DRO recommendation for Mill

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aka9950202

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My TouchDRO has been a game changer to my X2 mini mill. I found that the dials on the handles did not give the right feel when the backlash was taken up. The accuracy now achievable make the conversion worthwhile.

Cheers,

Andrew in Melbourne
 

Rudeboy

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I have a new Craftex CX600 mill/drill and would like to install a 3 axis DRO. A couple question:s;
1. Any recommendations on sourcing a suitable DRO.
2. I am baffled on how the scales are attached to the mill. Does this require drilling and tapping the mill frame or is is some other method of attaching the scales as I am not too anxious to drill holes into my new mill.

I'm installing a 3-axis DRO on a Craftex CX600. In my case, the DRO is one of the many (countless) offshore varieties (ToAuto is the brand) acquired from Amazon - the vendor offers pre-packaged sets, i.e., scale lengths, or you can tell them the lengths you need within 5cm increments (which I did). These are 5um glass scales. I did have an Easson setup from Dro Pros but parted with that a while ago. The cheaper products are cheap but functional. As others have alluded to or, in fact, strongly suggested, do NOT use any adhesive to attach the scales.

As I've more or less disassembled the entire mill - in part, this was to examine everything, clean up/adjust as required and, as much, understand how it all works - this greatly facilitated installing the DRO. I *am* drilling/tapping into the cast iron as required in order to attach the fittings. While good (sharp) HSS bits will work well - and I've utilized these - I also switched to equivalent diameter cobalt (5%) bits when the HSS were struggling (whether they dulled or my technique was off). You will read that tapping cast iron doesn't typically require fluid but, as with all tapping operations, do it carefully. Clean the holes in between with a (magnetized) screwdriver shank and/or compressed air to ensure the bits and filings are removed.

My approach is simple: threaded M4 and (mostly) M5 rod, spacers and aluminum plate/angle. Any design should provide some adjustment as to how the scales and reader lay so they have clear travel and allow them to be in alignment with each other - the placement will be your decision. For the CX600, the sides of the column casting are about 3 degrees off square from the way plane so you may have to account for that. Although I did my best to drill/tap 'true' in this location for the z axis, I used stainless conical/countersunk washers to accommodate any adjustment.

Google presents enough examples (search via Grizzly G0704 vs. Craftex CX600 - they're basically identical although the former has a longer table).

PS I'm no expert - just a hobbyist (and a hack at that)...
 
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Lloyd-ss

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When I purchased my Warco Minor/Grizzly G1005Z mill I found that there was excessive backlash on all axis. Having tolerated this for several months I decided to fit a 3 axis DRO. This was a "Wow" moment. Suddenly I had control of the axis with the ability to swap between mm and imperial, zero where I liked and use many other useful features. I can't emphasis how much this changed my ability to machine with accuracy. Clearly it is possible to work with backlash and badly made index wheels but it just makes simple jobs difficult. I quickly installed a 2 axis DRO onto my Myford which had very little backlash. Again machining became so much simpler especially with the added features.

I would always recommend modelers to fit DROs to their machines - yes there is a cost but it is worth every penny!
Mike, I have the exact same Grizzly mill, about 10 years old. And, exactly the same backlash issues, but overall, it is a good value for the $$. I have gotten into the habit of always going clockwise against the axis locks when I zero the handwheel dials. I guess I will finally get a DRO. It will be one of those things where I kick myself for waiting so long.

Some of these threads always cost me money, LOL. 😉
 

Mike Ginn

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Lloyd. Go for it! Yes I agree that it is possible to work with backlash - we all did it for many years but to me it is like using a 4 jaw chuck for round material. Yes it does work but what a pain. Go for the XYZ DRO and your life will be transformed.

BTW and off subject. Have you needed to replace the top bearing. Mine jammed due to lack of lub - my manual said sealed for life - it isnt. Its basically a cheap motor cycle steering head bearing. Not too difficult to change

Mike
 

Brian Rupnow

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You might find everything you need here. And forget about any kind of adhesives.
 

