Lathe levelling issue

[BelgiqueB]

Having problems getting the spindle parallel with the bed on my lathe, the bed/ways themselves are level (measured with a 0,35mm/1000mm bubble level), but can't seem to get the spindle axis parallel with the bed.

See the sketch below, I have a 200mm MT5 precision ground test bar (orange stripe on the sketch) that goes straight into the spindle taper, when i measure runout with the dial gauge measuring of the side of the bar i get barely any movement in the dial gauge needle, when i spin the spindle around there is also no movement in the dial gauge needle. If i then measure with the dial gauge needle on top of the test bar there is a 0,12mm difference in about 150mm of travel, so at the spindle the dial gauge reads 0, if i then move the carriage 150mm away it reads 0,12.

I tried levelling/tilting the headstock using the levelling feet on the lathe (marked A, B and C on the sketch) but the lathe is so rigid that if I come up on feet A it just picks up feet B off of the concrete, so the head stock does not tilt levelling out the spindle axis to the bed axis.

Any advice?

 

[Pete.]

Are you measuring with a dial gauge on the saddle and moving the saddle? If so you may be measuring wear in the bedway. Roll the saddle up to the headstock and bring the tailstock up as close as you can. Put your dial gauge on the tailstock and take your measurements by sliding the tailstock along the bed. Since the tailstock would seldom be used up close to the chuck there should be very little wear in the tailstock ways. If you get the same reading you're left with no option but to remove the headstock and check for rust. It's possible you might be able to adjust-out you 5 thou over 6" by manipulating the headstock clamp bolt torque.

 

[RWD3M]

Have you any weight at all on 'B'?

I'd try backing those two right off and measuring again. If that doesn't help I'm afraid I'm out of ideas, sorry.

Good luck!

 

[Hopefuldave]

How long did you leave it between adjusting the levelling feet and measuring? It *can* take a day or more to settle (yes, I know I'll be contradicted, but I've seen it!). Agree with Pete though, bed wear can throw the measurement off, and often gives a slope down towards the headstock.

Dave H. (the other one)

 

[BelgiqueB]

Did the tailstock test, when using the tailstock I have 0,04mm play over a length of 190mm. Using the crossslide I have 0,11mm play over a length of 190mm.

I then re levelled the lathe again only using the A and C bolts from the sketch in the original post, I then installed 2 concrete anchors in holes in the lathe feet just next to the B holes and when i tightened down on them the play started coming down to a bout 0,8mm before I pulled the anchors out of the concrete.

The only anchors i had on hand were short M16 ones, which only penetrated about 4 cm into the concrete, next week I'll install some chemical anchors well deep into the concrete and repeat the operation. In the mean time I've left the lathe positioned only on feet A and C, so maybe it will settle down over a couple of days as per Dave's suggestion.

thanks for the help!

 

[RWD3M]

Did the tailstock test, when using the tailstock I have 0,04mm play over a length of 190mm. Using the crossslide I have 0,11mm play over a length of 190mm.

I then re levelled the lathe again only using the A and C bolts from the sketch in the original post, I then installed 2 concrete anchors in holes in the lathe feet just next to the B holes and when i tightened down on them the play started coming down to a bout 0,8mm before I pulled the anchors out of the concrete.

The only anchors i had on hand were short M16 ones, which only penetrated about 4 cm into the concrete, next week I'll install some chemical anchors well deep into the concrete and repeat the operation. In the mean time I've left the lathe positioned only on feet A and C, so maybe it will settle down over a couple of days as per Dave's suggestion.

thanks for the help!

View attachment 302961

Hi BelgiqueB,

I may have implied in my previous post that I'm no expert, but the mounting instructions (such that I could find) for my lathe (a Harrison L5) reccommend that it should not be bolted down at all but levelled using the levelling bolts only The four holes in the base are threaded for that purpose).

Presumably your is different?

 

[BelgiqueB]

Hi BelgiqueB,

I may have implied in my previous post that I'm no expert, but the mounting instructions (such that I could find) for my lathe (a Harrison L5) reccommend that it should not be bolted down at all but levelled using the levelling bolts only The four holes in the base are threaded for that purpose).

Presumably your is different?

I think mine is meant to be bolted down, it has holes in the base casting for anchors and also if you look at the original sketch, that comes out of the manual of my lathe and it seems to imply that the lathe is meant to be bolted down.

Either way if the lathe doesn't settle down out of it's own weight I'm left with no other option than to bolt it down trying to get the spindle axis parallel with the bed axis.

Edit: just checked the manual and there is a paragraph mentioning how to anchor the lathe to the floor.

 

[RWD3M]

Ok, that's good.

Hope you get it sorted!

Bon Chance!

 

[daedalusminos]

Did the tailstock test, when using the tailstock I have 0,04mm play over a length of 190mm. Using the crossslide I have 0,11mm play over a length of 190mm.

I think as @Pete. Stated this is implying your saddle ways are worn, trying to distort the bed to compensate is never going to work.

 

[Pete.]

Did the tailstock test, when using the tailstock I have 0,04mm play over a length of 190mm. Using the crossslide I have 0,11mm play over a length of 190mm.

I then re levelled the lathe again only using the A and C bolts from the sketch in the original post, I then installed 2 concrete anchors in holes in the lathe feet just next to the B holes and when i tightened down on them the play started coming down to a bout 0,8mm before I pulled the anchors out of the concrete.

The only anchors i had on hand were short M16 ones, which only penetrated about 4 cm into the concrete, next week I'll install some chemical anchors well deep into the concrete and repeat the operation. In the mean time I've left the lathe positioned only on feet A and C, so maybe it will settle down over a couple of days as per Dave's suggestion.

thanks for the help!

View attachment 302961

Yes you're measuring bed wear IMO. less that 2 thou rise over 8000 isn't worth worrying about.

Incidentally 16mm threaded rod set in 150mm I pull-tested to 9 tons. I think 100mm embedment would be plenty so long as the concrete is sound and the holes blown out.