Amen

With small step overs it works fine. You can take even more than that safely. Just think like a centerless grinder. Cheers, Tom

Hah, You spotted that! Cheers, Tom

Poncho likes bacon With robrenz quietly smiling in the background for some reason…

If Robin wants to join in it's open to all comers. This Old Tony, Mr. Crispin, Joe Pie, let's have a pissing contest!

Hey Robin. You are probably right it would be better to have a steeper angle. I built one flexure before hand and tested it to see how well it behaved. It took considerable force to move the foot and seemed controllable so I decided I would trade fastener tension for resolution in this case. The goal is to lap the feet accurately but have an adjustable back door if needed. All the best, Tom

robrenz.....sir...the internet isnt the same without constant videos from you..I sure wish youd either stop making videos aLL TOGETHER SO WE SO SIT AND WAIT.,.,OR MAke some videos....youre missed ir!!

You got to separate Arnold the man from Arnold the actor, two different people.

That is a better name than composite. Its a nod to the Pratt Whitney truss design level and snap gages. Look them up as they are pretty cool looking. Best, Tom

Tom's Truly True Truss Square?

For squarish bases four points is more stable. The Hermann Schmidt has four lapped feet on it for this reason. Its over constrained but more stable in this situation. Three flexures would have been awkward with this design so I opted for symmetry. Cheers, Tom

Bobby W you're only cutting with the outside leading edge, and as it breaks down you still have the rest of the way towards the center, but it will round off vs leaving a nice square edge to cut with as the wheel breaks down. Hope this makes sense.

The edges of the wheel is what break down first. The diameter actually changes really slowly.

I've been wondering if it would be a good idea to have to wheel at an angle against the travel of the work. Any tiny imperfections on the wheel would be evened out. Of course it has to be perpendicular if you were to make some kind of profile cut on an edge.

