Hf 7x10 Carriage Problem

[grepper]

Hi Guys-

First post. First time lathe user, so I bought a Harbor Freight 7x10 lathe, barely used. It works fine except there is some play in the carriage.

One the back, under side of the carriage there are two bolts that hold a plate that clamps the carriage to the ways. Both of these bolts were loose when I purchased it. If I tighten them the carriage won’t move.

I’m guessing this is a known issue. Any ideas?

 

[Ulma Doctor]

Hi grepper,
i owned and loved the little 7x10 i had.
the part that you are tightening the screws against is a strip of metal called a gib.
the gib is a sacrificial adjustment mechanism, to put it in simplest terms .
it's not really there to clamp the carriage to the bed, more like a guide.
you want the gib to operate freely without binding, otherwise you will surely shear the plastic gearing when you put it in auto carriage feed.

to adjust it,
unlock the apron feed, if engaged.
then you'll actuate the apron handwheel to move the carriage left and right. if there is binding during the movement- you may have a maladjusted gib
you'll want to loosen both allen bolts (5mm hex), slightly
then repeat the process of using the handwheel to go back and forth across the travel of the bed, noting any places of resistance
if there is no resistance, slightly tighten both allen head screws until an equilibrium is achieved between drag and fluidity of carriage function.
a sharpie marker could be used to spot high and low spots, if you are unsure if there is binding.
you will need to readjust the gibs as the lathe wears in.
sometimes the gibs are quite crude.
gibs can be made smoother by lightly stoning them with a known flat stone,
or lapped quite nicely with some 180 grit wet/dry sandpaper and windex using a plate of glass as a backing to the abrasive sheet for flatness.

if you are so inclined, a google search of varmit al's mini lathe mods would provide hours of entertainment. it shows lots of easy and not so easy mods and tune up stuff.

if you have other questions there's lots of knowledgeable folk here,
or you can always send me a message, i'd be happy to share my knowledge.

 

[grepper]

Thanks for the reply.

The issue on the carriage is that the screws are very loose and do not have a lock nut like the ones on the cross slide do. If I loosen them at all they are totally loose and just rattle out. There is no fine adjustment there, just real tight or not tight at all.

I guess I could get longer bolts and add a nut, or goop them up with threadlock. Hmm… I wonder if I could find a needle bearing plate.

 

[Waterlooboy2hp]

Thanks for the reply.

The issue on the carriage is that the screws are very loose and do not have a lock nut like the ones on the cross slide do. If I loosen them at all they are totally loose and just rattle out. There is no fine adjustment there, just real tight or not tight at all.

I guess I could get longer bolts and add a nut, or goop them up with threadlock. Hmm… I wonder if I could find a needle bearing plate.

============================================

I went a different route. I shimmed the bar out, until I could lock the screws and the carriage still moved without binding. That was the first thing I did, when I bought the lathe a year ago. I may look into making new gibs, for the cross slide and the compound, when I get some down time. The adjustment is kind of touchy on those, also. ---- Bought the lathe to produce some custom carb parts, to make a fixed high speed jet adjustable, on some of the Predator engines. As far I know, I am the only one on the face of the earth, that is making them. That led to also making 10mm & 12mm oil drain adaptors, for the same engines. ------ "All machinery is the same. It is just a matter of making friends with it"---- John

 

[Ulma Doctor]

a bit of teflon tape on the screw threads or some blue locktite would be beneficial to retard the loosening of the screws in question.
the teflon tape is instantaneous, and adjustable- unaffected by grease/oil
the locktite needs a little time to cure, and must be reapplied if the bond is broken- the surfaces should be free of oil, pre cure.

 

[TakeDeadAim]

It is easiest to adjust if you get a pack of plastic, easier to cut than metal, and make shims for between the plate held on by the bolts and the carriage. This machine does not have a "standard" tapered gib so the shims are what is used to create the balance between being able to move the carriage but not have it vibrate or actually move when you are taking a cut. This makes a huge difference in the performance and accuracy of your machine. Taking the time to do this right will be rewarded almost as much as having your tool sharp and in the correct position. Please feel free to message me if you have questions.

 

[grepper]

Thanks for the replies guys. Great ideas! I’ll have a little look-see down there and come up with something.

WA said, “"All machinery is the same. It is just a matter of making friends with it"

My experience with HF stuff is that the friendship usually requires a little more work.