9/16 Acme Screw Machine - Collect Problem

Clean up the internal taper first. You may need to obtain a special reamer if there is damage to the metal. And the correct spelling is "collet".

Ed Weldon

Agreed. A little tap on the butt could be from over tightening, a burr on your tooling, a burr or mar on the collet itself, or as Ed Weldon stated grime and debris.

If the collet has been grossly overtightened it probably needs to be replaced, though not definitely.

get your feed screw coated with thick layer of teflon non stick..

I am not using pusher tubes this is a chucker which parts are loaded in the collet sometimes the collet does not want to open and close my operater clean the collet tube and change the fingers and pins but the chucking spool stills sticks.

Since the cutting oil and mechanical lubricant are one in the same, make sure the oil is not over used and in need of a good old cleanout with a check on the screen that filters the metal chips before being pumped to the carrier and collet area. I would thoughly inspect each tube for properly sized feed fingers to be sure they are smooth and match the contour of the stock. You can also have the smooth surface of each finger ground with grooves in a cross hatch pattern to grip the stock better. Too much clamping pressure is usually the result of an operator overcompensating for dull tools on the tool slide or the feed cam and gear combination is pushing too hard to make production faster. A machine that runs slower will always out produce a machine that has alot of down time. Make sure drills and facing tools have enough relief behind the cutting edge. The cutting edges also needs to be resharpened before they become dull. Pushing tools an extra 100 cycles or more might work but hard metals and fast production speeds have to be watched and tool resharpening should be done after a predetermined life cycle once the setup runs well. The best indicator of proper cutting speeds and properly sharpned tools is the chips from the cutting. Around .030 thickness is fairly common for most metals and tight curly chips are good. If chip buildup on the tooling becomes a problem, i always used cross slide and tool slide cams that have notches cut accross the ramp of the cams. Some cams have too many grooves and this increases the load also. If you have any extra positions open for tooling always take advantage and put roughing drills roughing form tools before the finish tools leaving enough stock to cleanup and create a good load on the finish tooling. Finish tooling should last 2-3 times longer than roughing tools. Last but not least, the draw back cam should be checked for loose bolts and the arm roller that rides the drawback cam should be free of any sharp edges or improperly aligned joints. The forks that push and pull the collet tubes need to work freely and the spring might not be strong enough to snatch the tubes if production speeds are greater than they should be. Oil pressure should always be maximum and checked for clogs. Use copper tubing to aim all oil instead of the plastic segmented tubes that are easy to adjust. Chips won't knock copper tubes away from the work area.

You can coat the surface of each finger with tungsten carbide to grip the stock better. This will also enable higher clamping pressure to compensate for dull tools. Please contact technovationsintl@gmail.com