Model Engine Maker

Supporting => Tooling & Machines => Topic started by: b.lindsey on June 08, 2017, 02:08:51 PM

Title: DRO for the Cowells
Post by: b.lindsey 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
Title: Re: DRO for the Cowells
Post by: Bobsmodels 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

Title: Re: DRO for the Cowells
Post by: Jo 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
Title: Re: DRO for the Cowells
Post by: kvom 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.
Title: Re: DRO for the Cowells
Post by: b.lindsey 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
Title: Re: DRO for the Cowells
Post by: Jo 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
Title: Re: DRO for the Cowells
Post by: b.lindsey 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
Title: Re: DRO for the Cowells
Post by: Chipswitheverything 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
Title: Re: DRO for the Cowells
Post by: Jo 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
Title: Re: DRO for the Cowells
Post by: b.lindsey 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
Title: Re: DRO for the Cowells
Post by: b.lindsey 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
Title: Re: DRO for the Cowells
Post by: Steamer5 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
Title: Re: DRO for the Cowells
Post by: b.lindsey 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
Title: Re: DRO for the Cowells
Post by: Steamer5 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
Title: Re: DRO for the Cowells
Post by: Steamer5 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
Title: Re: DRO for the Cowells
Post by: zeeprogrammer on June 11, 2017, 12:44:30 AM
Just read the thread...
That Colwells is a nifty machine. No doubt you will get (as you have already) much pleasure out of it.
Adding the DRO will increase that pleasure I'm sure.
As to size of display...hey...whatever works. That's always been something of a personal thing to me. i.e. size, color, working distance, etc.
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 11, 2017, 01:03:41 AM
Zee, it should make working in imperial measurements on a metric machine a bit easier for sure. Kerrin, I know what the problem is, the link I posted yesterday is for the igaging store, run by Anytime Tools. Here in the USA you can order from that site. If you go to the company site....igaging.com, then that is where the distributor list shows. Anytime Tools is just one of the USA distributors. A bit confusing I know.

Hoping to get the scale hooked up tomorrow so stay tuned.

Bill
Title: Re: DRO for the Cowells
Post by: Kim on June 11, 2017, 04:11:11 AM
Looks like a good start, Bill!
I think you'll like the iGaging DRO.  I've had those on my Taig Mill and they have worked great.  As you said, they aren't back lit, so I position one of my mill lights so it points at the DRO readouts. But for the price, they have worked wonderfully and done everything I need.  I am happy to have them, and I think you will be too.

One of these days, I plan to rig up a wall supply so I don't have to replace the batteries.  In the 18 months I've had them, I've only had to replace the batteries once, but they each take 2 coin cells, so replacing 3 of them takes six cells!

Kim
Title: Re: DRO for the Cowells
Post by: gerritv on June 11, 2017, 12:07:16 PM
Taylor Tool Works (http://www.ebay.com/usr/taylortoolworksllc?_trksid=p2047675.l2559) ships pretty much everywhere. Good prices as well.

Gerrit
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 12, 2017, 01:22:52 AM
Finished up the "Z" axis today. The indicator for the "X" axis won't be here till Tuesday or so. The "Z" axis was minimally invasive to the machine itself, only three holes in the base. Photo 1 shows the attachment of the left end of the scale. Photo 2 shows the right end with a 1/2" aluminum riser attached to the base and the scale bracket screwed into the side of the riser. In both cases there is enough adjustment to allow for lining and leveling of the scale relative to the carriage. Photo 3 shows the 5/16" square brass piece machined to fit to the back of the read head via two screws supplied with the DRO. I had hoped the undercut would fit flat against the top of the read head housing but missed this a bit, so carefully sanded down a thin washed until it just fit into the gap to provide more stability. Photo 4 shows the upper half of this same piece reaching up to the level of the underside of the carriage apron. The scale is angled by about 10 degrees matching the angle of the attachment point shown in photo 1 so the top of this piece also had to be machined by 10 degrees to be parallel to the carriage bottom. Then a 1/16" thick piece of brass strip was drilled for the existing screw on the lathe carriage on one end and for a 5-40 SHCS to screw into the top of the brass riser. Photo 5 shows a view down the length of the lathe bed after everything was installed. Everything seem to be working as expected so far, but a true test piece of machining will await the installation of the "X" axis, so a brief interlude until then.

Bill
Title: Re: DRO for the Cowells
Post by: Kim on June 12, 2017, 02:14:31 AM
Z-Axis looks pretty nice there Bill! Can't wait to see the rest of it :)
Kim
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 12, 2017, 03:15:58 AM
Thanks Kim. I hope it will all work out well.

