Shop Inheritance Machining Episode

[jgimp69]

I think it depends on the situation. For home use, a heavy Colchester or Stanko or Bridgeport would probably be fine on custom skates it you are still able to reasonably level it with no soft foot. A light duty craftex or bench top mill, not so much as I would imagine it would dance across the floor when trying heavy cuts.
Where I work, where tolerance and finish is absolute key and parts can get heavy, anchors and grout are a must.
Neither my home mill or lathe are currently anchored but I plan on anchoring both once I’m sure they are in their final resting places with no further furniture moving.
That said. The anchors I’ve chosen are flush mount anchors with leveling pads so that I can skate them later if need be.

 

[CWret]

or bench top mill, not so much as I would imagine it would dance across the floor when trying heavy cuts.

My RF45 clone bench top is 1000 lb. It sits on a 300 lb HD stand which has a built in tool cabinet and tools to add another 200 lb. So 1,500 lb total. Yes it did a dance, small but still a dance - steel legs on concrete, who’d a guessed. I put 3/16” thick fibre reinforced heavy rubber under each corner and then bolted it down with 1/4” Topcons. Certainly not moving (or dancing) now.

Note: there is no height adjustment in the legs. I custom cut each leg length to match the floor slope. This got it to within 1/16” of being level. Between the top of the stand and the mill at each corner is a 3x3x1/4” plate. One plate remains at 1/4” thick and the other plates were machined to the necessary thickness to both: level the mill; and ensure bolting the mill to the stand did not bend/stress the mill base. (thanks Susq for this tip).

 

[Dabbler]

The whole bolt-down, or on-wheels is a fairly complex decision, if you have a small shop and need flexibility. It also has issues concerning each machine, ans what you can get away with.

If you have all or the space you need, or more than you need, then bolting down may well be just fine. If your slab is nice and stable and thick enough this has clear advantages.

- what is actually needed?

Mills: they are a rigid structure by definition, and the unbalanced energy used to cut a part is a tiny percentage of the mass of the machine. Bolting down is not actually necessary. There is also no need to have the table level, etc. Several people have built bases that raise the mill off of the concrete, and allow a pallet jack to move the machine, and other have opted for full time wheels. There should be no difference in your work taking any approach, from bolting to wheels or in between.

Lathes: A fairly non trivial portion of the total weight rotates to cut the part, including the weight of heavy parts, so bolting is attractive. None of my lathes are bolted, but all are on feet sitting on the concrete. On the 750 lb lathe, with a 8.25" 4 jaw chuck, I have cut bores 4-ish inches off centre on a 5" work piece in aluminum that was almost 4" thick. so perhaps 750 grams of aluminum, at 250 RPM. The parts were accurate, there wasn't any shaking,or cutting problems. This lathe stand has a provision to attach wheels near the chuck side of the headstock so I can move the carriage to the headstock, the tailstock to the carriage, and wheel the lathe out of the way if needed. But for years it has occupied the same spot, and has been moved perhaps 4 times. My bigger lathes don't need bolting down, but some people do. Ensuring the lathe is true (some people say level) is far more work if you want to move it occasionally.

Surface Grinders: Mine isn't level, but I'd be cutting more accurately if it was. It cuts to around 4 tenths over the 12", and so accurate enough for me right now. There is no provision for bolting it down, and I don't have any mechanism to move it around easily (yet) but I am considering it. But with dust extraction and coolant pumps, it isn't practical to move it, really.

Everything else in the shop IMO is fair game for wheels.

 

[jgimp69]

The whole bolt-down, or on-wheels is a fairly complex decision, if you have a small shop and need flexibility. It also has issues concerning each machine, ans what you can get away with.

If you have all or the space you need, or more than you need, then bolting down may well be just fine. If your slab is nice and stable and thick enough this has clear advantages.

- what is actually needed?

Mills: they are a rigid structure by definition, and the unbalanced energy used to cut a part is a tiny percentage of the mass of the machine. Bolting down is not actually necessary. There is also no need to have the table level, etc. Several people have built bases that raise the mill off of the concrete, and allow a pallet jack to move the machine, and other have opted for full time wheels. There should be no difference in your work taking any approach, from bolting to wheels or in between.

