# Cast Iron Surface Plate - Frame Building and Alignment Table Design Input Requested



## xdpackin (Feb 5, 2007)

Hey guys,

I've got another request for the builders here at this forum. If you could have the ideal cast iron surface plate and alignment table what features would you want?

I find myself in the unique position of having a friend/business associate who owns his own cast iron foundry outside of LA. He also has the largest installation of privately owned CNC equipment and capacity I have ever seen. I've been around the building stuff out of metal business and this is the only guy I've ever met who has a degree from USC and a horizontal milling center with a work envelope you could park a Smart car in. It literally has 12 pallet racks with big iron tombstones that are filled with parts and the ability to machine lights out. This thing is a 50 taper machine with a tool magazine that has room for 240 loaded tool cartridges ready to hit the deck. Here are some pictures. I've only got a shot of the total machine from the back side with a 40 taper mori machine just barely visible on the left. It shows the double stack of 6 pallet rows loaded with huge tombstones he makes on site. Below the machine pics are some parts I designed to run at his shop on this machine.


































Needless to say I've had a couple conversations with him about tracking down my ideal cast iron surface plate. Its harder than I though to locate one of these and most were used before WW2 when they were recycled into tanks and replaced with granite. Since then they are few and far between. We have one at the shop he gave us rather than melting it down to make new parts. Most new iron parts come from old iron parts in this business so he had purchased it at scrap rate. It is a 36" x 48" size with a hexagonal 8" thick honey comb bottom side and a rough milled surface that looks like it was resurfaced with a 6" four tooth face mill and a fast surface feed rate. Its not the original scraped iron surface but plenty good for the simple tooling we have mounted.

Since I picked up a used Dynasty 200 SD I've been using the time to practice my welding and I've got a couple months to kill before I've mastered using both hands and a foot to weld. I can put down a nice stack of dimes but I want to really mature with the tool before I'm using it to make important welds on thin wall chromo tube that I'll have straddling my crotch.

After a couple conversations he offered to make me a 36" x 48" flat 2" thick close grain cast iron plate with stress relieving heat treatment. Its much easier to run a flat plate rather than a honey comb or square pattern tool because we avoid all the work of making low production quantity hardwood tooling. Instead we just buy Styrofoam board and use it to make the sand tooling that the iron is poured into. Then it will go out to a cheap grind to 0.002" flat and parallel. After that step the plate will get squared up in the mill using a big 2" end mill so the sides are square and parallel to about the same. Then it will get a pattern of tooling holes on the sides and face. I'm thinking something like a square grid on 4" centers with 1/2-13 tapped holes and a shallow counter sink to remove any burrs at the hole location. Then I can build whatever tooling I want on the top side or use magnetic v-blocks to build the main triangle. Once the front triangle is done I can use the table to bring it upright and put on the two rear triangles with some tooling and a dummy axle.

Short of a real old school scraped iron surface plate with a 0.0005" flat and parallel surface and three point support to ensure an ideal resting position that is pretty good for me. Its way over kill for building a bike but I'm not a pro bike builder. I'm an eccentric amateur with tools and unpaid hours.

As a pro what else would you want to include in the design? Would you want one at cost if we do a short run of parts? A 36x48 is literally twice the poundage and surface area of a 24x36 so the cost will be linear between the two. 36x48 is going to be almost 1000 LBS. At more than a buck and less than two a pound you can get an idea for price. Its real money but pretty cheap for the size and scope of something like this. I've got a DRW diesel truck so I can deliver in the SoCal / NorCal areas with a bit of lead time. Other than that it can be shipped on a pallet with or without an optional steel base.

I'm more interested in making parts than making any money on something like this. However, its just insane to do a run of 1 part and not ask anybody if they want one or have any good ideas to contribute. I'm hoping I can crowd source some more info I didn't already consider and help anybody out there who feels like contributing to an open source idea like this. I'm going to make one for myself one way or another so lets hear what you think.


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## smdubovsky (Apr 27, 2007)

IMO, you need to web it. It just wont stay flat w/o it, the stiffness isn't there. If you spend some more time on the mold, you'll have a lighter, stiffer, cheaper plate. Doesn't need to be hexagonal, a square pattern will do. If not webbed, why not just surface a hunk of steel? Will be just as (non)flat in the end, cheaper, and off the shelf.

If you just want a cheap magnetic plate, how about bonding ~1/4" steel to a granite surf plate, then grinding it? Big granite surf plates are cheap at auction since no one wants to move them


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## xdpackin (Feb 5, 2007)

I agree with some of what you've said.

