Thread: lathe alignment

Had a play this arvo with it. Its out a fair bit, not sure exactly but the level is going from one end to the other at each end of the bed. tried to shim it but its going to take me all year to shim it at the rate i was going, there has to be an easier way. I had a thought on using some 12mm threaded rod, HKDs and some nuts i could bolt the lathe onto the slab and using the all thread i will be able to jack up each point individually to get it to sit right hoping the slab doesn't crumble underneath it. Doing this seems like it would work, as the frame the lathe sits on is one of them sheet metal jobs, a decent stand isnt an option at this stage due to the difficulties in moving the lathe in and out ect ect. Someone else have a better idea?
thanks

When you check the level front to back and end to end put feelers under the level until the bubble is in the centre, take note of how many thou or mm this is.

Note the length of your level.

Measure the width of the base where the lathe sits on the floor front to back and end to end,note this down.divide the widt of the lathe by the length of the level then multiply this by the thickness of the feelers under the level,repeat this for end to end.

This will give you a start point for the packers to go under each corner,then just repeat.

Originally Posted by pipeclay

When you check the level front to back and end to end put feelers under the level until the bubble is in the centre, take note of how many thou or mm this is.

Note the length of your level.

Measure the width of the base where the lathe sits on the floor front to back and end to end,note this down.divide the widt of the lathe by the length of the level then multiply this by the thickness of the feelers under the level,repeat this for end to end.

This will give you a start point for the packers to go under each corner,then just repeat.

ahh makes sence ill give that a shot tomorow

Ive done some more test cuts on aluminium. No taik stock, 4jaw chuck, over 300mm it was out 0.73. Smaller at the chuck end, will add that ia with the gab left out so its probably causing a bigger error. Is it posible the headstock needs alignment? Is this posible, i know i still need to get the bed 100% but its pretty close as it is now. Just want to see my options.

What dia bar?
What sort of lathe?
What type of tool?
Just how far is the carriage over the gap?

Pictures?

"Is it possible the headstock needs alignment?"
sure, anything is possible, but depending on the lathe I'd say the chances are "unlikely" to "extremely unlikely"(fingers crossed on that for the minute)

You could run a DTI alone the front of the bar you've turned and see what that says.

I'm out for a couple of hours, good luck

Stuart

40mm aluminium bar, hss cutter taking light cuts and slow feed, over about 100mm.
Its a herless lathe, copy of the l 960b hare and forbes sell.

If the bed is twisted and the twist isn't caused by the stand/floor, it will prove nigh on impossible to level it on one of the sheet metal stands, they are just not sturdy enough. They make reasonably good cupboard legs for a bench top, but that's it. You have to have a solid platform off which you can work otherwise you are just chasing shadows. Do yourself a favour and make a decent stand first otherwise you will be there forever! JMO

I do understand that but at the moment the bed twist just isnt coresponding with the taper.

I have to disagree re placing the level on the cross slide. The carriage slides on the bed so if the level is placed on the carriage (cross slide) and the carriage wound back and forth it is going to mirror any discrepancies in the bed. The level has to be square to the bed of course and remain in the same position, gibs and guides also have to be checked. Whilst the cross slide is very slightly off square, the amount is miniscule so shouldn't make a difference. Most Chinese lathes have discrepancies in the bed so getting the bed level along it's entire length is virtually impossible. Mine has a bit of a hump 3/4 of the way along so I set up between the headstock and the hump.

I leveled mine with the level on the cross slide and the last time I turned something longish, without use of the tailstock, the taper was less than 0.01mm. From memory I think the stock was around 120mm proud of the jaws. I'm no expert though, so I'd be open to suggestions on why I shouldn't place the level on the cross slide. If I could remove the taper of around half an increment (0.01mm) on my lathe I'd be quite happy I think, but I would think that close to impossible.

What lathe is it and was it new or secondhand when you bought it.

There could be the chance the headstock is off given the other damage .

If you have it place a centre in the headstock and one in the tail stock and bring them together,check where the points are vertically and horizontally.

If the tips of the points are out horizontally ( hopefully you can see it ) check the rear of the tail stock for the alignment marks,if these look good then the headstock may be out.

If you remove the chuck you may be able to clean under the spindle enough to get a clean burr free area to run an indicator along that is attached to your cross slide.

Originally Posted by casjon

I have to disagree re placing the level on the cross slide. The carriage slides on the bed so if the level is placed on the carriage (cross slide) and the carriage wound back and forth it is going to mirror any discrepancies in the bed. The level has to be square to the bed of course and remain in the same position, gibs and guides also have to be checked. Whilst the cross slide is very slightly off square, the amount is miniscule so shouldn't make a difference. Most Chinese lathes have discrepancies in the bed so getting the bed level along it's entire length is virtually impossible. Mine has a bit of a hump 3/4 of the way along so I set up between the headstock and the hump.

I leveled mine with the level on the cross slide and the last time I turned something longish, without use of the tailstock, the taper was less than 0.01mm. From memory I think the stock was around 120mm proud of the jaws. I'm no expert though, so I'd be open to suggestions on why I shouldn't place the level on the cross slide. If I could remove the taper of around half an increment (0.01mm) on my lathe I'd be quite happy I think, but I would think that close to impossible.

What lathe is it and was it new or secondhand when you bought it.

not sure what your trying to say as in yes or no to the level on the cross slide, my reasoning for being it on there is thats where the cutting tool is and ultimately thats all that matters really.

i dont have another center to fit the headstock, MT5 i believe it is, ill try taking the chuck off and see if i can get an indicator in the spindle hole.
Im betting the headstock is out due to the other damage and the extreme tapper its turning. Ive attached a pic of the headstock, i believe this would be the adjustments? i think it speaks for itself. But before i got messing about with it i would just like a confirmation.

Ok I'm confused first you say over 300mm - 0.73 taper.
then you say over about 100mm... do you mean the carriage is over the gap 100mm?

What "other damage"?

What did a DTI on the front of the bar tell you?

A picture of your bar?

Stuart

Originally Posted by Stustoys

Ok I'm confused first you say over 300mm - 0.73 taper.
then you say over about 100mm... do you mean the carriage is over the gap 100mm?

What "other damage"?

What did a DTI on the front of the bar tell you?

A picture of your bar?

Stuart

yes sorry carriage overhanging the gap approx 100mm, are you talking about a dti across the face or length of the bar? the bar is just a peice of 40mm aluminum with undercut in the middle as to allow only 15mm machining at each end to avoid tool ware ect.

the history of the lathe is i got is 2nd hand with a bit of damage, broken change gear selectors, broken carriage face and hand wheel, if you look at my other threads theres pictures in there. that has all been fixed now and the only thing holding me back now is this taper cutting.

no problem, I get confused often
Oh that other damage, I remember the pictures. That does change things a little.(and with that type of headstock you were only in the "unlikely" pile to begin with)
I'm not so sure I'd trust any numbers I was getting with 100mm hanging over the gap.
dti at tool height at each end.
How good is the finish you are getting?

Stuart