3 or 4 axis dro for PM-940m-pdf?

[Dan_S]

I've had my mill for a few years now, and I'd like to install a dro on it. Currently I'm planing on getting an EL 700 lcd touch screen model from DroPros, as it has a feed rate readout that I think will be very useful. However I can't decide if I should go with a 3 or 4 axis unit. The 4 axis unit doesn't add that much to price, and I've had a few projects where it would have been handy.

Does anyone see any issue with mounting a 4 axis unit to the mill, or have any other opinions?

 

[mksj]

I have the EL700 with 4 axis on my mill, a bit of an expensive route depending on how you want to go. Installing the DRO scale on the Quill is challenging, let alone on a bench top mill where space is even more limited. I primarily went with the EL700 because of the axis summation and the integrated touch probe. The tough probe (which is the same as the Tormach with a different jack, is much more expensive through DRO Pros and was less accurate than my Haimmer). I do not use their tough probe , accuracy is around 0.001". I would use a separate battery operated quill DRO on a benchtop mill. The EL700 uses a touch screen, which is not that friendly to greasy or damp hands, I ended up putting a screen protector over it so it would not get damaged. I would have gone with a different DRO had I know that it was a touch screen. The user interface is good, but there are other DRO's that offer the same features. The EL700 with 4 axis mag scales will cost almost as much as the 940, do not see the cost benefit going that route.

3 or 4 axis DRO for 9x42 mill

I have an ailing 2 axis Mitutoyo on my home hobby '81 Bridgeport 2J and the eBay quill digital gauge has died too. Seems a good time upgrade. Ideally I'd like to spend no more than $1k. I use the mill for all kinds of odds and ends projects on our endurance road racing cars (ChampCar...

www.hobby-machinist.com

The feed rate is a common feature with most graphical displays. I would recommend the Easson 12B/C either with glass scales or you buy the head and 3 magnetic scales through SRA for around 1K, and get a quill battery DRO. They may have some packaged deals or buy the package for the scales/mounts and get a separate ES12B head unit. I use the ES-12B on my lathe, the 3rd axis is the SRA magnetic scale on the tailstock. DROPros also sells magnetic scales, but there was previously some question of compatibility with the Easson DRO.

Easson ES-12B LCD 3 Axis Digital Readout Display Console

Easson ES-12 colour 7" LCD graphical digital readout display console with 3 axis input. Universal milling and lathe function DRO. Please note this console has the same functions and specification as the Easson DRO-ES-12C-3LCD but has a different front panel layout.

www.sra-measurement.com

Magnetic Encoders for DRO Systems

We offer a range of magnetic linear encoders for machine tools, fabrication machines, chop saws, sheet metal machines, woodworking machines, printing, packaging and custom machine builds. Offering a reliable and robust encoder with a compact profile size, making it ideal when mounting space is...

www.sra-measurement.com

3 Axis M-DRO Mill Digital Readout Package including 350mm, 450mm and 750mm Cut to Length Magnetic Encoders - - Amazon.com

3 Axis M-DRO Mill Digital Readout Package including 350mm, 450mm and 750mm Cut to Length Magnetic Encoders - - Amazon.com

www.amazon.com

 

[RJSakowski]

I have installed glass scale on the quills of two mills, one a Taiwanese mill/drill and the other a Grizzly G0755. There was custom machining involved with both but nothing beyond the capability of the home shop. In both cases, the pickup was stationary and the scale moved with the quill.

 

[wrmiller]

I have a 3-axis 700 w/magnetic scales on my 935 and love it. My primary reason for getting this was the graphic display, and the measuring/layout features built in the software to use with the touch probe. I like the idea of a scale on the quill for the Z axis summation, but couldn't quite swing the extra cost at that time. So I will eventually put a digital display on the quill I guess.

My touch probe is normally +/- .0003-.0005" when measuring gauge blocks. But, I did spend a fair amount of time on it to get it to that accuracy. YMMV

 

[Dan_S]

It looks like I have some reading to do this evening.

I won't say the cost isn't a concern, as i don't like spending more money than I need to, but to me cost is secondary to having everything just work out of the box. I've got a 13 month old in the house, so time to tinker and experiment is at a minimum. It also doesn't help that the shop is directly under the nursery.

 

[davidpbest]

This may be a minority opinion, but on my RF45 (and now on my PM935), I much prefer to have the quill DRO display a glance up from the XY table and vise rather than off to the side with the other DRO display. When I'm drilling or setting end mill depth, I want to be able to just move my eyes from table to display rather than turning my head off to the right or left (and usually upward also).