However, I disagree with respect to the rigidity of the plate. This is an easy computation with a bit of applied theory. The trick is choosing the best fit mathematical model for the required problem and level of needed accuracy. In this case we can treat the 36" x 48" x 2" flat iron plate as a Kirchhoff Thin Plate. The Kirchhoff model for plate mechanics is a differential equation which applies to plates with a thickness equal to 10% or less of their shortest side. In other words the thickness must be an order of magnitude smaller then the shortest side of the length and width.

In this case 2 divided by 36 = 0.0555 which is 5.5%

Kirchhoff's theory of thin plates is a differential equation first applied by Kirchhoff in the late 1800s. It allows for the solution of plate mechanics problems in terms of stress, deflection, and applied force. There are a subset of specific conditions for which this differential equation can be solved by hand techniques. Most of the time it is faster and easier to use numerical methods on a computer to solve the differential equations. Then Kirchhoff's model is solved by energy methods using the Finite Element Method. However, in the case of a plate like this we happen to get lucky and there is an easily implemented computational route available by hand.

Here is Kirchhoff's Equantion borrowed form the book "Thin Plates and Shells" by Eduard Ventsel and Theodor Krauthammer and available free of charge online at Google Books.










In order to make use of this by hand we will need to examine a specific case with some assumptions as follows:

1. The load is uniformly distributed across the entire surface area of the plate
2. The edges are free supports with fixed displacement, or simply supported.

These two assumptions are valid because the weight of the plate is uniformly distributed nice and even across the entire surface area. Also, the plate is most likely resting on a square shape frame where a section of square tube runs along the outside perimeter of length and width. The square shape tube will not stop the outside edge of the plate from curling up ever so slightly, but it will stop displacement in the vertical direction of gravity. This is called simply supported. It will not resist a moment on the edge. If it was welded all along the edge we would assume that the plate was bound with a clamped support all along the edge and it would resist a bending moment.

For this case we can attack the differential equation using a convergent infinite Fourier series. In this case we approximate the differential equation with a never ending summation of computational terms. We can choose to use 2 terms, 2000, or 2 million and get ever closer to the exact answer. Good for us the rate at which some of these series converge is very quick and you can get a good answer by hand using a small number of terms. Navier was the first mathematician to apply this method to the bending of simply supported plates.


















If you look at the bottom just above where you are reading and below where it shows "Fig. 3.5" you will get to the meat of the computations. The most accurate method is to use the calculation just below the text where is has "Fig. 3.5". This is an infinite series and you would normally use about two terms for both the sum m and n. That will get you pretty close by hand.

p0 = unit applied load
D = flexural rigidly of the plate as shown above towards the top
E = Modulus of Elasticity
a = length of plate side 1
b = length of plate side 2

and away you'll go with the plug and chug. Thats going to be a bit of work so lets skip to the next step and get a good gut feeling with less work. At the bottom it shows a solution for the max displacement (w) of a square shaped plate with Poisson's Ratio (v) of 0.3. Ductile iron has a Poisson's Ratio of 0.275 so lets run with the 0.3 for this first cut approximation.

Wmax = (0.0454) * { (p0 * a^4) / (E * h^3) }

In order to find p0 we need to determine the density of ductile iron. This is available over at the Ductile Iron Society website, a trade group which publishes a great wealth of data about iron and promotes its use.

https://www.ductile.org/didata/Section3/3part2.htm#Density

From here we find a value of 7.1 grams per cubic centimeter (gm/cm^3). We need a value in inches on this side of the pond so using the power of google we can just type in "7.1 grams per centimeter cubed to pounds per inch cubed" into the google search box and it will do the rest and convert the units. Then we find a value of 0.256 pounds per cubic inch (lbf/in^3).

In the case of the plate it is two inches thick so we will use

p0 = 2 * 0.256 = 0.512

Lets assume a square 48" x 48" plate so we know it will have more sag than the 36" x 48". In this case

a = 48

In order to find E we do another simple look up at the Ductile Iron Society for the Modulus of Elasticity.

https://www.ductile.org/didata/Section3/3part1.htm#Modulus%20of%20Elasticity

E varies from 23.5 to 24.5 x 10^6 psi in most cases. Lets stay conservative and choose the lowest reported value of 20.5 x 10^6 psi as shown in bending.

E = 20500000

Because our plate is 2" thick we know

h = 2

Then we can do the plug and chug part for this case

W-max = (0.0454) * { (0.512 * 48^4) / (20500000 * 2^3) } = 0.00075"

That is 7.5 ten thousands of an inch which is quite a bit smaller than the +/- 0.002 blanchard grind the plate will get on both sides. The plate could be surface ground or hand scraped to get it closer to flat but I doubt it will be necessary for a bike.This is also the maximum displacement and occurs at the geometric center of the plate. All other displacements will be less than this value.

Because we stayed conservative for the above computation 0.00075" is a worst case scenario. If we assume a 36"x36" plate

W-max = 0.000238" which is a full order of magnitude smaller than the tolerance of grinding.

