Mounting a DRO on my RF45 clone mill

[arnoldb]

When I bought my mill two years ago, I commented that I'd get a DRO in my dreams.

Dreams do come true sometimes ;D - it takes a bit of planning, budgeting, a bit of hard work and a stroke of good luck. And a supplier who's willing to ship to a way-out location at a fair price.

Some weeks ago, I had a little windfall, and I decided to treat myself a bit. After watching currency exchange rates for a while and seeing a good opportunity, I pounced and ordered a two-axis DRO from TheDROStore.com. Scott there gave me great service, and a week and a half ago, this lot landed on my freezer after feverish unpacking :

A three-axis unit would be nice - in fact, if I had a knee mill I would have spent the extra money for a three-axis unit. My mill is not really suited for DRO on the Z axis - so there's not much to be gained for spending the additional money.

Yesterday morning I was awakened to a phone ringing - that call turned into an excursion to one of my new work sites to sort out a crisis, but I got home by lunch time and started work on installing the DRO

Easy part first, I thought... The X axis scale. It would have been nice to install it at the back of the table, but that would mean I'd lose about an inch of travel in the Y axis - no good, as I do use that travel once in a while. So on the front it has to go, but things were a bit tight for a conventional install, as the installation holes would be a bit awkward - wanting to break into the T-slot on the side of the table, things would interfere a bit with the locking screws which I use a lot, and the cover plate supplied wouldn't even fit without sticking up past the table's edge:

Installing it on-edge seemed a bit more sensible - though I'd have to make sure to add a bit more protection for the overhang:

The reader could be mounted where the table stop used to be mounted; I've never used the table stop; the only use for its mounting holes for me have been to cobble together a crude DRO using a digital caliper when I built the Coomber engines. The one mounting hole is a whopping 1mm lower than the other:

The DRO would also sit over the oiler hole in the photo, but that's not a problem, as I don't use that to oil the table; I just apply way oil to the ways from the bottom and work that through by traversing the table a couple of times.

Needing a mount for the reader head, I rummaged through the scrap pile; the only suitable bit I could find was a section of angle iron that was cut with a guillotine (shear?) on the one side and a bit deformed there. So I set it up for some clean-up:

A quick fly-cut - showing just how much it was deformed:

After a bit more work to square it up and so on, it ended up with some short 8mm slots to allow for adjustment - and compensation for the low mounting hole mentioned earlier:

I had to clean off the inside of the angle a bit as well, as the normal rounded corner would interfere with the bolt heads:

Finally done; not pretty, but practical and faced and squared up where needed:

The slight cut-out I milled away above the short slots is for clearance for the mill table once installed.

Next I marked and center punched the locations for the installation holes on the side of the table. As I'd be using a hand-held power drill, I really gave it a good whack to ensure good starting points for the drill:

I then drilled the spots 4.2mm and tapped them M5 - no drama there; the cast iron drilled and tapped easily.

Then I mounted the X scale and a dial indicator using a magnetic base, and started to tram in the scale. The installation instructions state that the scale needs to travel with at most 0.02mm (1 thou) run-out, but the DI was at a bit of an angle, I went all the way to get it dead-nuts with no deflection across the scale's travel:

I nearly went cranky there; cranking the mill table over about 15 times full-travel gets to be seriously hard work :big: - it's time I built a power feed!

Finally the X axis scale installation was done:

My shop session yesterday was pleasantly interrupted by a shop visit. A local bloke had heard about my shop and escapades on the grapevine, and came over for a bit of a look-see and gum-bashing session; He's interested in setting up a home shop too, and while he does not seem overly interested in building model engines, he is interested in other home machining projects. It's really nice to get a shop visit!

To be continued...

Regards, Arnold

 

[Ken I]

Thanks for the tut.

My mill's DRO is shot on the X axis so I'm going to speak to your mate about a kit.

I'll shift the old DRO over to my bigger lather when I get it.

Ken

 

[lazylathe]

Looking good Arnold!!

Funny you should mention a power feed!!
I have been spending the last few hours looking at ideas and options to build one!!
ebay seems to have about everything you need to build one for about $50, not too bad!
I have also seen a LMS unit for the X2 on there for $90.

I have a pooched 12V drill that i thought i could use but it is beyond salvage...
May look into getting a new motor for it and using it that way...

Will be interesting to see what you come up with!

