By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Nov 29

Boxford Screwcutting box / Leadscrew binding

Sticking Leadscrew?

All Topics | Latest Posts

Search for:  in Thread Title in  
SillyOldDuffer14/03/2019 22:24:27
4122 forum posts
831 photos
Posted by andrew wrigley on 14/03/2019 20:11:16:

Hi, I’ve been through a few checks including checking the leadscrew for straightness, it is. Checking things are running ok without the gearbox connected etc. and all is ok on the saddle. I’ve measured the current draw on the vsd and checked a few parameters, and think it’s possibly the vsd settings. So I’ve been through all the settings, optimized what I can upped a few parameters such as the ‘torque boost’ that ups the volts when under load (I think). Anyway things seem a little better and it’s not bogging down quite the same. Not having another lathe to compare it with leaves me guessing a bit, but I’ll try it for real tomorrow and report back.

Thanks for all the support so far

Might be worth getting a feel for how stiff the powered-off lathe is in normal conditions by turning the chuck by hand whilst everything is engaged. Then, next time it binds up, switch-off immediately and repeat the test. If it feels harder to turn the chuck likely something is binding. If it turns as freely as before, the motor/VFD is suspect.

Dave

Hopper14/03/2019 23:17:21
avatar
3515 forum posts
68 photos

Sorry, I misread VSD as VFD last post. Is it the factory variable pulley system? I would be suspicious of that as source of problem. The reason as I said in a very early post being that it seems odd that a leadscrew or apron problem coiuld seize up the system sufficiently to stall a 1hp motor. With the reduction gearing through the change gears and gearbox, it would take massive jamming force on the leadscrew to stall the motor. You would expect gear teeth to be flying off in all directions from the change gears, or at least a shear pin to shear somewhere along the line.

Hopper15/03/2019 00:59:52
avatar
3515 forum posts
68 photos

Or could be a combination of drive/motor and something like that apron clutch Brian Wood mentioned.

Speedy Builder515/03/2019 07:08:52
1715 forum posts
118 photos

Don't overdo the headstock greasers. On a cold day, if I screw the greasers down a couple of turns, it will reduce the speed of the headstock until things warm up. The headstock bearings don't need much grease. What gear train have you got between the headstock and the leadscrew ?

Hollowpoint15/03/2019 18:52:26
avatar
138 forum posts
27 photos
Posted by Speedy Builder5 on 15/03/2019 07:08:52:

Don't overdo the headstock greasers. On a cold day, if I screw the greasers down a couple of turns, it will reduce the speed of the headstock until things warm up. The headstock bearings don't need much grease. What gear train have you got between the headstock and the leadscrew ?

Mine does the same thing!

andrew wrigley16/03/2019 08:45:39
7 forum posts

Hi, I think it’s definitley motor related. It substantially better now I’ve tweaked the (inverter) vsd. But still struggles a bit on the really high feed rates not that I’d ever use anything this high, just testing. There’s no binding that I can find anywhere and generally all appears pretty good, but I suspect the motor is tired. Interesting over the course of a days use yesterday the motor running currents dropped by 1/3 amp so things are settling in and old grease in the headstock (perhaps) is loosening up.

I’m also getting some slip on the T-link belt so will address that next, the lathe has been out of action for 10yrs, so a few teething issues are expected. It’s definitley slack so I’ll try removing links as there’s no adjustment left on the lower pulley bearing blocks.

Hopper16/03/2019 09:19:31
avatar
3515 forum posts
68 photos

Treat the old girl to a new belt. They harden with age and glaze up, losing grip. Get a good brand name replacement so you know it won't slip from the get go. As per usual, some of the cheap imitations are not up to snuff.

fishy-steve16/03/2019 10:52:33
108 forum posts
30 photos
Posted by Hopper on 16/03/2019 09:19:31:

Treat the old girl to a new belt. They harden with age and glaze up, losing grip. Get a good brand name replacement so you know it won't slip from the get go. As per usual, some of the cheap imitations are not up to snuff.

Has luck would have it. I have some for sale on ebay! 😁

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Eccentric July 5 2018
Ausee.com.au
ChesterUK
Eccentric Engineering
Allendale May 19
Warco
emcomachinetools
Allendale Electronics
TRANSWAVE Converters
Sarik
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest