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View Full Version : If a Lathe doesn't have to be level, why not a Mill?



CCWKen
08-29-2017, 08:03 AM
I'm still trying to get time to set up the new-to-me Bridgeport. In my last thread on the subject, someone mentioned to be sure to level it using a machinist level. Is that necessary and why? I have a Starrett level I check the lathe ways about twice a year. The lathe is level because it makes it easy to check for twist and settlement. (Foundations move a lot down here.) It's been said on this forum countless times that a lathe doesn't have to be level and could be mounted to a wall. Why then does a mill need to be level? :confused:

Baz
08-29-2017, 08:06 AM
It doesn't. Simply a convenience for some people who have a level for setting tings up parallel to the table.

Fasttrack
08-29-2017, 08:37 AM
A mill "needs" to be level in the same way a lathe "needs" to be level.

In the end, being level doesn't really matter but having the machine well supported does. I also submit that machines should be close to level since the various moving elements were designed to operate with the machine mostly level. If you tried running a mill or lathe at, say, a 45* angle, you would probably run into lubrication problems, alignment issues, etc. But a well supported machine that is slightly out of level won't hurt anything.

CCWKen
08-29-2017, 08:44 AM
Thanks guys. That was my thinking as well. I guess I just needed to hear it. :cool:

Forrest Addy
08-29-2017, 09:07 AM
"Level" in this sense has two meanings, one is to preciselyy aligh one or more referencefeaturs in a level plane (ie, tangent to the Earth's surface) and installed ina manner whereits axes of reference are on precise alignment with one another.

Too abstruse? "Level" meaning actually level and "level" meaning in accurate alignment. Ver often a lvel is a tool of convenience in ensuring there is no twist and that vetical axes are perpendicular to horizontal."

It's been pointed out that machine tools have to be level enough for liquids to return to their sumps thereafter its a term of convenience in establishing and perfecting reference feature alignments to a horizontal plane.

Engine lathes made in the usual patters where as bed is set atop pedestals are flexible.Flexible enough their own weight if poorly distributed will distort the bed beyond factory specifications. Enough to where the saddle binds on the bed sufficiently to make it hard to crank by hand. It's noy unusual for a millwright to pitch the tailstock end of the bed down up to 1/64th per foot to ensure coolant between the ways returns to the sump. So long as the bed is straight without twist, hollow, or hump, the saddle on the bed will function correctly and if the spindle is in alignment will not turn tapers.

Knee mills are squatty and stiff because of their compact design. Its a knee mill that will function correctly if hypothetically bolted to a wall A knee mill needs to be level enough to ensure liquids return, etc but high precision is not really required. It's a convenience only if a knee mlll is accurately leveled so a precision level can be used as a tool to set work parallel to the X-Y plane

Other types of mills, HBM's, planer mills, bed mills etc are flexible enough to deflect from their own weight and have to be "leveled" in the accurate alignment sense.

flylo
08-29-2017, 09:39 AM
Why wouldn't you want both as level as you can make them?

KiddZimaHater
08-29-2017, 10:37 AM
I just used a cheap Home Depot level to level my lathe and mills.
I haven't had any performance issues, or accuracy issues in over 15 years.
I think using a 'precision' level, like a Starrett machinist level is a bit of overkill, unless you have one handy.

Forrest Addy
08-29-2017, 10:49 AM
Why wouldn't you want both as level as you can make them?

No reason why not but time is involved and with some people time is money. My turret mill is dead nuts level but I've seen more than one knee mill set on the floor and connected to power.

BTW strategic alignment (a bit out of level for drainage etc) requires about the same investment in time as conventional leveling (alignment) job. The machine is accurately aligned but not quite level by a deliberate amount.

Parenthetically, a good millwright can get phenomenal alignments with basic equipment. I recall a planer I ran back in the day that machined way surfaces and machine tables flat within a couple tenths in 7 feet. That's by actual measurement on a certified granite flat where its calibration sheet was employed to compensate for planarity error.


I just used a cheap Home Depot level to level my lathe and mills.
I haven't had any performance issues, or accuracy issues in over 15 years.
I think using a 'precision' level, like a Starrett machinist level is a bit of overkill, unless you have one handy.

And that depends on the scale and construction of the machine tools in question and their sensitivity to misalignment. A monarch EE has a stiff cast base designed to sit on three pads. It's nearly immune to errors in level. A Monarch Model C is of traditional construction and requires adjustment of all 8 of its leveling screws to bring its axis system into alignment.

If you get by with a Home Depot level and your machine tools operate to your satisfaction, so much the better for you. Not everyone has your advantages nor their machine tools tolerate less than precision alignment. 10 arc second levels serve a real need.

