BigPoser

If I were to get a 3/4" steel plate in either 24"x36" or 36"x48", does it need to be Blanchard ground to be used as a surface plate?

The yard rep had mentioned that their plates are .030 across that span. Since I know nothing about this, I'm looking for the experts advice.

Update: There is a shop in town that can Blanchard grind it for about $500. However he can only go up to 36". He told me it would be about .003.
Will a 24x36 surface plate be large enough for a BB post and head tube centers?

Thanks a lot.

Brandon

Andrew R Stewart 

With no certified spec don't trust any claimed dimensional tolerance until you do the checking. But can a basic plate serve as an alignment reference, yes.., Of course the details are the devil. The base level of this question is what's a flat surface spec? I can't answer this directly. I can say that those who survive in this business have learned to deal with what they can afford and what the market expects.

Any steel plate will droop from it's weight. So how it's supported, at different points along it's surface, will determine how flat it is in situ. A "proper" cast surface plate has webbing to add a 3rd dimension to buttress the surface and better controlling gravity's tug. Enough so that a three point base is the usual to insure that no twist is induced.

I would consider the plate's base/framework/stand as important as the claimed flatness. I would also research how to test for flatness to better understand the issues at play.

2'x3' is generally considered the smallest surface that will capture the main triangle and still have some relevance to the rear end. It's what I use. Were I to be doing this again I would consider a 3x4 but likely chose the 2x3 due to weight Andy (who just moves a SB9"lathe and has a weight memory in his back now)

Nessism

Yes on the Blanchard grinding. I use a thick slab of flattened steel as my level reference and it works fine. Mine is not as large as being discussed here and I have to use a long pointer on my height gauge in combination with rotating the frame at various points during the build. I'm not advocating this method just mentioning to provide a data point for those working on a budget.

BigPoser

Thank you gentlemen! I'll have to have it blanchard ground then it seems. I have a friend that is a wizard at fab work and has agreed to build a table for the plate and we'll make sure it's supported adequately. I'd prefer a 36x48 but I'd have to drive 2 hours each way to have it ground, not to mention the additional cost.

Andy - Are you able to also check the stays while on the plate? I suppose you would if using the BB post.

I've been looking at granite as well, but I wouldn't feel comfortable driling 3 holes in either a 4" or 6" slab. Annnnd I'd need a forklift to move the damn thing.

calstar 

$500 seems pretty spendy, a couple of yrs ago I was quoted $150 for a .003 certified grind(same size +-) on a table saw top(very old quality cast Oliver) by a large and reputable business in SoCal, might want to check around a bit. I never went through with it so I don't know if that was an accurate quote or much else other than my phone call with them.

Andrew R Stewart 

On my 2'x3' plate even with the HT being held alignment method and that HT holder all the way on the plate's surface the rear drop outs hang off the surface. I have a dropout/tube center gage held on a height gage that barely reaches the drop outs if the wheelbase is touring long. In my dream shop I'd have a 4'x6' plate. But I'd have to get more then a six pack and a couple of friends to move it Andy

Doug Fattic 

Brandon, since an alignment table is the foundation tool in my shop, I like it to be as flat as possible within reason. In our frame shop in Ukraine we had a table made out of a slab of steel that was also ground in some manner. I’m not sure of that manner. Anyway it is kinda flat but is still out a couple of mms in the areas distant from the post. I’ve learned how to deal with that (our transportation frames aren’t expected to be made to expensive custom frame specs) but I would love to have the accuracy of my States based cast tables over there. To put it another way the alignment table is my primary building tool and I want it to be as accurate as possible and I would be willing to pay extra to make it that way.

It is possible to use a smaller surface plate around 2’ X 3’ if the post is located in the SE corner.My preference is for a larger table so I can also get the rear triangle on the surface at the same time as the front.My cast iron table is 3’ X 4’.However, I had my cast aluminum table from Wolverine Bronze made 32” high since those 4 extra inches aren’t that important (it is 32” X 48”).Keep in mind that the “picture frame” of the fixture I have laser cut and etched in Ukraine is 45” by 27” and it needs to lay on table when I’m using it so of course I’m biased to have a table as least that large.I think the answer to this question depends on several factors including how many frames you make in the future and the money you have in your bank account and how spacious is your shop.What I know is that you will not regret getting a larger table if you have money and space for it but you might be remorseful for getting the smaller one when working on a rear triangle.

