Adding rigidity to Lathe?

Hello, this is my first post but I have lurked for a long time.

I am assembling a selection of medium sized machines for hobby, with potential for some side business income.

I am currently building a stand for my 500lb lathe, and am wondering if there are any techniques for adding rigidity to the lathe, in addition to making a rigid stand.

For example, I have seen some people adding bracing from the top of their smaller mills to the table. Would doing something like this to the middle bed of the lathe be of any benefit?

Kipling79 said:

Hello, this is my first post but I have lurked for a long time.

I am assembling a selection of medium sized machines for hobby, with potential for some side business income.

I am currently building a stand for my 500lb lathe, and am wondering if there are any techniques for adding rigidity to the lathe, in addition to making a rigid stand.

For example, I have seen some people adding bracing from the top of their smaller mills to the table. Would doing something like this to the middle bed of the lathe be of any benefit?

Click to expand...

.
best way to add rigidity is bolt it to many tons on concrete. sure a heavy metal stand can be used but often it needs to be heavy and prevented from rocking back and forth which usually means leveling to a concrete floor AND bolted to the floor

I'm not seeing any torsional resistance in that stand.

used to use a Monarch lathe not bolted to floor. whenever load off center like 4 jaw chuck or faceplate it would rock back and forth. lathes usually are bolted down to floor

Thank you all for the comments.

Regarding bolting: I have prepared for the possibility of bolting the thing down, but was hoping to avoid the effort/modification since I want to sell soon. But, I will probably end up doing so, I definitely want to maximize what I have.

Regarding torsional twist: Before adding the lower cross-bracing, I was surprised how flexible the 7" c channel was. Afterwards the unit seemed very tight. I could still add some boxing or support... which your comment has me concerned about and will consider heavily.

Nice ironwork, but IMHO the best way to add rigidity to a 500 lb. lathe is to trade it in on a 2000 lb. lathe! You could put a thick steel slab under the lathe, but the cost might be high and it would make the thing even more top heavy. What you've got looks perfectly reasonable for a 500 lb. lathe.

It is not just the rigidity, it's also the damping. Strike steel with a hammer and it rings. Strike concrete and nothing.

Tom

industrially i have seen large frames made of square tubing that was later filled with concrete. you need square and rectangular tubing for rigidity you need the heavy mass to lower resonance vibration.
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machine frames are often a thick cast iron frame AND designed to be bolted to a thick concrete foundation. a modern cnc might have a 2 foot thick concrete foundation that has a lot of steel reinforcement rod in it. literally i have seen 2 foot thick concrete foundation removed and a new one poured as the CNC manufacturer will not warranty machine unless it is on a concrete foundation to their specs

IMO I've never been a fan of "adding rigidity" to a lathe. Sure you can increase the mass it's bolted too, but you are still limited to how thin the castings may be (ways, saddle, head stock, etc.). A lot of those lighter lathes used a 1/2HP motor originally because if you're bogging it down, you're teetering on overtaxing the machine as a whole.

That said, bolting the lathe to the floor is probably the most rigid you can make it within it's engineered specifications. If doing that with the standard issue stand doesn't help, you'll need a bigger machine.

Manufactures don't make machines bigger and heavier to squeeze more money out of consumers, the do it because the jobs run on the machines require it.

Boy, you are going to a lot of trouble for a machine you plan to sell soon. Anyway,

Yes, bolting it to the floor will add stiffness/rigidity. You have a nice triangular structure at the lower, horizontal level: I guess that was a consequence of the three point support. But it adds little to the stiffness. Diagonal braces, either rigid or even cables in tension would add more. But they would interfere with those drawers. You could add them on the left side and not block the drawers. And on the right end. Triangular corner braces also would help.

I would have reversed the three feet: two at the headstock end and one at the tailstock. Better distribution of the weight and the vibration from the motor would be better resisted by the heavier end of the bench. But then, my welded steel lathe bench has four legs. I bought it that way and leveling is no problem. After leveling, I bolt it down at all four.

PS: Bolting it down to a concrete floor has another advantage: it prevents the table from flexing when it moves around on the un-level floor. If it is not locked down in one place, it WILL move around. And no concrete floor, actually no floor PERIOD is flat. Less than an inch in movement in the placement of the legs WILL introduce a twist in the table and negate any work that went into leveling it. Your three leg design may tend to avoid this, but your one leg at the headstock end is not resting on a POINT. It 's foot is about a foot across so it is resting on a great multitude of points. This negates the advantages of the three point/three leg suspension. You would be better off with four legs that rest on something closer to actual points. Certainly nothing larger than 1/2" or 3/4" diameter circular pads.

Kipling79 said:

Thank you all for the comments.

Regarding bolting: I have prepared for the possibility of bolting the thing down, but was hoping to avoid the effort/modification since I want to sell soon. But, I will probably end up doing so, I definitely want to maximize what I have.

Regarding torsional twist: Before adding the lower cross-bracing, I was surprised how flexible the 7" c channel was. Afterwards the unit seemed very tight. I could still add some boxing or support... which your comment has me concerned about and will consider heavily.

Click to expand...

For torsional rigidity use a square tube for the top member. For damping fill it with sand. Your 3 point contact with the floor is great. You can move it anywhere on an uneven shop floor and not disturb the lathe alignment.

Kipling79 said:

I am currently building a stand for my 500lb lathe, and am wondering if there are any techniques for adding rigidity to the lathe, in addition to making a rigid stand.

Click to expand...

Bolt it to 5 tons of cast iron and steel.

Glug said:

Bolt it to 5 tons of cast iron and steel.

Click to expand...

Now that is a lathe.

Regards Tyrone.

digger doug said:

I'm not seeing any torsional resistance in that stand.

Click to expand...

I'm not seeing a lathe on the stand.

Regards Tyrone.

Tyrone Shoelaces said:

I'm not seeing a lathe on the stand.

Regards Tyrone.

Click to expand...

Yup, and no matter how you would put a lathe ON that stand,
there wouldn't be much rigidity.

Must be a crapsman lathe, or a wood lathe.

"...wondering if there are any techniques for adding rigidity...."

Yes, easy.

1) obtain large hoist.

2) hoist existing lathe 10 feet off the floor.

3) slide larger, heavier lathe underneath old lathe.

4) remove old lathe and dispose of same offsite.

Done!

Tyrone Shoelaces said:

Now that is a lathe.

Regards Tyrone.

Click to expand...

Actually, there are two lathes in that pic. The Pacemaker has an unusual appendage (name forbidden on this site) where one would expect a tool post.

Larry

While the other people posting about buying a larger, heavier lathe are absolutely correct....I'm going to try to answer your question in the confines of your system.

If you are going to use a home, hobby lathe with a 1/2hp or 1hp motor, then that stand is likely going to be enough. You don't mention the thickness of steel that you used for the top, but if it's 1/4", I think it will be good enough. Using square tubing for the top crossmember instead of c-channel is a huge step up for torsional stability. A 500lb lathe is pretty small when it comes to lathes. I think that lathe stand is way more rigid than the stand that would have originally come with the lathe from the factory (assuming you didn't use 1/16" wall tubing or something like that). EPAIII is right on the money about reversing the orientation to have the single point be over the tailstock instead of the headstock. That will help a lot with rigidity. You could consider filling the legs with concrete, but I wonder if that's overkill. If you have trouble with rigidity with that stand, then you need to get a bigger lathe.

My favorite way

If your gonna add weight, add something usefull, like a 20 hp motor.

More ridgid and more power too.....