Bob La Londe
08-29-2017, 10:54 AM
I have my big mill "pretty level." A few weeks ago I setup a job to widen an adjustable bolt slot in a flange by throwing a level on it and closing the vise on the body of the part. Done. Ready to cut. Not every job is like that, but by leveling your mill you can make the ones that are so much easier.

Mcgyver
08-29-2017, 10:58 AM
Why then does a mill need to be level? :confused:

coolant flow. Lots of other benefits have been noted, but for the compact size and the geometry of a knee me, that imo is the reason that matters.

I've mine on three points. I make blocks of scrap with a slight angle milled and adjust them until level.....sometimes will even tweak the level on a machine to get better coolant flow.

old mart
08-29-2017, 11:02 AM
More by luck than judgement, I found that the drill-mill X axis is only one division out of true when using the 6" Moore & Wright level. The Y axis is half that error.
Knowing that, I can get pretty good angles using a sine bar with the level.
The other advantage of a level machine is that things like drills do not roll away.

Rich Carlstedt
08-29-2017, 11:22 AM
Someone on this board should notify the US Navy that all their shop equipment aboard their ships cannot work properly until they build a ship that stays level :)

Seriously.. its just a convenient method for setting up work on the table or in the chuck, and to make sure that the column or base is supported evenly when installed ( no twist) . Some lathe manufacturers use "3 Point" mounting to prevent twist

Rich

J Tiers
08-29-2017, 11:51 AM
Someone on this board should notify the US Navy that all their shop equipment aboard their ships cannot work properly until they build a ship that stays level :)

Seriously.. its just a convenient method for setting up work on the table or in the chuck, and to make sure that the column or base is supported evenly when installed ( no twist) . Some lathe manufacturers use "3 Point" mounting to prevent twist

Rich

ACTUALLY, the whole "level" thing is a convenient way to set up the MACHINE. It may also be useful for setting up work.

For short machines, like small lathes, "level" is simply a way to allow using the direction of gravity as a reference for getting the bed out of twist. And for mills, it is almost irrelevant, since mills are usually stout and rigid compared to lathe beds.

Now, go try to set up (or scrape-in) a gantry mill that is 10m long. The most convenient way is to make it all level and then the direction of gravity is a universal reference. Much longer than that, and you may need to compensate for curvature if you need crazy accuracy. Yes, there are other ways, surveying tools, taut wires, maybe even lasers, etc. They nearly all work best if the thing is level to start with.

Same with longer lathes that may have several bed sections, and so forth.

now, everything IS "made of rubber".... rather heavy rubber... So, if you tip a mill or lathe, etc significantly, you do distort it from what it would be when "level". And you can be pretty sure the manufacturer checked it out when "level" (if it was checked at all...in china maybe just set on the table) because that is the most universal reference. So if you mount it some other direction, there will be some difference in alinement, maybe totally insignificant, maybe an issue.

If you want to mount the lathe on the wall, go for it. But I can think of a few problems you will have, not necessarily related to "level" as per the above.

QSIMDO
08-29-2017, 12:49 PM
Someone on this board should notify the US Navy that all their shop equipment aboard their ships cannot work properly until they build a ship that stays level :)

Seriously.. its just a convenient method for setting up work on the table or in the chuck, and to make sure that the column or base is supported evenly when installed ( no twist) . Some lathe manufacturers use "3 Point" mounting to prevent twist

Rich

Machines on my ship were never level as we were constantly shifting ballast tanks and for attitude & load.

bborr01
08-29-2017, 12:54 PM
Having a mill level also keeps things from rolling off the table and landing on your feet.

Brian

dave5605
08-29-2017, 01:24 PM
Damn, level them both up and get on with it.
On a lathe the objective is to get the twist out of the bed. There are probably lots of convoluted ways to do that and not have the lathe level. Probably the easiest way though is to just level the lathe to start with.

On the mill let's say you want to 'machine' on an object that requires outward support from the mill table, having the mill table 'level' would sure make setup a lot easier. That's assuming you have the mill spindle correctly trimmed in.

Hopefuldave
08-29-2017, 01:42 PM
One advantage: My lathe's a little short sometimes (me, I'm always short), I have the mill aligned parallel with the lathe ways so I can put a tailstock on the mill table to support over-length parts that won't go through the lathe spindle - having them both level makes it a lot simpler to set up.

Dave H. (the other one)

MattiJ
08-29-2017, 02:18 PM
One advantage: My lathe's a little short sometimes (me, I'm always short), I have the mill aligned parallel with the lathe ways so I can put a tailstock on the mill table to support over-length parts that won't go through the lathe spindle - having them both level makes it a lot simpler to set up.

Dave H. (the other one)

Now that is a trick I haven't heard before :D
Should make it easy also to turn tapers or even variable tapers..

pinstripe
08-29-2017, 02:48 PM
Now that is a trick I haven't heard before :D

It's called a gap bed :)

Hopefuldave
08-29-2017, 03:13 PM
Now that is a trick I haven't heard before :D
Should make it easy also to turn tapers or even variable tapers..

