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max depth t-slots in work table
- Thread starter drcoelho
- Start date
- Replies 8
- Views 1,392
EPAIII
Diamond
- Joined
- Nov 23, 2003
- Location
- Beaumont, TX, USA
You are asking an engineering question with very little data to go on. 60" x 36" (5' x 3') is a fairly substantial hunk of steel. All by itself it will need quite a bit of meat to prevent bowing. Things like these will influence the answer:
How will it be supported?
What static loads will you be putting on it?
What dynamic loads?
How much deflection will be allowable?
Will the Tee slots be parallel to the 60 inch side or the 36 inch one?
Will the Tee slots go from edge to edge or will they start somewhere inside of the edge? How far inside?
Probably many more questions. Some thoughts on those points:
It can be supported in a variety of ways. There would be a lot of difference between just having four corner legs and having a solid support under all of it. An edge frame on the four sides would add a lot to the strength. Adding a single cross piece in the center would be another step beyond that. Or X braces from corner to corner. A center post or posts in the middle of the sides would also help.
Loading will make a lot of difference. At some point even the full thickness of that steel plate will bend or break. A basket of feathers would be negliable: a 1000Hp engine would not. And what kind of loads will the work being done on it produce?
Deflection? Is this for welding, milling, drilling, assembly, or what? It WILL bend to some degree. But what is OK and what is not OK.
The orientation of the slots? Most Tee slot tables have the slots parallel to the long sides. But that is not always the case. The table will bend more in the other direction and you may have to give it more support that way.
Edge-to-edge or not? Slots that go all the way across the table will weaken it a lot more than ones that are done in the manner typical of most milling machine tables where a drainage gutter and a full height outer rim is left on the table. That full height outer rim will add a significant amount of stiffing.
The above answers and probably some more will form the basis for some calculations on just how much steel will need to be left at the bottom of the slots. Without that you are just guessing. An educated guess can be OK for many purposes, but the fact that you are asking the question says that you are not educated in this area. Frankly, neither am I.
How deep? 25%, 33%, 50%, 66%, 75%, or whatever. Without real facts and data and proper calculations, they are just guesses.
How will it be supported?
What static loads will you be putting on it?
What dynamic loads?
How much deflection will be allowable?
Will the Tee slots be parallel to the 60 inch side or the 36 inch one?
Will the Tee slots go from edge to edge or will they start somewhere inside of the edge? How far inside?
Probably many more questions. Some thoughts on those points:
It can be supported in a variety of ways. There would be a lot of difference between just having four corner legs and having a solid support under all of it. An edge frame on the four sides would add a lot to the strength. Adding a single cross piece in the center would be another step beyond that. Or X braces from corner to corner. A center post or posts in the middle of the sides would also help.
Loading will make a lot of difference. At some point even the full thickness of that steel plate will bend or break. A basket of feathers would be negliable: a 1000Hp engine would not. And what kind of loads will the work being done on it produce?
Deflection? Is this for welding, milling, drilling, assembly, or what? It WILL bend to some degree. But what is OK and what is not OK.
The orientation of the slots? Most Tee slot tables have the slots parallel to the long sides. But that is not always the case. The table will bend more in the other direction and you may have to give it more support that way.
Edge-to-edge or not? Slots that go all the way across the table will weaken it a lot more than ones that are done in the manner typical of most milling machine tables where a drainage gutter and a full height outer rim is left on the table. That full height outer rim will add a significant amount of stiffing.
The above answers and probably some more will form the basis for some calculations on just how much steel will need to be left at the bottom of the slots. Without that you are just guessing. An educated guess can be OK for many purposes, but the fact that you are asking the question says that you are not educated in this area. Frankly, neither am I.
How deep? 25%, 33%, 50%, 66%, 75%, or whatever. Without real facts and data and proper calculations, they are just guesses.
thermite
Diamond
- Joined
- Sep 21, 2011
It would 'make sense" you go and purchase a "bed plate", used, wherever. New, from India or such. Tee-slotted already. Generally double that paltry 1 1/8" as well.
Cutting Tee slots from scratch into steel-not-Iron will eat your lunch on time and cutter life. No savings. Not even as good a table, either.
Yes, I already came around to the idea of using a bed plate on top of my very nice steel table rather than mess the table up...the table, FYI, was milled to 0.001" accuracy..intended to mount some machine tools.
Thx much for the "as usual" excellent advice!!!
Thx much for the "as usual" excellent advice!!!
thermite
Diamond
- Joined
- Sep 21, 2011
That's actually an awfully thin plate for its length and width to have Tee slots, anyway.
Bugger would try to take on a new role as a steel potato chip if stressed, if not just from the machining! If it's good as it is as it is, I'd be grateful and use it as it is.
