toolpost motor

[brickyParticipant @bricky]

I am going to make a toolpost drill/grinder from a disused small drilling machine quill.The motor from the drill is too big and too fast at 2000 RPM.I have sewing machine motors but I don't know wether they will be powerful enough .If not could someone suggest where to get a small motor and what power I would need.

Frank

[brickyParticipant @bricky]

[Joseph Noci 1Participant @josephnoci1]

Hi Frank.

It really depends on what you wish to do with the grinder. If only small internal grinding wheels, say up to 15mm diameter max, you 'may' get away with a sewing machine motor, but will probably have to step up the spindle speed a tad from the motor speed. This will cause loss of torque at the wheel, so that motor will be on the weak side.

Smaller internal wheels or mounted wheel types, around 5 to 8mm diameter will need high peripheral speeds – 5mm at least able to do around 10000 rpm.

I would suggest a motor of around 200 watts minimum, but I do not know what your drill quill is like – shaft diameter, what type of bearings,seals, etc – these will all take some watts from the motor so more info needed.

If only outside grinding is required you would likely use larger wheels, maybe up to 50mm, and then speeds can be lower – sort of 3000 / 4000 rpm area. However, larger wheels require more torque, unless you take numbingly fine cuts, so the sewing motor won't cut it..

If the grinder is for a typical 'tool and cutter' type, with larger wheels, say around 100mm or so, forget the sewing motor – and 2000 rpm is definitely not to fast for this setup.

Some pics of what I did – used a brushless DC motor from the Radio control world with variable speed. Motor on the T&C grinder starting 2nd down is around 65mm OD, and can deliver up to 1kW (!) at 40VDC in – 25amps for short periods…When grinding heavily I never see the amps go beyond 5 or 6, ie, 200 watts to 250 watts max.

Joe

[Clive Brown 1Participant @clivebrown1]

I agree with JN1. I have a GHT sensitive drill and a Quorn, each using a 2800 rpm induction motor of about 100 watts. The drill takes up to 5/32" at around 2500 rpm, the Quorn uses up to 4" wheels at 5000rpm. The available power is just about adequate in each case. The Quorn takes only very light cuts of course.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Joseph Noci 1 on 03/12/2018 08:45:03:…

…

Stunning! Thanks for sharing.

Dave

[not done it yetParticipant @notdoneityet]

You already have micro adjustments in two axes, so why do you need a third? Mounting a grinder on a cheap milling attachment would likely provide a better solution? What speed will the quill sustain? Likely not the speeds required?

[Nick HughesParticipant @nickhughes97026]

The Dynamic Toolpost Grinder kit I have from Hemingway, has a 250W, 2 pole motor.

Nick.

[egaParticipant @ega]

I was surprised to read in the review in MEW 52 that the Quick Step Mill motor is only 60W; it does, of course, drive through a gearbox which would be less suitable for grinding than plain belt drive.

Edited By ega on 03/12/2018 15:25:42

[brickyParticipant @bricky]

A beautiful piece of engineering Joseph and thank you for your input.

Frank

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