Author Topic: DRO Installation on a Mill/Drill  (Read 1005 times)

Offline MJM460

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DRO Installation on a Mill/Drill
« on: January 12, 2021, 11:20:32 AM »
I have been thinking for quite a while that my next machinery expenditure should be a DRO system for the mill.

At present, I have two cheap single axis scales on the lathe, one on the saddle long travel, and the other on the tail stock quill.  While I would like one on the cross slide travel, I can’t see how to do it without loosing necessary length for collet operations, which require the tailstock almost hard against the saddle which in turn is almost hard against the head stock.  So that is a future problem to solve.  But cheap and simple has been really useful, and convinced me of the value of doing even better on the mill.

On the mill, I have a single scale DRO on the quill, but none on the table.  Sometimes I set up long travel dial gauges to help with more accurate lengths and positions.  They work, but are tedious to set up and so many things collide.  A DRO is definitely called for.

The local machinery house sell a three axis kit which looks like a good compromise between the low end cheapest ones and the top quality, though I suspect that I have never seen the real top quality that a manufacturer might require.  Just as lockdown eased enough that I could travel to the store, they held their twice yearly sale, and I was able to take a couple of hours between helping with domestic chores while my wife’s wrist healed.  The one I purchased is SINO brand.  The package includes the display head and three scales to suit my mill and the bracket kit.  The two shorter scales each came with a predrilled backing plate and a nice protective cover.  The long scale also had a protective cover but no backing plate. 

I spent an hour or two in the showroom seeing how they installed the scales on the mills that come with them pre installed.  I was a bit disappointed to note that they only install the two axis kit, and resort to an independent single scale on the quill, similar to what I already have.  But that is certainly a clue that installing that quill scale is not easy to do.  It will be a challenge to come up with something neat that allows the depth stop to continue to be used.

The costs are such that it is better to buy the three axis kit with the scale, even if the scale eventually goes on the lathe, as you can’t add it later if you only buy the two axis display.  So fingers crossed, I bought the three axis system which comes with the three scales and a “universal” bracket kit.  That of course means the supplied brackets do not fit any specific mill, and I cannot see how to use the brackets provided on my particular mill, but the selection of bolts and shims will be quite useful.   The mill I have was bought some years ago.  It is labelled with the house name and the model HM-46, but it looks suspiciously like it comes from the same factory as the Grizzly.  They now sell a new model, HM-46B, which is very like the Grizzly that Stewart recently equipped with a DRO in his shop thread, and only quite small differences from my earlier model.

After some time “looking and patting”, I have come up with a scheme that feels like it will work.  I made brackets from 6 mm thick aluminium strips and some 62 x 62 x 6 angle that I had on my shelves.  The actual machining operations to shape the brackets, along with plenty of drilling and tapping is all very simple.  For me, the biggest difficulty is the necessary freehand drilling and tapping small holes (M4) into the base casting of the machine.  I was concerned about breaking, particularly in areas where the room to try again in a slightly different location is limited.  I was able to get help from my mentor, who has more experience and a steadier hand for such tasks.  However, the arrangement I came up with might help anyone else contemplating a similar project, even if just what not to do.

My plan for this thread is to concentrate on the arrangement, and my solution to the issues which arose.  Along with a few photos.

Next time, the y- axis.

I hope this project is of interest to someone.

MJM460

The more I learn, the more I find that I still have to learn!

Offline derekwarner

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Re: DRO Installation on a Mill/Drill
« Reply #1 on: January 12, 2021, 12:07:11 PM »
Following on with interest MJM  :happyreader: .. .....& learning.......

Derek
Derek L Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
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Offline propforward

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Re: DRO Installation on a Mill/Drill
« Reply #2 on: January 12, 2021, 03:27:23 PM »
Very nice MJM, I shall be following along too!

I found that a relatively cheap right angle head for my hand drill was really useful to make holes on the backside of my mill table. It was about $25, so not silly expensive, and it has since been useful for other projects as well.

My DRO has made a huge difference - it turns out that my backlash was a lot more than I had realized, so I had inaccuracies of ±0.02 and more in my parts.
« Last Edit: January 12, 2021, 03:31:06 PM by propforward »
Stuart

Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #3 on: January 12, 2021, 11:21:45 PM »
This all feels quite familiar!

I love your dry observation that a 'universal' bracket doesn't actually fit on anything...  :)

In my case there was no obligation to buy 3 scales as they were sold individually. I bought my DRO kit with the mill and knowing that the mill has its own small inbuilt DRO on the quill I decided not to reinvent that particular wheel given how notoriously fiddly fixing a scale to the z axis can be. Not as good and not as nice as a proper 3 axis setup going through the display, but it works.

I too was trepidacious (is that a word?) about going into the main casting with a hand drill, but it was surprisingly easy. I find cast iron to be an extremely forgiving material. That said, I wasn't too worried about things going a little out of true due to squint holes as I had designed quite a bit of adjustability into my setup.

Following along...

 :popcorn:

Offline MJM460

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Re: DRO Installation on a Mill/Drill
« Reply #4 on: January 13, 2021, 02:33:16 AM »
Hi Derek, good to have you following along.  I hope you are getting some quality shop time with the current restrictions and staying away from those hot spots.

