[chrisnis]

Can someone help me with this please. I need to be able to thread stuff and having a big problem . I know how to change gears to get the TPI i need but its not working. If i put on gears to thread lower coarse tpis i can get it to work somewhat but when i start getting higher in TPI the leadscrew gets so tight that it wont turn. I tried putting gears on to thread 20 tpi and i can even turn the chuck by hand and as soon as i try to turn it on the foward/reverse leadscrew lever just pops right out of gear. Im sure this is because the leadscrew is so tight its not turning. Has anyone experienced this before?

There is 2 nuts to adjust the gears so the teeth line up and iv tried adjusting them so they are making good contact and so the teeth are just touching and nothing i do makes it any looser or able to turn at all. I even tried holding the lever so it cant pop out of gear but even then it wont turn even when raising the speed control . in regular turning gear setup everything works fine ,i just cant get the threading to work at all and thats what i need the lathe for most .In the tpi im trying to cut its using 3 gears the middle gear im using is a 65tooth which is the blank one on the chart. Im so frustrated im about to give up and get a 9x20lathe with a quick change gearbox.

Anything you got on this please let me know. i need to thread some parts asap for a job. Thanks

[Tall Man]

Pics would help. I only threaded as fast as 32 tpi on a 7x8 mini, but never had issues.
Changing gears was a breeze and adjustment to those 2 nuts did not pose a problem
Mind you, my lead screw is bent.

[basalt]

All gears need backlash, just touching is too tight, by holding one gear stationary and wiggling the other gear there should be some noticeable play. Sometimes the bore of the gear(s) aren't concentric to the teeth so make a full turn to ensure the gears in mesh are free to turn. Then, with the carriage at the far tailstock end of the bed and the 1/2 nuts engaged adjust the pillow block (2 cap screws) holding the end of the leadscrew, vertically so it engages freely. Do the same at the headstock end--you will have to remove the electrical box to access the screws. Now with the 1/2 nuts engaged, spindle in neutral and the change gear lever engaged, turn the chuck--the leadscrew should turn freely. I have a Craftex lathe which is similar to yours and I can cut all the thread pitches no problem. One trick I do is to hold my thumb on the carriage wheel to provide some resistance while threading so the carriage repeats and doesn't "float". This is all assuming that your diagnosis is correct and it is the leadscrew and not a problem with the headstock gears. I hope this helps and you get this before you go out and buy a new lathe 'cause that doesn't solve this problem. Good luck.

[chrisnis]

thanks. Im am still gonna pick up a new lathe even if i can get it working. Just not a big fan of this lathe anymore. Planning on getting a grizzly g0602 and CNC'ing it real soon.

When i change to the threading gears i have tried it with the gear teethe just barely touching and with them tight and no change . Leadscrew is still too tight to move without popping out of gear.i cant even turn the chuck by hand. With the change gear lever in neutral the lathe works perfect with no resistance. With the standard gears on and the change gear lever in foward or reverse the leadscrew still turns perfectly with no bad resistance so i dont think the issue is with the leadscrew. Its only not being able to move when using and change gear set 16tpi and higher. lower TPI's still is very tight but works and doesnt pop out of gears except for maybe one or two times.

So your saying to adjust the pillow blocks holding the leadcrew on? I have removed them plenty of times when shimming the carraige gibs etc so i guess it is possible i made them too tight. The carraige moves fine though and feeds under power fine in normal gears as well.

So in my diagnosis so far it really seems like the problem is not the leadscrew itself or id think the leadscrew would have a issue when feeding under power or bumpy when moving the carrage which it isnt. I really think it has to do something with the gear area somewhere. I emailed grizzly and they said this problem is common with the 7x lathes and they didnt really have a fix for it .They told me to try loosening up the gear bracket mounting screws but i havent got my stress level down enough from last time to try it yet lol. i will also try your idea of adjusting the pillow blocks.

the half nut also engages great btw and even locks the carrage without any play and smoothly.

[Tall Man]

Before you'll dump tons of cash into a new lathe, why not posting a hi res picture of your change gears? Take 2 shots - along the lathe and across the lathe.

Just going out on a limb - does each gear rotate freely when not engaged with the others? What if one of the stems is a dad too short and washer is bottoming out on a gear instead the stem?

This is how you trobleshoot complex systems - break them down into simple elements and eliminate one after another. You should be able to rotate each gear and leadscrew by hand with ease for the entire system to work. Disassemble, then start assembling one by one checking where problem occurs.

Like I said, I am threading fine with a clearly bent leadscrew and still having no issues.