Andrew

 

[arnoldb]

Thanks Ken . I'm not sure if this kit is professional quality, but it's plenty good enough for my hobby needs. Now, what's this about "my bigger lather when I get it" stickpoke - are you getting some new toys ? ;D

Dankie Andrew - I have a lot of old medium volume dot matrix printers lying around, and I'll use the head positioning servo motors and a worm wheel to try my power feed. A good old-fashioned 555 timer based circuit should provide a nice PWM speed control. So I have a clutch system, control board and power supply system to design and build, as well as a worm and wheel. I like to make life hard on myself Rof}

This morning I started on mounting the Y axis scale.

In my previous post I didn't mention that the DRO kit comes supplied with a diverse range of adjustable mounting brackets - and a bag full of cap head screws, washers and spring washers. I actually made the bracket for the X axis, as I'd need most of the supplied bracket material for the Y axis.

The Y axis installation was not so easy, as there is nowhere flat, straight or square enough on my mill to actually mount it using the kit supplied : :

After scratching around a bit for suitable installation locations, I found that I could mount one end of the reader bracket on the coarse section to the right of the turning handle in the previous photo. Sometimes it helps to literally poke a finger at things, and on one such poke in the one corner, some casting sand came off . After a bit of work with the end of an old file to scrape a bit harder, I had half a foundry's worth of casting sand removed; this had just been left on the machine and painted over :

Then I drilled and tapped the mounting holes in that rough section. It pretty much horrified me to run my good-quality M5 taps through there, but as the saying goes: What needs, must. :

I made up two adjustable mounting brackets for the scale from some 6mm aluminium plate - three M4 threaded holes in each to form a tripod platform, an M5 threaded hole in each for mounting the scale to, and a central 5.5mm hole to run a cap screw through to mount to the mill:

All so far loosely mounted together, it looks like this:

The main thing is to not distort the scale in any way, so the scale was bolted to the plates, and then the plates loosely bolted to the mill with two M5 cap screws. Next I turned each of the M4 cap screws in by hand till they just touched the mill base.

Next it was time to tram in the scale. I went about it completely arse-about-face :hDe: I'll blame it on a mid-life moment... I did the vertical alignment before the horizontal alignment - and it would be much easier to do the horizontal first! As it was, I mounted the dial indicator magnetic base to the end of the mill table, and ran it across by cranking the Y handwheel - adjusting the scale to get zero deflection across the run on vertical deflection:

That lot was followed by checking the horizontal deflection. I had to adjust the back end mounting out by nearly 1mm to get things aligned - Adjustment was done by loosening the central screw a bit (fortunately it has a spring washer on it; that makes life easier) - and cranking each of the three M4 tripod screws on the "shallow" bracket in the same amount:

Like I stated earlier, I went about it the wrong way around, and after the horizontal deflection adjustments, I had to re-do the vertical check. Either way, it's a good idea to check both alignments on completion anyway to make sure the scale is aligned properly.

Even with the hoard of mounting brackets supplied in the kit, I had to make another one - this one to mount the read head to the Rube Goldberg assembly already required. So more angle plate with holes and slots:

The Y axis lot finally mounted together - Like I said; a bit Rube Goldberg, but here I'm more interested in function over looks:

A different view. If you click on the photo, you'll see where I had to add shim stock to the bottom of the L joint that's bolted to the mill's cross-slide - that was needed to get the reader bracket square:


An overview of progress so far:

The X axis still needs it's cover installed with some modification to the supplied one needed, the console has to be mounted and the cabling suitably routed and fastened. A minor bit of electrical work is also outstanding to wire the DRO system to the mill's wiring.

I ran out of shop time, but I couldn't resist a quick fire-up to check things though:

MmBwooHahaHaaa... It's alive ! Darn ugly, but it works ;D

Regards, Arnold

 

[Ken I]

WTH Arnold - its midnight in our neck of the woods.

Isomnia or enthusiasm ???

Ken

 

[arnoldb]

Ken, with Namibia now on Winter time it was half an hour before midnight - but more enthusiasm than insomnia; I promptly went to bed after posting that lot... Now what kept you awake that late :big:

Kind regards, Arnold

 

[Ken I]

I didn't know you employed daylight saving time - its something that raises its head in SA periodically but never gets actioned.

I never go to bed unless I'm sleepy - so that's normally between midnight and 2 am - I frequently work through the night if my muse is with me.

Not much of a morning person - something of a knuckle dragger until 10 am.

Regards,
Ken

 

[Blogwitch]

Like all things you start Arnold, you make a real good job of it. Very nice installation.

