Lathe not cutting straight :(

[Biggermens]

Hello everyone

Have have this lathe here
Buy Craftex Metal Lathe 13" x 24" complete with Stand - CT089 from Busy Bee Tools

I am having a hard time make it cut straight, I cut from right to left and on a 5 inch shaft and it tapers about 0.008" to 0.005" 0.005" on the left and 0.008 on the right

Would anyone know what would do that ?? i checked every thing and every thing is tight .

Thanks
Biggs

[holbieone]

most likely it's the pressure of the cut that's pushing the stock away

try a lite finish pass

try using a center ,steady rest or a follow rest

[Biggermens]

Oh yes i forgot to mentions that i do use a center and i take a 0.001 to 0.002 cut and it is consistent all the way

[holbieone]

the center bass should be adjustable to remove taper

[Biggermens]

ya i have adjusted it, Do you think a twisted bed would cause that ??

[holbieone]

yes , also a misaligned headstock could cause a taper

[HorridHenry]

Do you think a twisted bed would cause that ??

The chances of that happening are low,not saying it can't happen but I would suspect that you are not familair with lathe set up?

Do a check of spindle runout with a DTI,it also might be one of the chuck jaws has not been properly seated ie one notch out in insertation? which would produce your problem insert new stock and do a DTI test on this near the chuck and near the stock end and see if there is a considerable difference..

Have you got the 3 jaw model or is it 4 jaw?

[Biggermens]

I have checked the run out on the chuck and it is perfect, I have a 3 jaw and a 4 jaw
But even if your stock is in the jaw is off after a few good cuts, would it not get perfect ??
I have a friend that is a machines of 30 years and he says my lathe is a peace of s**t and their is nothing i can do

Thanks
Biggs

[txcncman]

Your friend is right on the first part, wrong on the second part, and not much of a friend. If he has 30 years of experience, he should be helping you correct the problem.

[fizzissist]

Tailstock alignment is the VERY first thing you do with a new lathe, to make sure that you get straight cuts. (if the tailstock isn't adjustable, it's junk to start with)

If the headstock isn't aligned, and you can't RE-align it, then it's junk to start with. You need to check that the headstock isn't just aligned left-right, but vertically as well. (yes, vertical)
Who knows how they build these things in the first place, and given the price, what do you expect?

Take a large dia disk and face it, leaving a 3/4" dia nub that you'll chuck on when you flip it around.... then face the other side and measure the thickness. If it isn't a uniform thickness, your headstock is out.

When you're all done screwin' with this exercise, you'll understand why a cheap machine is never a bargain.

[underthetire]

A twisted base will cause that. Only a precision level will tell you. Zero the level on one side and move the carriage to the other side and see if there is twist. My dads cheapo lathe had twist, and the chip pan wasn't helping. Bolted the lathe down to a ground alum plate, without the chip pan and shimmed under the legs. That helped. All machines including cnc lathes are set up this way. Unfortunately for hobbiest, the levels to really dial this in cost half has much as some of these lathes. After we leveled his lathe correctly, we then had to align the headstock. Wasn't easy, had to scrape the v surface somewhat to get it in. Once it cut without taper, then the tailstock.

Anytime I got a call for a cnc cutting a taper, it was check level, check headstock, then do tailstock. Lots of machines are "leveled" by customers that really had no idea how to properly level a machine. Level to the world never really matters much, it's level to itself that matters. Any bow or twist is bad.

[Biggermens]

What is the first thing on my list now is to make it perfect level, ( with a machinist level )
I have notice that the base of my lathe is kinda week, i was planing to make a new base

What would you guys recommend ????

Thanks
Biggs