[chrisnis]

Ok Thanks guys. I finally found the issue and got it fixed .Had this problem since the day i got the lathe. Still going to get a new lathe as i need to thread a lot and 10min gear changes just isnt very practical for production imo. Not that its a bad lathe.It turns stainless pretty well for such a small lathe but i just want something with a semi quick gear change box,a little more beefy and something id be happy converting to cnc so i think im gonna go with the G0602 and do a 3phasemotor/vfd and cnc.

As for the problem here are some pics .Let me know if you see anything wrong with the before pics and anything on the pics after fixing it. Before i fixed i could barely turn the leadscrew with no gears on it even and like i posted before with threading gears it wouldnt turn at all. So after trying to turn it with just the leadscrew gear on and no other gears and it still being very tight i figured something had to be wrong in the leadscrew area. I had never taken the electronic cover off since i got the lathe which is the only thing iv never touched. Well heres the pics of gears,leadscrew and when i took the electronic cover off . the leadscrew looks very straight and true so that wasnt it.











Anything look off with the pics above? Pics below is what i think the problem was. When i took the cover off i saw that the leadscrew was not going all the way up to the pillow block mount. Notice the gap at the pillow block mount. There is no gap on the opposite side (tailstock) of the leadscrew. I was thinking that had to be it so i took off the leadscrew completely to check it out. I had to bang the leadscrew out because it was kinda wedged in the pillow block. Not only that but when i took the pillow block off to inspect the inside of it i noticed the oil hole had a little burr on the inside. Maybe the problem?






I took a file and filed down the burr on the inside,cleaned up the mount and leadscrew as well as put some mobil spindle oil on everything .i put the leadscrew back in and wholla it slid right in all the way and smoothly(no more tightness) Do the pics below look correct? I noticed now that it slid all the way in if you look in the pic there is now space behind the leadscrew gear spacer. is that right? I tightened both pillow blocks up with the carrage locked so it would adjust itself and now its on there with no gap like before and best of all i can now turn it by hand and smoothly. Is that the correct method for reinstalling the leadscrew and pillowblocks and does everything look correct? just want to be sure. Anyway i put 24tpi thread gears on that would not even come close to turning before and now i can still turn it by hand.Turned on the lathe and its all working smoothly. YAY! All good now just please let me know if everything looks correct now ?





Also one other very small issue i was wondering if you guys could help with. When i get the lathe past 500rpm it starts shaking and making a little noise (not too bad) like woh------woh----------woh-------------woh. It doesnt do either things at all below 500rpm .Only 500rpm + . Its minor so im not too concerned with it just figured while i have you guys attention id see if anyone knows. It may be just the belt a little off alignment but not sure.

Thanks for the help guys .i really appriciate it. Its working good now. other then that i have always felt i lucked out with this chineese lathe since when i got it everything was in very good tram (spindle,ways,tailstock etc) right out of the box and its almost perfect now with just minor tweaking.I have heard some horror stories on alignment with these lathes so at least i got lucky there.

Btw anyone want to buy a lathe with extras lol . Comes with a 4jawchuck + 3jaw,OXA QCTP with a bunch of holder,carriage lock and stop,cam lock tailstockw/live and dead center,drill chuck,DRO etc.I have it on craigslist right now for $890.Need to fund my next lathe.

[Tall Man]

The alignment with pillow block is correct now, good. And everything rotates freely, which is good.
As to noise at higher RPMs - do you hear it only in Low gear or High gear or both?
With lead screw engaged or regardless?

Mine is somewhat noisier in Low gear.

[Crevice Reamer]

Btw anyone want to buy a lathe with extras lol . Comes with a 4jawchuck + 3jaw,OXA QCTP with a bunch of holder,carriage lock and stop,cam lock tailstockw/live and dead center,drill chuck,DRO etc.I have it on craigslist right now for $890.Need to fund my next lathe.

Congratulations for solving your problem!

You may want to hold off on the sale until you check availability. The G0602 is so popular that Grizzly often runs out. If you are lucky, you'll get it right away, but it MIGHT take several months to arrive.

CR.

[chrisnis]

The alignment with pillow block is correct now, good. And everything rotates freely, which is good.
As to noise at higher RPMs - do you hear it only in Low gear or High gear or both?
With lead screw engaged or regardless?

Mine is somewhat noisier in Low gear.

Gotta see . I have actually never used high gear. Its does it the same with the leadscrew engaged and not engaged.

[chrisnis]

Congratulations for solving your problem!

You may want to hold off on the sale until you check availability. The G0602 is so popular that Grizzly often runs out. If you are lucky, you'll get it right away, but it MIGHT take several months to arrive.

CR.

Thats a good point.Hopefully they are in stock. It says they are on their site but not sure if that means anything . I sent them a email but they arent open til tomorrow.