Bill
Title: Re: DRO for the Cowells
Post by: crueby on June 12, 2017, 03:38:17 AM
How do the sensor bars work, are they a toothed bar like a dial caliper, or some sort of optical or magnetic sensor? Why doesn't fine swarf mess them up?
Title: Re: DRO for the Cowells
Post by: Steamer5 on June 12, 2017, 06:26:46 AM
Hi Gerrit,
Thanks for the info.

Bill,
  Looking good!

Cheers Kerrin
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 12, 2017, 11:44:05 AM
Chris, it is the same technology as digital calipers which do not have a geared rack to drive a pinion as is the case on analog calipers. I assume it is optical or magnetic but honestly don't know which, only that everything is pretty well sealed though these are not claimed to be coolant proof. If I have any issues with swarf, I have already figured a way to add a flexible shield covering the scale and read head without interfering with the read head's movement. I am not expecting it to be a problem though.

Bill
Title: Re: DRO for the Cowells
Post by: vcutajar on June 12, 2017, 05:44:02 PM
I may be wrong, but if my memory serves me right, they are capacitive.

Vince
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 12, 2017, 05:49:50 PM
Could well  be Vince, and that makes more sense too!  All I know is that it works. I leave the technology to the experts :)

Bill
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 14, 2017, 07:10:58 PM
The digital indicator with the remote read head arrived yesterday, though I didn't even have a chance to look it over until today. Opening the box revealed it as shown in the attached photo. At first glance I was concerned that the indicator body was plastic, but on closer examination it is all metal. It seems to be very smooth in operation and otherwise just as advertised. I hope this evening to have a chance to see how far back it will need to be behind the lathe and with the cross slide fully cranked in. I may not get to do much as to mounting it until the weekend, but if all goes well the little Cowells will now be complete with DRO!!!

Bill
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 17, 2017, 08:31:43 PM
Got a start on the "X" axis readout this morning. The remote readout that came with the indicator did not have the thumb screw supplied with it as the DRO's do so in order to stack the readouts I had to make on. The thread is 1/4-20 so it was a simple task to do that. The result is that the readouts are now stacked one on top of the other as shown in photo 1.

Next was to come up with a way to mount the indicator body to the carriage in a way that the tip of it will engage the back side of the cross slide as it moves in the +/- X direction. As I had noted previously I think, there is an existing 5mm threaded hole on the headstock side of the carriage which will be used for attachment.  Rather than using a square piece, I took a length of .375" drill rod and flatted the bottom over the section that will rest against the carriage (photo 2), then drill a clearance hole for a 5mm SHCS. Note that this hole is slightly offset so as to match the tapped hole in the carriage and still provide some clearance between the rod and the cross-slide. The top side was spot faced to give a flat for the SHCS to bear against (photo 3).  The rod is shown installed in photo 4, and the approximate position of the indicator shown in photo 5.

Now I need to make a coupling piece  with two 3/8" hole in it, one hole to slip over the rod and the other to slip over the 3/8" collar on the indicator. This will allow the indicator to be moved fore and aft on the drill rod as needed for more major changes in the set up of the cross-slide/ I suspect that under normal usage this will not require much if any adjustment once set up.

Bill
Title: Re: DRO for the Cowells
Post by: 90LX_Notch on June 17, 2017, 08:51:24 PM
I'm green with envy Bill.  Very nice.


-Bob
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 17, 2017, 09:01:47 PM
Thanks Bob. This should make the Cowells much more user friendly when working with imperial dimensions, and metric too for that matter.

Bill
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 18, 2017, 01:50:40 AM
Calling this one done except for replacing those pan head screws with some shorter SHCSs. The indicator clears the display arm with room to spare and the "X" axis setup seem plenty stable. All in all a rather neat addition I think, now back to making parts. Thanks for looking in.

Bill
Title: Re: DRO for the Cowells
Post by: Chipswitheverything on June 18, 2017, 08:33:47 AM
Thanks for writing up the fitting of this DRO set up, Bill, it looks neat, and has not needed very much modification of your pristine lathe.
  The small separate read outs placed where you can see them readily are a much nicer solution than the "vernier" type of built in display on some devices that I have occasionally wondered about fitting.  Also, your X arrangement can be almost instantly demounted if work piece / cleaning requires that.  Should be a big enhancement of the handy machine.    Dave
Title: Re: DRO for the Cowells
Post by: b.lindsey on June 18, 2017, 01:17:06 PM
Thanks Dave. I plan on giving it a good trial run today with an actual part.

Bill