In the case that the plate is 48" x 48" again but it turns out to be closer to the more normal range of stiffness for its modulus of elasticity then we pick a value of 24 x 10^6 psi and

W-max = 0.000642"

Back to 36"x36" and a stiffer modulus at 24 x 10^6

W-max = 0.0002"

These tolerances are not tight enough for a tool room inspection plate that is going to inspect parts bound for NASA but I sure hope they are good enough for a bike frame. If you really want to split hairs you can go over to www.efunda.com and find the calculator for Kirchhoff Plates and have it do the summation of the Fourier series for you to avoid the hand labor with a 36" x 48" plate via summation terms. Doing this or by hand shows a W-max of about 0.00035".

https://www.efunda.com/formulae/solid_mechanics/plates/calculators/SSSS_PUniform.cfm


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## unterhausen (Sep 28, 2008)

That was a nice obfuscation by C&P.

I have no experience with 2" thick plates, but I doubt you're going to have any problem with a properly stress relieved plate. If it's not stress relieved, the stiffness isn't going to help you.


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## xdpackin (Feb 5, 2007)

Exactly, without a stress relief heat treatment there is just too much internal stress from the rolling process and the flame cut to get a 36" x 48" shape from a larger steel plate. Plus a steel plate is going to be quite a bit more expensive in the end. Just the flame cut 36x48 is going to be $891 from EMJ before I grind it, finish the sides, and put some tooling holes on top. Then the flame cut edge will be a pain to run a end mill across with a healthy speed and feed because of all the nasty left over from the flame cutting. The foundry does stress relief heat treatment on the tombstones they make and it is a process they have on site.


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## Blaster1200 (Feb 20, 2004)

I'm not sure if I missed it, and I'm sorry if I did, but has any pricing been established?


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## smdubovsky (Apr 27, 2007)

Note: I *DONT* want to discourage you. If fact, I think it would be neat if you did it but as an engineer Im of the "If you're going to do it, do it right" mindset.



xdpackin said:


> In order to make use of this by hand we will need to examine a specific case with some assumptions as follows:
> 
> 1. The load is uniformly distributed across the entire surface area of the plate
> 2. The edges are free supports with fixed displacement, or simply supported.


Great idea, but I don't think either of your two initial assumptions are valid. 
1) While the plate mass itself is uniformly distributed, but the stuff you're putting on it is not. (If you grind it supported the same way as will be used later, the matls own weight doesn't come into the equation anyway.) If you want to drop a couple grand on a surface thats only good for 5# bicycle frames than thats your prerogative, but I like to make other stuff
2) That requires the supporting surface to be flat to be valid. In essence, being the ribbing that you won't cast into the top. You going to grind that square too? How about keeping it square when you mount it on the crooked concrete floor? The ubiquitous 3-pt mount for a surface plate solves that problem - the mount doesn't affect the plate.

A Busch Precision 3'x4' plate has a 1.5" top and is 8" deep (so the ribbing is 6.5" tall). 1250#. So for only ~25% more matl cost than you originally estimated (1000# vs 1250#) its probably at LEAST an order of magnitude stiffer. I suspect these easily run 5-figure $.
http://buschprecision.thomasnet.com...st-iron-surface-plates-1000-series/item-1018?

Then you're up against used pricing. Ebay is pricier than real auctions or even horse trading but here are a few I found:
30"x40" w/ T slots $500 OBO
http://cgi.ebay.com/40-x-30-Steel-C...102?pt=LH_DefaultDomain_0&hash=item1e5d6029b6

4'x6' $2000 (mikekandu asks crazy high prices)
http://cgi.ebay.com/Welding-Table-4...304?pt=LH_DefaultDomain_0&hash=item438f028ea0

3'x6' $1500 OBO
http://cgi.ebay.com/36-x-72-Cast-Ir...516?pt=LH_DefaultDomain_0&hash=item5ace730ab4

Edit:
FWIW, typ specs for load rating are 50 #/sqft w/ deflection <1/2 rated tolerance.
http://www.tru-stone.com/pages/forms_lit.asp
(See Federal Spec GGG-P-463c link)


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## Clockwork Bikes (Jun 17, 2006)

I got this guy for $50 and had it blanchard ground for $100. The bottom is webbed and it's about 500 lbs. Works great and is just big enough.

http://www.clockworkbikes.com/shop.html

-Joel


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## Rody (Sep 10, 2005)

Dude,

I admire your devotion and focus to the scientific aspect of frame building equipment, however, I'm gonna be blunt and honest.

There is an overwhelming number of builders who frequent the web who would have you believe that the alignment table is the most important tool in the bicycle fabricators shop. While it does provide excellent feedback on your construction process, it is no substitute for properly mitered joints, welding sequence, heat control/penetration, and exquisite technique learned from repetition and experience. 

