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Author Topic: Denford ORAC lathe retrofit.  (Read 31427 times)
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DICKEYBIRD
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« Reply #10 on: March 28, 2013, 01:28:16 PM »

Iím using an ER16 5/8Ē straight shank collet chuck in a QC boring bar holder to hold drills in my ORAC.  Trying to align it properly in all 3 axes was a fiddly nightmare.  Hereís what I came up with that works well.

I turned 2, 7075 aluminum discs with steel shafts to fit a collet in the spindle and the boring bar holder. The discs were made with a tight press fit on the shafts and I finish turned them once pressed together and dialed in.  It out worked real well and a little juggling with a feeler gauge and a parallel had it in very good alignment and drilling spot on.

Once it was aligned properly, I locked the adjustment down on the toolholder and added its location to Mach3ís tool table.






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Milton from Tennessee ya'll.
mc
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« Reply #11 on: March 28, 2013, 02:22:45 PM »

Neat idea.
However, why not just use one disc in the QCTP, then mount a Dial guage in the collet chuck?
You'll probably need a mirror to read the dial in some positions, but I'd personally do that than have to play with feeler gauges.
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DICKEYBIRD
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« Reply #12 on: March 28, 2013, 03:25:02 PM »

Neat idea.
However, why not just use one disc in the QCTP, then mount a Dial guage in the collet chuck?
Dohh!  Thanks MC, that makes perfect sense.  That's why I spend so much time here: to further my edumacation!:)
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Milton from Tennessee ya'll.
DICKEYBIRD
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« Reply #13 on: July 16, 2013, 09:23:37 AM »

Time for an update on the ORAC

Added a tachĖgenerator to input a feedback signal into the KB speed control to stabilize the spindle speed for better threading.  KB says 1% variation over its 50:1 speed range using tach feedback and the results were great.  Picked up a used 7V/1000 rpm Servo-Tek tach for peanuts on ebay and cobbled together the nec stuff to mount & drive it off the back end of the Baldor.





The coupler is just a bit of soft rubber tubing with a couple o-rings slid on to make sure it doesnít slip. 



The KB instructions cautioned that correct polarity must be observed and if spindle reversing is used, the tach input signal polarity must be reversed along with spindle motor reversal.  I made up a couple relay boards to do that and to switch power to the 12V cutting oil pump motor.  The DPDT polarity reversing relay is in series with the tach output triggered by a 5V relay hooked to the B.O.B. and pulled in only upon M4 command.

One board mounts inside the base enclosure and (a) sends a 12V signal to the DPDT relay on the other board in the speed control enclosure and (b) switches power on & off to the cutting oil pump.  The bigger pump relay in the pic was snagged off an A/C control board they were throwing out at work.  I love making stuff using free parts!



There was a reverse polarity spike when braking to a stop after a reverse command so I stuck in a couple diodes after the DPDT relay.  That stopped the funny noise from the KB when stopping after running the spindle in reverse.



Hereís the cutting oil pump I rigged up using a 12V auto sunroof blind motor (another freebie from work) and a Suzuki 125cc 2-stroke oil injection pump.  I tried a 250cc pump but it put out too much oil.  The rate is easily adjustable using the rotary valve control that used to be connected to the throttle but I found that all the way back to the idle position gives the steady drip Ė drip Ė drip I was looking for.  Plenty good for keeping the work & the tool wet but no so much that it makes a huge mess.

The 250 pump has 2 outlets & I may make another motor drive & relay control for it later to lube the ways & ballscrews.  The ORAC relies on the operator oiling it frequently so automatic oiling would be great.



Finished installation pic.  The reservoir is a plastic1 pint brake fluid bottle.  No need for a huge tank with the slow drip-drip-drip feed.





I used Tygon tubing off ebay to plumb it as the stuff is very resistant to most oils and is pretty cheap.  The flexible plastic nozzle is an aeresol brake cleaner straw and I used a mini DTI stand to position it.  Quick & easy to get the nozzle right where itís needed.

Iím real happy with how well the oiling system works.  It starts dripping immediately on command and also stops instantly with maybe one solitary drip after itís turned off.  Iím not planning a major rebuild to add an enclosure to support flood coolant so this methodís here to stay.

I did my 1st threading over the weekend and it came out pretty well considering the cheap-o brazed carbide tool I had on hand.  Iíll get some decent inserts & a holder one of these days and should get even better results.  The test was on a piece of crappy hardware store cold-rolled steel and I chose 16mm x 1.5, the only size die I had on hand close to the 5/8Ē stock to check the thread with.





The 300 rpm spindle speed held very steady through the whole process but my puny little stepper & control were overworked at .002Ē D.O.C.  The die screwed on & fit snugly but the threads were ragged & looked like a few steps got lost in the struggle.  The next try at .001Ē D.O.C. was much better.
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Milton from Tennessee ya'll.
Hood
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« Reply #14 on: July 16, 2013, 02:43:27 PM »

Looking good Smiley
Good idea with the two stroke pump, may have to do something like that on the wee conect.

