Surface Plate Questions

[Andrew R Stewart]

When I got my plate I chose it with moving in mind. 2'x3' steel cast and ribbed under the surface. About 250lbs I guess. I'd not want to move more up or down stairs having watched stairs bend and creak... But a 3'x4' would be REAL NICE.

My milling machine is an Asian copy of a South Bend. Maybe 800lbs. One move was with a rental trailer. The farmer used his come along and tractor to place it on the bed. We used a Jonny bar, pipe rollers and a home made lever (from 2"x4" and lashing straps) to pull the mill off the trailer. Move #2 I paid a moving co. Three guys, their lift gate and my rollers did the trick. Andy.

[incepi]

I'm planning to build an inexpensive flat work surface. Something like a torsion box that is common in wood working shops. MDF or laminated particle board will form the surface. The obvious concern is with measuring overall flatness. That's where a precision straight edge will be required.

[Doug Fattic]

I think one option that might work well as an alignment table for hobby builders will be something made with an epoxy surface. One of my framebuilding class students with a background in engineering made one by creating a base with wood from Lowe's and then pouring the epoxy on top of the supported MDF board with metal sides. Epoxy based surfaces are used as building and checking platforms in the car industry. They are poured out as a liquid and solidify flat . I think he spent somewhere around $400 total. The epoxy itself was around $100. He checked its fatness overall to be 0.0015". I think the only thing missing for them to become more popular is for someone to write detailed plans for others to copy. While I have been intrigued with the concept for a long time, I haven't actually seen one personally myself.

Doug Fattic
Niles, Michigan

[incepi]

I think one option that might work well as an alignment table for hobby builders will be something made with an epoxy surface. One of my framebuilding class students with a background in engineering made one by creating a base with wood from Lowe's and then pouring the epoxy on top of the supported MDF board with metal sides. Epoxy based surfaces are used as building and checking platforms in the car industry. They are poured out as a liquid and solidify flat . I think he spent somewhere around $400 total. The epoxy itself was around $100. He checked its fatness overall to be 0.0015". I think the only thing missing for them to become more popular is for someone to write detailed plans for others to copy. While I have been intrigued with the concept for a long time, I haven't actually seen one personally myself.

Doug Fattic
Niles, Michigan

Wood surfaces are planed and sanded by hand. Traditionally, metal surface plates were(and still are) hand scraped. I believe that granite surfaces are also calibrated this way. If a precision straight edge can detect surface irregularities within 0.001' or less, then it should be possible to hand finish a wood surface to a precision that is adequate for frame building. I doubt that framebuilders need less than 0.001" surface flatness to tack a frame together.

[rauce]

But would that wood surface maintain that precision?

[incepi]

But would that wood surface maintain that precision?

Not likely, due to moisture and temperature effects. If the support is rigid enough, the surface could be checked and rescraped as required. A metal surface is preferred. It can also be .

[incepi]

Surface plates have to be flat to within less than 0.001". 0.0001" or better is common. Could a wooden surface be maintained at 0.005", and monitored to ensure it is within tolerance over time? I don't see why not. I will find out soon enough, once I get a precision straight edge.

[Andrew R Stewart]

There was a thread either here or in Bike forums about someone making a flat surface with a poured epoxy surface a few years ago. Had quite a few posts over time. Links to race car fabricator shops looking good enough to eat off the floors.

IIRC factors like stability, weight, thickness, base construction, hardness, curing were talked about. Andy.

[Mark Kelly]

But would that wood surface maintain that precision?

Not as is, wood equilibrates to the moisture level of the air around it and swells / shrinks in the process. It also swells at different rates in the three different axes.

To get decent dimensional stability with wood you need to completely seal all surfaces, preferably with something that penetrates into the wood. If you just use say epoxy as a surface seal, a scratch will allow localised water ingress which will result in the surface layer peeling: the wood around the scratch will expand, the epoxy won't and the two will part ways.

[jclay]

Enco - Guaranteed Lowest Prices on Machinery, Measuring Tools, Cutting Tools and Shop Supplies

48x36x6 for ~$350.

If you want to spend less then check out granite countertop cutoffs.

[Michael Gordon]

Enco - Guaranteed Lowest Prices on Machinery, Measuring Tools, Cutting Tools and Shop Supplies

48x36x6 for ~$350.

If you want to spend less then check out granite countertop cutoffs.

It is interesting that they list the 6" thick Grade A for less money than the 4" thick Grade B 36 x 48 plate. Either way, for me the price of $350-400 is right, but the weight of 1,140 lbs and the stairway into my basement is not.

It seems as though you can find 2'x3' granite plates all day at very reasonable prices, but this seems a little small to me. I may be overthinking it for a hobby, but at this point I am not calling it a habit.

I've been looking into getting a steel plate ground. The best price I have found for steel plate on line is through: ASTM A36 Hot Rolled Steel Plate | A36 Steel Plate | Buy Online | Cut to Size | No Minimum Order

Here, a 3/4" think 3' x 4' plate is $270 and weights 370 lbs. I can manage these, but then it has to get ground flat. Not sure what that will cost just yet.

My other problem is that they are in Minnesota, and I am in Chicago. The other online metal shops charge much more for steel. My dad has a friend who owns a machine shop with a Blanchard Grinder, so I'd imagine he can get me a much better price on the plate, more in line with Discount Steel | Buy Metal & Industrial Supplies Online | Buy Cut to Size Metals Online | Steel, Aluminum, Stainless, Galvanized, Copper, Brass | No Minimum Order | CNC Laser Cutting | CNC Machining

If I do go this route, does anyone have a recommendation the plate thickness? 3/4" vs. 1" ???

[Ken Holmes]

Here is my two cents...