Only the "high spot" of the wheel is contacting the surface as it moves along it. Grinding wheels are used to "machine" crankshaft journals and other precision shafts that have sufaces that aren't concentric with the centerline, but in those situations the work is rotating as well and there is a lot of coolant involved and the stone is grinding only a portion of the width of the journal. It's also done post-heat treatment and final polishing is done with emery cloth bands that are like a narrow belt sander against the journal. The other major difference is that crankshaft journals have plain bearings supporting them in the block and supporting the connecting rod and those bearings are made with steel backs but have relatively soft "babbit" surfaces in contact with the journals. There is oil clearance built into the "joint" so the bearing "floats" on a hydrodynamic '"film" of oil and in theory the shaft never contacts the bearings. And that is pretty much true except for at startup with no oil pressure or high-load situations with insufficient oil pressure. Then there's a slight amount of wear in the first case and very short part life in the second. The bearing and journals are obviously of different materials and "self-lubricate" and are never TRULY "dry" at startup. Really high-quality bearings used in some heavy-duty diesels actually have a "depression" in the middle of the bearing so oil can "puddle" there at shutdown. Surface tension and the fact that the engine begins cooling and the oil thickens immediately after shutdown help keep oil in bearings as well. I can't say that I've ever seen a flat and straight surface ground for precision and it seems counter-intuitive to me since a grinding stone is going to leave a rougher surface finish and scratches that are small "ditches" with some of the material "dug" out of them sticking up around the edges. I'm not a machinist but I've been turning wrenches for a long time as a professinal diesel mechanic for 25+ years and I've done some "minor" machine work and a lot of fabrication and surface prep and I know a lot of machinists and have pretty extensive experience in every diesel industry except marine. I've also done a lot of automotive work and I'm a "gun nut", so I'm pretty familiar with most things that are machined to precise tolerances. And I've used a lot of precision instruments and standards and learned "the old fashioned" way how to dress grinding stones, sharpen drill bits, properly use files and hacksaws, etc. I've gotta say to me this looks like one hell of a lot of work and time and material put into something you can't make without having the commercial tools and standards and gauges to make sure its right. The only way to get them is to buy, rent, borrow or steal them. That's the case with all quality tools that "DIY" guys use to make their own "made it myself" tools that are usually made because its "cheaper". Well, it may be "cheaper" but if "cheaper" is in part due to borrowing or renting or stealing a tool from someone else, the only one paying for your tool in its entirety is still you. And if its a purchase to keep or rental then the owner and everybody "upstream" of you and that owner benefit from the hard work and effort and skill and investment other people put into the tool and they've been compensated in some way. But if its a tool borrowed from someone under the guise of "personal use" to make or fix something to keep and use or to repair or make something for someone else "gratis" and offers to compensate the lender anyway are refused, that's also a "pay it forward" situation. But buying a tool to use and then returning it for a refund in my book is stealing and stealing is stealing and if its to make a "DIY" tool to then use to produce MORE "commercial" tools for sale or trade, that's stealing and fraud. No matter what nobody is ever a TRUE "DIYer" unless the "project" is "living off the land" and that project is started by leaving all your current commercially manufactured possessions behind and starting out bare-assed naked from scratch. Like I said, I'm no machinists but I damn sure have used lots of quality tools and I know that you can make any standard really quickly and pretty easily from plain stock if you have quality machine tools and gauges and very basic materials to start with. Standards for checking micrometers 1-2" and larger are just precisely machined and lapped pieces of round stock that aren't going to grow or shrink providing you keep them and use them in the same environment in which you made them and machinist squares and straightedges are typically mild steel stock milled and lapped to be straight and perpendicular and flat. Most parts in even the best and most expensive heavy-duty diesel engines don't have tolerances tighter than .0001" and even then its going to be several ten thousandths on top of a thousandth with a +/- of a few more ten thousandths. I think the main reason we even seen ten thousandths in machines and areas easily accessible with ordinary tools and where the same fundamentals and processes apply whether its a 5 hp Briggs and Stratton or a 500-hp Caterpillar, is specifically to keep amateurs - mechanics AND machinists AND "remanufacturers - with cheap tools and/or no clue what they're doing from destroying parts and engines and potentially lives by using "good enough" techniques and processes and tools to "repair" or "rebuild" or "remanufacturer" machines where in operation it really DOES matter. It might seem like anybody who doesn't have the experience and skill and tools to do a job properly and is taking a shot at it anyway to "make" or "save" money doing it for themselves or someone else wouldn't be hesitant to work on an engine or other component or machine where the tolerances and clearances go to .0001" instead of just .001", but that extra decimal point requires vernier-scale micrometer to accurately measure and even though there are el-cheapo micrometers all over these days and "budget" tools aren't something new, vernier micrometers are typically the "too expensive" brands and ELECTRONIC CALIPERS, which are VERY commonly and incorrectly used AS a "micrometer" do NOT go to .0001". Even if they measure to .0005", that's not .0001". And the thing about DIYers looking to "save" or "make" money is that just like there's always that point where SOMEONE ELSE'S TIME AND EFFORT AND SKILL is "too expensive", there's a point where they realize that their OWN TIME AND EFFORT AND SKILL could get REALLY expensive. Especially if they're "DIY" project is owned by someone else who is ALSO "frugal" and doesn't want to pay professionals for their time and expertise and tools and probably isn't going to want to pay for even a "cheap" job twice. Much less pay for a NEW or REBUILT component or machine or part when the "mechanic" or "machinist" who took on the original job "dropped the ball" and the results was what a service manager I used to work with (RIP Andy) called "fuckage". Overall, what I see here with all the fancy and unnecessary machine work on what is really just a piece of square tubing with some plate welded onto it when the tubing itself if good enough for the "foundation" could have simply been milled flat and square and true itself as evidenced by the commercially-made example, is someone trying to put a lot of "value" into something that they know they're not going to get back out of and that is costing them a lot of extra time and money to make and that they're also going to end up paying someone else to "manufacturer" at least in part when they have it heat-treated. I'm not sure WHY you'd want a precision standard that would be very easily broken or chipped if dropped or struck with something harder than it accidentally while being used or when left unattended on a bench or table (the small portable toolboxes a lot of machinists use to store gauges and standards and other delicate, fragile and expensive tools and that are usually Kennedy and brown in color in contrast to red for regular toolboxes so "visitors" don't raid them and thieves overlook them) are small and portable so they go with the tools to the work area or the work is brought to them. And the bench or table they're on is usually on along a wall out of harms way and even then the tools are put back as soon as they're no longer needed. That's so they don't get left lying around where they're easily "lost" or damaged by some "visitor" seeing a new and unusual and NEAT tool to "inspect". Anything with a DIAL and a PLUNGER to make the needle move is a MAGNET for "visitors" to be drawn to and amuse and distract themselves with while a mechanic or machinist is working and they're "helping" or just "watching". And just like a shiny new toy to play with gets old quickly for a child when it turns out to not do anything that special despite outward appearances and children rarely put "toys" back where they got them, its very easy for a "visitor" to set the new toy aside when he finally has the mechanic's or machinist's attention, OR never notice them at all if he's in "pay attention to me mode" from the get-go and happens to catch the mechanic or machinist when he's "not busy" and knock them over or shove them out of the way with or for his own convenience when he needs a spot to put himself or something he's brought in to have worked on and one or both have to be FRONT AND CENTER and TAKEN CARE OF IMMEDIATELY OR SOONER IF POSSIBLE. Even then, shit happens and tools and gauges and standards get used and damaged or just plain wear out. GAUGES are very OFTEN hardened and polished on their anvils or contacts or jaws where they frequently contact HARD and possible sharp or gritty parts (that shouldn't happen but again, shit happens) and are moved on the part to get an accurate and precise measurement in one or more locations. But STANDARDS should be "soft" to save wear on the gauges and for toughness.

I'm not sure I'm following you. Could you go into a little more detail? Don't leave anything out.

See comment above. The edges break down first and the diameter lasts a long time.

Hi Robert, Qualifying the entire surface is pretty tough. You can do multiple points but you still have to extrapolate between them. That said once you have a good master you can probably easily make a facsimile of a squaremaster with a precision preloaded linear bearing.

Gilberto Diaz Castro i believe it’s a wet cloth to help catch the grinding dust and grit. it keeps some of the mess down that is surface grinding!! fun but messy.

Mark Fryer I second this though. I'd love to see how they treat such a large item.