And with a cylinder on the lathe faceplate, a crank in the mill spindle pushing a lap back n forth, it lets you hone cylinders the easy way... (if you can get the speeds to match)

Dave H. (the other one)

754
08-29-2017, 03:23 PM
Forrest was the only one to mention it, but running coolant gets strange if you are not near level. One side may not drain, and it gets easier to lose coolant on the floor... equals more time spent cleaning up.
Just try to get it near level at least.

HWooldridge
08-29-2017, 04:39 PM
I'm surprised nobody has mentioned "twist". In the old days when relatively small swing/long narrow beds were the norm, you could easily twist a lathe along its axis if the feet under the headstock weren't on the same plane as the tailstock. This also applies to those lathes that have another set of feet under the middle of the bed. Now you have 6 points of contact that need to be equal - all sorts of havoc can happen if legs are bolted down hard to a foundation or jacked up on isolation mounts with no regard for applied stress.

Knee mills don't suffer from this same issue but long machines can be affected by improper pressure points.

andywander
08-29-2017, 04:52 PM
I'm surprised nobody has mentioned "twist".....

..and I'm surprised that you have obviously not read the complete thread...:)

Forrest Addy
08-29-2017, 05:15 PM
Let's just agree that "level" as used in our trade has two meanings:

1- parallel to a plane tangent to the surface of the earth centered on the object being leveled; that is leveled in a traditional sense, and

2- adjusted into factory alignment where deflections from gravity are neutralized and the Cartesian axes rendered mutually perpendicular and/or in plane to the best compromise for condition with the understanding there may be some departure of one or more axes from true actual level; that is in alignment with secondary regard to actual level.

Axis: definition - a system of guiding ways and way bearings restricting machine element motion to a single degree of freedom in translation and deviations from the axis path in either perpendicular or all three freedoms of rotation are constrained ideally to zero.

Does that cover it?

A.K. Boomer
08-29-2017, 05:29 PM
Coolant mentioned aside - why would you still not want to level your precision machinery?

you level your workbench ( I hope ) you level your floor when you pour it if it's not supposed to self drain, you level your toilet, why would you not level your machine?

are we hillbillies ?

even a crappy carpenters level will suffice and even one that's way off, just try it and then turn it around 180 degree's to see if it's a match - if not you know it's off and by how much, this will guide you to the proper adjustments...

no does not have to be perfect but Geeze don't just throw something on the floor and leave it there without checking... I guess if your a hillbilly then go ahead...

J Tiers
08-29-2017, 06:32 PM
....

are we hillbillies ?

.....I guess if your a hillbilly then go ahead...

Yep. In many cases, anyhow.

What's wrong with hillbillies?

Now, if you had said "Bubba's" that would be different....

CCWKen
08-29-2017, 06:46 PM
Default









Quote Originally Posted by HWooldridge View Post

I'm surprised nobody has mentioned "twist".....


..and I'm surprised that you have obviously not read the complete thread...:)

I believe that was covered in post #1. :confused:

dave5605
08-29-2017, 09:19 PM
Food for thought. Just imagine a person fairly new to machining, and they run across this thread, expecting some meaningful info on leveling lathes and mills. What do the see? Confusion at best, BS at worst.

I'm trying to gear up my 38 year old son to take over my lathe and mill, and other fabrication tools, welders, etc. All the tooling is worth more than the basic machines. He has almost no machining experience.Universally I have to tell him to take all these sites with a big grain of salt. This site is in the top 5 I gave him along with 3 or 4 YouTube channels. People like him will survive learning our trade but we could sure make it easier on them.

J Tiers
08-29-2017, 09:29 PM
This site is not too bad. Want way worse? Look through the minilathe forums.... there is some serious BS there. And some good info, of course.

Mcgyver
08-29-2017, 09:38 PM
Food for thought. Just imagine a person fairly new to machining, and they run across this thread, expecting some meaningful info on leveling lathes and mills. What do the see? Confusion at best, BS at worst.


thats why you buy books and subscribe to magazines. Forums and utube are unvetted, self publishing. Lousy place to learn, great places to solve specific problems and get ideas. Over time you get to know who is who and their competency level and you also have context - even if you don't know the speaker the truth often rings true with a bit of domain knowledge. But it takes time and context, the beginner newcomer doesn't have that.

Even if everyone contributing to a thread is competent, they are not all going to write 3 pages on every aspect and nuance of their statements with endless details, diagrams and photos or fully describe exactly what their particular paradigm is.....you could have 4 views that on the surface looked different but all were right - under certain conditions.

