So the instructions for squaring the base/legs are incorrect
https://docs.v1engineering.com/mpcnc/Pbase/#base-layout
The diagonal approach only works if the sides of the rectangle are all connected/same length, which at this point they aren’t. You’d need to measure both the diagonals and the distances between the legs for this to work.
You’d be better off adding the tops and the side bars, making sure distance between tops is equal and then using the diagonal method.
You’re just checking the square of the base at that point.
Further on you check square again (at the top):
Right, but measuring those diagonals doesn’t help with making it square and this is the point where you’re being told to screw the bases to the table. I realize there is some level of adjustment you can do later but still.
For example, diagonals match, but it certainly isn’t square.
Yes, it is possible to do it wrong, but if you follow the steps, and start by laying out the feet as determined by the cut calculator, using the diagonals to make adjustments, it should work. Using the diagonals to do the layout, there are definitely ways to get it wrong, sure.
If there is an error there, it is in not specifying that you need to check that your length and width remain consistent, which is something that I took as assumed. I knew that the diagonals could be forced to be wrong, but since I was also checking X and Y distances at the same time (As per the cut calculator measurements) it was fine.
I agree that if the sides aren’t the same length then measuring the diagonals will not get it square.
There is an instruction before this,
- Layout the foot assemblies on your table according to the dimensions from the [cut calculator.
[snip]- Screw down the two assemblies along the front edge of the table. These will be your fixed references.
Which implies that you have set out the front, back and sides according to the lengths from the calculator, and have fixed the front as your reference line.
So I would suggest that the instructions aren’t wrong, just not as clear as they could be.
Hope this helps.
Andrew
Edit: Damn, beaten by Dan !
“If there is an error there, it is in not specifying that you need to check that your length and width remain consistent”
Right, that’s what I said, they are incorrect in as much that if you just follow the instructions you can end up with a base screwed to your table that isn’t square, it says to triple check the diagonals but doesn’t have you re-check the distances, the assumption being that checking the diagonals alone is sufficient.
As others have mentioned, it tells you to “Layout the foot assemblies on your table according to the dimensions from the cut calculator.”
I think we can all agree they could be a little clearer, but I would not go so far as to say the instructions are incorrect.
The above instructions could quite easily result in you not getting a square base which is the whole point of this step, it’s having you adjust the legs and verify those adjustments by checking the diagonal’s but that adjustment isn’t necessarily changing what you think it is, and even after you triple check you could very well still not be square.
@vicious1, what do you think?
@dpenney, there is a little pencil in the upper right of each page of the docs. You can make the edits you want, and then submit a pull request. Then we can argue about the actual text, or just accept it (which usually happens). I’m not that interested in arguing the details. My guess is that since you are adament about it, it could at least use some clarification, but it could also be wrong.
Looks like a sentence in both places that says to verify the lengths before diagonals would fix this?
I thought for sure I had that in there. Either way, under " Layout the foot assemblies on your table according to the dimensions from the [cut calculator]." if it says keep your X and Y dimensions as precise as possible before and after each time you adjust your diagonals. That work?
The idea is mount the front rail, match it with the back one, only adjust the back one. How can we word that better.
Good catch no one has noticed that in years.
Yeah that would do it, just call out that opposite sides have to be equal along with the diagonals.
You could also have people assemble an entire top and bottom rail and then use the diagonal method to mark positions, might be easier than measuring everything after each adjustment.
First thing I did was to use a pencil and square to layout a rectangle on the table. Checked the diagonals to make sure it was perfectly square before mounting the feet. This gave me a perfect reference to start with.
For me the hard part was not making a square on my table top, but getting those feet to line up and not move around when screwing down. That is where I lost it. Good idea to predrill some holes before placing feet.
I did one screw per foot, then when happy with placement drilled and screwed the rest. Ended up with a very square base to build up from. Just like a house, if the foundation isn’t good, the rest of the house will have issues.
Gonna be honest, i didn’t even really read much out of that step much besides “screw down the feet in a square”. Seems like basic things along these lines always requires me to make a jig anyway and figure some method to idiot proof it against myself.
I figured what my diag was supposed to be from center to center of leg pipes, layed out where the intersection of the diags should be on my board, put a pin in it and used a rigid ruler to pivot about that point to find where the legs needed to go. Made sense to me.
I had a paper template that unused to center punch mounting holes relative to the leg pipe centers.
I did a crappy job of explaining it but please try my method to set all four post complete and absolutely square.
BEFORE you screw anything down just cut 4 battens (thin strips) out of anything scrap laying around that are a little longer than your sides. Clamp/tape all four together. Center punch the centers of your desire post and drill with a appropriate post diameter bit through ALL four pattern strips at once. They are now all SPOT ON for X and Y distance.
Drop them over all four post not yet screwed to your table but loose to slide and shuffle about but they are an exact size but not yet square.
THEN cut two more but these are your EXACT diagonals. Only one is required but with two criss crossed they assure no error and make it really rock solid.
Then slide it around the table where you want and when happy shoot in the base screws.
This sounds so complex perhaps but I can make these battens in less the 20 minutes but the swing is being dead nots square and you can to that is 5 minutes. Then take off the battens and store them for later if you ever need to remount your Primo on a new table.
I wish I can explain how simple it as spotting center points and drilling can’t get easier.
I have TONS of 3 ply baltic birch and would be happy so cobble some up and UPS if anyone domestically wants to try.
-Craig
@dpenney I think this should address it. Would you agree?
(https://github.com/V1EngineeringInc/V1EngineeringInc-Docs/pull/319/commits/d17ff7c7c99bd9da27b3f627bf3042c6d56b9fc0)
I ended up with a version of this for my 2x4 primo, except I cut them out on my other cnc, lol. 100% effective, and I think this is probably the best way to jig up with hand tools, even for clowns like me.
Of course, now i just cut the leg holes for the primo with a bigger cnc.
This is my rebuild too as I’m also moving it to a new table and this is the method I went with as well, in addition I also used some clamping squares to keep the legs in place while screwing them down.