The photo below is an install I did for a friend on his RF45. It consists of a Mitutoyo 6" vertical scale with simply made brackets to attach to the head and the quill. It also included a Newall DP500 DRO for the XY table. The Newall DP500 is about the same price as kit for a mill/drill as the DRO Pro a 2-axis units and it is far easier to install the scales on the XY table and saddle.

On my own RF45, I had a 3rd scale for the head position and found that I used it about twice in 18 years, so I do not consider that an important DRO to have on your PM-940. Yes, I was moving the head up/down often, but in every case, I needed to indicate the Z-axis quill DRO to the part being worked on anyway.

Here are details of the quill DRO components I made up for several RF45's - and stick with the Mitutoyo scales, everything else eats batteries 5 times faster. Click HERE.

If you want more details, let me know.

 

[Dan_S]

Here are details of the quill DRO components I made up for several RF45's - and stick with the Mitutoyo scales, everything else eats batteries 5 times faster.

Yea, my 940 came with a quill dro, and I really don't like the thing. it's a only a 0.0005" display, and it eats batteries.

 

[Dan_S]

I did a bunch or research last night since the boy kept me up past 1am.

It looks like I can go with an Easson 12B/C as it does have a feed mode. I didn't know that, and I really had to dig to verify it, and determine what the limitations of it are.

Assuming I got all the information correct (I'll contact sra to confirm), If I use Easson glass scales on the X & Y and an M-Dro magnetic scale on the quill, I can get the price down to $910. The most expensive option at $1149 was M-Dro magnetic scales on the X & Y and a 6" Mitutoyo scale on the quill. M-Dro magnetic scales on all 3 axis comes in at $1065

One thing I noticed and though was an initiative concept, was that I can buy an additional scale and this $95 interface at a later date to sum two scales and the display won't need to know anything about it.

M-DRO Linear Encoder Summing Interface

The summing interface combines the output of quadrature encoders into a single quadrature output. Applications include combine mill quill with knee travel or lathe compound travel with main carriage travel.

www.sra-measurement.com

Based on some of your comments, I went out last night and popped the cover plate off the front of the head to take some photos and measurements. The M-Dro 6" scale is under 1" wide by 1" deep. For reference the head of the current scale is roughly 1.7" wide. I haven't mocked anything up in cad yet, but is their something I'm missing, because it doesn't seem like it would be to hard to mount a scale in place of the old one?

 

[mksj]

The Easson ES-12B/C does have a feed rate which is shown in the graphics display window, but needs to be selected and shows up in the soft key window. It is a bit awkward as the axis needs to be selected that you want the feed rate and you need to exit the function to enter any axis info. The nice feature is that you can select each axis for feed speed. The EL700 does show the feed continuously and has a few more features, there are also a number of other display possibilities when you get into that price range. It is a very nice display as to screen resolution and depth of functions, but I still am not a big fan of the touch screen and need to clean my hands before using it.

As far as the quill axis scale, you are correct that the SRA scale is much easier to adapt and significantly smaller then those of the EL700. The magnetic scale and SS cover strip are not attached to the provided backing plate so they could be mounted to a smaller backing plate of your choice, and/or you can trim down their back support so it is less wide and attach the same way as the current DRO scale. You will need to make a guide in the head to hold the reader and for the scale to held in place. The SRA scales are very forgiving as to alignment, my head initially had a 0.25" gap and read fine, but readjusted it for a 0.050" gap. I use a 5 micron scale which gives a 0.0002" increment and it is spot on with the dial over 5".

Similar to David"s comments, when I had my bench-top mill I had no column scale and never felt I needed it. Even with axis summation, the column scale would not be very accurate because you get some sag of the head as the gibs get worn. I would always need to lock the head to get an accurate depth of cut and recheck the quill height. The ES-12B/C comes with 3 axis, so you could do a summation box for the column or a use a RS232 switch box if you needed.

If you purchased the ES-12B display from SRA and their 3 axis DRO package with all magnetic scales you would be into it for $1014. All good choices whatever you decide.

SRA Magnetic scale reader with guide for magnetic strip

 

[Dan_S]

If you purchased the ES-12B display from SRA and their 3 axis DRO package with all magnetic scales you would be into it for $1014. All good choices whatever you decide.

Ahh, I missed that. I was pricing buying the ES-12B and individual scales. Buying a SRA package is cheaper, and you have a spare display if the 12b goes bad.