CCWKen
08-29-2017, 09:40 PM
Well, the topic got beat to death and as such, tends to raise the BS meter. I mean; what else can be said? My question was answered by the third post and acknowledged in the fourth. Everything after that was repetition and a few sparing challenges. I typically don't come back to these posts for that reason. You have a choice; read it or don't read it. :cool:

HWooldridge
08-29-2017, 10:27 PM
Default












I believe that was covered in post #1. :confused:

Win some...lose some - was too busy reading ahead - my bad.

ken
08-30-2017, 11:13 AM
I have a 10X20 Colchester Bantam lathe that was setting on 4X4 skids. This little lathe has a short wide stiff bed.
Sitting on the skids it turned a taper of .007 in 6" on a 2" piece of 12L14.
looking at the ways one would not think that it would cut that much taper the machine is in very nice shape .
I made a set of leveling feet for it and got it leveled up next cut .0015 in 6" with a little adjustment I got the taper to under .0005 in 6".
This tell one how important it is to be level. Ken

MattiJ
08-30-2017, 11:30 AM
I'm trying to gear up my 38 year old son to take over my lathe and mill, and other fabrication tools, welders, etc. All the tooling is worth more than the basic machines. He has almost no machining experience.Universally I have to tell him to take all these sites with a big grain of salt. This site is in the top 5 I gave him along with 3 or 4 YouTube channels. People like him will survive learning our trade but we could sure make it easier on them.
Nature of the beast.
38 year old boys usually already know how the internet forums work and that there is also pictures of naked girls to be found somewhere around internets ;)

One machining book is worth of 100's hours spent reading internet forums and one hour on forums is worth 100 books. Depending on case.

Fasttrack
08-30-2017, 11:43 AM
Nature of the beast.
38 year old boys usually already know how the internet forums work and that there is also pictures of naked girls to be found somewhere around internets ;)

One machining book is worth of 100's hours spent reading internet forums and one hour on forums is worth 100 books. Depending on case.

And one hour of *actually* machining is worth 200 hours spent reading, surfing the web, etc. :D

Forrest Addy
08-30-2017, 04:28 PM
And one hour of *actually* machining is worth 200 hours spent reading, surfing the web, etc. :D

Make that "...mentored actually machining". Hard to beat the local community college or trade school for the basic stuff.

This is off topic but it's been stimulated by recent posts:

I used to teach this stuff. A number we batted around was one hour of classroom teaching was equal to 20 hours of monkey see, monkey do. This was a figure not too far from the truth for the narrow specialties I looked at ball bearings, seating valves, assembling bolted pipe connections, aligning double suction pumps to their motors. Especially where a paper trail had to document each action.

The trouble with picking up information from the internet is the noob has no filters. A plausible BS artist may seem more credible than a real expert whose writing skills suck. Another point is seeking info from the internet is like drinking from a fire hose. There is way too much info related to but maybe not specific to the question. It makes it hard to discriminate while avoiding tempting distractions.

If I had my druthers for introducing a likely apprentice to any trade, I'd send him to a trade school with strong ties to local industry or an apprenticeship where an "area and elements" method was used to rotate the apprentice several times through the shop experience over his time (usually 4 years.) The home shop guy would be well advise to seek out night schools at the local community colleges and trade schools. There you'll be grouped with like-minded people and taught by someone experienced.

Don't forget the ancillary skills like welding and carpentry. It's almost impossible to function as a machinist without some welding skill. I've never had a lack of job opportunities in my career even in recessions and local economic "downturns." My skills as a machinist got my foot in the door but my multi-process welding and fabrication experience cinched the job. When the floor superintendent found I knew about stellite facing valve seats he had me on the floor in my interview clothes coaching the poor guy screwing up high pressure steam valve bodies.

So my advise is don't limit your work experience to how to run a lathe. Learn everything about it and from that build to the next step the milling machine and so-on. I started messing around my dad's lathe when I was in junior high school and started my apprenticeship when I was 19. I'm 76 now and I think I'm still learning but I may be re-learning stuff I forgot long ago. Pretty soon, I can hide my own Easter eggs.

BCRider
08-30-2017, 07:10 PM
I have a 10X20 Colchester Bantam lathe that was setting on 4X4 skids. This little lathe has a short wide stiff bed.
Sitting on the skids it turned a taper of .007 in 6" on a 2" piece of 12L14.
looking at the ways one would not think that it would cut that much taper the machine is in very nice shape .
I made a set of leveling feet for it and got it leveled up next cut .0015 in 6" with a little adjustment I got the taper to under .0005 in 6".
This tell one how important it is to be level. Ken

I'm reminded of a story I read about the 1895 Paris exposition. One of the displays on technology and engineering was a massive 3 foot tall I beam section about 6 feet long. In the middle of the upper cap was a super sensitive dial gauge. Apparently it was all the rage for petit corseted women of the day to press on the beam near the gauge and see the needle move some number of divisions. The novelty being that even a light woman could bend steel.

