Hi Jason, I just thought of something. If I were one of those shops you asked to make your frames, I “might” have read the prints you supplied a little differently.
I know the prints say 20” MAX and 20-1/4” MAX, but the prints also say +0,-1/16”. Which I think “could be” easily misread as +/- 1/16” meaning they could be oversized by as much as 1/16” as well as undersized by that same amount.
IF the prints were mistakenly read that way, (which again, I think could be an easy mistake I think) then you’d need to set your fixtures to 20-1/16” X 20-5/16” and would only let no more than an 1/8” shim through.
I’m not sure just how much you made it clear to those shops how critical that maximum measurement was, and maybe you did take the time to make it perfectly clear, but I just realized that if the shops made that mistake, I’d be interested to see if they pass the dimensions portion of your test.
Don’t get me wrong… I 100% agree that fixture tables are THE way to go for fabricating, and I still love how easy and accurate it is to fabricate using my table, but I just had that thought today while re-watching your video.
Interested to hear your thoughts.
Also, I swear I saw a video of you fabricating these frames using your table and showing how fast it took you, but I can’t find it. Did you make a video about it or am I thinking of something else?
No, the person doing the building would fixture it at the correct size, but the person doing the testing would fixture it at the largest size allowed, like a go/no go gauge.
Jason did setup his fixtures as a no/no go gauge at the maximum allowable measurement, I was just thinking If the builder misread the prints.
I often see specs that will say something like: +/- 1/16” but I don’t think I’ve ever seen prints that would say: +0,-1/16” before.
As a fabricator/engineer seeing a tolorance of plus 0 minus X tells me that this item must fit inside of something else and I will build it as such, I would lean towards the bottom end if the tolorance. This is a very common callout in industry especially in tight tolorance machining.