Author Topic: DRO for the Cowells  (Read 5327 times)

Online b.lindsey

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DRO for the Cowells
« on: June 08, 2017, 02:08:51 PM »
While doing "inch" work on a metric machine is certainly do-able, it would be much more convenient to have the capability (via a DRO system) to have direct readout in inches with the added benefit of being able to switch between metric and imperial at the push of a button.  This is what I have been looking for in a conversion to DRO, but the small size of the Cowells limits the options to some degree. I think I have finally found not only a workable solution but a desirable one as well, with minimum modifications to the machine required... basically just a couple of mounting holes in the aluminum base. 

A top down view of the Cowells and its bed is shown in photo 1 below. Photo 2 shows the system I will use for the longitudinal axis. More details can be seen here as well: http://www.igagingstore.com/6-Absolute-Digital-Readout-DRO-Stainless-Steel-Su-p/205470.htm

This is a more robust 2nd generation of their earlier and less expensive 6" scale and readout and remote display. Both the scale and reading head are stainless though the gray cover on the reading head is still plastic. This replaces an all plastic read head on generation 1 models. The remote readout has also been enlarged and additional features added. Push buttons allow for switching between MM, decimal inches, and fractional inches, ABS vs Incremental, presets, HOLD and ON/OFF, and also an origin set that the system remembers on each power up. Additionally, a bracket and swing arm are supplied for mounting the remote read-out with the capability of stacking 2 or more read-outs on top of each other. The user must supply whatever mounting pedestal they desire for mounting the bracket to.

Given the low cost of this system, I was dubious to say the least as to the quality, but decided to order one of the 6" systems just to have a look, and was surprised and even impressed by the heft, quality machining, and materials used, and the smoothness of the reading head on the scale. The resolution is stated to be .0005" with an overall accuracy over the 6" range of .001" While it remains to be seen how well this will match the physical dial readings on the Cowells (in the MM mode), several "fondling" sessions with the system (not yet mounted on the lathe) have turned up no glitches or any other unexpected surprises.The plan currently is to mount the scale on the front side of the lathe, mounted to the Cowell's aluminum base with brackets I will fabricate. Perhaps not the ideal location but there is less room on the back side of the lathes bed. Given that the Cowells will be used far more for small parts, and the fact that the read-head will follow along directly under the carriage, I do not think that swarf build up should be a problem. If it should become one, I think some type of plexi shield over the scale could be easily added. Once the scale and read-head are mounted a simple connection from the carriage to the read-head will be required but pre drilled and tapped holes on the back of the stainless read-head should make this rather simple.

The cross feed or "X" axis, presented a greater challenge until yesterday. I had been looking at a digital 2" indicator (as shown in photo 3) with integrated display and similar setting features as a workable solution but also wanted a remote readout to be stacked together with the one for the "Z" axis. Several emails back and forth with the supplier indicated that this was not possible though there is a SPC cable that will connect with a computer but still not what I wanted. Then I came across the system shown in photo 4, basically the same thing as the 2" indicator but lacking an integrated display and instead supplied with a remote readout identical to the one supplied with the 6" DRO.  Mounting this will require only a bracket attached to the carriage (there is already a tapped hole there for a traveling steady).  Then a rod extending back from this bracket with another right angle piece which will accept the 3/8" stem of the indicator.  This right angle piece will have split holes to clamp both the rod and the stem of the indicator so that the indicator can be moved along the rod depending on position and what portion of the cross-slide is being used, while still remaining within the 2" range of the indicator's travel.

I will get these sketched up and posted but hope to get started on the 6" DRO mounting this weekend. The 2" indicator won't be here till mid next week.

Going back to photo 1, the top view of the Cowell's base, the pedestal will be mounted to one of the already existing holes there on the elevated part of the base behind the tailstock, most likely the one farthest to the rear of the base.

Stay tuned for further updates.

Bill
« Last Edit: June 08, 2017, 02:16:09 PM by b.lindsey »

Offline Bobsmodels

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Re: DRO for the Cowells
« Reply #1 on: June 08, 2017, 03:37:53 PM »
Bill

Where did you find the 2" indicator?  I set up one on my Myford and it is a bit clumsy to mount this might work easier.

Thanks

Bob


Online Jo

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Re: DRO for the Cowells
« Reply #2 on: June 08, 2017, 03:41:15 PM »
:thinking: Will be interesting to hear how you get on with such small displays..

I'm sticking to my BIG analogue ones  ;)

Jo
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Offline kvom

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Re: DRO for the Cowells
« Reply #3 on: June 08, 2017, 03:50:52 PM »
I have a Mitutoyo digital indicator, and like yours it has a plug for a remote display.  I've never thought of it as a DRO scale until now.

