. Really like the stuff you've made apart from the nice engineering the designs are a bit above the majority of self built tools and machines which tend to be more traditional.

The drilling spindle construction interest me as the shaft appears to be supported on three bearings. As the shaft is rigid the standard of concentricity for shaft and the bearing outer races must require so highly accurate grinding so I wonder what method you used. How did you align the front aluminium bearing support to ensure axial alignment?

Did you base the alterations to the shaft on the ER collet taper as supplied or did you true the taper later?

Where can I find some information about the Miklos balancing software? I googled but could not find a website.

Ian P

[Peter SpinkParticipant @peterspink21088]

Nice work! Am also looking for a motor for a high speed, sensitive drill but so many to choose from. Any more details of the one you're using and where from much appreciated.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Peter Spink on 02/12/2016 22:53:20:

Nice work! Am also looking for a motor for a high speed, sensitive drill but so many to choose from. Any more details of the one you're using and where from much appreciated.

There's a thread on this type of spindle here

Russell

[Joseph Noci 1Participant @josephnoci1]

Hope this post/reply is not to long..

Ian,here are some prior attempts at ways of making up a spindle – I do a fair bit of design on CAD, but sometimes it has to be in the head and in metal..

This test spindle shows the HACKER motor fitted with the Ali boss. Also shows the spindle shaft – this one I tried to grub-screw fix the spindle to existing motor shaft – it works, there is very little load on the spindle with the small drills, etc, but there is always some induced runout this way at the coupling, and at 25000 RPM it shows, so, no good. I think you get the idea of construction. I gave up on this idea and went for a full length single chuck shaft/spindle..

Then, your question on how I aligned the bearing/tube at the collet end –

I inserted a very snug fitting SSteel bush between the Ali boss and the motor shaft and fastened the cap screws holding the boss to the motor mount see below-

The collet Chuck was machined down to 5.1mm at the motor end, and then I mounted a piece of SSteel in the lathe collet chuck, and machined a ER11 Male end onto it, so the the Spindle female collet end fitted over accurately. The other end of the collet chuck shaft already had a good center hole. I used a wiggler to check that it was running true with the to ER11's mated tight. I then brought the live center into the dimple in the rear shaft of the spindle, and just tweaked the tailstock up. Check with a dial gauge for parallel and the brought one of the toolpost grinders into service, and gently did it..Worked a treat.

I did not true the taper of the collet after – I could not measure any TIR on my 0.005 indicator..

Here are some more motors, all quite suitable for use in these applications, and even on heftier routers, etc.

This one is the HACKER, same as I used in the drill – it is 37mm diameter, 42mm long, can take 50amps for 50 seconds, uses 4 amps max on the drill at max RPM. This type of case construction is prefered for a Hi-Speed application – note the cooling 'fan' at the rear – sort of side slots that suck in cooling air. This one is very quiet when running fast – some of the other pics show inlets direct in from the motor rear – these are unbelievably noisy – your ears curl backwards, your eyes water, and your shoulders crunch up….And that high frequency screech goes through ten walls…

The only thing I do not like about these HACKERS are the rather small bearing – 5mm ID x 11mm OD

This motor is about 9 Pounds..(BP)

Below AXI ( Czech) Motors, except for the larger one.

The left one is 35mm diam x 45 long, '400watt' – The middle one is 50mmx50mm '950watt' – the Right hand one is 65mm x 60mm long – '2KW' (!) They all have various RPM/Volt ratings (kv).

For a hi-speed drill or engraver application a kv of between 600 and 900 is good. The large motor below is a 250kv, and can be fed from voltages ranging from 16Volts to 80volts – 80 volts would give 20,000RPM – SCARY… Note the larger bearings on the smaller motor – 5MM ID x 16mm OD. This smaller one is an eqivelent of the HACKER I used.

This is a MAYTECH motor, with an 8mm shaft – I used this on my CNC engraver ( see my other postes) – it runs up to 28KRPM no problem – a bit loud as the air is rear entry, but a very nice motor – 50mm Diameter x 40mm long – '600watt' Cost about 11 Pounds..

And here are some typical speed controller –

The top one is a 40A 'no-real-name-brand' and it works fine. The next is a 70A, and the biggy is a 200amp…

The 40A one is about 2 Pounds, from any reasonable hobby shop.

[Joseph Noci 1Participant @josephnoci1]

Ian, Miklos does not sell himself to well on the internet – he is a Hungarian, did a lot in the military UAV world, and does amazing work with Model Jet Turbines – hence the development of his Balancer. His first one is an engineering masterpiece – 'floating' bearings to hold the spinning shaft, and two loudspeakers, end each and at 90deg to the shaft as vibration sensors! Very nice work. There is then also an optical ( or magnetic) RPM pickup, These signals are then fed into a PC Sound card and his software does it all! Magic.

If you google "Soundcard Based Dynamic Balancing Machine for Model Gas Turbine Miklós T.KONCZ, HUNGARY'

or similar you will pick up the thread. I do suggest you contact him via email – kmiklos@vnet.hu – he will send you all the info you would need, PDF's of everything,user manual, pictures of setup, etc. He does supply all the kit – sensors, cables etc, if you wish, else if you are 'handy' you can easily knock the bits up yourself – two accelerometers, and most 'aurduino' type suppliers these days have 'break-out' boards with the sensors fitted, enabling you to easily use them, for 1 or two Pounds. The opto sensor can be the slotted type sensor, or a reflective one, or if magnetic, a coil of wire..I can help you with info on all those issues if you go that far.

Here are the bits I made: upper left are two Accelerometers and the RPM Reflective Opto Sensor. Below id the switching and interface box. All cables are USB cable, Except for the 3mm jack to the sound card. USB cable from the control box to each sensor only take the analogue signal and +5V to/from the sensor – not actual USB – the cable are shield so work well and keep it all neat. The USB cable from the control box to the PC is just for +5V from the PC to the sensors. Each Accelerometer module has a 3 axis sensor in it, I use Z and Y axis, and selt the axis on the control box – this allow some freedom when mounting the sensor on the item to be balanced – flat or vertical.

The RPM sensor – I made this , and the sense electronics inside, but these are available – heideheim, etc, as reasonable cost.

Inside one of the Accelerometer modules. – The box is 20mmx15mmx8mm

[Author]

Posts