As a lesson to us it's a good one to point out that all metals are basically elastic bands. And how it is important to even up the pressure on all legs on any machine to avoid twist or sag regardless. Your story just reinforces the need for this sort of attention.

Going back to the original question I do use a basic level to level my machines if for no other reason that round things stay put instead of rolling off. I also see a machinist's level as a worthy tool. But since I don't have one I just got it as level as the basic construction level allowed then relied on test cuts on the lathe.

wierdscience
08-30-2017, 09:32 PM
I'm reminded of a story I read about the 1895 Paris exposition. One of the displays on technology and engineering was a massive 3 foot tall I beam section about 6 feet long. In the middle of the upper cap was a super sensitive dial gauge. Apparently it was all the rage for petit corseted women of the day to press on the beam near the gauge and see the needle move some number of divisions. The novelty being that even a light woman could bend steel.

As a lesson to us it's a good one to point out that all metals are basically elastic bands. And how it is important to even up the pressure on all legs on any machine to avoid twist or sag regardless. Your story just reinforces the need for this sort of attention.

Going back to the original question I do use a basic level to level my machines if for no other reason that round things stay put instead of rolling off. I also see a machinist's level as a worthy tool. But since I don't have one I just got it as level as the basic construction level allowed then relied on test cuts on the lathe.

That was an old question I heard asked once-Which puts more pressure per square inch on the ground?A Sherman Tank or a 120lb woman in Stiletto heels?

wierdscience
08-30-2017, 09:47 PM
Coolant mentioned aside - why would you still not want to level your precision machinery?

you level your workbench ( I hope ) you level your floor when you pour it if it's not supposed to self drain, you level your toilet, why would you not level your machine?

are we hillbillies ?

even a crappy carpenters level will suffice and even one that's way off, just try it and then turn it around 180 degree's to see if it's a match - if not you know it's off and by how much, this will guide you to the proper adjustments...

no does not have to be perfect but Geeze don't just throw something on the floor and leave it there without checking... I guess if your a hillbilly then go ahead...

I no longer even own a precision level,I have owned several over the years,but either sold them off or traded them for something I could use more often.They are handy tools for millwrights who routinely deal with out sized machinery often isolated from their mates by feet or yards,but for the HSMer or even commercial jobshop they aren't much use.Anything that needs to be THAT precise there are better tools available than a spirit level.

My current go to level is a $25 milled"billet" Aluminum level with two horizontal vials.I picked it out a contractor's supply I frequent,chose it for two reasons,quality construction and long vials with ten or more graduations meaning odds are it would be more sensitive than a cheapo torpedo level,which it is.It does everything the last Starrett 98-12 I had did,but if I drop it I'm not out $200.

J Tiers
08-30-2017, 09:52 PM
That was an old question I heard asked once-Which puts more pressure per square inch on the ground?A Sherman Tank or a 120lb woman in Stiletto heels?

Assuming 3/8" on the spike heel diameter, and a 2/3 :1/3 distribution between heel and toe, I get a tad over 720 PSI from her spike heel with all weight on one foot while she is taking a step.

I'd estimate a 30 ton tank as around 35-50 PSI ground pressure.

wierdscience
08-30-2017, 10:31 PM
Assuming 3/8" on the spike heel diameter, and a 2/3 :1/3 distribution between heel and toe, I get a tad over 720 PSI from her spike heel with all weight on one foot while she is taking a step.

I'd estimate a 30 ton tank as around 35-50 PSI ground pressure.

Yup,and her weight...um...distribution and direction of travel in relation to the Tank also affects the forward velocity and direction traveled by the Tank ;)

macona
08-30-2017, 10:36 PM
CNC mills have to be leveled, that gets them close to being square. And then you need to use an indicator and a granite square to tweak it the rest of the way square by adjusting the feet.

CalM
08-31-2017, 11:40 PM
CNC mills have to be leveled, that gets them close to being square. And then you need to use an indicator and a granite square to tweak it the rest of the way square by adjusting the feet.

Alignment via "indicator and granite square" could as well be achieve "out of plumb"

It's all in how you look at things".

I prefer the coolant to drain to the sump.

Regarding the "heels vs tank tread" ground load. It's the bicycle that gets one in trouble. Those high pressure tires develop small contact patches.

larry_g
09-01-2017, 12:21 AM
Assuming 3/8" on the spike heel diameter, and a 2/3 :1/3 distribution between heel and toe, I get a tad over 720 PSI from her spike heel with all weight on one foot while she is taking a step.

I'd estimate a 30 ton tank as around 35-50 PSI ground pressure.