Online b.lindsey

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Re: DRO for the Cowells
« Reply #4 on: June 08, 2017, 03:52:23 PM »
 Bob, although not shown anywhere in the igaging website, I found it on Amazon, but sold and shipped by the same people that manage the igaging store website ( Anytime Tools, Inc. ). A quick email to them confirmed that it was in stock.

Jo, the readout numeral size is adequate, given that everything resides within the footprint on the Cowell's base. I dare say larger than the numerals on an analog dial.

Bill

Online Jo

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Re: DRO for the Cowells
« Reply #5 on: June 08, 2017, 04:54:41 PM »
Analogue vs digital is a human factors thingy: You don't read the values on the dial except at the every end, most of the time you just watch the relative position of the hand on the face  ;).

Jo
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Online b.lindsey

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Re: DRO for the Cowells
« Reply #6 on: June 08, 2017, 05:47:28 PM »
True enough Jo and I admit that digital can be infuriating at times especially if you are OCD as to that .0005" that displays on many of them. My reason for going digital has far more to do with easily changing back and forth between metric and imperial, setting a new zero point with the push of a button and/or going back and forth between incremental vs. absolute measurements...all doable with analog of course, just not quite as simply in my mind. Analog faces that display both metric and imperial are available too, but get a bit too busy for me. Oddly enough I have both analog and digital calipers but use the analog the majority of the time when i just need "close enuf" as Eric says. All of my micrometers are analog only, so i understand your position too.

Bill

Offline Chipswitheverything

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Re: DRO for the Cowells
« Reply #7 on: June 09, 2017, 02:56:15 PM »
It will interest me to see how this project works out, Bill.   I use my Cowell lathe from time to time, and , unlike Jo, I prefer to work in inches despite the metric proclivities of the little Cowell.  I have seen Jo's very neat set up with the dial indicators, at Guildford, and wondered about doing similar at some time, but it will be nice to see the digital route for a comparison of methods.   Dave

Online Jo

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Re: DRO for the Cowells
« Reply #8 on: June 09, 2017, 05:04:47 PM »
Dave, that was C1.... I sold it on to SCO who took the dials off in amongst a number of other improvements he did to it before he sold it on  :headscratch:

I kept my second Cowells  :embarassed: and "Little C" has 50mm scales fitted with the larger faced dials which makes reading easier ;)

Jo
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Online b.lindsey

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Re: DRO for the Cowells
« Reply #9 on: June 10, 2017, 03:27:58 PM »
Jo, I measured the height of the digits on the readout and they are .750" high. Plenty large enough I think since they will be mounted to the base and not on a wall several feet away.

Bill

Online b.lindsey

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Re: DRO for the Cowells
« Reply #10 on: June 10, 2017, 10:54:04 PM »
A little progress today on the readout mount. After looking things over, I determined that the bracket holding the mounting arm for the readout(s) would not be needed. It became apparent also that the readouts will need to be angled somewhat to read easily since they are not backlit. So, given that the molded arm is .590" in diameter, I decided to drill and bore a tight fitting hole through the pedestal and to use a SHCS down through the top so that the arm can be rotated for best viewing and then locked with the screw.

Photo 1 shows the pedestal, a piece of 7/8" aluminum rod, just machined to clean it up a bit. the bottom was drilled and tapped 10-32, as was the top end. A clearance hole was then drilled through the base and the pedestal mounted from the underside (photo 2). Photos 3 & 4 show the readout view from both a standing and a sitting position when using the lathe.

Bill

Offline Steamer5

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Re: DRO for the Cowells
« Reply #11 on: June 10, 2017, 11:34:34 PM »
Hi Bill,
 Looking very tidy!

Checked out igaging & they have some nice DRO's that would fit my lathe as a 3 in 1 kit....they don't ship to NZ!!  :facepalm:  :thinking: maybe I could get thru my U.S. postal address.......

Cheers Kerrin
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Online b.lindsey

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Re: DRO for the Cowells
« Reply #12 on: June 10, 2017, 11:40:02 PM »
Kerrin, if you go to the igaging.com site and click on "Where to Buy" on the home page there are several distributors listed for Australia. Surely those guys would ship to NZ.  Hope that helps.

Bill

Offline Steamer5

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Re: DRO for the Cowells
« Reply #13 on: June 11, 2017, 12:13:22 AM »
Hi Bill,
 Thanks for that! I didn't spend enuff time crashing around there site!......off to look!

Cheers Kerrin
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Offline Steamer5

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Re: DRO for the Cowells
« Reply #14 on: June 11, 2017, 12:24:43 AM »
Hi Bill,
 The issue yesterday was I was using your link & the "home" button didn't take me to the "home" page...go figure that! Son in Canada just order a bit for hi scar that's here...guess who's working on that....getting ready to ship to Calgary. He ordered it about 1600 Friday & it was in NZ by 0100 the next morning! Just sent him the list of outlets in Canada to see what's close to him as we will be there in a couple of weeks.....my turn to do some shopping!

Cheers Kerrin
Get excited and make something!