BigPoser

Thanks Doug. Right now space isn't the issue as I have a decent sized shop to put it in. I have a 3x4' welding table that I would just have to move around a bit to place the surface plate where I want it. I plan on making frames as long as I can. I don't really have any overhead so that won't impede my progress. I believe I've found my calling and I'll continue to build and learn until I can't any longer. The money is small issue, as it always is when getting going purchasing equipment, but at the same time, I like things to be right.....the first time. I have a few calls into a steel supplier for both sized steel plates in 3/4" and 1". It is very close to a Blanchard grinding facility in the LA area so I could have it drop shipped there so I'd only have to make one trip. To have a 2'x3' plate ground it would be $200 and $400 for the 3'x4'. They would also drill my holes for me. So for about $1200 (if I go with the larger size) I'd have a pretty nice surface plate.

Regarding the actually grinding process, just how flat is acceptable for a surface plate? .005? .0005? .0002? This is still something that I'm learning.

Thanks again.

Brandon

bark_eater 

I did a little research on having a scrapyard plate Blanchard ground. From talking to the grinding shop, both sides of the plate need to be ground to equalize stresses. they did think that I could get away with using a large c channel and only grinding the face. The yard near me has some 12" wide channel that are my back up plan if I cant find a milling machine table.

Andrew R Stewart 

Bringheli's alignment and fork jug use a C channel that's been "ground" (faced?) Bicycle frame alignment is way loose in acceptable tolerances, way sloppy. When holding a mm or two is fine the "grade" of the surface doesn't need to be lab level. But whatever "flatness" you end up with you have to learn it as the surface is just another tool. Some of what you can do with one is pretty cool, some is just needless time sink Andy

smontanaro 

And then we have this from Dave Moulton:

unterhausen

that sounds like a pretty loose definition of checking alignment. More like checking dimensions

vintage cellar

I wouldn't expect much from getting a random piece of steel blanchard ground without knowing what you're getting into.
3/4" thick ain't even worth the effort - it's too thin and flexy. Utter waste of time and money IMHO. Tough love, I know.
What Andy Stewart noted is also important WRT how you hold the thing. Plates without support ribbing underneath are
more at risk of "droop" or twist.

Cold - rolled ? It won't be dimensionally stable (i.e. FLAT) after grinding unless it is stress-relieved in a big oven before you grind it.
Hot-Rolled is supposed to be somewhat better, but I was advised that it too would benefit from stress relieving before grinding.

If you are going to make a Bringheli-style c-channel plate, get some Railroad channel - it is substantially thicker and better suited than the
regular structural stuff. Still will need stress-relieving, tho.

But that also begs the question of why not just get a Bringheli or find a used one ? You'll have all the attachments and the cost will probably be less
than making your own, especially if you figure in the substantial time and aggravation involved with getting all the raw materials in small quantities.
A channel-type set up is not without it's issues, but it is good-enough and I've even seen some in Flickr pics of some well-known builder's shops.

Whatever you do - Good Luck !
Michael in (unfortunately de-industrialized) SF

Tdotbikes

If space isn’t an issue why not get a stone surface plate? I see them go cheap at auction all the time.
Your Blanchard ground steel plate will droop over time and will no longer be accurate.

BigPoser

Michael, Thank you for your input. I'm okay with tough love especially since I'm still learning. I do have a friend that would make a base for the plate and we've discussed that it would need a lot of support underneath, not just a single support through the middle. However if 3/4" or maybe even 1" plate still wouldn't get the job done, then I'll have to keep looking. How think of plate would you think would work? Or is it not even worth the effort of getting plate at all?

I've been on the hunt casually for a while now and I've not really seen what I think would work that's anywhere close to me. I did actually email Bringheli about his larger table but hadn't heard anything back and then heard that he's having health issues. I feel that his table would be perfect. I should reach out to them again and see if I can contact them.

BigPoser

I have looked at granite, but I would like to have holes in it for my BB post as well as my HT centers. Drilling 3 holes in 4-6" granite would suck at best. With steel, at least I could perform some mild cold setting if needed. At least that's my thought.

Maybe I need both a granite slab and a small steel set up like Bringheli's small table to help align things as needed.

duanedr 

I have a 3'x4'x4" granite plate and drilling the granite isn't difficult at all - probably took me 90 minutes to figure out the set up, drill the hole and clean up. I set my drill press up so the table pressed up against the bottom of the granite and then had a longer Paragon-like arbor with a $15 diamond tip hole saw. Make a puddle with plumbers putty and go at it. make sure you put a pan on top of your drill press table before you drill through otherwise your puddle will flow through and make a mess. It was actually sort of fun. I'm getting ready to do it with a 2nd granite table I just picked up (for $30!).