Lathes: A fairly non trivial portion of the total weight rotates to cut the part, including the weight of heavy parts, so bolting is attractive. None of my lathes are bolted, but all are on feet sitting on the concrete. On the 750 lb lathe, with a 8.25" 4 jaw chuck, I have cut bores 4-ish inches off centre on a 5" work piece in aluminum that was almost 4" thick. so perhaps 750 grams of aluminum, at 250 RPM. The parts were accurate, there wasn't any shaking,or cutting problems. This lathe stand has a provision to attach wheels near the chuck side of the headstock so I can move the carriage to the headstock, the tailstock to the carriage, and wheel the lathe out of the way if needed. But for years it has occupied the same spot, and has been moved perhaps 4 times. My bigger lathes don't need bolting down, but some people do. Ensuring the lathe is true (some people say level) is far more work if you want to move it occasionally.

Surface Grinders: Mine isn't level, but I'd be cutting more accurately if it was. It cuts to around 4 tenths over the 12", and so accurate enough for me right now. There is no provision for bolting it down, and I don't have any mechanism to move it around easily (yet) but I am considering it. But with dust extraction and coolant pumps, it isn't practical to move it, really.

Everything else in the shop IMO is fair game for wheels.

I agree that bolting down vs portability is based upon the user, available space, quality of flooring etc. But I also think that the machine needs to be leveled to at least a reasonable degree with no soft foot present to give you the best results. My mill isn’t currently anchored, but is levelled with machined shims. I neglected at the time to check for soft foot. I was doing some heavy cuts and felt the machine shimmy a bit which traslated into the finish. Turns out, one of the thinner shims danced out slightly from the one corner because of soft foot. I reinstalled the shim with an added pc of thin shim stock and put a mag base on the base of my mill on all 4 corners with the indicator point on the floor to check for no soft foot.
I’ve also seen a lathe give questionable cuts and variances in tolerances if not leveled through its length. Of course the machines vary and it’s generally on very long lathes that these variances grow. It’s amazing how much flex you can get with cast over time.
I also like having a machine that is bang on within .001”/12” with my master level, knowing I can use a bevel square/bubble level for quick setups knowing it will be square/level.
I once saw a toolmaker flip a mill over when he cranked the table over too far with a small injection mold half on it. Mill wasn’t anchored and when it landed it ripped the dovetail right from the knee. Expensive uh oh that some $10 anchors would have prevented.

 

[CWret]

Well Dabbler and jgimp69 you have several tons more experience than I do.
The little dance that my mill did (mentioned in my above post) i don’t think had any effect at all on the quality of the part. Note - I’m very new to machining, don’t even have a lathe. But i have read and been told (also seen on the 100% accurate info source, YouTube) that it is very important that the mill is sitting on the stand with even weight distribution before being bolted to the stand. This is to avoid distortion to the mill base. So my thinking is that if the mill stand is moved (by dancing or on a mobile base) it stands to reason that the floor’s unevenness will translate into the stand legs and then to the attachment of the mill to the stand. I agree that a mill being level is not that important and i didn’t get too concerned about setting it up perfectly level - but I was extremely careful to get even weight distribution at each corner before gradually tightening the 4 bolts in sequence. I might add that my fabricated stand is far more rigid that the one that came with the mill. It weighs 3 times as much and includes lots of cross bracing both horizontally and vertically.
Also - since setting up my mill i have acquired a machinist level. On my to do list (job # Z59) is to use that beautiful tool to accurately level my mill.

 

[Tomc938]

The whole bolt-down, or on-wheels is a fairly complex decision, if you have a small shop and need flexibility. It also has issues concerning each machine, ans what you can get away with.

If you have all or the space you need, or more than you need, then bolting down may well be just fine. If your slab is nice and stable and thick enough this has clear advantages.

- what is actually needed?

Mills: they are a rigid structure by definition, and the unbalanced energy used to cut a part is a tiny percentage of the mass of the machine. Bolting down is not actually necessary. There is also no need to have the table level, etc. Several people have built bases that raise the mill off of the concrete, and allow a pallet jack to move the machine, and other have opted for full time wheels. There should be no difference in your work taking any approach, from bolting to wheels or in between.

Lathes: A fairly non trivial portion of the total weight rotates to cut the part, including the weight of heavy parts, so bolting is attractive. None of my lathes are bolted, but all are on feet sitting on the concrete. On the 750 lb lathe, with a 8.25" 4 jaw chuck, I have cut bores 4-ish inches off centre on a 5" work piece in aluminum that was almost 4" thick. so perhaps 750 grams of aluminum, at 250 RPM. The parts were accurate, there wasn't any shaking,or cutting problems. This lathe stand has a provision to attach wheels near the chuck side of the headstock so I can move the carriage to the headstock, the tailstock to the carriage, and wheel the lathe out of the way if needed. But for years it has occupied the same spot, and has been moved perhaps 4 times. My bigger lathes don't need bolting down, but some people do. Ensuring the lathe is true (some people say level) is far more work if you want to move it occasionally.

