Warco Major CNC build log

When Garry at Zapp finishes machining my ball screws I'm going to have another go at CNC'ing my poor old Warco Major mill.

The plan is to have all the milling done for the X and Y axes so I can strip the machine back then do all the final fitting using a lathe.

The story so far is the pile of bits in the piccy, only a couple of parts left to mill before I'm ready, wonder what I've forgotten.

The theory is simple, combine Garry's 20um backlash screws with a 5um half step resolution and see what it does :beer:

Hope Gary gets me my screws soon, I'm running out of bits to make.

Had a bit of a fright when I located the bolt holes that hold the Y handle to the machine. They look like they were drilled at random with a Black and Decker. One is far from straight, had to drill my hole far from straight to match.

Need to buy some grub screws, best selection and price seems to be from J & S Fasteners, they offer a choice of tips so I can get a flat point rather than those horrid cup ends. I've used them before, have a link...
http://shop1.actinicexpress.co.uk/sh...ners/index.php

More when the screws arrive :beer:

4 days off, a good time to start :beer:
First the Y screw. On the Warco the Y screw locates in to a 21mm diameter pocket 6mm deep cut in the bottom of the carriage (First pic).

I had to finish the nut holder after the machine was apart so I left a rod projecting out the other side for chucking it in the lathe. Looking to mininmise backlash I cut an interference fit with a groove around the bottom to catch any crut.

Pic 2 shows the Y nut fitted but not screwed down yet.

Pic 3 shows the carriage fitted with the spindle sticking out. The first of 2 angular contact bearings is fitted.

The idea is to hold the shaft between two angular races with a quarter ton of thrust locking it in place. To get a quarter ton I'm using pairs of belleville washers.

I have to crush the washers by 1mm and it would be nice if the nut ended up flush with the end of the shaft so I measure it, Pic 4, at 2.95mm then remove 1.95mm from the collar in the lathe.

The fitting has to do both push and pull on the ball screw so it's one solid lump of T6 alloy with a plate for the stepper screwed to it.

Next the X axis. Warco bolt the X nut on from below which is a pain because the Y screw is very much in the way. So I'm bolting it from above.

My X nut holder has a lip to hold it square, luckily I can use the mill to cut a square edge in the carriage for it to run against. Pic 1

Now some hard work. The ball nut fitting is slightly larger than the cutout in the end of the table. I know I could jiggle it over the top but it would be a pain forever more, so now I'm setting out for a jolly afternoon with files and angle grinder opening it out. Pic 2 :rolleyes:

More later

Robin

What's the extra spigot poking up/down from the nut mount for?

http://www.mycncuk.com/forums/attach...4&d=1239369960

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Originally Posted by BillTodd

What's the extra spigot poking up/down from the nut mount for?

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Something to hold on to when I turned the other end :beer:
After much angle grinding and filing the bed slid comfortably past the nut housing so I put in one bolt to fix it to the carriage. First pic. Not very brave but it's easier to move one misplaced hole than 4. It isn't defying gravity, there's a roller stand supporting it, makes it real easy to put on and take off.

Then the driven end, Pic 2, it sticks out a lot so I can use more of the bed, got this very wrong when I first CNC'd it so this is a slight overkill. This end is in 3 pieces, which is okay because the screw will hold it in tension with the same quarter ton I put on the Y. I plan to Loctite it in place when I drag it all together with the Bellevilles.

Then the handle end...

I haven't cut the bearing seat in the handle end yet, wanted to get my calipers on it first, Pic 3, and find out exactly how far the shaft sticks out.

Next I put that measurement in the drawing and decide how much I trim off and where. I have leeway.

The last pic was supposed to show that my single bolt went in the right place and the shaft is concentric. Would have looked a lot better if I'd put the camera a couple of inches to the left :rolleyes:

The Y axis feels amazingly precise from a backlash point of view. The dial test gauge will reveal all.

More soon...

Robin

Looking good Robin :)

I'm Looking forward to the Z axis; it's the one I've yet to figure out for my drill/mill.