Forget the fancy plate, it aint worth beans to the beginning fabricator. We're talking bikes here...anyone who says that their frames are toleranced to the nearest .005" (feel free to substitute any ridiculous number here) are more about creating an illusion of accurate fabrication than actual execution.

Spend your time and money more wisely...start working forward on a solid design, miter up several sets of tubing (sg 4130, butted 4130, high end alloyed steel, Ti) and then work with each, learning and adjusting to the variables each present. The experience will be more valuable than your project table, as then you'll actually understand how to use the feedback/measurements the table will later provide.

Nothing personal, just tired of lots of folks who dabble, continuously spouting half truths they've read floating around out there. If it's on the web, it must be true, no?

good luck,

rody


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## Linnaeus (May 17, 2009)

Looks nice, Joel. Has a great patina on the sides to boot.


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## Clockwork Bikes (Jun 17, 2006)

Before I got the alignment table I would indicate off my jig and make other various measurements and comparisons. The alignment table just speeds up the process. A perfectly dished set of wheels are crucial, too.


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## xdpackin (Feb 5, 2007)

50 bucks is a score for that plate. Its sweet! I check craiglist daily looking for cool stuff and not much of that pops up around here like that. There are plenty of good size granite plates in the $500-700 range that are about 30x60.

The whole making an iron plate tangent came up when I was talking to my buddy who offered to make one for free. I won't take one for free but you get the idea. I'm looking to make it a great general fabrication and work table for all of the projects I've got going. I figure it would also double as a great jig and alignment table for a bike frame. Then I thought if I was going to make one maybe somebody local would want one. I already made my primary hobby a full time profession so playing with bikes gives me freedom to do whatever I find inspiring. I have zero interest in making any money off of this hobby and its fun to follow whatever road I might find interesting.

Just for fun I did a quick analysis of the plates in question. Three different but similar cases. The computations were done using LISA which is powerful and has a very reasonable price at $50 Canadian. The free version works with up to 1300 nodes and was used for the computations below. I've never used LISA before but I'm impressed. It only took about 2 hours to do the following.

Simulation 1:

- Verify hand calculations for 36x48x2 plate with simple supports all around the outside border.
- Modeled with 2D quad4 plate elements
- Two axis of symmetry were used so only 1/4 plate was meshed and solved
- The weight of the plate was applied as a face load of 0.512 psi across the surface
- Results show a max displacement right in the center of about 0.00035










Simulation 2

- Expand out to a more complex simulation with a 1500 lbs point load off center towards the middle.
- Include the weight of the plate in addition to the point load of 1500 lbs. 
- Change the supports so the plate is only supported at the four corners.
- Results show a max deflection around 0.0075 which isn't too bad considering.
- This simulation is run with the plate full size and no symmetry.










Simulation 3

- Re-run the first simulation on the full size plate with no symmetry to verify convergence between the two meshes.


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## DWF (Jan 12, 2004)

I don't know whether to laugh or cry...


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## vulture (Jan 13, 2004)

DWF said:


> I don't know whether to laugh or cry...


laugh until you cry


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## Schmitty (Sep 7, 2008)

The war efforts, the man on the moon, etc... American Industry... those guys all had it wrong. Their tables didn't need webbing after all.


-Schmitty-


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## xdpackin (Feb 5, 2007)

I think its hilarious... after all that there is still somebody willing to say it needs webbing without providing any additional information other than "because I think so". 

I'm not attempting to invalidate the use of webbing but to put it into perspective. If you really need a plate that is flat to the 0.0005 range you're going to need to control many more variables besides adding webbing.

None of the parts I've engineered for the US and UK military were built using a table with webbing and they are currently in service at the obvious hot spots without issue


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## TimT (Jan 1, 2004)

It will need webbing if you want to add legs to it and if you start putting a load on top of it . Also helps if you want to move it around. (webbing makes a great hand hold) Also what happens to your very strait plate when you drill some holes in it and start torquing down BB posts? Drop a flat plate one time and its toast. With webbing you have a chance to keep it flat. All this is from my experience (22 years ) as a tool and die maker. Any one can design them and they look great on paper/computer screen but till you have to actually use it.........

Tim


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## HomeGrownSS (Jan 18, 2006)

xdpackin said:


> I think its hilarious... after all that there is still somebody willing to say it needs webbing without providing any additional information other than "because I think so".
> 
> I'm not attempting to invalidate the use of webbing but to put it into perspective. If you really need a plate that is flat to the 0.0005 range you're going to need to control many more variables besides adding webbing.
> 
> None of the parts I've engineered for the US and UK military were built using a table with webbing and they are currently in service at the obvious hot spots without issue


you obviously know exactly what you want to do and dont really give a flying hoot what anyone else has to say, so go jerk off on your theoretical surface plate somewhere else.