I'm sure glad I don't have to rely on your estimates to know where my wife can walk and I can drive my crawler.

lg
no neat sig line

J Tiers
09-01-2017, 12:34 AM
I'm sure glad I don't have to rely on your estimates to know where my wife can walk and I can drive my crawler.

lg
no neat sig line

So... what numbers do YOU get? I gave the numbers for the spike heel.

The tank is almost surely high, since I estimated a rather small area of track in actual contact with the ground. The true number there is likely to be half to 2/3 of the estimate, possibly less, I had no estimates handy for contact area, and estimates a rather narrow track and something like 8 or 10 feet of ground contact per track.

30 tons is 60,000 lb. a squar foot is 144 inches^2, so all weight on one square foot would be 416 psi, and using 10 feet of track 18" wide per side, is 30 square feet, resulting in about 15 psi for the tank. I think I may have used 12" wide x 8 foot for the estimate.

The sherman was anything from 33 to 42 tons, and probably had 15ft of track in contact, possibly 15" to 18" wide.

If 15', and 15" wide, a 42 ton unit would have 15 PSI

oldtiffie
09-01-2017, 03:10 AM
Really, in many or most cases it is more important that the machine (mill, lathe etc.) table is "co-planar" and so that it is for the table to be horizontal.

"Horizontal" is just one of many "co-planar" planes for the bed to maintain the bed and job accuracy sufficient for most cases/jobs -even on many surface or tool and cutter grinders.

CCWKen
09-01-2017, 09:29 AM
Why would it matter? If the table is flat and you tram to the table, anything you put on the table will be "co-planar" as you put it. Horizontal and level mean nothing. :D

larry_g
09-01-2017, 03:48 PM
So... what numbers do YOU get? I gave the numbers for the spike heel.

The tank is almost surely high, since I estimated a rather small area of track in actual contact with the ground. The true number there is likely to be half to 2/3 of the estimate, possibly less, I had no estimates handy for contact area, and estimates a rather narrow track and something like 8 or 10 feet of ground contact per track.

30 tons is 60,000 lb. a squar foot is 144 inches^2, so all weight on one square foot would be 416 psi, and using 10 feet of track 18" wide per side, is 30 square feet, resulting in about 15 psi for the tank. I think I may have used 12" wide x 8 foot for the estimate.

The sherman was anything from 33 to 42 tons, and probably had 15ft of track in contact, possibly 15" to 18" wide.

If 15', and 15" wide, a 42 ton unit would have 15 PSI

Well son it's all well and good to charge in waving your slide rule but as an owner/operator of a tracked vehicle I know that the tracks are not flat exerting even pressure on the ground. I know that the grousers provide a point load. I know that the ground is not flat and can concentrate the load of the rig on a very small area. The rails are flexible and the lower rollers also provide point load. So you keep your head in the books and leave the real world to those of us who operate in it.

lg
no neat sig line

Forrest Addy
09-01-2017, 04:32 PM
Well son it's all well and good to charge in waving your slide rule but as an owner/operator of a tracked vehicle I know that the tracks are not flat exerting even pressure on the ground. I know that the grousers provide a point load. I know that the ground is not flat and can concentrate the load of the rig on a very small area. The rails are flexible and the lower rollers also provide point load. So you keep your head in the books and leave the real world to those of us who operate in it.

lg
no neat sig line

Condescending yet arrogant. The book guys made your tracked vehicle possible. Your tracked vehicel in the form of heavy equipment makes our roads and excavations possible. We all work together and are mutually dependent. Things go better when we work together cooperatively with with good will. Sneering and sniping, thinking in terms of "us" and"them", etc leads us into pointless, counterproductive conflict.

Arguing point loads comparing tracked vehicles Vs spike heels started as an illustration but devolved into ridiculous bickering. Enough. This thread has gone on too long.

Close the thread.

3 Phase Lightbulb
09-01-2017, 05:06 PM
Assuming 3/8" on the spike heel diameter, and a 2/3 :1/3 distribution between heel and toe, I get a tad over 720 PSI from her spike heel with all weight on one foot while she is taking a step.

I'd estimate a 30 ton tank as around 35-50 PSI ground pressure.

The woman's 3/8" heal is exerting ~80 lbs (assuming the heel is yielding 2/3 of her 120 weight). Since 3/8" square is 7.1111 times smaller than 1" square, you would need 7.1111 women all standing with their heel on the same 1" square footprint to yield ~568 PSI. Good luck getting 7.1111 women to do that :)

Mcgyver
09-01-2017, 05:10 PM
you would need 7.1111 women all standing with their heel

or a couple of "plus" sized ones. :D

3 Phase Lightbulb
09-01-2017, 05:23 PM
The woman's 3/8" heal is exerting ~80 lbs (assuming the heel is yielding 2/3 of her 120 weight). Since 3/8" square is 7.1111 times smaller than 1" square, you would need 7.1111 women all standing with their heel on the same 1" square footprint to yield ~568 PSI. Good luck getting 7.1111 women to do that :)

Correction, I just noticed you said 3/8" diameter.. That changes things a little bit...