X handle fitted and screw tensioned, Pic 1

An overall pic 2

I'm going to test this out before I redo the Z, see how Gary's screws perform before I buy any more.

I have to take it all apart tomorrow, add the other 3 bolts to the X nut housing, lube the slides, add some Loctite so things can't twist etc.

2 problems

I'm getting a collision at either end of the X travel so I'm not quite getting quite as much as I was looking for, need to go back to the drawings for that one,

The old pulley on the X motor doesn't want to come off. Easy to shatter the magnet in an Escap Discmagnet motor if you end load the shaft, I'll have to contrive some kind of puller.
Still, not bad for one day :beer:
Incidentally, I have a new 16mm drill chuk on there, 100% better than the Warco supplied one, got it from RDG tools for £22

Robin

Quote:

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Originally Posted by Robin Hewitt

Incidentally, I have a new 16mm drill chuk on there, 100% better than the Warco supplied one, got it from RDG tools for £22

Robin

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Looking good Robin - I wonder how similar my Minor is? BTW, I have the same chuck, is yours on an MT3 or R8 taper?

Hi Irving it's Morse :D

I got the lack of travel nearly sorted today by angle grinder. Tested it with a loose Gibb, lost about 1cm with a tight Gibb. Can only be a few thou left to remove think I'll leave that until I need it an extra cm. Pics attached.

THE BIG BACKLASH TEST (this being the whole point of the exercise)

Put a DTI on the bed and turned the handle, by hand. I could feel the stepper motor cogging and with the 2.5:1 reduction the slide should move .01mm per clunk, 0.0004".

Well it didn't move that far when I sat there rocking it back and forth one clunk, but it did move a little bit so backlash is now <10 microns, not bad for 20 micron nuts :beer:

I totally destroyed one of the stepper motors while trying to remove the old pulley. I was thinking to replace them anyway with some of these new fangled hybrids.

Robin

I have just sent the picture for the Z axis screw machining to Gary and ordered a girt lump of aluminium.

The spindle doesn't like running at 5000 rpm which is top whack, 2500 rpm of the pulleys and 100Hz from the inverter, the bearings run hot. I would actually like twice that so I can run tiny ball end mills.

The plan is a false spindle set inside a 3MT soft end arbor and a lay shaft with two timing belts. That way the false spindle with it's ER11 collet can turn at 9 times the main spindle speed.
Give me something to do while I wait for the Z screw :beer:

Quote:

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Originally Posted by Kip

I tried a micro grinder in a 20mm collet...it works well at 60.000RPM

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Sounds tempting, I'm having a slight alignment problems with the double axial race on my tiny collet gizmo. Going to have to bolt a boring bar to the mill bed, cut the seat oversize in situ then fit a sleeve.

To do that I need to make a 1/2" BSW drawbar. Can't make the drawbar because my 1 1/2" die holder has gone walkabout. Can't make the Z axis bottom plate 'til I know if I need to fit the layshaft etc. :rolleyes:

However the Z axis screw has arrived and fits inside it's sleeve okay.

More soon

Robin

Quote:

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Originally Posted by Robin Hewitt

To do that I need to make a 1/2" BSW drawbar.

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Do what I did and buy a 36" length of 1/2" BSW threaded rod and 4 matching nuts. Cut rod in half, screw into tool (through quill), place 1/2 washer, screw on 1 nut till tool retained, then a second nut and lock together. Remove bar and nuts together as one assembly, weld up the nuts, repeat and hey presto two draw bars! (one for mill, one for lathe as they share the same MT3 taper and tooling).

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Originally Posted by irving2008

Do what I did and buy a 36" length of 1/2" BSW threaded rod and 4 matching nuts.

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Where did you manage to buy archaic studding in an ISO world? Enquiring minds need to know :beer:

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Originally Posted by Kip

I got mine from Sowerby Bridge (on recommendation from RDG) Archaic.....are you incinerating it's bent :naughty: :D

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RDG got it for me, think it was from the same place Kip.