I dont know what your situation so I'll just imagine it was me starting out in hobby building again and I'm telling my young self what my older wiser self knows.

So... Don't get it. Save your money, buy home shop size machine tools to make what you need.

Its definitely nice, something big like that would really help cut down on the confusion of figuring out whats going on with your frames while building. And a nice free tool is awesome, but don't fetishize the tool if you just want to build bikes (you'll might spend more time tool hunting than building and riding- though thats not all bad). Its absolutely not necessary, particularly if you are going to stay a hobby builder. My younger self would have not agreed with that, but my older self knows better. As you probably know the reason its free is probably because it is such a pain in the ass to move that they have to give it away to get rid of it. Pretty typical for the value of big machines to be reduced substantially because of this problem. I am personally looking at having to pack up my entire shop space in a month and I cringe at the idea of moving the big stuff (which isin't all that big). So buying tools I can fit in or tow behind my subaru is key.

FWIW I use an old NECA alignment table, which is essentially a ground plate with a whipping post @ 36"x8". Find a friendly machine shop to surface grind some steel channel for you and your in the same place. Mine is old, beaten up and not perfectly flat. It has slight a bow in it across its full length (which does not really matter, its really runout under your reference surfaces you care about). I use two or three surface gages at different points and flip the frame like a dishing tool which if I ensure that the gages are in relatively the same place on the plate everything comes out right. I use a small rule and even feeler gages (sometimes) to check the amount of deviation and adjust from there.

Start doing the basic math of what bottom bracket shell distortion of only .001" across a 1.5" diameter (used as a reference surface) might mean for a head tube and you can start to imagine the accuracy problems inherent in frame building (my technique with my setup has proven to be highly repeatable/precise, yours may vary). All this is really about is getting to a point where the frame is straight enough for you and your internal standards.

Remember too that your initial fixturing is only so accurate as well. There are people that build more than acceptable frames with 8020 and the acceptable runnout for 8020 from the factory is something like .005" or .015" per foot.

[rauce]

Thanks for the advice. I got some quotes for moving it and they were both more than I am willing to spend. Still waiting to hear back from the one place which I thought might be more reasonable.

Funnily enough the one mover told me he has a bunch of smaller plates lying around, so maybe that will turn into something.

[incepi]

Thanks for the advice. I got some quotes for moving it and they were both more than I am willing to spend. Still waiting to hear back from the one place which I thought might be more reasonable.

Funnily enough the one mover told me he has a bunch of smaller plates lying around, so maybe that will turn into something.

What are the quoting for delivery?

[rauce]

One place said probably $1200.

Other place said $100/hr, guessed at least six hours total.

Would be moving it from Toronto to Hamilton.

[Craig Ryan]

Ross, I gather you're not going to be making a lot of frames. If so, why bother with a piece of rock like this? If you do get it into your garage, someday when you sell your house it'll be sitting there when it's time to move. I'd get a thick 4'x8' sheet of MDF, cut it in thirds, and clamp and glue it together. It'll work fine and be flatter than most people will ever build to. Alternatively get a chunk of plate glass.
Craig

[incepi]

Ross, I gather you're not going to be making a lot of frames. If so, why bother with a piece of rock like this? If you do get it into your garage, someday when you sell your house it'll be sitting there when it's time to move. I'd get a thick 4'x8' sheet of MDF, cut it in thirds, and clamp and glue it together. It'll work fine and be flatter than most people will ever build to. Alternatively get a chunk of plate glass.
Craig

I would have disregarded this advice until recently, when I discovered that you can buy inexpensive precision straight edges. If I can create an MDF surface plate, and VERIFY it at reasonable cost, I will use that to build frames before considering other options.

Professional frame jigs(no names mentioned) guarantee positional accuracy within 0.003". They cost thousands of dollars. If you can produce a flat surface for less than $100, with flatness within 0.010", then you are off to a good start as a framebuilder.

[rauce]

I see myself building a few frames a year in the immediate future. I genuinely enjoy framebuilding and if I get to a point where I feel I'm willing to take people's money I may do so.

I think I'm being reasonable. I just picked up 30ft of practice tubing to today and I'd like to go through all of it before I start my next frame.

I currently use a 80/20 "beam" style fixture.

[Eric Siepmann]

No need to re-invent the wheel. Stronghand Tools has welding table sections that are already pre-drilled and meant for the professional welder. They weigh less than a huge slab and can be combined to make a table of any size. They even have fixtures for them. Blanchard grind it if you want the precision.

Huge pro is you can disassemble them and move them yourselves and add more sections as you need them. BuildProâ„¢ Framing Application

BLUCO Precision Modular Fixturing for Welding, Machining and Positioning is another example and they are in Chicago. Nice folks that will let you stroll the store as well. These are meant for the best Pro Welding shops and are priced as such.

[jclay]

No need to re-invent the wheel. Stronghand Tools has welding table sections that are already pre-drilled and meant for the professional welder. They weigh less than a huge slab and can be combined to make a table of any size. They even have fixtures for them. Blanchard grind it if you want the precision.

Huge pro is you can disassemble them and move them yourselves and add more sections as you need them. BuildProâ„¢ Framing Application

BLUCO Precision Modular Fixturing for Welding, Machining and Positioning is another example and they are in Chicago. Nice folks that will let you stroll the store as well. These are meant for the best Pro Welding shops and are priced as such.

There are many ways to skin this cat but I think you'll find that a surface plate, whether bicycle specific or general industrial, is the most convenient and cost effective approach and that CI, steel and granite are the most suitable materials for most circumstances. Certainly one could use other approaches with varying degrees of success and hassle; I tried a CI tablesaw extension wing for a time (lousy) and parallel beams (also lousy), but there is a reason that professional builders and many serious amateurs use a standard surface plate with the typical accoutrements.