Hood
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DICKEYBIRD
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« Reply #15 on: July 16, 2013, 04:25:49 PM »

Thanks Hood; my wife says I have a good idea occasionally. Grin
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Milton from Tennessee ya'll.
Hood
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« Reply #16 on: July 17, 2013, 12:52:09 AM »

We all have good ideas now and then but for your wife to admit that I reckon you must have more than most Grin

Hood
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DICKEYBIRD
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« Reply #17 on: August 04, 2013, 10:06:56 AM »

After further review, I added a manual cutting oil flow control knob to the oil dispenser.  Iíve been making a few parts with the ORAC lately and found that different cuts wanted more or less oil.  I could change the flow rate during the cut but had to walk around behind the machine & tweak the pump control arm.  Not cool!

Never ignoring a chance to use stuff in my junk drawers to rig up a Rube Goldberg (Heath Robinson for my English brethren) contraption, hereís what I came up with.  The bellcrank & connector widgets were from my R/C model airplane drawers.  The rack & pinion remote cable was given to me back in the 80ís.  Dunno what it was made for but it works smooth as silk and was perfect for the job.  Anybody else got packrat disease as bad as me?







Iíve been messing around with my Denford MicroMill (runs on Mach3 & W2000) and made a little label plate to go under the knob.  The little thing does a pretty decent job!  Funny, even after a lifetime of adjusting carburetor needles & turning water faucets CCW to increase the flow, my automatic instinct to increase the oil flow was to turn the knob CW like a volume control.  Brain defect I guess.  Thatís why the wacky linkage was used.  Sidenote:  Pi$$ed me off when I used acetone to clean the ORAC graphic before sticking the label on & found out Denford screen printed the clear film on the outside!



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DICKEYBIRD
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« Reply #18 on: September 11, 2013, 10:19:55 AM »

Made a gang toolholder for the ORAC.  I whittled the AXA dovetail out of a stick of CRS and added a bracket at the far end to lock it in solid.  After drilling the 3, 23/32Ē holes on the mill, I bored them to final size in-situ with a ĺĒ endmill chucked in the spindle.





I made up some ĺĒ straight shank ER16 chucks from 1144 steel.  The shanks and 8 degree tapers came out perfect using Mach wizards but cutting the 22 x 1.5mm threads failed miserably.  Not Machís fault though.  I just need to build a 3 or 4:1 reduction system to increase the torque at low spindle speeds for threading jobs in steel.  Most of the passes were perfect but the deeper cuts at the end got things out of synch and snapped an insert.  I switched over to my manual lathe and got them done using a HSS tool & hand-cranking the spindle.







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Milton from Tennessee ya'll.
DICKEYBIRD
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« Reply #19 on: December 01, 2013, 08:37:36 AM »

More ORAC updates if anyone's looking:

Recently finished a speed reduction belt drive system to give it more grunt & speed stability for threading in steel.  Itís getting a bit busy out tíback porch of the machine these days!  It can be switched back & forth between direct & reduction drive in about 10-15 min.  More time than Iíd like to spend but a lot cheaper than a bigger motor & wiring upgrade.  The whole thing was done with stuff I had on hand other than the 2 belts and a couple cheap ebay bearings for the countershaft.





The big pulley is the cast iron flywheel from SWMBOís dead treadmill with a V-groove cut in the OD to fit a Gates 7M Polyflex belt.  Didnít have much room so I chose the small belt and made my own QD style taper locking pulley to fit in the small space behind the direct drive pulley.





Making the pulley is a story in itself but it works great and runs very true.  Once the screws are torqued down, Iíll bet the thing would stay on with the screws removed!





I keep coming up with British parts from the junkbox to go on this thing which should make its Yorkshire builders happy; if anything can make a Yorkshireman happy, that is.Cheesy  The idler pulleys came from a long ago Landie Disco recall & the eccentric adjuster came from an MGB hang-on A/C kit from 1972.  I installed all the A/Cís for the local BL dealer here in the steamy south way back in the day and an extra one came in the box .  Itís been lying in the toolbox bottom drawer for 41 yrs. just waiting to be used.

The 2 tensioners allow the reduction belt to be put on & off  without disturbing the fiddly alignment of the countershaft pulley bracket assy. and maximizes belt wrap to (hopefully) prevent slippage.  That tiny little pulley worried me but the 10-groove belt & good tensioning seems to prevent any slipping.








The drive motor is mounted on 4 rubber isolators and I had to cobble up this little adjustable rubber tipped widget to keep the 7M belt tight.  The tube nut came from an MGB valve cover.





The thing works great and so far has allowed good threading in steel but Iím still playing with G76 settings trying to get my head around it.  With the motor at full chat (1850 rpm) the spindle runs 398 rpm. Thatís still a little higher than Iíd like but slowing it down to 250 with the KB drive doesnít seem to bother it.  If I donít get any slipping at the little pulley after using it a while, I may make a smaller motor pulley to get the final speed down to 200-250.
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Milton from Tennessee ya'll.
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