What is the best route to flip something over and car on the opposite side?

[ColdCoffee (Robert)]

I’ve found several ways to screw up, so let me tell you about my mistakes.

• If you flip it the wrong direction, you feel stupid.
• If the actual size of your stock material doesn’t match your measurements things can get off. And getting your stocks actual size is MUCH harder than it sounds, because even with an accurate X and Y measurement that method is built on the assumption that your stock is perfectly square.
• If you base a two sided flip using a corner, any error gets multiplied (at least it was for me).
• If you base a two sided flip using the center, you still have to worry about rotational alignment but I seem to have better results (assuming I found the actual center). Best analogy I can think of is an old record, there’s a reason those had a single hole in the center.
• If I can start a job by creating (drilling) two reference holes, I can use those to “flip” and realign the stock. This produces the best results (for me). My wasteboard has threaded inserts every 1.5", so I will design a job to have flip-holes outside of the design area, that are multiples of 1.5" apart. My last “flip” job was making something that was 12x12, and I had the flip-holes 13.5 inches apart (both 1.5" outside my design area).
• Run a surfacing job on at least one side. Whatever thickness the material claims to be, it probably is not. While the surfacing step is running, make sure the bit at least skims the entire material area. Uneven surface can cause you to unknowingly carve side “A” deeper than side “B”, which may or may not be a big deal (depending on your design).
• I don’t know the percentage to tell you here, but if you are working with wood, the more “material” you remove from side “A” the more that material is going to warp-bend-stretch on you and your “flip” won’t be symmetrical.

[CullenS (Cullen Simpson)]

Great info. I have not found the need for the registration holes yet and to be honest thinking about them scared me away from doing flips for a while.

I am sure so will encounter cases where I will need them though. Can you explain where you put them more? Maybe a sketch? And in the case you describe below where did you set zero? The center or the corner? Or is it somehow related to the pins. How do you know that you have the stock placed such that the registration holes align with you inserts? Do you just pull their location into your CC file?

[Pan (Andy photenas)]

This seems like it may take a little bit of practice!

[CullenS (Cullen Simpson)]

Just don’t overthink it.
Try it on some scrap and learn from the mistakes.

Worst case is you have something that looks really nice in MDF and you wish you had used walnut.

[Pan (Andy photenas)]

Lmao thanks again team!

[ColdCoffee (Robert)]

The image below is from my last two-sided job. The design is 12x12 and the material I used was roughly 16x13 and not square.

The red (selected) holes outside of the design are my flip-holes. They are 13.5 (center to center) apart from each other which lines up with my waste-board threaded inserts.

Step 1 is I drill out these holes, and it does not matter if I’m off center or my material isn’t perfectly square. At this point it’s just two holes 13.5 apart, the right size diameter for my threaded inserts. I then bolt the material down to my waste-board.

So even if my material was REALLY off (pretend the highlighted square below was the edge of my material)…

… when I flip it over, as long as I re-bolt into the same threaded inserts my design is still centered in reference to the two holes. I do NOT change my zero settings, I just run the job for the other side.

It’s basically the same concept as doing “tiling”, instead of moving the material you’ll be flipping it over.

Community challenge #17: Maps (closed)

The community helped me make my topographic Skyrim map, and I learned a lot from that process. I wanted to make for another game-map that would look similar, but using a different technique. The same company that made Skyrim also makes a game called Fallout. Unlike Skyrim, the Fallout games use real locations and Fallout 4 was based in Boston. To make this map I decided to do everything by hand. It was a VERY manual process as it took me roughly a week to build this design in Carbide Create…

[CullenS (Cullen Simpson)]

So you bore the holes and then fasten for side 1 and then set zero I assume.

[ColdCoffee (Robert)]

I set the zero before I made the flip-holes. 90% of the time my Z-zero is the top of my wasteboard (not top of stock). And almost as often I X&Y zero to the center of the stock.

If I zeroed after drilling the holes I would have run the risk of the holes not being equal distance from the center, so the flip might have been off (depending on which axis I flipped on).

[Pan (Andy photenas)]

Wow, a lot of info here think I need my hands on my machine to understand it all I’ll be working with this for the next few days, so thank you all so much!

[CullenS (Cullen Simpson)]

Ok. I guess I just don’t understand how you ensure that your holes perfectly line up with the threaded inserts then.

[abcnevin (Andrew Nevin)]

I’m likely under-thinking this but I have always used either: Homemade flip-jigs or multiple 0,0,0 homes for multiple soft-jaw set ups (G54, G51, G120, etc.). Manually entering in coordinates and correcting for errors when moving the workpiece by altering the generated G-Code. Seems like the CC community has some great ideas though, much easier probably!

[Tod1d (Tod (with 1 'd'))]

My guess would be they are designed that way. Machine the holes with your machine and make them multiples of 1.5" apart. He said the threaded inserts were on 1.5" centers.

