DRO's -Small Mill

In article , Steve writes

Hi Steve,

I fitted Sino DROs to my Emco FB2 a year or two back. Marvellous, would never willingly be without it again. The fitting was reasonably OK, bit of fiddling with brackets. Had to fit a stop to prevent the Y feed crushing the X scale (rear mounted) against the column. Never had any trouble with any of the kit, just works exactly right every time (so far!).

I did a full 3-axis job. The Z axis was the trickiest to do, but well worth it IMO. The FB2 has a leadscrew to raise and lower the head, in addition to the quill. Broadly, the latter is used for drilling, the former for milling. The DRO is on the former, I didn't see there was as much need for a DRO reading to 0.01 mm on the drill feed. I have considered filling a cheap scale on it, like the one you have, and may get round to it one day.

Assuming your mill has a raising head and a separate quill for drilling, and you fitted the scale to the quill, I suggest you leave the scale where it is and fit a "proper" DRO to the milling Z-axis. The FB2 has a rectangular key on the column to prevent the head rotating when you are raising or lowering it. If your mill does not have this, I suggest you do this before fitting a Z-axis DRO as otherwise it will risk getting damaged. (You really should do this anyway, those mills with a freely rotating head are a total pain for any accurate work).

Remember, the pleasure and functionality are enjoyed long after the bill is paid and forgotten...

David

best money you will spend for a long time, don't skimp on the head unit either.

I bought the SIno brand here in the UK

at the time I blogged the following observations

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1/ the scales come with small yellow plastic tabs holding the reader head to the scale itself, at the correct "ride" distance and so forth, leave these in place until the last minute, they make setup a lot easier.

2/ for each scale note they only fit the carriers properly one way around, but the head unit has the facility to select the direction of reading for each scale so don't worry about getting them the right way around.

3/ mounting the scale is straightforwards enough, just make absolutely sure that you install it perfectly parallel to the direction of motion, do NOT try to mount the reader head before you have the scale set up perfectly parallel.

4/ once the scales are fitted, you can move on to the reader head mounting, before you attach the reader head to the mounting, do a couple of full travel tests, make sure travel is inside scale limits, and make sure head / scale separation remains constant throughout travel, ONLY THEN can you attach the head to the mounting.

5/ If, like me, you bought the slimline scales, you're in for a lot of fun if you take the dimensions shown in the supplied literature as being gospel, so, think thrice, measure twice, cut/drill/mill once.

6/ The only things not supplied in the kit that you'll need apart from basic tools are a set of 3, 4 and 5 mm taps, numbers 1, 2 and 3 to each set, and appropriate twist drills, and a decent vernier, scriber, set square and my preference of using a battery drill to run the taps in and out.

7/ Now you're at the stage I'm at, and only things left to do is tidy everything up, clamp back the armoured cables, etc etc.

8/ It took me an easy going relaxed day to do the X and Y, and to get as far as I could with the Z in preparation for buying some 8mm silver steel rod this am to make the Z linear slide so that I could fit the Z without worrying about the reader head / scale clearance changing during quill travel.

I assume that the z axis is a Chinese scale and has a data connector? Rather than Yadro, DRO350 will just plug in and work. You then have the option based on your cashflow to splash out on a pair of glass scales from MachineDRO, and QCC modules to plug them into the DRO350, or pick up a couple of cheap calipers ( I'm using a 12" one on one table ) which can be 'reused' later as calipers when you can afford to upgrade.

You will be looking at a couple of hundred pounds for two glass scales, while a 6" and 12" pair of calipers would be around £50. The scale cables can be as expensive as the smaller scales which is a pain. The QCC module can be supplied complete with cable for the Sino scales.

Hi Lester,

The scale I bought off Ketan at ARC. I was about to say it didn't have a data connector, but I just took the cover off and there are four "fingers" etched on the PCB, it looks like you have have to cut the case to push in a connector, the inner housing is also manufactured to accomodate a connector there too, so I guess its good to go on that front.

So does the QCC only convert to a quadrature signal for the DRO 350 and would it drive a Sino console too? Smart idea just to use the existing scale and plug into the console, I hadnt considered that.

I'm sold on the idea of using glass scales on the table and I had alook at the Sino console at Harrogate, so pretty comfortable with that, but haven't seen the DRO 350. I do like to "kick the tyres" at that kind of money.

Thanks

Steve

Thanks for the really great replies guys - prompts another Q though - If I use a glass scale on Z, can I fix the head and move the scale? (That's how I've got the current chinese scale installed)

TIA

Steve

In article , Steve writes

Trouble with that is it takes up far more room than fixing the scale and moving the head. Needs either a big hole in your bench, or a lot of headroom above the top of the column (roughly equal to the head vertical travel). Also, the glass scales really do need fixing at both ends, so you end up with a lot of bracket material.

Fixing the scale can be done within the height of the column, and only needs a bit of angle at each end (the backing for the scale is robust enough if supported at both ends).

David

That's what I did when I fitted a Sino set to my Tom Senior mill. The Sino is so sensitive that it registers a difference between the knee being locked or not,I'm really pleased with mine and the service and quick reply to any queries from Jade products.

The initial expense seems high,but they really are worth it in my opinion.

Allan

yes, the scale only cares about relative movement between the parts, however, you out to fit the scale to the non moving part and reader to the moving part for rigidity and safety of the scale.

Personally I'd always recommend bite the bullet and buy all glass scales and a head in one go.

I bought one of these

and three slimline scales I rang up and negotiated and got a hefty discount for ordering and paying then and there.

0.005 mm resolution so about 0.010 mm absolute accuracy

If you want to move exactly 122.45 mm in any axis you can do it

the head also has trig functions, plots a series of points equidistant at an angle, arcs and circles, absolute and relative positions, 99 memory positions XYZ, etc etc etc.

what's more the glass scales come with a calibration certificate

And you didn't see the DRO350 opposite side of the aisle from Arc Euro ;)

QCC takes quadrature scales and converts to Chinese format, so only needed with the DRO350. Although the daughter board for the DRO350 SHOULD be available soon and that will handle a couple of glass scales direct ... first production batch is being built.

My neighbour fitted one to his Tom Senior also and the accuracy is annoyingly high for normal use and not adjustable on his version except with a nicely placed bit of electrical tape. Don't use black as it blends in too well and I was asked to look at why it seemed to be misbehaving and it took me a few minutes to remember the tape, it's now blue IIRC.

If the initial expense of the Sino seems expensive just look at Mitutoyo, Sony, Newall etc, the Sino will seem cheap in comparison.

The only issue we found with the Sino was a firmware bug that may now be fixed. One of the embedded functions like PCD or similar would only work with mm and not inch, not a major issue and I think my neighbour mentioned it to the machinedro guy a couple of years ago when he fitted it.