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## smdubovsky (Apr 27, 2007)

xdpackin said:


> I think its hilarious... after all that there is still somebody willing to say it needs webbing


FACT: You could use less matl for the same stiffness w/ webbing. Or have more stiffness for slightly more addl matl. If all you want is 1 thou accuracy, then weld up some 1/4" steel plate w/ deep ribs. Heck, weld some wide flange beams together. Cheaper, lighter, stiffer. You can hammer on it too w/o fear of cracking.



HomeGrownSS said:


> you obviously know exactly what you want to do


x2. 
If all you want to do is make yourself a thick plate, then do it. Just don't look to us for validation. It doesn't make sense. Its a far from optimal soln.


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## dr.welby (Jan 6, 2004)

<snark>When your only tool is a foundry, all your problems look like large slabs of metal. </snark>


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## RoyDean (Jul 2, 2007)

Dude... there are people building awesome bikes on this forum with nothing more than wooden blocks and E size drawings.

From one engineer to another, it's just a rectangle. Focus your brain power on the bike....


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## jay_ntwr (Feb 15, 2008)

RoyDean said:


> Dude... there are people building awesome bikes on this forum with nothing more than wooden blocks and E size drawings.
> 
> From one engineer to another, it's just a rectangle. Focus your brain power on the bike....


I'm one of those engineers. And it works just fine. This is the most valuable post on this thread me thinks.

XDP, you're clearly a very bright guy. I think if you actually built a bike frame before building a bunch of really fancy tooling, you'll find that what you thought before you built one and after you built one may be very different.


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## mhmacw (Mar 16, 2010)

If you want flat...get a Bluco modular table. Relatively cheap..light..and perfectly square 6 ways to way tighter specs than youll ever keep while tacking. Leave the flat table building to the guys that build flat tables. Kindly thank your friend for his offer and keep it in your pocket till you need unique tooling that he could blow out easily on that gorgeous mill hes got. Also...what part of a bike frame or load do you plan to present to this "flatness" in your fab process that makes you believe it will stress the table? Why use a table instead of a fixture? Lots of questions... I've spent a lifetime deciphering all the crap that comes down the pipe from engineers (no offense) that think you have to overthink how to unzip your fly. I'd be very surprised if you can keep the joints within .001" after the application of heat. so why bug about a table thats .0001?


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## xdpackin (Feb 5, 2007)

Its not my intention to turn this thread into some sort of a flame war because it really isn't necessary and I hope nobody is actually offended. I'm just trying to present the reasoning behind arriving at the choice to make a plate without ribs.

Somebody said it wasn't going to be flat enough and I respectfully disagree. I've still yet to see any analytical foundation for the importance of ribs in maintaining flatness offered by the proponents. I do agree with the post about the ribs being a design choice to improve weight/economy vs. stiffness which I'll elaborate on. Chipping or fracture isn't something I'm worried about. I regularly drive cast iron differentials and covers into rocks and they don't actually chip or fracture. They generally become abraded due to scraping into and over the rocks. I've seen axles come back looking like a smile after somebody abused it past the limit. One guy didn't even know he was heading over an 8ft drop off at the top of a rocky climb up hill. He hit the peak and went right over the ledge and landed on the front tires so hard it bent the axle housing. The iron center section stretched but didn't fracture. Thats a lot of impact energy considering the truck weighed in close to 6500 lbs. I'm not worried about moving it around by hand with the webbing. I'm not sure if anybody noticed where I noted that the plate will be 2 inches thick and weight in around 900 lbs. If I need to move it off the table I'm going to use a hoist.

In addition, building a bike isn't the ultimate goal and I'm in no hurry to get one finished. This whole project started in effort to resist the urge to put a Corvette LS3 into my Jeep. Since I helped a friend put an LS6 into his CJ-7 its been stuck in my head. After adding new axles, transfer case, body armor, and suspension she weighs in around 5000 lbs. The stock 4.0L isn't exactly blowing the doors off and it tends to lug down a bit out in the desert. In the rocks it really isn't an issue with the 115 to 1 final gear ratio of low range. At the moment there is a rig torn down to the bare frame in the R&D area getting new suspension with double bypass shocks and coilovers. Its going to be a while before I've got room to work on any major Jeep modifications.

Easter Jeep Safari 2010 in Moab Utah









Personally, I find building the tools like a miter jig, table, or bender for seat stays just as fun as building and riding the bike itself. The other half of my degree is in computer science so that part is on equal footing with the rest of it. CAD, CAM, and CAE tools are just plain cool. That and a sweet table will have quite a bit of use working on jeeps and guns.

