Sl20 Lathe Problem

[MR D]

Making Bolt 6.25 Long With Thread 1.0 Long 7/8-9 On End. Can Make Thread Without Live Center. Not Program Or Tooling. Only When Center Is Engaged Do We Get Chatter, Haas Has Been Here To Check Machine Says Ok. Has Any One Seen This Before. Stock Is 1-3/4 Head Dia, Turned To .986-.990 Bolt Dia. Should Not Have To Make In Two Set Ups. Simple Turn Job. Whats My Problem? Tried Everything.

[martsto]

How good is your live center? I have had similar problems with an "economy" live center - problems disappeared when I switched to my cnc qualified Royal live center. Make sure that your tailstock pressure is adequate, and that you aren't at the end of the tailstock stroke.

[MR D]

2 royal ctrs, 3 new tailstock sleeves, more -less pressure 20 pcs same results checked center blued full contact

[GOLETABRIAN]

Try putting an indicator on the part when the center engages. It may be off center and moving the part off center when it engages.

[MR D]

done that,part moves.0005 one side and .0002other side 90*when engaged only happens when tailstock is engaged. can thread perfect without.

[rickyt]

Try to shorten the quill stroke so it only moves maybe an inch or two, then contacts the countsink.

[GOLETABRIAN]

Try turning down the pressure on the tail stock. Also measure the part over the entire part with the indicator. The part may be bowing with too much pressure. That would cause your chatter.

[DEAN]

Looks like he tried different pressures....
Maybe your countersink is not of the correct size or depth and the point on the live center is bottoming out????

[MR D]

tried bigger cs, blued center perfect

[Blaster33442]

Check your center line for the tool, machine turret may need to be adjusted for center

[MR D]

seems to be tailstock, machining in 2 setups ran 10 pcs 11 part ts walked back just enough to disengage. it might be hyd. issue? valve or solenoid. gauges read fine dont drop off on pressure maybe needle thickness flux.

[Geof]

Originally Posted by MR D seems to be tailstock, machining in 2 setups ran 10 pcs 11 part ts walked back just enough to disengage. it might be hyd. issue? valve or solenoid. gauges read fine dont drop off on pressure maybe needle thickness flux.

Does the gauge needle actually move when you operate the tailstock? Seems like a funny question but on some of the Haas lathes they had problems with pressure pulses in the hydraulics damaging the gauges. We have replaced two gauges where the needle was jammed in one spot and never moved. If your gauge is not working correctly you may get a pressure drop that you don't see.