Hi Propforward, I do also have one of those right angle attachments.  Very useful in awkward places.  I have planned to try that if I have to drill the table where the column will obstruct the drill, but if I can locate the holes in the table further apart, it will just about be possible with a bit of contortion.  We’ll see when I get to the x - axis.  It will need a backing plate anyway,

Hi Gary, yes the basic catalogue shows the display and the scales as separate items with the two and three axis display both available.  But they also sell a package deal which includes which ever length scales you need at a reasonable discount compared with the separate items, less than the cost of the third scale.  Hence the economics of buying the three axis package and see what I can do.  It looks like some of the profiling and radius functions will work using the x - axis with one of the other two, so worth a try.  And the separate data memory function will definitely work with the third axis. I will get the other two going first.  If all else fails, I can just continue to use the stand alone quill scale that I already have, I can see that it is not simple to include, so I am forwarned.

I don’t know if trepidatious is a word, but it’s meaning is quite clear.  One of the interesting foibles of our language.  I don’t know how it goes with google translate though.  I will definitely have a try at drilling some of the holes myself, but in locations where there is plenty of room to try again if it goes pear shaped.

I will try and post more progress this evening.

MJM460
« Last Edit: January 13, 2021, 08:47:42 AM by MJM460 »
The more I learn, the more I find that I still have to learn!

Offline MJM460

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Re: DRO Installation on a Mill/Drill
« Reply #5 on: January 13, 2021, 11:27:05 AM »
I decided to do the y -axis first.  I suspect it is more difficult in many ways than the x - axis, but it is a little more accessible.

The problem can be seen in the first two pictures.  First, looking at the table end on, you can see that the handwheel potentially intrudes into the space that is available for installation of the scale and reader.  Looking at the table and hand wheel side on, with the table at the end of its travel, you can see the extent of the problem.

My first thought was to make a mounting plate for the scale that had the outline of the handwheel cut out.  A bit of CAD work (cardboard aided design!) helped me find the centre of the wheel, but as you can see from the photo of my work, it takes a big bite out of the plate and I felt it might not be very easy to keep it straight.  After three tries, I realised that the handwheel was only a problem for the last 15 mm of table travel, 15 mm that so far I have not had the occasion to use, but in principal, not a good idea.  Then I realised that the handwheel is held in place with a simple set screw, and it was easily removed if I needed that 15 mm.  I could still operate the x travel from the other end.  If it becomes a problem, I can work on a shaft extension, so the wheel can stay in place.

With the handwheel removed I was much happier with the bracket shape and you can see the template fits quite nicely.  The remaining photos show machining the required shape.  The only wrinkle was chewing out a little extra to clear the gib strip adjustment screw.  I don’t want to have to remove the whole scale and reader to adjust the gib strip.

Continuing the y - scale installation tomorrow.

Thanks for looking in,

MJM460

The more I learn, the more I find that I still have to learn!

Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #6 on: January 13, 2021, 11:33:05 AM »

 ...they also sell a package deal which includes which ever length scales you need at a reasonable discount compared with the separate items, less than the cost of the third scale.  Hence the economics of buying the three axis package and see what I can do.  It looks like some of the profiling and radius functions will work using the x - axis with one of the other two, so worth a try.  And the separate data memory function will definitely work with the third axis. I will get the other two going first.  If all else fails, I can just continue to use the stand alone quill scale that I already have, I can see that it is not simple to include, so I am forwarned.

Yes, three for (more or less) the price of two makes sense.

I'll admit that I have only scratched the surface of my DRO so have not yet encountered any operations which require three-axis functions. If and when I do, that would be the time to bite the bullet and install a scale on the z. But even the few basic ways in which I have used the DRO have made its benefits really clear.

Yeah, these right-angle attachments for hand drills. I also have one. I hate using them - they're a nightmare to keep straight. But sometimes they will reach a spot that nothing else can get to! Give it a go, I say, and do not succumb to trepidationalism!

Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #7 on: January 13, 2021, 11:43:11 AM »
MJM - I assume there was a reason why you couldn't install your y axis scale at the other side of the saddle?

That said, I installed mine at the opposite side from the handwheel but still had to mill down the end bracket to make space.

What we need are universal mounting brackets really  ;)

For what it's worth, I'll stick my youtube videos on my DRO install in your thread shortly. I have been justly criticised for the camera work (I'm working on it!), and I make no assumption that you will see anything of use in the approach I took, but at the very least it will do no harm.

'Cardboard Aided Design'. Love it!  :lolb:


Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #8 on: January 13, 2021, 11:49:37 AM »
t=575s

Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #9 on: January 13, 2021, 11:50:27 AM »
t=767s

Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #10 on: January 13, 2021, 11:55:14 AM »
Couldn't get the video embed function to work for some reason. I seem to recall there is a problem with this/fix for it. I just posted the links instead, for now.

Offline propforward

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Re: DRO Installation on a Mill/Drill
« Reply #11 on: January 13, 2021, 01:17:34 PM »
Neat work MJM - I like your approach.

Gary - there is a lot of vocabularization going on in this thread.  ;D
Stuart

Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #12 on: January 13, 2021, 05:34:54 PM »
Clearly in that case we need to start a political party.

Of no particular leaning, though, this being a neutral forum.

Offline propforward

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Re: DRO Installation on a Mill/Drill
« Reply #13 on: January 13, 2021, 07:03:40 PM »
If there’s tea and biscuits involved, count me in.
Stuart

Offline gary.a.ayres

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Re: DRO Installation on a Mill/Drill
« Reply #14 on: January 13, 2021, 07:13:02 PM »
Tea but no biscuits.

Cuts.

Sorry.