With respect to the very accurate and intelligent observation above the primary value of the webbing on the bottom is to improve weight/economics while maintaining stiffness. In a large production run extra material means more cost and less profit. Webbing isn't a silver bullet to achieve a necessary flatness. With granite it is actually less economical to add webbing so the geometry of the web doesn't have any magical properties. In my situation adding webbing makes the part less economical as well. I'm not going to make a bunch of them so why develop tooling for the more complex webbed shape? That and once you start adding thin webs to the bottom of a thick section you'll often find it can take a try or two with the gates and risers to get the casting to run into all the little areas. A flat plate doesn't require any special tooling other than a hunk of styrofoam.

_*Here is a comparison of a webbed plate with one that doesn't have webbing. In both cases it is still up to the designer to determine the appropriate value for flatness depending on the design requirements. How flat is flat enough isn't solved by adding webbing.*_

Here is the webbed plate which will be compared to the flat plate. The webbed plate has a 1" thick top. The webbing is 1" wide all around and 2" tall.










Here the plate has been meshed using Tetrahedral elements with 10 nodes. The solution is run with the four corners fixed. With the plate supported at the outside four corners the rigidity will focus on the shape of the plate rather than the support. The load is the weight of the plate under 1G of gravity.










This plate weighs in at 645.9 lbs and has a maximum deflection of 0.0009699".

Here is the same solution for a plate 2" thick and solid without webs.










This plate weighs in at 886.5 lbs and has a maximum deflection of 0.001841".

Comparing the two it is clear to see that the webbing has better rigidity for the amount of material used. It is a more efficient shape for a production run. The same level of stiffness can be achieved with a flat plate but it will be heavier. There really isn't an advantage to a webbed plate for a production run of 1 or 2. By the time you amortize the cost of tooling across 2 parts you'll find the flat plate is more economical. Plus you'll have the benefit of a nice sturdy table for the thing to rest on with a beam that goes around the outside perimeter and perhaps one across the middle. I also like the idea of having two ground surfaces on top and bottom. After one side gets beat up you can flip it and use the bottom.

I'm a big fan of PVD's work and here is a link to the details for his table.
https://www.pvdwiki.com/index.php?title=Motorcycle_Frame_Jigs










Its clear to see the table is 30" wide by 72" long and about 3/4" thick. You can see where he has the post for the bottom bracket attachment and I doubt he has any trouble building a very high quality frame using this tool. The simple truth is that it will cost me about the same to build something like this as it would to make one out of a casting. I doubt he feels like the table isn't rigid enough.


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## smdubovsky (Apr 27, 2007)

A 3/4" steel top should weigh ~30#/sqft. * 12sqft = 360#. @ ~$0.50/# = $180. And 2 people can carry it. So why is a table like his going to cost you over a grand again?

No expensive pattern is required. Can do the same lost foam for the ribs too for low prod qty. I don't see how the runners affect a simple design like a plate. They're going to be in about the same places and the basic problem is still the same. Plus, if you have a rib that doesn't fill entirely, big deal - its on the bottom. If its filled upside down, it simplifies the design.


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## CdaleTony (Jun 21, 2005)

Click

Thats alot of granite for $1250!!!
hmmm maybe a pool table project....with a fork lift!


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## Bah (Mar 20, 2007)

The fact that your meshing a square domain with tetrahedrals to me says something. You also ran your sim with the for corners fixed? Not a good representation of reality. 

From someone that has spent the last year doing advanced non-linear FEA on complex plate structures, your waisting your time. You don't need FEA for this.

You did say I think that you wanted to use it for other things as well? So where's your live load?


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## xdpackin (Feb 5, 2007)

Tough crowd huh? This place is like county jail, I better get a tooth brush to sharpen up quick!

I was wondering if somebody would call me on the tet elements. I understand its much better practice to use bricks for this shape and with enough resolution in the thickness to get the best detail with bending. Its quick numbers with the automesh and you can see it is pretty close to the other 2D solutions and the plate formula. It gives a fair representation of the phenomenon and no I wouldn't go to space or build a Vegas hotel with that level of modeling detail. The goal was to illustrate the value of webbing. Everything is an approximation and FEA models can always get more accurate. I'm interested in what you've got to contribute if you want to post some stuff up. I bet you've got some unique insights that we could all learn from.

As for the plate steel idea there isn't $0.50 a pound steel in LA. EMJ in Lynwood wants $1.16 per pound and $75 for the flame cut charge. That works out to $498 dollars. Pricing was from about 2 weeks ago and IMS in Irvine wanted $1.20 a pound plus the cut charge. Yikes! Thats what I said when I saw that. Then I get hit with all the lot charges at stress relieving ($150), and machine setup to mill it square and add holes ($200+time), plus grinding will be a bit more expensive ($65 more). I can kill a few birds at the same time by doing it from scratch. One vendor for the whole solution at a good price. Its even less gas and miles used up on this oil change.