Now you will really find out why we have been shouting from the rooftops that fitting a DRO isn't cheating, but as a great aid in getting things made easier and more accurate than ever you thought possible. I for one couldn't work as accurately any more purely because of eyesight and manual control, it has extended my enjoyment for many years to come, and I hope it does the same for yourself.

Just enjoy the new dimension (no pun intended) of working.


John

 

[arnoldb]

Ken, I'm a bit of a night-owl myself - and don't mess with me until I'm on my second mug of strong coffee in the morning :. For your sake I hope they don't implement DST for you guys. If it was not for the fact that I have to self-moderate and abide by forum rules, I'd have really let rip now - suffice it to say DST was implemented here in Namibia for all the wrong reasons, and it's just a plain PITB.

John, thank you very much. I've never considered a DRO as cheating; it was on my wish list for the mill right from the start. But I'm actually very glad that I had to make do without it so far; I feel that I learnt a lot of very valuable techniques and skills by working without it, as well as getting tuned to how my machines work and what to look out for. It also taught me to think machining steps through before-hand to take things such as backlash and all of that into consideration. In fact, I think I'm in a better position now to appreciate it's true potential in the shop and use it to better capacity One thing that I immediately noticed on the quick test was how much stick-slip my mill has, and how the handwheel readings are affected by it. I think I'm going to have a lot of fun using it!

This evening I mounted the console and started to route the cabling. Unfortunately, while I was busy doing that the power went down for the city block I live in. So I did what any good kid would do and went into the house, fired up the gas lantern and poured some of Scotland's better stuff in a glass :big:

The power is still off, so I can't start up my main PC to add the photos; this lot was typed up on the laptop with cellular data access, the steady hiss of the gas lantern supplying background sound as well as light, and a very unhappy Shrek the 'Grey complaining from his cage as he's not allowed to fly around with the gas lantern lighting things...

Regards, Arnold

 

[arnoldb]

Some more done... No update yesterday evening; I had to attend to some other matters...

On Monday evening before the power failure, I mounted the console mounting arm. I was in two minds about mounting it on the mill column, or on the head, and eventually decided to mount it on the head - purely because it would move along with the other controls. If mounted to the column, the console would be less convenient to use. There was a nice spot open on the head to mount the arm between the main wiring box and some cabling - in a space where I could drill safely and not break through into the gearbox - the darker grey bit is the arm as mounted:

With the the console mounted on the arm, things looked on the up:

That's the point where the power went down, so I surfed the 'Net in old-meets-new style :

This afternoon after work, I carried on with the job. First off, some electrical wiring was needed. The DRO console can be connected to power completely independently of the machine, but I wanted it to be incorporated into the mill's supply as there would be less plugs(outlets) required, and I can work it off the mill's master power switch that I'd installed back when. So first off I, unplugged the mill from mains completely, and opened the wiring box:

To the left bottom there is an empty grommet - that's left over from when I removed the wiring for the irritating spindle "safety" cover cut-out switch.

A quick - but careful - bit of work later, I made up a the necessary bit of wiring harness to wire into the mill's electrical box:

That was easily installed:

The DRO console has a separate earth connector at the back. I checked continuity between that and the earth wiring that I wired to the mill's own, as well as the mill body, and there's no measurable difference. The installation instructions show that that connector has to be wired to the mill body, but in my case that's not needed. If you have a VFD or different wiring setup for your mill, especially if you're using 3-phase, make sure about the earthing requirements. If in doubt, wire that earth connection up.

I finished the wiring by tying down all the cabling out of the way where needed, taking great care to leave adequate loops where movement would be required:

With the mill's mains power plugged back in, everything fired up just dandy, and ready to use:

Well, not quite ready to use... I still need to mount the cover for the X axis - that requires making some brackets as I want it sturdy. Then I need to get to a hardware shop to get some rubber sealing tape; the Y axis cover has quite a gap between it and the mill base because of the uneven surface there, and I want that sealed up to prevent swarf getting though.

