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[Lathe] New to me Yangzhou TY-CO632 13x40 Gear Head Lathe.

ChrisAttebery

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Hi Dabbler, so you're saying instead of putting the gear train into neutral that I should pull the idler gear back off? I don't know if I can get to it without pulling the spindle again. I'll have to take a look.
 

BtoVin83

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So if I understand correctly you have the feed forward/reverse lever in neutral and still 110 dB. That's really noisy you need ear plugs just to turn it on. What I would do next is check each spindle speed both forward and reverse. In one of my speeds rotating forward is noisier than reverse. I removed the cover but couldn't find anything out of place. This way you might narrow it down to one of the countershafts and check the gears/bearings. My dad made a set of gears one time as he had numerous times before but these howled so bad the operators couldn't stand them. Made a replacement set and they were fine, never did figure out why they howled but running too close or zero clearance on gears makes them noisy.
 

Dabbler

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most lathes have a series of gears on the left side of the gearbox. that is under the cover. It isn't worth taking the gear off the spindle. the next gear should be on a yoke that can engage and disengage the spindle gear. You can usually loosen the yoke, move the gear to disengage, tighten it up, and then spin the lathe.

It will tell you if you have excessive play in the head stock gears on in the qucik change gear train. There are dozens of possible sources, but I'm trying to get you to distinguish between head stock gearing noises and the gear train that ultimately moves the carriage. Are you using an 80 wt oil in the head stock, and is it up to the right level, etc...
 

Silverbullet

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Need some of lucus oils gear box oil. Or the fancy purple gear oil. It's famous for quieting gear box noise. It's more tacky and slides around the gears slower. Might help.
 

ChrisAttebery

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I tightened the spindle bearings another 1/8th turn or so and it helped quiet the bearing noise a bit.

I also made a discovery tonight. The dB Meter app I’ve been using seems to be pretty far out of calibration. I downloaded two different dB apps and they both read within 1-2 dB of each other but much less than the first one.

Using the most pessimistic of the two new apps I see 92dB at 2000 rpm with the gearbox engaged and 90dB with it disengaged. 1255 rpm is down in the 85-88 dB range and the rest are 82 dB or less.

The new belt helped reduce the vibration I was seeing.
 
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ChrisAttebery

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So, on to the next issue. When I back the cross slide away from the work the cross feed screw starts getting tight over the last inch or of it's travel. I've taken the screw and nut off the machine and even with the backlash adjustment backed all the way off the nut is very tight over that last 1-2 inches of thread. The rest of the screw has ~.010" of backlash. I've tried cleaning it and chasing the threads with a large screwdriver to remove and crud or burrs. It didn't seem to help. Any suggestions on how to free it up?
 
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RandyM

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If it isn't your nut and screw, then it is probably a gib adjustment that is needed or at the very least a cleaning.
 

ChrisAttebery

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What I'm saying is that even with the screw and nut off the lathe that portion of the screw is tight.
 

ChrisAttebery

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Yes. I took the screw and nut out. Washed them in my parts tank and then oiled them up. the nut screws on fine until that last 1-2 inches. Then it gets tight in a hurry. I don't see any burrs either.
 

RandyM

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Dabbler

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So your problem is usually associated with wear on the dovetails. Scraping them is a pain, but it's hard to make things worse. Get some 1/2 inch dowel pins, and using a micrometer - not a vernier, check the distance. I'm sure at the ends, you are .001 or .002 more than the middle. That will give you a diagnostic, or not.
 

ChrisAttebery

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Dabbler,

The nut is tight on the screw. It screws freely until the last 1-2 inches. I've taken the screw and nut off the machine and it's still tight. The dovetails /ways are fine.

Chris
 

Richard King 2

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It sounds as if the screw is screwed up...lol
Do you have a caliper you measure the OD, ID and thickness of the treads.
I know the ID will be hard to measure as the treads are off set, but measure it on an angle where it is loose first and then down on the tight end.