Richard Hed

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Mike, I have the exact same Grizzly mill, about 10 years old. And, exactly the same backlash issues, but overall, it is a good value for the $$. I have gotten into the habit of always going clockwise against the axis locks when I zero the handwheel dials. I guess I will finally get a DRO. It will be one of those things where I kick myself for waiting so long.

Some of these threads always cost me money, LOL. 😉
Yes, you guys cost me a lot of $$, however, it also saves me a lot time! Time is $$, so it's a good thing. I have purchased many things because I read someones blurb and saw their photos. A few days ago I recieved in the mail my first VFD. Been studying the utub vids to get a handle on installing it. The booklet that came with it was so clear that I got quite angry. The booklet is printed for about a dozen different VFDs, but I don't have that dozen different VFDs. I have a specific one and clawing thru the damned crappy booklet to find the info specific to mhy model was NOT , let me reapeat that: NOT, pleasureable. Plus the text is about .5mm tall--had to use glasses and magnifying glass to read it. What total sh*te.

Anyway, many things have I purchased to ttry or on recommendations from you fellows here. Thanx.
 

Lloyd-ss

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Lloyd. Go for it! Yes I agree that it is possible to work with backlash - we all did it for many years but to me it is like using a 4 jaw chuck for round material. Yes it does work but what a pain. Go for the XYZ DRO and your life will be transformed.

BTW and off subject. Have you needed to replace the top bearing. Mine jammed due to lack of lub - my manual said sealed for life - it isnt. Its basically a cheap motor cycle steering head bearing. Not too difficult to change

Mike
Hi Mike,
No problem with the bearings, but a few other annoyances, all of which I either fixed myself or ignored.
The contacts burned out on the switch. Replaced the switch.
The bracket that holds the stack of idler pulleys in the top cowling cracked, but is still functional. Ignored.
Noisey vibration from the plastic cowling over the belts. Just wedged stuff here and there till it stops temporarily.
Noisey vibration from the spindle retract spring in the little can on the left side of the spindle. Have not investigated. Ignoring it.
The Z fine feed knob seems to be slipping, but I am not positive. Need to investigate.
The 2 big pinch bolts that clamp the head casting to the column stripped out, and I generally do not do that sort of thing. I replaced them with good high strength bolts and nuts.

I use this mill several times each week, and that's 10 year's worth of problems on a $1,000 machine, so not too bad I guess.

I am about to take the DRO plunge before I get too old to appreciate it.
Lloyd
 

Mike Ginn

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Lloyd
Apart from the noisy cowling (which in my version is sheet metal) and the bearing issue I have been trouble free.

Take the DRO plunge and rejoice in your "new machine" Get a "proper" DRO with XYZ display. If you need photos of my fix just ask

I'll wait for an update..........

Mike
 

Drawfiler

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I have been through all of this on two mills, I took advice from Machine Dro and they told me to go for magnetic scales as they have less customer problems with those than the glass ones.
The control boxes are mostly made in China and seem to work well. In my experience the digital vernier battery driven one’s are not as robust or reliable as the ‘proper’ scales.
 

Mike Ginn

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I did the same and used Machine DRO kit. I have both glass scales on my mill and magnetic on my lathe. No issues with the glass scales on the mill and there is ample space to fix them. For the Myford lathe things are different. The bed could accommodate either the larger glass scale or magnetic. The cross slide is a different matter. I did not want the large housing of the glass slide getting in the way of machining operations so I fitted a magnetic scale into a machined grove in the underside of the slide. MDRO sell a cross slide extension which allows full movement to the cross slide. It works very well and could easily be made in the shop. No issues with the mag scales or the adhesive holding it in place under the cross slide. I was concerned about this as oils can attack adhesives.

It is possible to install a scale onto the top slide but it is a messy installation which restricts the 360deg movement of the slide and complicates slide removal etc etc. I have not found this omission to be an issue and I seldom use the top slide. Should I need to accurately indicate movement I would use a dial (digital) indicator but this is a rare event.

Picture shows the MDRO cross slide extension which is basically a block of Al set about 0.5mm below the face of the slide and has an extended grove for the mag scale. I have 2 control boxes both from China. (XY for the lathe and XYZ for the mill)

In my experience DO NOT use the cheaper digital vernier scales.

Mike

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