I think I might be misleading people when I say styrofoam. This will be run on a standard squeeze box style flask where the tool is pressed into the sand in 1/2 the box to make a negative. Then the two halfs of the boxes join up the negatives at the parting line. The tool needs draft to get out of the sand. I can hit the edge of a styrofoam rectangle and make a quick taper with a hot wire and mount it to a plywood board. Then use that as the tool to make the negative. The styrofoam will live for shapes where you've got lots of surface area for the height. Long skinny sections cause problems and its easier just to use wood. Then I've got a carpentry project with lots of sanding involved to draft it out for stiffness to weight ratio I don't desperately need.

I should have been more specific. My whole reason for posting up was more directed at what I should add to the machining of the plate. Like T-slots, holes, scribed grids like graph paper, etc. What would you want if you were building a sweet man table for bikes and etc? Don't get me wrong, I love a good ration of crap and its a time honored shop tradition. Other than complaining about the project maybe ya'll can prove you're not just what we call "web wheelers" on the 4x4 forums. Your the bike experts... maybe you can focus on that aspect and contribute something interesting.


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## dr.welby (Jan 6, 2004)

The first thing that came to mind was some sort of cast-in details for something like the Doug Fattic jig. I can't find where Doug hides the pictures of it in his Ukraine bicycle tour site.

I can't see much use for a grid as a layout tool. Holes or T-slots - also I don't see the use either, but then maybe I'm not being creative enough.


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## j-ro (Feb 21, 2009)

This whole thing reminds me of a story I read in the paper a while back.
Theres this guy, he's a lawyer for a day job and a woodwooker for a hobby, he designs a table saw that would stop automaticly if your finger went into the blade, leaving you with a minor scratch at best. He sunk millions into the project of his own and others money. Turns out it wasn't the biggest hit ever and only a few places actually bought it, nowhere near what he had talked everyone into believing and what he belived himself. So after several years of scraping by he decided to try another tactic, he set out to sue everyone he could think of for not buying his technology on the grounds that since the technology existed that the accident that had happend at the H.S., tech school, junior college, city works dept. etc. was avoidable and that they were all negligent in that they chose not to purchase it. What a fricken tool. Typical lawyer IMHO
anyway, the moral of the story is that those that believe don't need convincing and those that dont', no amount of convincing will do.
My advice to you is to just make some plates to sell, pick a number that will allow you to get a free plate for yourself when they are all sold, put a hole in them where the BB post goes,(you may have to poll again to get the location right) and post them up for sale. I bet they sell like hotcakes. 
Good luck.
J-RO out.


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## dbohemian (Mar 25, 2007)

dr.welby said:


> I can't see much use for a grid as a layout tool. Holes or T-slots - also I don't see the use either, but then maybe I'm not being creative enough.


Actually, I have been wanting something like this for a long time....Yes there is the bluco or other T-sloted tables but I have not had the opportunity to get one yet.

I end up building items other than bicycles and would love a table with various fixturing capabilities.

Also, I would add that I find many frame building types like to move around and therefore some sort of portability is important to them. Making the item weigh less while still doing its job is a positive attribute.


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## mhmacw (Mar 16, 2010)

Aside from the fact that you already have more time in this than its worth....it seems to me the answer to your actual question (Like T-slots, holes, scribed grids like graph paper, etc. What would you want if you were building a sweet man table for bikes and etc? )is rather easy. Scratch the idea of tslots unless you are sticking with the 2 inch plate.if your going with the webbing idea and a thinner top plate you wouldn't have the material thickness to broach the tslots anyway. Scribed grids are about useless whence you have your fixtures built as your obviously a bright enough guy to figure your specs off the attached fixture rather than adding an extra step in the measuring process by having to refer first to the scribes rather than the actual clamping fixture. So I guess this leaves the "holes" option. For this I refer you, again, to the Bluco (http://www.bluco.com/our_system/Advantages/tolerances.html) table and fixture accessories. Use the KISS method man. You'd already be leveling the table and thinking of your fist frame instead of running in circles around tolerances that are way overkill even in the world of automotive machining. I wonder just how in the world we ever got by building simple machines without the added complication of computer aided drafting?

p.s. Bluco are on wheels if desired.


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## dbohemian (Mar 25, 2007)

mhmacw said:


> For this I refer you, again, to the Bluco (http://www.bluco.com/our_system/Advantages/tolerances.html) table and fixture accessories.
> 
> p.s. Bluco are on wheels if desired.


The Bluco stuff is sweet. I didn't ask for a quote but I read that a 3*5 table is around 10k? Do you know how much some of this stuff runs?