Then position the part using the threaded inserts, set your zero & go Hawaiian

[CullenS (Cullen Simpson)]

But this is what he wrote.

@ColdCoffee

I set the zero before I made the flip-holes

[Tod1d (Tod (with 1 'd'))]

If he’s very careful to make sure the tool goes through the stock but doesn’t hit the inserts, I suppose they could be machined right over the inserts. Then he just threads in his locators through the holes. compressed air to get all the dust out??

If you didn’t have the inserts, you could program the hole path to drill the holes through the stock & into the table or spoilboard, creating both the hole & the locator hole at the same time.

[LiamN (Liam Newcombe)]

I’ve found the following to give me decent precision and reasonably low mistake rates.

Bolt down a temporary fixture board, surface it flat and machine the front and left sides square and straight.

To get a really good repeatable zero I put a little CA glue in the sides of the MDF at the front left corner and re-machine the two edges, that gives a smooth and solid pair of faces to zero off.

Zeroed off that front left corner I then bore the pin holes I need for this project (you can re-use the fixture a few times before it’s too swiss cheese). I now have a repeatable zero and bored holes in known locations from that zero. If you can do these on a regular pitch, that makes re-use easier. I also like to put a bit of CA glue in these, set it with activator and then re-run the boring toolpath to get a good solid repeatable pin fit.

I then put the stock on top of the fixture, align it by eye and bore the matching holes for the locating pins and, if necessary, surface the stock. Now attach the stock to the fixture using the pins.

I then machine the first face, using the fixture as the Z=0 point, this way the stock just needs to be ‘thick enough’ and I can cut all the way through accurately.

Once that’s done, flip the workpiece in whichever direction you flipped it in CAM, put it on the pins and machine the other side, again, using the fixture as Z=0 and the same X=0, Y=0 off the front left corner.

You can keep doing this for many parts over power cycles by just re-zero-ing off the fixture, you can even put an old fixture back on the machine by running up the side with a dial indicator in the collet (best done at 0 RPM).

In this particular case, the two ‘sides’ were two separate workpieces which were to be glued together to make a single ellipsoid profile table leg and top through mortise.

[ColdCoffee (Robert)]

whoops, guess I left out an important detail. I don’t move the machines zero to the center of the stock, I move the stock to the center of my machine. Sorry for the confusion, take a look at the attached Carbide Create file. I will zero my machine to X -17.244, Y -8.386 (the true center of my work area).

I then take my (close enough) measured center of my material and move it until that marked dot on the material is under the bit which is located at X -17.244, Y -8.386. That way I know any hole I drill lines up with the threaded inserts below.

Template.c2d (516 KB)

But all of that isn’t actually required for flip machining, I could have reset my X and Y zeros after drilling the holes and finding the center between those holes. Or maybe even use the machine to mark the center (between the holes) when it is drilling the holes.

So sorry for all the confusion, it appears my attempt to help may have done more harm than good.

[CullenS (Cullen Simpson)]

No harm at all. Good clarification though. I have not been leveraging the machine coordinates or rapid position locations much but no see there are multiple good use cases.

I like this approach although I don’t have the threaded inserts. Maybe I could make a supplementary spoil board that would have them and some runners on the bottom to precisely align it in the T tracks.

I have been thinking about re-doing the fence I use for tiling and adding runners on the bottom for that same reason. It would allow me to more easily remove and replace that fence. Probably best to make it extra wide so that it can be cut along Y for fine adjustments as needed multiple times before tossing.

[Pan (Andy photenas)]

Good lord I’m gona pop from all this info! I think this is what they mean when they say you opened a can of worms.
I’ll reread and then re-reread this post again then I’ll go play with my machine!

[EJL (Edward James Lamb)]

If I have a large sign with an odd shape, I drill a 1/16 through hole in my exact centre. When programming the piece on the computer every design I use the centre as well as a straight edge usually I have the machine carve a straight line into my spoil board. It’s usually fool proof if I’m using both sides. When you flip the piece I set the 1/16” bit and move the router till it sets right into the hole and square to the straight line on the spoil board that’s about exact as I can make it. Just remember to orientate the program image accordingly. Also if you are adding something to a piece. Try placing the datum point in the exact centre of an image then place that centre point any where on the surface of the piece. The cnc should cut exactly from that centre point just remember to square the piece on the spoil board.

[gwilki (Grant Wilkinson)]

@Pan You don’t say what CAD/CAM software you are using, but you will find a couple of excellent vidoes on Mark Lindsay CNC on youtube that cover an excellent method for doing double-sided jobs in Vectric VCarve. It will work on any shape material and is fool proof - as much as any method can be. The method can be used with pretty much any CAD/CAM program that can handle double-sided projects.