Levelling a lathe on my concrete bench...

[John Hill]

Today is the day I mounted my 12x36 Chinese lathe on my concrete machine bench.
 
These lathes have 6 mounting points, 4 under the headstock and 2 at the far end.
 
I got everything apparently level easily enough but on further checking I found the lathe bed was arched upwards (very slightly of course). I presumed this was due to the 4 jacking nuts under the headstock not being adjusted correctly.
 
My level has a vee bottom and does not sit well on the ways (cross wise is OK) so I put it on the top of the cross slide and wound the saddle between the limits of its travel while adjusting the outermost jacks at the head stock end. That seems to have done the trick.
 
Now the point is, I have never seen any of the on-line accounts of how to level a lathe ever check for this condition of arched (or swayed) back and I dont think a short test bar would find it either. It might show as a tail stock centre high or low but you would have to check that in two or more places to find if the bed was arched. You migh even be able to get an arch backed lathe to pass some of the common tests perfectly.

[GerryB]

G.Day John,
I was wondering ,is the top surface of your Concrete Bench Flat.
Also Concrete will bend.so how about the surface that the bench is resting on.
It may sound picky but all these little things can amount to problems.
I like the idea of a concrete bench to mount the lathe on,the weight would help to give the lathe stability.
Mine came with Steel Cabinets,not very heavy,actually quite light,but no problems so far.
When i was in the Navy they had concrete benches in the Hanger for the Engineers to work on but if i remember correctly they were fitted with a wood top.
GerryB

[Davo J]

Hi John,
I don't think there is much reference to it because older lathes where rigid enough that the beds would not move that way. I always wondered about it on small lathes like the Hercus with it's 2 skinny legs going down with no support across them, they would have to spread over the years bringing the centre of the bed down. It just goes to show our lathes have some flex in them.

If you look around at different lathes in this size and the larger 1000mm between centre lathes and you can see the different designs in the bottom of the beds which would make them less prone to this.

Some have a large step up under the bed like ours
https://www.machineryhouse.com.au/Products?stockCode=L183

Where ones like this have a small step up (which mean more cast)
https://www.machineryhouse.com.au/Products?stockCode=L563D
https://www.machineryhouse.com.au/Products?stockCode=L186D

Or others with a small or large arch
https://www.machineryhouse.com.au/Products?stockCode=L240D
https://www.machineryhouse.com.au/Products?stockCode=L179

After that they go to the cast base which would be machine true for the lathe bolts to
https://www.machineryhouse.com.au/Products?stockCode=L632D
https://www.machineryhouse.com.au/Products?stockCode=L625D

I have even seen some lathes with no step up at all, just strait through from the headstock to the tailstock.

This is something I have taken notice to as I would like to upgrade to a 1000mm between centers lathe. From looking at ebay etc there are a lot of different designs in this area, and it is one that will make the lathe bed more rigid.

It is good job you checked this and sorted it out, as over the years it would settle and take a set in the bed.
Over on the wood work forum we have a member at the moment who has a lathe like ours with a twist in it. He bought it second hand and is not sure how the guy had it set up and has tried leveling it but one side of the tail stock leg is up in the air. We have suggested sand bags in the cupboards or bolting it down. Maybe he needs a bench like yours to sort it out.

Dave

[John Hill]

G.Day John,
I was wondering ,is the top surface of your Concrete Bench Flat.
Also Concrete will bend.so how about the surface that the bench is resting on.
It may sound picky but all these little things can amount to problems.
I like the idea of a concrete bench to mount the lathe on,the weight would help to give the lathe stability.
Mine came with Steel Cabinets,not very heavy,actually quite light,but no problems so far.
When i was in the Navy they had concrete benches in the Hanger for the Engineers to work on but if i remember correctly they were fitted with a wood top.
GerryB

Gerry, have you ever put a level on your ways and checked that both ends and the middle match for level in all directions?

[John Hill]

It is good job you checked this and sorted it out, as over the years it would settle and take a set in the bed.
Over on the wood work forum we have a member at the moment who has a lathe like ours with a twist in it. He bought it second hand and is not sure how the guy had it set up and has tried leveling it but one side of the tail stock leg is up in the air. We have suggested sand bags in the cupboards or bolting it down. Maybe he needs a bench like yours to sort it out.

Dave

Hi Dave
My lathe was sitting for 8 years on a broken pallet in the dealer's 'showroom' so I would not be suprised if it has taken a bit of a set.  Hopefully I can tweak it out on this chunk of a bench.  Time will tell!

[Davo J]

It is good job you checked this and sorted it out, as over the years it would settle and take a set in the bed.
Over on the wood work forum we have a member at the moment who has a lathe like ours with a twist in it. He bought it second hand and is not sure how the guy had it set up and has tried leveling it but one side of the tail stock leg is up in the air. We have suggested sand bags in the cupboards or bolting it down. Maybe he needs a bench like yours to sort it out.

Dave

Hi Dave
My lathe was sitting for 8 years on a broken pallet in the dealer's 'showroom' so I would not be suprised if it has taken a bit of a set.  Hopefully I can tweak it out on this chunk of a bench.  Time will tell!

Now that you mention it, I remember you posting about your lathe sitting before you got it.
That little lathe is match for that big solid bench.   
From what you have said it has all ready pulled it strait, so no problems their. You will just have to keep an eye on it over time as everything settles in. I remember when setting mine up I checked it every week for a few weeks, then after a couple of months, then after 12 months and gave it away as it hadn't moved.

When I moved it I noticed it was turning a taper with a shaft mounted in the chuck, it didn't take to long before I remembered I hadn't re leveled it. It is amazing what a little bit of twist will do, and how far out it can throw a job.

I checked mine along it's length when I first set it up and bolted it down to the concrete floor around 7 years ago, as it is only supported by 2 boxes like yours was, and I wasn't sure if the boxes where pulling in or out, but I have never checked it again. After the recent move and after hearing your out come, I think I will check again.

So thanks for the post reminding us these lathes come with a rubber content in the cast iron. LOL
Ant more thoughts on the paint or finish for the top?

Dave

[nearnexus]

For paint you could try two pack marine epoxy.

The last lot I bought was made in New Zealand - Epicraft.