DRO for Warco Major mill

[PekkaNF]

Hello,

Got the round column mill and pretty soon noticed that it takes three hands and patience of the saint to keep up required accuracy with these mills.



Story of stand:
https://madmodder.net/index.php/topic,12667.msg152459.html#msg152459

Although generally I am happy with the mill and it does much I want, 3 mm backlash on handwheels and a mushy feeling of it convinced me that the X/Y stage needs a closer look, probably new bearings and that sort of work. While at it, adding a DRO might be a good idea.

Ordered and got 3 axis (two will be used primarly and maybe third added later) magnetic scale system:
https://www.machine-dro.co.uk/3-axis-mill-dro-kit-with-magnetic-encoders.html

Planning to mount the magnetic tapes flush inside the slides on non sliding surfaces I.E. not planning to use the typical scaffolding type mounting.




I am sure that someone has done this before, but I could not find story. Any links to similar installations or advice?

Pekka

[BillTodd]

From memory, there is nothing flat or square on the unmachined insides of these . Catch 22nin action, you need a working mill to fix the mill 

I would mount the X heads to the (Y) saddle and the the mag tape to the table with a straight bar to carry the tape . It'll be a pita to get the things aligned so mount the reader head close to one side of the saddle (easier to get at)

Not sure if there's enough room to get the tape under the Y saddle for the Y axis , but the saddle is close to a straight-ish side of the base casting so you might be able to use that.

[PekkaNF]

Luckily I have a second mill and it is biger...therefore I don't need to resort Heath Robinson solutions.

I took off the rubber cover of Y-ways and also disaasmbled the table screw out to gain better look inside....interesting....there are possibilities, but they all need a serious consideration.

I sort of like the stops on front of the table. There is about 30 mm space behind the table that is used by this rubber shield now. Maybe I could construct different swarf guard to replace it and get more space behind the table for magnetic tape.

Mounting the tape underside the T-slot table is possible, but it would require serious slotting for the reading head, because if I want to use original movement range the table movement does not really allow mounting the transducer on side of the middle part (Y-sledge).

Mounting it behind of the table using the supplied aluminium profiles for the magnetic tape is a squese. Need to build a mechanical stop, because just looking the dimenssions, there is just 0,7mm to spare.

[tom osselton]

I have a craftex mill that I put a dro on from Dro Pro’s. I went with a 4 axis and can use the quill by combining the quill and z axis using one readout if I choose to. Mine has the mag strip on the back and I made brackets for the side of the machine.

[tom osselton]

Here is a pic of the y axis.

[BillTodd]

The only broken scale  I' ve replaced ( as opposed to many failed ones) was on a bp mill and that had the scale on the rear of the table.  It seems more vulnerable there than it looks. we've several xyz mills with scales on the front that have been ok.

[PekkaNF]

I have a craftex mill that I put a dro on from Dro Pro’s. I went with a 4 axis and can use the quill by combining the quill and z axis using one readout if I choose to. Mine has the mag strip on the back and I made brackets for the side of the machine.

Thank you Tom. Looks like really solid bracket. Looks like you have the X-axis scale right behind of the table....very much the same way I envisioned assembling mine. Do you have any advise on that style assembly?

The only broken scale  I' ve replaced ( as opposed to many failed ones) was on a bp mill and that had the scale on the rear of the table.  It seems more vulnerable there than it looks. we've several xyz mills with scales on the front that have been ok.

Thank you Bill. That is something to think over, I might think that the scale is more vulnerable on front - operator errors i.e. my butter fingers comes to mind----like adjusting the table stops with magnetic tool and poking the scale accidentally

I like the mechanical table stops on X-axis, not extremely attractive mechanically, but seems to work. I was thinking of keeping it, because sometimes it is pretty handy (used it couple of times allready). This is the main reason I thought of putting the X-axis magnetic scale somewhere else than on front of the table.

The original tape rule "scale" on the front is pretty bad, barely adequate to verify while counting cranks of the handle.

Pekka

[chipenter]

I fitted dro's to my Warco minor by brackets on the end face of the table with clearance for the centre stop , and replacing the lock levers with grub screws , but still have the use of the adjustable end stops , the Z axis scale reads 92.5 thaow per revolution ( I have no idea how that works ) .

[tom osselton]

The x axis wasn’t bad installing as it’s all on a flat surface you do lose some machining area and it’s not just the scale but the way covers too in my case 1/8 rubber so when it folds up there’s a 1/4” added but hasn’t affected anything I do.
I’d put it on the back and try it and see what you think, worse case scenario you could change it which would take maybe 1 hour.

[WeldingRod]

Here's a super compact magnetic tape installation on my hardinge cross slide.

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[PekkaNF]

Here's a super compact magnetic tape installation on my hardinge cross slide.

That surely is super compact and looks like read head has a cover that should keep the swarf away. Looks a little out in the wind location and you probably don't have a habit of putting a magnetic stand ant that side of the cross slide.

Pekka

[PekkaNF]

Disassembled the table and saddle. Taper gibs looks fine and threaded spindle nuts are cast iron.

Need to make some measurements to verify results, but looks like the easies way is to do hang the scales outside of the machine.