Or here: http://www.thesitebox.com/Product/12...-12-x-3ft.aspx

or here: http://www.fastfixdirect.co.uk/code/navigation.asp?Diameter=1%2F2*&Thread=BSW&Length=a ll&Filtered=True&PageID=1&MainCategoryID=4&Product CategoryID=129

Quote:

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Originally Posted by Kip

Have you seen these on ebay Robin? Looks like a plan :)

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Interesting but I wonder about backlash... aircraft positional control doesnt need high spec in terms of backlash and since it has a 'mechanical detach' I suspect the backlash could be problematic

These are for the First class chair control, i helped design one for a company a few years ago.
Backlash will be a problem.
Also they normally have a long lead so it can be back driven if the power fails.

Quote:

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Originally Posted by irving2008

Interesting but I wonder about backlash... aircraft positional control doesnt need high spec in terms of backlash and since it has a 'mechanical detach' I suspect the backlash could be problematic

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Quote:

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Originally Posted by Kip

A honking big lump of Al mixed with a tube and a 20mm NSK

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Great minds think alike :beer:

The honking plate holds the screw square to the quill with minimum flex, I was thinking two 8mm pinch bolts at the back.

One vital feature missing in your picture though, probably early days and not forgot but still worth mentioning, you have to be able to release it before you hammer the chuck out of it's taper :eek:

I don't have any convenient flat to bolt a plummer type bearing mount to so I have to extend the sides of the quill housing forwards. This is almost convenient because it ain't easy to get a precise measurement for the separation 'twixt spindle and screw, I thought a bit of slack before I drilled the fixing bolts wouldn't be a bad thing.

Back again and cutting metal...

Going for the larger stepper motor this time with half the pulley reduction to put me in the power band. 1 rev = 4mm, half step = 10 microns.

Same pair of angular contact races with the Belleville washers holding it in tension as before.

The front of the mill is to extend forwards with bolt on cheeks. The bearings are set in a 16mm plate which fits into grooves in the cheeks to hold it square and rigid.

The ball nut is enclosed a la Kip, the bottom of the housing is wider to take a pair of 8mm set screws which tie it to the spindle, or not, as the case may be.

Next job, fitting the cheeks so they wedge tight in the ironwork :beer:

I don't really do 'excited' anymore :yahoo:

I think I have to fit this top section then fudge to connect it to the quill.

Once it's all bolted together and moving I can measure the fudge and get precise dimensions for the honking plate.

Robin

Robin,

Been watching this with interest as I want to do the same to mine going forward, although not sure my engineering skills are up to the challenge yet.

I am still struggling to understand how the Z-mechanism will work. Does the 'honking plate' clamp to the quill flange under the head and, if so, where does the remainder bolt to on the head itself. What is the advantage of that over motorising the quill handle itself?

On the X-axis, I can understand why the motorised element sticks out so far to allow more X travel, but again, how is that better than driving the handwheel end? And could it be done without it sticking out so far as this would give me space problems?

I know Kip has done something similar.

I've yet to strip it down and draw it all up to work out how to do it, but just starting to do some planning for later on this year.

Hi Irving

Let's not forget that trying to screw this kind of accuracy out of a Warco mill/drill puts us deep in to the realm of silk purse and sow's ear. Silly has already been left way behind :joker:

Motorizing the Z axis handle would be much more in keeping with the machine, but you would never push the boundaries that way.

Would you like to have the z-axis I'm ripping out? It's much the same as the one that's going in but a lot less beefy and made without the benefit of cnc.

One more set of pics and the operation should become clear.

Robin

Quote:

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Originally Posted by Robin Hewitt

Hi Irving

Let's not forget that trying to screw this kind of accuracy out of a Warco mill/drill puts us deep in to the realm of silk purse and sow's ear. Silly has already been left way behind :joker:

Motorizing the Z axis handle would be much more in keeping with the machine, but you would never push the boundaries that way.

Would you like to have the z-axis I'm ripping out? It's much the same as the one that's going in but a lot less beefy and made without the benefit of cnc.

One more set of pics and the operation should become clear.

