calstar 

Looks to me all the engineering calcs are made under load, zero load in the case of a small steel surface plate, I remain very skeptical. Any material will deflect/shear/fail given an adequate force/load, a small unloaded steel plate will not "droop" by gravity.

bark_eater 

Pokeing around I found that there are threaded inserts made for guiding the facing cutter. Park tools has a similar product. They have a museum of tools and hopefully can confirm compatibility.

duanedr 

Make sure you get the one with the roach storage space at the end!

Doug Fattic 

I found the tolerances on this unit to be less than I could tolerate. Cyclus makes a decent tap and facer all-in-one-unit that is more to my liking and cheaper than Park. Of course my Campy tool kit has the precision that I am used to.

JohnDThompson 

That's the impression I got from the Park tool as well. The Campagnolo bottom bracket facer has a high precision, full-length two-piece, pilot sleeve that securely stabilizes the facer. And the shaft is wider diameter than Park, which should make it less likely to flex in use.

Andrew R Stewart 

By pressing in towards the shell on only one handle the cutter will be loaded against one side of the slop, within the pilot inserts, and the cutting will be less uneven. I do this with my Campy and can feel the change in cutting amounts. At work with it's Park cutters this is even more easily felt. Andy

bark_eater 

I made an expensive leap of faith and bought a set of GURPIL taps that the seller says appear identical to a set of Italian Var taps he has, so here hoping.

GURPIL TAPS

Andrew R Stewart 

be- So the seller confirmed the pilot and notch dimensions and they are those of Var (which I'm pretty sure isn't the same as Campy)? If so great! Andy

bark_eater 

I'm not sure if he got farther than a visual comparison, but assuming their
var clones, I'm hoping their within spec.

JohnDThompson 

That's correct: the Campagnolo taps mount on a 22.0mm shaft, while the VAR taps mount on an 18mm shaft.

bark_eater 

I'm just going to ask here and not start another "plate" thread. Locally what looks to be 48x32x1.25" granite table top popped up. I'm debating picking up a "cheap precision" 48" Straightedge rumored to hold .003 mm and going to check it out.
I'm guessing it would be about 200lbs and if its reasonably flat I can use it as a surface plate and do alignments on the milling table.

Heres the question: if I decide that the slab is not flat enough as is, would it be a a good stable base for pouring a epoxy surface on?

unterhausen

where do you get a cheap precision 48" straightedge?

bark_eater 

There a couple 50" ones on amazon for under $50. I decided to get a $65 36" Woodpecker straight edge from Woodcraft, because of tolerance trust issues and its designed to be stable standing on edge, which is useful for machine set up. It also comes in protected in a MDF holder.

Andrew R Stewart 

be- My concerns about using the stone counter top for a base is it's possibility of flexing/droop. Having a pattern of adjustable supports under the stone might be needed (as opposed to only three supports, like cast steel surface plates use) to insure initial and future flatness. Whether it's also covered with an epoxy pour I don't think is the real issue. But to answer your question- I think the counter top would make a good stable (excepting poor support) foundation for a pour.

bark_eater 

The slab is on a metal frame right now. It's set up as a coffee table, low with some over hang. I would fully support the top if I was going to pour epoxy. I'm looking at the table tommorow. I have 2 sets of feeler gauges so I can map any sag or crown. Any suggestions as to tolerances to look at?

unterhausen

it's best to put something like a counter on a compliant base. They make rubber mats for this purpose, usually called "vibration damping pads" I have some under my granite plate so that it doesn't conform to the frame it's on

Three point mounts are called "kinematic." A big cast iron base uses this because they are worried about it taking the shape of the thing it's mounted on. Kinematic mounting means that the resulting shape should be fairly close to planar. Most granite bases are mounted on some sort of compliant base. These are people that are worried about tolerances a lot finer than what is appropriate for a weldment like a bike frame.

bark_eater 

Heres the listing photo.

bark_eater 

The top was impressively cupped across its width. It was also up a 16' flight of steps.

calstar 

I copied this off another forum, thoughts? I think they're available in 3/16 up to 1/2. Strong enough to install a whipping post for alignment? For a hobby builder this might be a good value.

CertiFlat PRO Series Table Top Kits

​​​​​​"An economical welding table that if built with care is pretty damned flat, more than flat enough for frame building."

https://weldtables.com/collections/p...ab-slot-u-weld

https://weldtables.com/products/lk36...kit-heavy-duty

unterhausen

a welding table top is probably going to be fine. I would get a thicker one.

Another kind of table top that probably would work is an optical table. They show up used occasionally

BigPoser

I actually have this table. It's a nice set up for sure. I bit high with the additional legs but nice none the less. I admit that when we were welding it up, we didn't do it correctly and each of my corners have a bit of drop to them. I didn't see the proper way to do it until after it was already built. SMH. There's no doubt however that if we had followed the proper procedures it would be very flat.

bark_eater 

got this today for $30. It's a 28x30" powermatic shaper table. It will take another 8" extension if I can find one. Hope to get this clean and flat enough to build on and then use the CNC milling machine table for alignment.