The woman's 3/8" diam heal is exerting ~80 lbs (assuming the heel is yielding 2/3 of her 120 weight). Since the area of a 3/8" round heel is 9.090909090 times smaller than 1" square, you would need 9.090909 women all standing with their heel on the same 1" square footprint to yield ~727 PSI. Good luck getting 9.090909 women to do that, let alone anything else :)

MattiJ
09-01-2017, 05:55 PM
Correction, I just noticed you said 3/8" diameter.. That changes things a little bit...

The woman's 3/8" diam heal is exerting ~80 lbs (assuming the heel is yielding 2/3 of her 120 weight). Since the area of a 3/8" round heel is 9.090909090 times smaller than 1" square, you would need 9.090909 women all standing with their heel on the same 1" square footprint to yield ~727 PSI. Good luck getting 9.090909 women to do that, let alone anything else :)

I don't understand your stupid inches. How the f*** you are going to fit the 40 ton tank on a square inch?!? :confused::rolleyes:

J Tiers
09-01-2017, 06:15 PM
I don't understand your stupid inches. How the f*** you are going to fit the 40 ton tank on a square inch?!? :confused::rolleyes:

Same way you fit it in a square metre.

J Tiers
09-01-2017, 06:20 PM
Well son it's all well and good to charge in waving your slide rule but as an owner/operator of a tracked vehicle I know that the tracks are not flat exerting even pressure on the ground. I know that the grousers provide a point load. I know that the ground is not flat and can concentrate the load of the rig on a very small area. The rails are flexible and the lower rollers also provide point load. So you keep your head in the books and leave the real world to those of us who operate in it.

lg
no neat sig line

Condescending bull**** by a Bubba wannabe.

I guess you never have seen soft ground....

You are just arguing special cases for the pure pleasure of arguing. You have more pressure under a roller, and less between... more on the tops of grousers than if the grousers have sunk in..... lots of details. Not a single stinking one of those details are important to the point made, as you without any doubt KNOW....... unless you just want to make trouble, as in your case.

Next you will argue that there is tread on the spike heel, so the actual pressure is only on the points of the rubber of the tread..... sheesh

Go away, boy.

oldtiffie
09-02-2017, 03:27 AM
Originally Posted by CCWKen

Why then does a mill need to be level?





coolant flow. Lots of other benefits have been noted, but for the compact size and the geometry of a knee me, that imo is the reason that matters.

I've mine on three points. I make blocks of scrap with a slight angle milled and adjust them until level.....sometimes will even tweak the level on a machine to get better coolant flow.

The requirement for "drainage" is only that the return flow of the coolant is sufficient to drain or clear the drainage slots.

This can be achieved in the casting process or simply by increasing the grade of the drainage slots/grooves etc. by use of an angle grinder at any time that is convenient.

Simple as that to get the same end result and not a spirit level of any type or grade either necessary or in sight.

A normal hand or pneumatic chisel (in the hands of a good operator) will do just as well too.

pinstripe
09-02-2017, 03:37 AM
I don't understand your stupid inches. How the f*** you are going to fit the 40 ton tank on a square inch?!? :confused::rolleyes:

Try and keep up will you. The tank is wearing heels :)

OhioDesperado
09-02-2017, 06:04 AM
Wow, 6 pages over leveling machines.
As far as why would you want to as opposed to say, setting it on an old wood pallet and a couple bricks.

Lathe first.
A lathe can be out of square because it's not level.
Easiest way to tell is make a test bar. Take a cut at one end of a 15 inch heavy bar 1.5 inch min diameter, then make a cut at the other end without adjusting the cross slide. Measure the two cut areas and see if there is a difference, that difference is a taper.
Now, for you Navy guys, I am guessing that you were running 3 point mounts on ship board lathes. No they don't stay level with respect to the earth, but they did with respect to the deck of the ship to which they were bolted. And i am pretty certain they WERE bolted to the floor.

Of course there is the checking of material on either machine to verify it's position. If the table is level, then it can be assumed that what is on it and square is also level. If you lathe or mill is a half or so bubble off, then so is the material being cut. Does it make a difference, it can during setup. Being level provides you with the ability to quick check that. If the machine is not level, then the face of the material is also not level. So then you need to remember that it's such and such amount of bubble to the left or right. Front or back. Do you remember what that amount is? When it's level in means the bubble is in the middle. No remembering anything. It's right or its wrong.

Specific to a mill.
The first thing is drainage. Do you want water based coolant laying in the table of the mill?
Lubrication is a consideration. The top of the knee and table are square with the base. And as such don't cause the lube to run in any specific direction. Unless of course you are using axle grease to lube your ways, but at that point, all bets are off anyhow.