Surface Grinders: Mine isn't level, but I'd be cutting more accurately if it was. It cuts to around 4 tenths over the 12", and so accurate enough for me right now. There is no provision for bolting it down, and I don't have any mechanism to move it around easily (yet) but I am considering it. But with dust extraction and coolant pumps, it isn't practical to move it, really.

Everything else in the shop IMO is fair game for wheels.

I would wholeheartedly heartily agree on the mill point you make. The guy I'm buying it from, who is a retired tool and die maker said I have no worries about anything - most of my cuts the mill won't even know I am there. Getting 1 ton of cast iron vibrating enough to induce chatter with a 1/2" cutter and 0.20 depth of cut will be nigh impossible.

I am going to put the corner "feet" on some 2" x 10" just to help tithe lifting should I have to move it some day. And to help spread the weight out a bit more.

As far as the lathe, he did have it on an anti-vibration pad, but not bolted down. I think I will bolt it down primarily because a lathe is inherently top heavy and here on the Island there have been/could be times when the earth gives a little shake. Rather not have to lift it up off the floor.

 

[thestelster]

I think I will bolt it down

I'll tell you a little story.

Many years ago, when I acquired my Ex-Cell-O milling machine and Standard Modern 1654, I decided to put them both on rubber feet so I could adjust for level, especially for the lathe. Well several weeks go by with no issues; all was good. Then I needed to put my 14" 4-jaw on. When I turned it on, I didn't realize that I had left it in high gear, 1,000rpm, from the previous job with the 8" 3-jaw. Well doesn't it almost get to full speed when I notice one of the corners at the tail stock end start lifting off the floor and bouncing!! I quickly shut it down. Scared the bejesus out of me! The next day I bolted that sucker to the concrete floor.

 

[Canadium]

I have another cautionary story to tell. Sorry I can't remember the original source, it was somewhere on the net. A professional machinist was bitching profusely because his large expensive industrial lathe was ruined after he followed the common wisdom of bolting down his lathe to the floor. The concrete slab he bolted it to cracked under his lathe and irreparably twisted the bed.

 

[Susquatch]

I have another cautionary story to tell. Sorry I can't remember the original source, it was somewhere on the net. A professional machinist was bitching profusely because his large expensive industrial lathe was ruined after he followed the common wisdom of bolting down his lathe to the floor. The concrete slab he bolted it to cracked under his lathe and irreparably twisted the bed.

I call BS on that story you read. Any lathe I've ever seen had plenty of STRENGTH to resist that kind of damage.

I think it's just the world getting confused between strength and rigidity. They are not the same.

I'd add that one-off stories like that are a bit like seatbelts. The world has a few examples where people survived because they were NOT wearing their seatbelts. That doesn't mean the rest of us should take our belts off. The statistics are overwhelmingly in favour of wearing them. I'd rather play 99 in 100 odds than 1 in 100. Same goes for damage like that. I'll bolt mine down if it needs it. If not, it will at least have vibration isolating pads.

This rigidity vs strength thing comes up far too often. Maybe I'll try and do a writeup some time in a way that makes sense to everyone.

 

[CWret]

Cracking the concrete floor is very conceivable due to the stresses from the lathe and the thin non reinforced concrete it was sitting on. In manufacturing facilities, the concrete under large machine or equipment is specifically designed to be thicker and with much more steel reinforcements. I’d have expected that damage to lathe would be unlikely. Once the concrete failed, then all stresses would be relived and I’d expect that the lathe would not be subjected to additional external forces. BUT - on the other hand - the concrete could load up with stress like a spring and then suddenly and violently snap loose. Yep Canadium, sorry Susq, but i think it could happen. In underground mining - this is called a rock burst. The geotechnical forces build up and then suddenly let loose. Like an explosion - thus the name rock burst.

 

[mbond]

Think about this for a minute. A lathe can certainly be damaged by falling over. But no matter how bad the concrete is that it's bolted to, it won't fall over _more_ easily because it has been bolted down. And if the lathe does not fall over, then cracking concrete could throw it off level, or possibly introduce a twist. These impair accuracy, but unless the twist exceeds the elastic limit of the steel, don't ruin the machine and can be cured with some shims.

