2016 POTD Thread Archive

bunch of reasons:

- smaller pulley than I can get with a V-belt (min. 2in diameter - what I put on originally - for a 1/2in belt and even then it slipped occasionally). I wanted to gear down the motor so the spindle rpm range was more useful
- less slippage, although that's not a big deal as there's only a 3/8 v belt going to the spindle
- pulley should be concentric to the motor spindle = less vibration (ha!). It wasn't trivial adapting a V-pulley to the motor spindle and although it worked, it was hard to get it running true. If I'd made on from scratch with the LH threads and right bore size, that would probably not have been a big deal
- more mass/ rotational inertia for heavy or interrupted cuts. Motor speed used to vary a fair bit (simple MC controller), now with the flywheel on it doesn't vary much at all, even though I have only a couple of hours on it.
- built in fan. I made one for mine out of a 120mm PC fan which worked wonderfully until I accidentally moved the lathe a smidge and forgot to move it back. V belt pushed fan into fan shroud = no fan = hot motor :(

The smaller pulley (and larger countershaft pulley) alone has made a huge difference - low gear is now 300-1000rpm instead of 600-2000rpm, which means I don't have to use the back gears quite as much. My lowest useable speed is now 30rpm :)
 
Are you using the control from the treadmill or some other power supply and controller? I looked at the PWM controllers on the Bay for cheap, but I would need a 90 VDC supply at 10 amps which is difficult to get. So I get a DC motor controller for about $80 of the Bay.
 
mark_f said:
I looked at the PWM controllers on the Bay for cheap, but I would need a 90 VDC supply at 10 amps which is difficult to get.
Click to expand...
As long as all the parts are rated 200VDC or better (which they almost certainly are) those controllers will work fine on full-wave-rectified 120VAC. They probably include rectifiers and are intended to connect directly to the 120VAC line.
 
It's a technique for making a nearly-zero-clearance, low friction leadscrew nut from acetal/Delrin - machine the ID of the plastic to halfway between the root and outside diameters of the leadscrew, then split it. Coat the leadscrew with a release agent (oil, or even soot has been used). Clamp the plastic halves over the leadscrew and heat the metal it until the plastic melts and flows into the threads. When cool and hardened, chuck the leadscrew in the lathe and clean up the OD (and, to the extent possible, the ends) of the plastic.

The name EvaNut derives from Evan Williams, who appears to have been the originator of the technique (see first link).

Links:
http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts- the-easy-way
http://rick.sparber.org/EN.pdf
 
Started the die cart some months back but had to put on back burner as other pressing jobs came up as well as other shop upgrades. Yesterday I turned some large pins to allow storing the six dies for the Ercolina pipe bender. The two larger dies (1-3/4" and 1-1/2") have a bigger hex than the other four dies requiring the pins to be a different diameter.
The 2" material used came from an old hydraulic cylinder shaft that I salvaged.
IMG_1686.JPG
The four jaw scroll chuck with independent adjustment came in handy to dial in. The small custom "T" handles have a small earth magnet imbedded at the ends allowing rotation of the chuck while dialing in (a gift from Mark Jacobs) .
IMG_1687.JPG
After the pins where turned and chamfer added, then the piece was flipped around for a 1/2" shoulder allowing the dies to clear the 3" channel once in place. This same end was drilled and tapped for a 1/2"-13 bolts x 2".
IMG_1697.JPG IMG_1696.JPG
This HD cart will serve for securing the dies for the Profile roller as well so a considerable amount of weight will be carried on the cart. The cart will also allow me to convert the punch end of the iron worker to break flat bar. The break die comes in at 150 pounds and has gotten too heavy for my old back to carry. The final elevation of the top of the cart will match the iron worker platform allowing me to slide the heavy dies from cart to machine and vise versa. The final top will be 1/4" plate overhanging the sides and ends of the rolling cart. An indexing feature was added to the cart providing a positive lock to the iron worker ensuring no side to side movement. All four casters also have wheel locks.
IMG_1708.JPG IMG_1707.JPG IMG_1709.JPG
A close up of the indexing feature for the iron worker.
IMG_1712.JPG
Indexed to the machine.
IMG_1711.JPG
I had fabricated caster mounts on the iron worker many years ago and worked with the design to make it work.
IMG_1710.JPG
This is a shot of the heavy break die that will live on the cart when not in use.
20150102_100422.jpg
Over the years, I had the dies for all three machines on the floor and it was hard on the back to move, find and install the required tooling. This project will serve me well into the future preserving my back and fingers.
The cart will be kept towards the back of the iron worker near the other machines that require the tooling. It rolls very nice considering the amount of weight its supporting.
So far so good, the only money spent was on castors, the rest of materials used where remnants from previous jobs.IMG_1714.JPG
This photo shows the two machines that use said tooling; Ercolina super bender(110vac) with digital readout with pre assigned angles and spring back allowance. The larger profile roller also sits on castors and a breeze to move. The transformer is required for this machine as its 460V 3 ph and works with the RPC system. The digital control stand sits on the main stand when stored.
IMG_1718.JPG IMG_1719.JPG IMG_1716.JPG IMG_1717.JPG
Thanks for looking and allowing me to share some ideas.
Turn and burn guys!
 
hman said:
It's a technique for making a nearly-zero-clearance, low friction leadscrew nut from acetal/Delrin - machine the ID of the plastic to halfway between the root and outside diameters of the leadscrew, then split it. Coat the leadscrew with a release agent (oil, or even soot has been used). Clamp the plastic halves over the leadscrew and heat the metal it until the plastic melts and flows into the threads. When cool and hardened, chuck the leadscrew in the lathe and clean up the OD (and, to the extent possible, the ends) of the plastic.

The name EvaNut derives from Evan Williams, who appears to have been the originator of the technique (see first link).

Links:
http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts- the-easy-way
http://rick.sparber.org/EN.pdf
Click to expand...
Awesome. I have a lathe with terrible backlash in the cross slide (more than 1/2 turn) and a rod of Delrin in the scrap plastic stock pile. :)
 
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