Robin

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Robin,

I'd be happy to get a reasonable degree of accuracy, not interested at pusing the boundaries at first. Cost is still an issue, but if i am going to invest a few £100 in ballscrews etc. I need to be comfortable I know what I am doing and I have a reasonable chance of success.

I may well be interested in your old Z-axis... its still likely to be an order of magnitude better than anything I can produce (yet).

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Originally Posted by Kip

Robin have you given much thought to the "hammering out ceremony" once the ballsrew is attached?

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I'm doing it the same way I did last time, the screw housing bolts to the honking plate. Only difference is I'm using 2 screws this time instead of one. I think it needs a bit extra to lock the screw parallel to the quill.

Quote:

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Originally Posted by irving2008

I may well be interested in your old Z-axis... its still likely to be an order of magnitude better than anything I can produce (yet).

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Not exactly pretty but you can have the X and Y screws if it helps They are cluttering up the workshop, probably going in the bin next time I tidy the shelves. If I find a box I could send the whole she-bang standard parcels.

I bought zero :joker: backlash nuts from Marchant Dice for the X and Y, odd things that you had to crush sideways to set. I never got the backlash below 3 thou. Also I didn't get the ends machined, just glued on extension sleeves with Loctite. With the benefit of hindsight, a false economy.

The Z axis was a disappointment, nice screw off ebay but I didn't eliminate flex and it always fell slightly short of the mark. I'm hoping the honking plate will fix that.

Robin

Quote:

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Originally Posted by Robin Hewitt

I'm doing it the same way I did last time, the screw housing bolts to the honking plate. Only difference is I'm using 2 screws this time instead of one. I think it needs a bit extra to lock the screw parallel to the quill.



Not exactly pretty but you can have the X and Y screws if it helps They are cluttering up the workshop, probably going in the bin next time I tidy the shelves. If I find a box I could send the whole she-bang standard parcels.

I bought zero :joker: backlash nuts from Marchant Dice for the X and Y, odd things that you had to crush sideways to set. I never got the backlash below 3 thou. Also I didn't get the ends machined, just glued on extension sleeves with Loctite. With the benefit of hindsight, a false economy.

The Z axis was a disappointment, nice screw off ebay but I didn't eliminate flex and it always fell slightly short of the mark. I'm hoping the honking plate will fix that.

Robin

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Robin,
That sounds very generous of you, if it would get me up to speed quicker and allow me to create updated parts later then that would be great. How likely are your Major parts to fit the Minor ?

Pic 1: Cheeks put in with a couple of bolts. Needed a bit of extra removing from the left cheek because the casting was far from straight. Heavy application of the angle grinder at the bottom before the ball screw bearing plate would slide home, had to cut out an extra 7.5mm

Pic 2: Ball screw fitted, view from the side. This is as close as you can get the ballscrew to the quill. Hence requirement for honking plate.

Pic 3: Pile of bits removed, Irvings' if he wants 'em :joker:

Should have taken a front view with the ballscrew installed. Maybe next time.

Next I have to relieve the cheeks a tadge so I can fit the motor plate, bit of a poor measurement there.

Then make a false honking plate, cut the pulleys and wire it up so so I can make a real honking plate :beer:

Robin

Quote:

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Originally Posted by Kip

Honking plate is the word indeed....I'm going to aim at 63mm thick for my honking plate.

You had 3 thou backlash with the Isel ballnuts? Did you use oil or grease?

Snatch his arm off Irving :D

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I'm snatching... Robin, I want please... I'll even come and collect if you want me to... (although may be a while before I can as I have broken the rear suspension on the car)

Quote:

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Originally Posted by Kip

Honking plate is the word indeed....I'm going to aim at 63mm thick for my honking plate.

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Uh? :naughty:

If your thickness goes beyond the height of the lump you are clenching it on to, surely it will be in the way, one way or t'other.

I'd better go try and find an Irving box.

Robin

Quote:

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Originally Posted by Kip

Does your quill twist....peg in slot or other type of guide?

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Peg in slot, slack enough to convince me that I can't hang a spindle motor off the side.

Only got an hour on it last night, wife dragged me down the pub, forced me to drink beer then drove me home. I was in no condition to continue.