Lastly and most importantly. Why the hell not do it right? Do you aspire to machine to tight tolerances, or just cut it till it fits? I assume that you are at least attempting to hold some tolerance better than grind at it till it goes in the hole. If not, I can save you a ton of money,,,, just go buy a drill press and lay it on it's side for lathe type work. And the old crusty hole laden workbench top will hold material as you hog it off with an angle grinder. Sell the expensive machining gear... you really don't need it.

Lastly, and specific to another comment, as far as hanging a lathe or a mill on the wall. I wanna see that done with my 3600 pound Excello 604 or a Monarch 15X60 lathe. Yes, I know that there are those of you that are using little Sherline machines. I would hope that you realize that this don't apply to those little table top machines. So I suppose that if your tools are small enough that your lathe is small enough to be chucked in a 15 inch lathe, or your mill is small enough that you could mount two or more on a standard Bridgeport and still have plenty of work space between them then it may be counter productive to take a 12 inch machinists level and try to square them up.

Mcgyver
09-02-2017, 09:25 AM
The requirement for "drainage" is only that the return flow of the coolant is sufficient to drain or clear the drainage slots.

This can be achieved in the casting process or simply by increasing the grade of the drainage slots/grooves etc. by use of an angle grinder at any time that is convenient.

Simple as that to get the same end result and not a spirit level of any type or grade either necessary or in sight.

A normal hand or pneumatic chisel (in the hands of a good operator) will do just as well too.

So now you're taking an angle grinder or chisel to your mill? I wouldn't sweat leveling too much, in your case, just tilt the camera

oldtiffie
09-02-2017, 11:50 PM
I would not hesitate for a minute if I thought it feasible and practical and could get the end state requirement - i.e. getting the drains to "flow" as required.

I could see that I may need to have two, three or perhaps more drains if required if the end justified the means.
"Tilting" may be an option as well either as a "stand alone" solution or in conjunction with "drainage".

I don't get too "wound up" about "levelling" or "out of level" on a mill in particular - or perhaps other machines etc.as well.


So now you're taking an angle grinder or chisel to your mill? I wouldn't sweat leveling too much, in your case, just tilt the camera

I'd probably screw the camera instead.

GNM109
09-03-2017, 12:03 AM
My Mill when installed, was almost perfectly level. That is, the bubble in a level was in between the marks on the X and Y axes.

On my lathe, however, it leaned toward the rear more or less evenly across. I cured that with an 8' length of 4" X 4" angle placed across the table risers on either end.

I think you should try to get a mill or a lathe as close to level as possible when doing your installation and then try to forget about it.

:)

larry_g
09-03-2017, 12:23 AM
I think you should try to get a mill or a lathe as close to level as possible when doing your installation and then try to forget about it.

:)

One should not forget about it. Machines move, buildings settle, and wear happens. You should periodically check that things are where you expect them to be.

lg
no neat sig line

oldtiffie
09-03-2017, 02:43 AM
My Mill when installed, was almost perfectly level. That is, the bubble in a level was in between the marks on the X and Y axes.

On my lathe, however, it leaned toward the rear more or less evenly across. I cured that with an 8' length of 4" X 4" angle placed across the table risers on either end.

I think you should try to get a mill or a lathe as close to level as possible when doing your installation and then try to forget about it.

:)

Good practical advice - well done.

Good enough is not well enough but well enough is perfect - in/for practical situations mainly.

Leave well enough alone but occasional checking and "fine tuning" is good enough for many shops - mine very much included - which is kept at a situation that is quite adequate for what I want or need my machine/s for.

I really do keep to "Class of Fit", "Class of Finish" and "Tolerances" and "Limits of Fit". And I don't just pull any of them out of thin air as I use the "Tables" for them.

macona
09-03-2017, 06:24 AM
Correction, I just noticed you said 3/8" diameter.. That changes things a little bit...

The woman's 3/8" diam heal is exerting ~80 lbs (assuming the heel is yielding 2/3 of her 120 weight). Since the area of a 3/8" round heel is 9.090909090 times smaller than 1" square, you would need 9.090909 women all standing with their heel on the same 1" square footprint to yield ~727 PSI. Good luck getting 9.090909 women to do that, let alone anything else :)

80 pounds on 3/8" diameter works out to 725PSI. I think you are thinking of this wrong.

GNM109
09-03-2017, 07:47 AM
One should not forget about it. Machines move, buildings settle, and wear happens. You should periodically check that things are where you expect them to be.

lg
no neat sig line

Great suggestion. I check both the lathe and the mill every time I walk into the shop. The Mil is on the West wall of the barn and the lathe is still in the center of the floor. So far, both are where I expect them to be.

I would be very upset if sometime I go out to the shop to work and one or both of them were missing. :)