X-axis scale could fit right behind of the table.

Y-axis has more freedom and there are more possibilities. Several places, it could be fit nearly, or it almost could be hiden out of harm's way - and many places that it would be pretty crampped installation.

Traditional course of action would be to fit the magnetic tape onto plinth (cast, tapered side) and attach the read head into Y-slide (saddle). Mecahnically easy, but would need stand offs for the scale spar to keep it out of the plinth (and dripping oil, coolant, swarf) and the read head would be in the moving part.

Thinking of making a mount into saddle and hang the tape face down (i.e. attach the tape into moving part, under the table - mostly) and the read head mount into plinth. Need few more measurement to verify if this is a good plan.

Pekka

[PekkaNF]

Did a little mockup for both X-axis tape options.

Pic 1: Permanent marker pen (left) where magnetic tape would come if I want it out of the way. Ballpoint pen (right) if I want to hang the tape behind of the table.

Pic2: This would be the easy option: Measurement behind of the table. Hardly any machining to Warco mill parts. Could use supplied parts to mount the magnetic scale. Mounting the reader head would be easy, could use supplied hardware or make simple mount.

Pic3: IF want to mount the magnetic scale inside the table (as in pic 1), the reader head needs to be recessed into saddle. Position needs to be 10 mm down and into machined surface from the place it is lying in the picture. Dove tail comes into way with straight endmill. This needs a bit special endmill with thinned shank or small T-grove end-mill make it. Therefore this will be not my prefered method, unless I need all the movement range in Y-axis (and therefore can't mount the scale behind the table).

Pekka

[BillTodd]

Pekka,

while you have the Yaxis apart, check the flatness and fit of the Y nut to the saddle  . I found that this interface was a source of backlash in my rollernut conversion.

[PekkaNF]

Pekka,

while you have the Yaxis apart, check the flatness and fit of the Y nut to the saddle  . I found that this interface was a source of backlash in my rollernut conversion.

Thank you. I will check that.

I noticed that all of the threaded spindle nuts and bearings are mounted onto painted cast iron. Not the normal industrial practice.

One thing that baffles me that that ground way surfaces are flaked lightly, probably to retain oil, but mounting surfaces are pretty rough. Also the taper gibs seems to be very agresively scraped on the way side (but that part of the way itself is not flaked....). The gibs are unfinished on the other other side, couple of deep scores, I flatten with file, just to knock burr off.

I am also eyeballing it to see if it would benefit from way lubrication points, way oil seems to stick onto surface, but I have used plenty. Maybe a little less would be more.

Pekka

[seadog]

I think the accepted view of Chinese 'built' machines is that you should view them as a kit of parts which need stripping, fettling and reassembling. You then end up with something that's not too bad for the price.

[PekkaNF]

I think the accepted view of Chinese 'built' machines is that you should view them as a kit of parts which need stripping, fettling and reassembling. You then end up with something that's not too bad for the price.

I agree with this. And availability of these machines. And ease of working with them.

I tried to get semi decent Aciera F3 or something nearby...not too keen on buying from a dealer from other country before seeing one in person.

Pekka

[PekkaNF]

Pekka,

while you have the Yaxis apart, check the flatness and fit of the Y nut to the saddle  . I found that this interface was a source of backlash in my rollernut conversion.

And while at it, I decided to check why my mill had only 180 mm of cross traverse instead of advertised 203 mm. Someone forgot to snag the cast iron plinth opening.

5 min with hack saw sorted it and now cross traverse (Y) is pretty much exactly 200 mm. But now there is no room for X-scale behind of the table with standard mounting hardware anymore.

Pekka

[seadog]

Snagging is what we, in the UK, call fettling. An old Middle English word derived from German.

[chipenter]

Take a bit from the front and put a stop at the back .

[PekkaNF]

Snagging is what we, in the UK, call fettling. An old Middle English word derived from German.

Thank you, I always thought that fettling was more akin to cleaning and knocking of shar edges and such. But I never heard snagging being used in UK, only in US. But then again that was not my primary intrest then.

Take a bit from the front and put a stop at the back .

Hmm. There is no T-grove on the back of the table.

[chipenter]

The stop would have to be for the lead screw nut to hit , it's the nut that limits travel on my minor the casting was curved and angled the nut was flat , and only about 6mm thick just filed it square and got another 10mm .

[PekkaNF]

The stop would have to be for the lead screw nut to hit , it's the nut that limits travel on my minor the casting was curved and angled the nut was flat , and only about 6mm thick just filed it square and got another 10mm .

Yesh, there is a curve at the front end of the plinth. Cuout is U-shaped and I was working on with pilar end. Need to chek if the spindle reaches far side of the table.

Pekka

[WeldingRod]

You could do like I did on my cross slide, and bond the magnetic tape directly to the machined back side of the table.  If you put the reader off center, you could get it on there with no loss of travel.

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[PekkaNF]

You could do like I did on my cross slide, and bond the magnetic tape directly to the machined back side of the table.  If you put the reader off center, you could get it on there with no loss of travel.

Sent from my SAMSUNG-SM-G891A using Tapatalk

That is a pretty good option. Easy to make and maintain.