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## mhmacw (Mar 16, 2010)

Why yes I do. Having operated on a Bluco for a few years ....but I guess I am mistaken then. I was under the impression we were after precision not cost effectiveness. With all the fancy software pictures and all duhhuh! lol. In all truthfullness, gong to this extent in the research only to balk when it comes to price is sort of like fantasizing instead of actually searching for answers. Cheap, Versatile, Flat/Square...pick two!


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## mhmacw (Mar 16, 2010)

On a different note... have you considered the adjustable precision fixtures on a rough ground(.003)table? I ask this because it seems the op is after a level of precision for 1500 bucks that is clearly well into the tens of thousands. What makes the op think this is even remotely possible?


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## smdubovsky (Apr 27, 2007)

mhmacw said:


> the op is after a level of precision for 1500 bucks that is clearly well into the tens of thousands. What makes the op think this is even remotely possible?


Because it is. IME, his $ figures for iron aren't far off. You do know that a $15000 Busch plate prob only costs a couple grand to make, even in the US. The rest is called profit.


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## Andy FitzGibbon (Jul 7, 2007)

You might be able to buy this one and get it shipped out to you for less than you'll spend on your custom one:

http://www.hgrindustrialsurplus.com...SC=&pageSize=50&currentPageIndex=0&searchNAP=

If you do call them, make an offer on it. They are always willing to deal on price (I have bought a lot of stuff from them).

Andy


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## mhmacw (Mar 16, 2010)

Now I've spent more time on this than its worth....enjoy gents!


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## antbikemike (Sep 30, 2010)

*"Wow"*

I was surfing around looking for a new cast iron surface plate and came upon this thread. I had to sign up to MBTR to make a comment. Great stuff here, wow you guys really go at it!

I use a cast iron webbed plate, old printing press table. It is kind of rough and to small for what I want [28" x 42"].

I could have it re-ground flat, but I would rather find a bigger table.

While it is best to make sure you have a good tube cutting system, frame fixture and welding aligment methods...you really need a good flat surface table to check and correct your work. Other wise how do you know your making good work?

Tonight I did find some good links to new tables, but I am sure they are out of my price range. I have been on Craigslist and Ebay way to much looking for the perfect table and just about gave up and was going have a steel machine base made for me to use a surface plate, but I think I will keep looking for a cast iron table and have it resurfaced.

The ground steel base at 1 1/4 or 1 1/5" thick may be just fine, but I would just feel better with a webbed cast iron plate with a good leveled base.


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## Linnaeus (May 17, 2009)

Hey Mike,

I know you're in the NE (NH?). I see old cast iron machines and bases on CL rather frequently for short money. You could easily have one reground.


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## antbikemike (Sep 30, 2010)

Thanks.

I am in MA and I have been looking on Craigslist everyday and Ebay for a few years. I look in every NE state daily. Some tables have come close, but non have been the size I want [to big or to small] and or are to beat with many holes drilled in it. Tables may be out there, but they are not listed.

I just got a quote from Busch for a new 36" x 48" cast 1,500lb table...cost $11,000!

There is one on Ebay in NY that looks like a in good shape cast iron table 36" x 60" for $900. I am going to have a friend in NY take a look at it for me. Shipping will be about $300.00 Grinding if needed will cost about another $200?


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## Linnaeus (May 17, 2009)

I know a guy out past NoHo who has a large work bench made of a cast iron machine base. He was clearing out his shop -- I might still have his contact info if you want it. If memory serves it was about 6'x3' and would certainly need to be reground.


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## cement shoes (Aug 10, 2010)

Andy FitzGibbon said:


> You might be able to buy this one and get it shipped out to you for less than you'll spend on your custom one:
> 
> http://www.hgrindustrialsurplus.com...SC=&pageSize=50&currentPageIndex=0&searchNAP=
> 
> ...


What kind of wiggling will these guys do? I've been checking a couple of items on their site lately. My own table is also cast iron, webbed. 30x36. It works fine but I've always wanted something a little bigger.


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## Andy FitzGibbon (Jul 7, 2007)

cement shoes said:


> What kind of wiggling will these guys do? I've been checking a couple of items on their site lately. My own table is also cast iron, webbed. 30x36. It works fine but I've always wanted something a little bigger.


Depends what you're buying and how long it's been there. They like to move inventory through fast. If it sits for a month or so with no interest, the price starts dropping quickly and you can get them to knock off some pretty substantial amounts.
Be forewarned that everything is totally as-is. They have a 30 day return guarantee, but there's a lot of broken/screwed up stuff there, so you really need to inspect in person on more complicated stuff. Something like a surface plate is most likely going to be fine, though probably not up to making rocket parts.
Andy


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