I did cut the extra relief in the cheeks so the motor plate can slide home then bored and faced a 40t XL pulley to fit the ball screw shaft.

Took the camera but forgot to put the memory card in it so no pic.

Robin

Me again

Put the pulleys on, belt was too short.

Checked all the measurements, I don't usually get a belt wrong.

Eventually found I'd mounted a 44t pulley where a 40t was required :whistle:

RS seem to be taking orders at 7pm for next day. Wonder if I'll have it tomorrow. Perhaps it will it be a 44t pulley in a 40t bag, don't remember buying a 44t, fairly sure it said 40t on the bag :naughty:

Robin

40t pulley just arrived. RS must be slacking, I ordered it at least 11 hrs 30 minutes ago :naughty:

Quote:

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Originally Posted by Kip

You must feel awful so I'll not mention that I intend using a pair of 30mm SC30UU linear bearings to prevent the trig equation needing to be worked out :D

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Okay, curiosity aroused, what trig?

Robin

Quote:

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It could be pythagsrus not trig....

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It's trig whether you use pythag or not ;)

BTW Was Michael Jackson's last hit called 'the floor'?

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Originally Posted by BillTodd

BTW Was Michael Jackson's last hit called 'the floor'?

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Dunno but the O2 comeback tour is sure going to be special................

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Originally Posted by Kip

11.5 hours....useless!

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Strangely true, when I looked in the box I found an empty 44t packet and a brand spaking new 40t. Nice to have a spare I suppose :whistle:

Quote:

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Originally Posted by Kip

My thought on the swivelly bit at the bottom..if it twists it shortens the effective length of the ballscrew=bad?

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I don't think it can twist without bending the screw, I didn't stint on the metal :nope:

I now have the 40t pulley and belt in place with a faux honking plate fudged out of a bit of 2" x 3/4" iron.

It feels good, any shift on the motor moves the handle, moving the handle spins the motor. I would have wired it up but when I looked for a bit of chocolate block connector all I could find was 80A :rolleyes:

Time for some G-code to make the real honking plate :beer:

Robin

Quote:

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Originally Posted by BillTodd

BTW Was Michael Jackson's last hit called 'the floor'?

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I had heard he was a bit off colour but it was still a surprise.

Quote:

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Originally Posted by Robin Hewitt

Strangely true, when I looked in the box I found an empty 44t packet and a brand spaking new 40t. Nice to have a spare I suppose :whistle:




I don't think it can twist without bending the screw, I didn't stint on the metal :nope:

I now have the 40t pulley and belt in place with a faux honking plate fudged out of a bit of 2" x 3/4" iron.

It feels good, any shift on the motor moves the handle, moving the handle spins the motor. I would have wired it up but when I looked for a bit of chocolate block connector all I could find was 80A :rolleyes:

Time for some G-code to make the real honking plate :beer:

Robin

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Is 'honking plate' a real term or one you made up to describe a 'big lump o' metal'?

I am looking at the pics but still not seeing quite how the quill gets moved... and still moves the motor when you turn the quill handle...

It's actually British Standard Honking Plate.

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Originally Posted by irving2008

I am looking at the pics but still not seeing quite how the quill gets moved... and still moves the motor when you turn the quill handle...

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The frictional losses on a ball screw are low. The screw can turn the nut if you have the means to push hard enough.

Spin the motor by pulling on the handle and you can feel if something is binding. Should be smooth :beer:

Quote:

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Originally Posted by Robin Hewitt

The frictional losses on a ball screw are low. The screw can turn the nut if you have the means to push hard enough.

Spin the motor by pulling on the handle and you can feel if something is binding. Should be smooth :beer:

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Ah, what is the lead on the screw... I hadn't realised it was that big a lead. But what stops the quill dropping under its own weight then when the motor is powered off? Or is there sufficient stickiness in the cogging to stop that?

It's 5mm lead, the 32:40 pulley reduction gives 4mm/motor rev

The quill return spring is there but it wouldn't drop under it's own weight anyway. You gottta pull to spin it.