Instead of having your friend make a base, have him help you move this:
Surface Plate in Temecula

guy153

I don't think steel droops over time. The advantage of a steel tabletop is you can drill it, tap it, weld to it etc. I will repeat what others have said that any kind of machined flat surface is a luxury not a necessity. If your frame is aligned to within 1mm that's close enough-- it will look fine, ride fine, and everything will fit. Obviously part of the fun of making frames is to get them as perfect as you can so I totally respect anyone who wants to measure things down to the thousdandths-- just saying you can get started without all this stuff.

BigPoser

Oh ok cool. Maybe I can do that way then. Only thing is that my drill press is a small table top version. Might not have the throw it needs.

Not sure what you mean about the plumbers putty puddle. Forgive my ignorance.

Makes me wish I was closer to a bigger city where auctions are more common.

unterhausen

I had a diamond tipped hole saw that I passed on to some framebuilder. Wonder where that is now? My granite plate came with inserts glued in. Holes aren't all the way through. If you hold out, someone will be giving away a granite plate in your area. Probably with inserts, because that's the way most of them are used. The number of granite plates that are used for pure metrology is pretty small.

I know the traditional alignment table was used to bend the crap out of 531 frames that were built in a way such that alignment was definitely something you had to do afterwards. Those days are gone, for the most part. I imagine that checking alignment without attaching anything to the table is doable.

duanedr 

Here's a picture of my set up as I was drilling it. You can see the puddle of water contained by plumber's putty to keep the bit cool and grinding through. If I was to have a benchtop drill press, I would put the drill press on top of the plate with something under to not damage the surface. Then I would loosen the head and rotate it 180* from the base. 'Strap' the base down with a 2x4'' and clamps at the ends of the table and then get a long arbor. I forget if I used a long Paragon or if I made one. Happy to make you one (or send the one I have if I can find it) and send it down. It's just a 3/4" bar with ends. for a smaller drill press, it might make sense to have one that extends by threading 2 together...I would guess one could do it with a handheld but that would be harder.


The nerve wracking part is knocking the cores out as you make progress:
Untitled by Duane Draper, on Flickr

unterhausen

Thanks for the pics. What do we have to do to get a "Draper" sticker?

duanedr 

HA! That is one half of a downtube wrap decal.

Doug Fattic 

My thoughts on alignment tables. Granite tables are very flat and comparatively inexpensive. Many of my students don’t choose this option because they are very heavy in the size they want and difficult to move. They may not yet have a permanent shop space or it is someplace fork lift inaccessible. Cast iron tables are awesome but have the same weight problem. They have the advantage over granite in that they don’t chip and magnetic hold downs can be used in a variety of ways on them. Steel slabs an inch thick or less can be ground to decent tolerances and work well. The one we have in Ukraine was poorly ground but has been stable for years. My associate Herbie made his table out of hot rolled flat stock too. He got it cut to exactly the dimensions he needed to fit precisely in his cramped space. He had it Blanchard ground 3 times. The top was ground and then the bottom and then the top again for maximum flatness. He was able to cut and weld the legs and support out of square stock. The whole process cost him less than $1000. This whole process is too much for some beginners to get done themselves.

My Blanchard ground cast aluminum table (with ribs) has worked great. I can flip a frame back and forth between my cast iron table and get the same reading. Its advantage is that they can be ordered in almost any size and is light enough for 2 guys to easily move it around. My top weighs around 170 pounds and the legs are removable. The surface can be scratched if one isn’t careful. However, in years of hard student use that hasn’t been a problem yet. They don’t require luck in finding one, you just have to have $1500/$2000 to buy one. This convenience is an important for some starting out. The Wolverine Bronze Company where I bought mine drilled my post hole for me.

I use my alignment tables as tools and not as some tenderly cared for inspection only table. I do so many tasks on them I can’t imagine not having a full sized one. In my system this is my foundation piece of equipment in my shop. It is far more important to me than my expensive fixtures and give me more accurate results. Of course if I had to I could use a straight edge with an adjustable pointer but I wouldn’t want to. Beams and milling table tops are fine too. A 2’X 3’ is better yet. But I don’t want to be limited. I can ride a century with DT friction shifters. I don’t prefer doing that either.

Andrew R Stewart 

Doug- That you can still ride a century is the best bit from your post! Andy