Regards, Arnold

 

[arnoldb]

The home stretch ;D

I did a C-o-C and cut some bits of 20x20x3mm angle iron to make the brackets for the X cover, as well as two bits of 5mm thick flat bar to make square nuts:

The blade I have currently in my band saw cuts horribly skew, so the bits above had to be squared up on the mill, but I didn't want chips getting into the unprotected scale, so I clamped it to the side slot on the table with the trusty toolmaker's clamps to give protection:

The bits were cleaned up and some holes drilled, and then I fired up the stick welder to stick them together:

It's been more than a year since I last welded, and I literally had to clear cob-webs out of my welding helmet :

I had to break out the 115mm angle grinder to clean some welding excess of critical faces, and after some more drilling and tapping ended with two suitably sturdy brackets:

The brackets were cleaned off and given a coat of quick-drying paint from a rattle can to make them a bit more presentable. While the paint was drying, I turned my attention to the cover itself. The bottom lip is not really needed for this installation, but it adds some rigidity that I want to keep. However, the two corners on the ends are nice and sharp, and when installed on the mill would be at a level just below my nether regions - too close for comfort though, and likely to give a nasty scratch to any body part that contacts it:

The sharp corners were quickly smoothed off to a more friendly curve; I just used a file and eyeball MK1 to file a half-decent looking curve on either end:

Then I applied some foam rubber strip to the end that would sit in the side of the slot of the mill table. Not so much for sealing as for preventing rattling after installation. One of my few pet peeves is something that rattles:

I also removed the Y scale cover and added it's foam rubber backing to prevent chips or coolant getting between the cover and the mill base; there was a fairly big gap.

Finally, everything installed and job done :

The X cover is as nice and sturdy as I wanted it; I can press down on the center of it with about 20kg of force before it starts to deflect, and there's more than adequate space for significant deflection before it would come even close to the scale.

After finishing the installation, I spent some time working through the functions on the DRO and familiarising myself with it. For the most part, it's pretty straight-forward and easy to operate, and it has some really nice functions built into it. I really think I'm going to enjoy this bit of kit ;D

Over on MadModder some members mentioned that the DRO, while storing it's last setting on switch-off, does not track movement while it's switched off. This is true; if you switch off the DRO and move the table, and then switch on the DRO, it will still have the same readings on it as it had when it was switched off.
There is, however, a BIG BUT to this...
I read in my DRO's manual (OK- I'll admit it's frowned upon to read manuals, but I do it anyway :) that it and the scales have a function where there's a physical reference encoded on the scales at certain points, and that this can be used to regain the last-set absolute 0 coordinates - as long as the DRO was calibrated to these reference points before losing power by getting switched off or a power failure.
I tested this feature, and it does work as expected. The physical reference point on my Y scale is at it's center which is very convenient, and the one on the X scale is just to the right of where I normally have my vise positioned; which is equally as convenient. It's really quick and easy to pick up these hard-wired reference points, and will make it a pleasure to get right back to where things were at a last shop session or after a power failure - even if the table had been moved while power was down. In fact, in my setup, its possible to use this feature to work on a delicate and precision part on one side of the mill table, store the settings, switch off the DRO, and then work on the other side of the table on a workpiece nearly as accurately using the handwheel readings, and then get back to the original workpiece. I think this feature is really nifty ;D

Hmmm... Now, what to build/do next ???

Kind regards, Arnold

 

[firebird]

Hi Arnold

Thats very nice, very nice indeed. I have been looking at and yearning for the 3 axis version like this

http://www.ebay.co.uk/itm/TDS-3M-Di...633?pt=LH_DefaultDomain_0&hash=item3cc5566e41

At £318.00 for the complete kit including postage it sounds good. Has anybody ever bought one of these kits from china?

Cheers

Rich

 

[vcutajar]

Nice work Arnold. Enjoy a new dimension in milling.

I had the DRO for nearly a year but never bothered to install it. When I finally installed it I kicked myself for not doing it earlier.

Vince

 

[arnoldb]

Hi Rich
The link you supplied looks exactly like the 3-axis version of mine. In fact, the "TDRS" initials bit sounds suspiciously like the supplier I got mine from, even though its from a different seller as far as I can see. So I don't have much of a clue there; you might want to check out my original supplier against the ebay link you provided; just to make sure someone's not trying to pull a fast one through an "auction" - also check the pricing; you might be getting the same thing for either more or less quid.

;D Darn Vince! - What kept you from installing it for so long ??? ;D - I can't wait to try out and max each new bit of kit I can get my grubby hands on! Though I must admit I've got a small lathe sitting in the wings and rarely used for the same amount of time... ; I really need to get my finger from you-know-where and get it going!

Kind regards, Arnold

 

[johnmcc69]

Wow Arnold, great job, great pic's & post.
Nice work!

 

[arnoldb]

Thanks johnmcc69

Regards, Arnold