"Maybe" grid it with drilled and tapped holes.. and then..use it as the support for shiney-wood Tee-slot extrusions done-up for one purpose one time, some other layout next go?
Otherwise - those among us who've done-up "welding tables" have shown us a faster and cheaper way with near-zero machining. Spacing strips of ignorant rolled steel plate with a gap between them that becomes a Tee-slot or bespoke clamp anchor slot/edge.
"Both", with at least "some" tapped holes, is on my RTWL (Round Tuit Wish List AKA "Dance Card").
.. however..
As a matched pair - mayhap even a trio? - of small worktops 30" by 30", mebbe only 18" or 24"-by ...or perhaps as "Mandarin Duck" as the Chinese call a MIS-matched pair - so as to form a Tee.. Idea is to have iron wheels plus 3-point jackscrews so they can be spaced some arbitrary distance with a square tube, or a schedule 40 or 80 round tube, or a deep-section shiney-wood I-beam backbone between "islands", each on 3-point mounts.
They would, of course, need some leveling-fu to act as-if in plane for a particular project. Carpenter's laser prolly good enough.
I'd WISH to be able to make each of them also tiltable. For storage, if not also for USE.
Flat surfaces here otherwise seem to get infected with the notorious doppelganger fungus. Most of us have seen it.
The one that just GROWS layers of the most convoluted and interestingly intertwined junk out of thin air. The individual components having an uncanny resemblance to odd nuts, bolts, screws, washers, and "drops" mixed in with all the missing tools out of the storage drawers, of course.
A clean work area being the sign of a sick mind, there's is an upside.
By periodically "mining" that slag heap, one can save a ton of money off not having to buy new tools for all the missing ones.
Christmas in July sort of thing.
Why fight it?
Tony Quiring
Titanium
- Joined
- Nov 5, 2008
- Location
- Madera county california usa
Too thin for this as not enough meat under t slot.
It will roll up as the top stresses are released.
Drill and tap a grid or as needed over time far better options
Sent from my SAMSUNG-SM-G930A using Tapatalk
It will roll up as the top stresses are released.
Drill and tap a grid or as needed over time far better options
Sent from my SAMSUNG-SM-G930A using Tapatalk
EPAIII
Diamond
- Joined
- Nov 23, 2003
- Location
- Beaumont, TX, USA
If I wanted to clamp things on this table top I would do one of two things:
1. Drill and tap a pattern of holes for a clamp set. I have a "milling table" for my SB9 lathe where I did that. I used a 1" x 1" grid, using every other hole and alternating used and unused locations on every other line. That put the holes in a 45 degree diagonal grid with a 1.414" spacing. It works great with my 3/8" clamping set: I have been able to clamp a variety of items on it. For your table I would use a 1/2" or larger clamp size and a larger hole spacing - but not too much larger.
Before someone asks, the smaller holes in the center are to attach a mounting button on the bottom for the lathe's cross slide.
2. Purchase some flat ground stock and build up instead of milling down. One thickness and width for the level where the "heads" of the Tees will sit and a second thickness and a wider width for the upper layer. Use SHCS to hold them down. Drill holes every 4 or 5 inches in the strips and counterbore the upper layer for the heads of the cap screws to sit down below the surface. Tap the matching holes in the table. This also allows you to use a standard clamping set.
Both of these ideas will retain almost the full, original strength of the steel table top. And both of them will be easier than milling Tee slots in a 60" x 36" chunk of steel. Perhaps you have a mill that is big enough for that, but it will still be a real chore.
1. Drill and tap a pattern of holes for a clamp set. I have a "milling table" for my SB9 lathe where I did that. I used a 1" x 1" grid, using every other hole and alternating used and unused locations on every other line. That put the holes in a 45 degree diagonal grid with a 1.414" spacing. It works great with my 3/8" clamping set: I have been able to clamp a variety of items on it. For your table I would use a 1/2" or larger clamp size and a larger hole spacing - but not too much larger.
Before someone asks, the smaller holes in the center are to attach a mounting button on the bottom for the lathe's cross slide.
2. Purchase some flat ground stock and build up instead of milling down. One thickness and width for the level where the "heads" of the Tees will sit and a second thickness and a wider width for the upper layer. Use SHCS to hold them down. Drill holes every 4 or 5 inches in the strips and counterbore the upper layer for the heads of the cap screws to sit down below the surface. Tap the matching holes in the table. This also allows you to use a standard clamping set.
Both of these ideas will retain almost the full, original strength of the steel table top. And both of them will be easier than milling Tee slots in a 60" x 36" chunk of steel. Perhaps you have a mill that is big enough for that, but it will still be a real chore.
