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Quick and Dirty X2 Mill feed

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klank:
(Moderator, please excuse me if this topic should be added to the on-going one started by Darren on May8 - please move or remove my post if its in the wrong place).

I need a power feed on the X axis of my Sieg X2 for no more good reason than "arthritis" in my wrists.

There is an excellent thread topic (Darren - May8) a bit further down the board on a mill power feed with a load of advice re. electronics and designs of the mechanical linkage between motor and table leadscrew.
As a newbie, as far as the machining work is concerned, I do not think I have the skills to make some of the necessary "clutch/gear" components accurately enough, so I have been pondering a simpler "basic" solution.

The "ox-cart" type feed wheel on the X axis of the mill table needs a helluva lot of turning to get from one end of its travel to the other and its becoming too painful to tolerate.
I just need a motor feed to get the X axis "in the ball-park" and then go to manual operation. Possibly, milling under power might be useful, but this is not my prime consideration.
I have read a number of threads on this good site and others where a WW motor is usefully employed, but obviously some type of "clutch" mechanism is necessary if manual feeding is required in the operation.
I was fortunate in obtaining a selection of 12V motors from a Ford Fiesta when it was scrapped after our last bout of snow down here (my No. 1 son wrecked his wheels in an ungritted lane!).
My first thought was to utilise either the radiator fan motor or the car heater motor. Both of them would not need any form of "clutch" as there is no reduction worm/pinion to prevent manual operation with the motor connected to the X leadscrew.
I have a good 30amp p.s.u. with volt/ammeters from my ham radio gear and so did some quick tests with it. Both motors would start with the ammeter kicking to around 5 amps and then settle down to spin freely at about 1 amp. They are both quite powerful and would do the job easily, but the physical mounting of them presented problems and also they ran quite fast if uncontrolled.
I discarded the heater/blower motor - nicely as it ran, mounting it would be difficult - the unprotected brushes are at the output shaft end and are fully "open" eg. - to flying swarf/suds and what have you
Motor control is no problem - I have a three pwm controllers from previous electronic projects, but at low revs., the radiator fan motor did not sound too happy so I discarded this.
The tailgate wwm has a mechanical linkage internally to give to-and-fro movement on the output shaft which could be removed but the casing would need re-drilling and a new output shaft fitted - so I discarded this one.
The main wwm looked the best bet.
Fortuitously, my old Dad's motorised 12V bath hoist became surplus to his needs and so I plundered its guts to see what might be worth having.
It is powered by a nice little Bosch wwm type of affair that was easy to remove. This turns over quite slowly at 15V and responds well to a pwm controller - right down to a slow crawl. The output shaft has a flat machined on it.





Motor control has been covered so well in other posts - all I can add is I am using the controller suggested by Websterz in the May8 thread'
http://www.electronickits.com/kit/complete/motor/k166.htm
In the UK - available from:-
http://www.quasarelectronics.com/3166v2-bidirectional-dc-motor-speed-controller-5-32vdc-10a.htm
This is a surprisingly elegant design and very efficient - "H" configuration of 4 power Mosfets - means no need for a reversing switch (must be rated at at least 5 amps) and easy control by a single pot. left, off or right in the event of "exciting problems" when in use. Carries 5 amps easily and can be used up to 10amps if some of the circuit board tracks are "beefed up" with tinned copper wire.
I built one into an old 18v minidrill case I had, using a scrap transformer.





I have put some dimensions in the following if they are of use to any other X2 owners.
My Sieg X2 mill has a slot ready cut in the end of the X axis leadscrew (I don't know if this is standard with all the similar "clones"). the shaft is circa. 12mm dia. with the slot 4.5mm wide for about 30mm. (I measured these without stripping the whole thing down - so might be a slightly out).



I made a shaft to connect with the slotted end from 12mm steel bar, milling the tongue 4.4mm, 30mm long.
Length of bar to suit needs - mine is 140mm.
Took a 45mm length of 20mm dia. steel bar and bored it 12mm - to a nice slide fit over the tongue.
Fitted this with 10mm projecting proud of the tongue with a cross drilled bronze pin at the other (inboard of the tongue) end.



I machined down the rest of the length to (arbitrary) 10.5mm.

I had a piece of 6mm black steel plate, 150mm x 100mm - which I used to replace the "end" plate on the mill table (held by two M5 screws). These appear to be on 72mm centres, 21.5mm down from the top face of the table.
To allow for the leadscrew not turning exactly true with the shaft added (mine described a bit of a circle at the outboard end when engaged with the slot), I drilled the mounting holes oversize at 7mm to allow for some "adjustment" - see later.
The hardest bit was spotting the point where the shaft would pierce the new endplate. I measured this as accurately as possible - exactly dead centre between the mounting holes and 38mm down vertically.
I machined a substantial bush from a bit of gunmetal bar I had blagged from a scrapyard - 15mm length of 28mm dia.
Bored to a running fit over the 10.5mm length of what will be the "input" shaft.
I made the bush a very tight fit in a 14mm hole bored in the end plate.



The bush is thick enough to take the shaft "wobble" when slotted into the leadscrew and smooth everything out - helps eliminate backlash on this screw too!
The shaft can be pushed into engagement, but with the extra length of the collar, it can be pulled out with the end of the collar meeting the endplate and turning smoothly without engaging in the slotted end of the leadscrew - my "clutch mechanism". It moves in and out with a smooth clack each time - most satisfying.





All that is left is for me to fit the end of the motor output shaft to the end of the input shaft, hook up to the psu/controller and test.
Will post this later.

Bernd:
Nice mod klank. No problem with starting your own thread on how you did it. Keeps the confusion down if you post something like this in a new thread. People won't have to search through a single thread to find an answer.

And the mod looks quite simple so far.

Keep up the good work.

Bernd

Brass_Machine:
I agree with Bernd on all accounts. Looking good and keep it coming!

Eric

John Hill:
Good work Klank!

The thought did cross my mind when I got to the bit "I just need a motor feed to get the X axis "in the ball-park" and then go to manual operation"  that a battery screw driver with some sort of crank on the end would make an easy and convenient "knob/wheel" turner.

Darren:
Very nice, very nice indeed.

I really like your "clutch" method. Should be a joy to use.

I've seen those power supplies before, and nice they are too. I have one reservation, well two really.

I have heard that finding the center off can be fiddly. Easy to put the motor into reverse by accident. Is this true?
Second, to reverse the motor you loose the "sweet" speed setting and have to find it again every time you change direction.

Though if you are not going to mill under power then this won't be an issue.

Sorry I didn't mean to cloud things, just speaking aloud  :(

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