Not knowing your machinist level or if you have a thread mic or thread wires, use a dial veneer. Can mic the OD.

You could probably order a new screw and nut, but first chuck the screw up in the lathe and slide the tail stock in to support the other end. Have the nut on the screw in the loose area. Oh and put the spindle in the slowest RPM. You should have measure it and know where it is big. Then you some die makers files and file the thick area's. Or if you know someone with a lathe have him chase the threads. If they know how to cut threads. If not file it. every now and then shut off the spindle and try to screw the nut up there. If the nut was tight the whole way I would suggest using some Timesavers Lapping Compound. It won't embed in the brass. But you can't lap it now, as it would lap the nut smaller.

If Im not clear on here call me. 651-338-8141. CST. Rich

PS a picture would sure help all of us
 

ChrisAttebery

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Hi Richard,

Thanks for the reply. I'm a hobby machinist with 20 years of experience. I have a dial caliper, 0-1 micrometer and thread wires. I can pull the screw back off and measure it.

I thought about chasing the thread on the lathe, but couldn't figure out how to do it without a cross slide screw. I don't know anyone in the area with a lathe. I wouldn't trust most people around here to use a screwdriver. ;^)

Thanks,


Chris
 

ChrisAttebery

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Thanks for the offer. I think Richard's plan to turn it on the lathe with files should work.

I just pulled this off this morning.

IMG_6075.jpg

IMG_6076.jpg
 

ChrisAttebery

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This morning I pulled the screw and nut off the cross slide and mounted them on the lathe as Richard suggested. I used a needle file to clean up that last couple inches of the threads until the nut would screw on and off smoothly. There were definitely some burrs on the screw.

Next, I put the cross slide back on the carriage and worked on the adjustment of the gib until it would slide freely over the entire throw.

Once I had the gib adjusted I loosely attached the nut to the cross slide. It was better than before but still a little tight at the near end. Once I tightened the nut to the CS the last 3/4" of throw was still a bit tight.

I think I need to clean up the screw a bit more and then make a .003"-.005" shim for the top of the nut.

That said, it's a lot better than it was before.
 

Richard King 2

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Run the nut as close to the front before tightening up anything. Be sure to stone everything sharp and the ways. Did you ever link to a print ? would help to look at a print.
 

Richard King 2

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If you have some Dykem paint on or spray on marking ink that dries, use it up on the tight threads before running up on the thread and see where it rubs off the most and then file that area. Sounds like it's coming your way.
 

ChrisAttebery

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I pulled the screw and nut back out of the machine this morning. I measured the OD of the screw at both ends and near the middle. It was about .002" larger at the end where the nut was sticking. I ran a file over that end while the screw was turning at about 300 rpm until it was the same diameter as the middle. Then I used a small triangular file to clean up the threads and that area. I adjusted the nut so that there is only about .005"-.010" of backlash and the nut doesn't get tight anywhere on the screw now. Once the screw was taken care of I worked on the cross slide gib adjustment until I could slide it all the way back and forth without any binding. I hooked the nut back up to the cross slide and there is almost no perceivable backlash and it doesn't bind up at any point in its travel.

Thanks to all of you for your help.
 

ChrisAttebery

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Over the weekend I was trying to turn some steel and I found that even the lowest feed rate was too fast at .0036"/rev. I decided to dig through my box of gears and come up with a lower feed rate. I put a 30T on the shaft closest to the spindle. I mated it up with the 127T gear. Then I put a 66T on the gear box shaft and mated that to the 120T gear. That should reduce the feed to .429 of the normal rate. .0036 x .429 = .00154". That seems more reasonable.

I also noticed for the first time that the feed and threading charts say that the lead screw is 8TPI but the gearing shown seems to indicate that the leadscrew is actually metric. I've been threading imperial threads with the 40 x 120 x 40 gearset, but it looks like I should have been using the 40/120 x 127/40 transposition gearing.

According to the charts you need three completely different gear setups for normal feed, imperial threading and metric threading. WTH were they thinking?
 

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