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elliot omnimill convert to cnc?

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chris mcnicoll09/07/2020 17:02:29
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img_2216.jpghi there, has anyone converted a similar mill to mine before? im looking for info as to what,where,when and how if anyone can advise. thanks

img_2215.jpg

John Haine09/07/2020 17:42:39
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That's one beefy mill! In principle there shouldn't be any special issues except that as it looks like a knee mill the Z (vertical) feed will need a hefty motor.

You would need to replace all the feed screws with ballscrews anyway.

It would be a nice machine when converted!

JasonB09/07/2020 18:16:42
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Would be worth trying to up the spindle speed if you do it otherwise it could take a long time to run any code

chris mcnicoll09/07/2020 18:23:30
40 forum posts
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Posted by JasonB on 09/07/2020 18:16:42:

Would be worth trying to up the spindle speed if you do it otherwise it could take a long time to run any code

Ok, how would I go about that? Faster motor? It’s on belts and pulleys and belts so I can speed up quite a bit.
thanks

JasonB09/07/2020 18:49:50
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Depends what the bearings can take and also what condition they are in. Also what type of things are you thinking of machining? non ferrous materials ideally want a higher spindle speed that steel/iron and fine detailed small parts will need smaller diameter cutters which again work best at a decent speed. I would say 5000min and 7500 if you can get it even then you won't be upto optimum speed for small non ferrous work.

Would almost be easier to fit a high speed spindle on the end of the tubular arm and junk the head, motor and belts.

Paul Kemp09/07/2020 19:47:03
509 forum posts
18 photos

I would echo John's suggestion re the knee and torque required as the standard set up takes a bit of turning (I have a larger diameter hand wheel on mine) although with a ball screw I guess it may be less?

From memory top speed as standard on the vertical head is around the 2000 mark, well short of CNC speeds but I don't suppose the bearings would mind too much they are a decent size, check the specs maybe? They could perhaps be swapped reasonably easy to something better suited to the speeds.

Nice machine even in manual form though, I was taking 50 thou cuts with a 2" facemill in steel on mine last weekend for fun. I love it.

Paul.

chris mcnicoll09/07/2020 20:14:05
40 forum posts
15 photos

so are we thinking nema 34 would be strong enough? **LINK**

Bazyle09/07/2020 21:31:42
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Don't worry about the speed until you have got the movements sorted out after all if the computer is doing the work it doesn't matter if it takes all night. It is about the same size as a mill drill table so there are lots of equivalent conversions on the internet to look at, and some kits of motors and screws which althugh not directly usable in your case will show you the sizes.

John Hilton09/07/2020 21:58:06
116 forum posts
28 photos

I have converted a couple of mills to CNC.

Nema 34 is probably the size to use, but you need a high torque motor as they have to hold the work as well as move it.

I would get ball screws and fit them.

I would drive the 3 axis indirectly, with a timing belt on pulleys between the motors and the lead screws.

My first conversion had a top speed of about 1500 rpm, and to be honest this was perfectly ok with hss tools.

To operate I recommend Mach3 or mach4.

For the saddle I suggest you rig up a counter balance to take the weight off. A spring or weight over a pulley would do the trick. Maybe even an old car spring?

Good luck. It looks a useful mill.

John

chris mcnicoll10/07/2020 14:23:34
40 forum posts
15 photos
Posted by John Hilton on 09/07/2020 21:58:06:

I have converted a couple of mills to CNC.

Nema 34 is probably the size to use, but you need a high torque motor as they have to hold the work as well as move it.

I would get ball screws and fit them.

I would drive the 3 axis indirectly, with a timing belt on pulleys between the motors and the lead screws.

My first conversion had a top speed of about 1500 rpm, and to be honest this was perfectly ok with hss tools.

To operate I recommend Mach3 or mach4.

For the saddle I suggest you rig up a counter balance to take the weight off. A spring or weight over a pulley would do the trick. Maybe even an old car spring?

Good luck. It looks a useful mill.

John

thanks john, by counter balance im taking it you mean at the oposite end to where i would fit the motor?

thakns

chris

JasonB10/07/2020 16:20:02
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No, something to counter the weight of the table. A lot of the mills with moving heads have a gas strut or spring so the motor does not have to lift all the weight. Your table is quite likely to be heavier than a typical mill head so need more counterbalance.

chris mcnicoll10/07/2020 16:34:47
40 forum posts
15 photos
Posted by JasonB on 10/07/2020 16:20:02:

No, something to counter the weight of the table. A lot of the mills with moving heads have a gas strut or spring so the motor does not have to lift all the weight. Your table is quite likely to be heavier than a typical mill head so need more counterbalance.

ah, i think i get it now so @JasonB. put a strut underneath that is closed so it will help push the table upwards as the motor trys to lift it?

thanks for all the help

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