That means that we're looking at a situation where some bolts hold and others don't. And some event so violent that it bends the lathe bed without tipping over. No lathe this weak could be useful for cutting anything

 

[mbond]

Cracking the concrete floor is very conceivable due to the stresses from the lathe and the thin non reinforced concrete it was sitting on. In manufacturing facilities, the concrete under large machine or equipment is specifically designed to be thicker and with much more steel reinforcements. I’d have expected that damage to lathe would be unlikely. Once the concrete failed, then all stresses would be relived and I’d expect that the lathe would not be subjected to additional external forces. BUT - on the other hand - the concrete could load up with stress like a spring and then suddenly and violently snap loose. Yep Canadium, sorry Susq, but i think it could happen. In underground mining - this is called a rock burst. The geotechnical forces build up and then suddenly let loose. Like an explosion - thus the name rock burst.

Let's suppose that the concrete fails in this way. What could happen? Chips will be sent flying and the lathe will or will not fall over. If it does not fall over, then the chips are unlikely to cause much damage to it. In a mine, the chips can be lethal, but those rocks are under stress from tons and tons of overburden - much more than even the heaviest machine. If you are standing there and get hit, I'm sure it will hurt a lot, but the most damage you would expect are some dents in sheet steel

If it does fall over, then surely severe damage could result. But does adding the bolts make that more likely? For the bolts to make it worse, they would have to be pre-tensioned to at least 1/2 the weight of the machine so that the added stress concentrations can contribute to the 'blow out' cone - something impossible to do with ordinary hand tools. pre-tensioning bolts like this can help to reduce vibration and can _greatly_ reduce the deflections experienced under dynamic load (since the substrate has already been deformed to supply sufficient load), but this is hard enough to achieve that it seems very unlikely to have done it by accident.

 

[CWret]

Like i said above - IMO it is very unlikely that a cracked floor would damage a lathe. But under certain conditions - the sudden release of a built up of stress could be extremely violent. For many years i specialized in concrete demolition by blasting. I am a retired mining engineer. I was almost killed by a rock burst.

 

[Susquatch]

Yep Canadium, sorry Susq, but i think it could happen.

I still call BS on the guy who wrote the story. But I didn't say the floor couldn't crack or that it couldn't heave violently. But even so, the lathe should be able to handle it and the odds don't support worrying about it.

I've heard of rock doing that, but we are not talking rock here. I could see rock wrecking a lathe stand that way. But it would be an extremely rare event. I'm not sure it could wreck a lathe though. I would think the stand would break or bend first (sort of like a shear pin breaks to protect a more important machine) and the lathe would survive just fine albeit requiring some "adjustments".

Ya, if the concrete buckles up and the lathe falls over, it could happen.....

But my main point was that there was very low odds this could happen. I'll take those odds and anchor my lathe all day any day.

To do otherwise, I might as well not even have a lathe cuz an asteroid might hit it.

 

[CWret]

Yep - agreed that anchoring a lathe or a mill is a no-brainer. Why the heck would you not anchor it!!!
If you want to move it, remove the anchors- then move it and anchor it in the new location.
But i continue to disagree Susq - it is possible that a concrete floor could have a sudden stress release that would look like a bomb went off. It could be very damaging to anything to which it was attached. I call BS on your BS.

 

[140mower]

I still call BS on the guy who wrote the story. But I didn't say the floor couldn't crack or that it couldn't heave violently. But even so, the lathe should be able to handle it and the odds don't support worrying about it.

I've heard of rock doing that, but we are not talking rock here. I could see rock wrecking a lathe stand that way. But it would be an extremely rare event. I'm not sure it could wreck a lathe though. I would think the stand would break or bend first (sort of like a shear pin breaks to protect a more important machine) and the lathe would survive just fine albeit requiring some "adjustments".

Ya, if the concrete buckles up and the lathe falls over, it could happen.....

But my main point was that there was very low odds this could happen. I'll take those odds and anchor my lathe all day any day.

To do otherwise, I might as well not even have a lathe cuz an asteroid might hit it.

Just keep 'yer tinfoil hat on, and the lathe will be safe from the rock aliens. As to the rest of it, I just flip a coin, I am going to be wrong anyways......

 

[Susquatch]

I call BS on your BS.

Too funny! I'll see your BS and raise you 10 more!

I guess we just have to agree to disagree for a while then.

Someday when we are swapping stories over a bbq, you will have to run me through the details of how you think concrete could do that to the lathe itself though.

In the meantime, at least we both agree that it isn't a likely event.

 

[CWret]

I agree to disagree to disagree to agree to disagree etc
I raise you one tenth BS on your ten. Small but still on top

 

[Susquatch]

I agree to disagree to disagree to agree to disagree etc
I raise you one tenth BS on your ten. Small but still on top

I'm out of BS so I fold.

 

[CWret]

Best answer ever