Cowells lathe -Now With DRO's

[Twizseven]

Finally managed to finish installing DRO's onto my Cowells lathe.  I had done the Cowells Mill last year and used the Android App "TouchDRO" from YuriysToys website along with his electronics to read the head data and an Android Toughshield T700 tablet.  Until I get chance to make a duplicate controller I will share the one between both machines.

I have used magnetic read heads from Machine-DRO (no connection just satisfied customer) as the size of the magnetic scale is very small (25mm x 7mm) in cross section.  I have used 5 micron head on the carriage and 1 micron on the cross-slide.

Trouble is with the size of the Cowells there is not a lot of meat on the saddle or cross-slide for attaching extra bits of hardware.  I also did not want a lot of extra weight.  I played with TurboCAD Pro 2015 to try and design the brackets, but never having used a CAD package before I got so far before reverting to pencil and paper and lots of little drawing to work out how to get it all to hang together.

The photos below show what I ended up with.  All machining was done on the Cowells Mill.









I did make things a bit awkward for myself as I decided the scale for the carriage needed jacking screws, As there were three mounting screws, one every 200mm, I decided to put 4 jacking screws per fixing screw.  Setting it up and levelling it in three directions with 12 adjustment screws was a b......d, but at least I had a nice 10thou gap along along as the read head went from one end to the other. 

The other complication was the fact that the rear face of the cross-slide was not at 90 degrees to the top, so my plan to have no adjustment slots (as I worked on all dead measurements) went out of the window.  I had to return the bracket for the cross-slide to the mill and change the head mounting holes to slots to give me the required adjustment.

Just need to calibrate it now, and away we go. No more counting turns:

Colin

[Jo]

Hi Colin,

The new computer will let me see those, nice 

  Why haven't you thrown off that nasty fibreglass cover   

Jo

P.S. I can recommend the Sherline 4 jaw self centring chuck (adapted for the Cowells nose using a backing plate ) as one of those must have goodies for the Cowells

[PJW]

Nice lathe Jo, but I thought you would have wiped its back side before you took its pic

[Twizseven]

Jo,

Told you you'd get the computer up and running quickly.

Trouble is if I remove the fibre glass cover there is a very good chance that the nice brand new carpet on the floor will get oil sprayed.   It does have polycarbonate cover on carpet, BUT.   I'm doing my level best to not get swarf on it.  Every so often I realise I have left a swarf line down the new stairs and hall carpet as well.  Tends to put me in the bad books.     I can pick up swarf but have little difficulty with oil.

PJW

Its not Jo's it's mine.  I know what you mean but see comment above re swarf and oil.  Need to be very careful. 

Colin

[Bjorn_B]

Seeing this gave me some ideas on how to make my cross slide scale more stable, a wobbly DRO makes no one happy. Thanks for the pictures. Hope you don't mind me stealing an idea or two..

[Twizseven]

Bjorn,

I guess your referring to the 3mm steel rod.  This was a bit of an afterthought.  I was going to use a piece of 25mmx3mm aluminium bar but weight saving and neatness led to the tension link.  The scale is held onto the carriage bracket by 4 off M3 countersunk screws, 2 in the back and two from underneath.  I used three engineers squares and three engineers clamps to hold them all in nice alignment whilst the holes were drilled, but the scales was still slightly out of true.  I relieved the screw holes slightly and was able to square it up and look it up nice and tight.  It was still out by about 15 thou at the outer end so I put the rod in place.  It is in fact pushing the beam very slightly so as to get perfect clearance between the read head and scale. As a side benefit it stops any vibration and will hopefully prevent any slight knocks from knocking the alignment out of kilter.

Colin

[Bjorn_B]

Yes, I'm refering to the steel rod, good thinking!

[PJW]

Your DRO's are the dogs jewels but that is something a long way off for me, but I have been in touch with Cowells and they can sell me handwheels with re-set dials that should fit my existing feed screws, Cost per handwheel + reset is £35 + vat & top slide £28 + vat.
this is an option I am thinking about.

[sco]

Your DRO's are the dogs jewels but that is something a long way off for me, but I have been in touch with Cowells and they can sell me handwheels with re-set dials that should fit my existing feed screws, Cost per handwheel + reset is £35 + vat & top slide £28 + vat.
this is an option I am thinking about.

Sherline do some handwheels that look like they could easily be adapted and are a bit cheaper than the Cowells: http://www.sherline.com/3420pg.htm

Simon.

[PJW]

gone are the days when postage from the states was cheap, so they would not be much cheaper, they may not fit & they look a bit cheap to me. Has anyone replaced the hand wheels on a cowells? It is so much simpler when you can reset the wheels.

[Twizseven]

You mention postage from states. I've just ordered Texas Instruments msp430 launchpad processor to read the scales as per Yuriystoys site. $9.99 + postage which I think is $7.  All the way from North Dakota for total of £11.xx. Including buying the processor.   Can it beat that, especially when delivery is 3 days.

Colin

[Jo]

Your DRO's are the dogs jewels but that is something a long way off for me, but I have been in touch with Cowells and they can sell me handwheels with re-set dials that should fit my existing feed screws, Cost per handwheel + reset is £35 + vat & top slide £28 + vat.
this is an option I am thinking about.

Who reads handwheels any more?

I am still happy with the pair of £25 long reach (50mm) dial gauges I fitted to the axes on C2. Ok so they are a poor man's DRO but who would want to be forced to work without easy to read accurate measurements  on their lathe as well as their mill

Jo

[Jasonb]

Who reads handwheels any more? Jo

Those who can

[Twizseven]

I guess I could count turns on the handwheels, but I was bored counting 36 turns or thereabouts (and keeping track) whilst doing the cylinder bores on the two little Elmer's Standby engines I built.  Plus its lot easier being able to move back and forwards between Metric and Imperial.  Also thought I'd spend it now whilst have it rather than wait till retire.

On the topic of Imperial to Metric conversion, I bought a Moore and Wright height gauge a few months back, it does Metric, Imperial AND 128th's.

MSP430 Processor just delivered, 2 1/2 days from North Dakota, total cost £11 including delivery,  Amazing

Colin

[Jo]

It has been so long since I needed to that I hadn't remembered that I used to count turns on the hand wheel 

Also thought I'd spend it now whilst have it rather than wait till retire.

Always the best way: mitigate the investment over the longest time possible

Jo