I did some more indicating with the goal of levelling the granite and there seems to be (inconsistent) variation over the entire surface, ranging in the +/- 0.01mm in most places, but reaching +/- 0.03 across others. This seems to be natural variation (highs and lows) and not from the plate being out of plane with the spindle XY.
So how to proceed…
I can try something else, like a thick cast piece of tempered glass,
or work to find a XY span on the granite that shows the least variation between the points I will use to tram my spindle,
or not sweat the hundredths of millimeters variation as it most likely will not matter except for aluminum work I plan to do, and even then these would be, from what I have been reading, quite respectable tolerances for this type of CNC
Please keep in mind I have absolutely no real life experience with CNCs or milling anything… yet… so my outlook and expectations will likely come across as unrealistic and misguided at times. I am looking forward to machine time changing that.
OK, I’m stumped. I got the granite surfacing plate (aka inspection plate) from Lee Valley. I leveled it (following Mark Lindsay’s approach (Tramming My Gatton CNC After Moving It - YouTube). Then, I mounted the Edge Technology Pro Tram into the router. With a 2" thick granite slab under it, there is just barely enough room under the Z-slider to mount it. There is absolutely no room for the Pro Tram to rotate 90° under the Z-slider to check Y-axis (nod) tramming.
With the Pro Tram in the X-axis position (i.e., parallel to the front of the machine), my tram looks OK (within .002" left to right). Then, I just jogged the spindle on the Y-axis from the front of the granite slab to the back of the slab and referenced one gauge. I guess my nod adjustment from last time is still OK (within .002" from front of slab to back). I don’t think this is a real measurement, but for now, I’m calling it good, having made no adjustments. But, really, the slab is not useful based on the way Onefinity designed the Z-slider - not enough clearance. Even with their built-in tram adjustment screws, I don’t see how you can use proper instrumentation to measure/adjust Y-axis tram - no gauge I’ve found can pass under it if you’re using a proper inspection plate. If you can’t properly measure the nod, how can you make an adjustment?? I must be missing something.
I’m returning the slab. I may pickup a piece of 3/8" float glass and try again. Painful.
Both of those are designed for industrial CNC’s. Onefinity is designed to be a hobby CNC. You might be chasing some level of perfection you’ll never achieve (and usually doesn’t matter at this level of CNC) with a lot of $.
I’m not “chasing perfection.” I’m merely trying to get the best out of a great machine and it’s frustrating that I can’t measure the current calibration. Plus my level of experience means I don’t know what I don’t know, so I try stuff and follow advice from lots of sources. When I get the TayTools float glass I will report back. If it works, we’re all ahead. You can’t manage what you can’t measure (Peter Drucker).
The best way to ‘measure’ tram is to flatten your wasteboard, then check out your ‘tram marks’. If you can see them but not feel them, 99% of users are good to go at that point.
The 1% are enthusiasts chasing perfection.
Old habits die hard, honestly. What makes matters even worse is that the design of the machine gives the solid impression that a certain level of precision can, indeed, be achieved. When I look at Shapeoko, I fully expect precision to be somewhere along the lines of ± 1/16". Lunacy would be chasing perfection on that.
Shame on you for building such a nice desktop cnc.
There’s absolutely nothing wrong with perfection!
Our worry is that new/beginner users read the talk from experienced/enthusiast users about ‘tramming this’ accuracy .0001 that’, and they get hung up on this, taking away from just using the machine and the joy of seeing a project appear before your eyes and rather get caught up in the frustration and addition of what they don’t know, which, more often than not, wouldn’t even matter in their cuts.
We don’t suggest any new user to even try to tram until they have several dozen cuts under their belt so they start knowing the machine and how it operates.
Joy is our focus!
Oh, that makes sense. Machinists tend to obsess over that last .0001 because that’s what we were beaten into submission to do but, yes, there’s no fun in that. There’s nothing rewarding at all about missing that mark, either.
I also fully understand what you’re saying, that stressing over the discrepancy of a couple microns is pointless if the machine can’t really reliably and repeatedly hit that level of precision. And nobody outside of making dies, fixtures or rocket engines really needs that level of precision anyway.
This one company I was working for would spend thousands of dollars making precision dies for automotive brackets… and apparently GM, Ford and Chrysler would pay the premium… just to bend pieces of steel into products that the consumer would only see in the event of a dash disassembly. We’d still have to hit those tolerance marks even though the end product was essentially something you could bend into shape with a bench vice.
But that’s the level of crazy that defines some of us. It’s indoctrination into the wonderful world of production machining. No joy whatsoever.
Thanks. I was a happy 99 per center until on a specific project I was using my 1" surfacing bit to flatten a 3/4" board. That’s when I noticed faint lines. Then, I noticed that the thin resin layer I put down on the surface further exaggerated the surfacing lines. That’s when my tram became not good enough. So, it’s not perfection for the sake of it, but to eliminate an undesirable artifact in my work. This is what generated the need to measure the nod so I can “dial in” the machine better. Believe me, I’d rather be carving than calibrating!
Best of luck to anyone reliability holding +/- 0.001" when working with dead tree carcass as a medium, even if you do it’ll change by tomorrow
The one step I think gets overlooked and should be done before tramming is ensuring the 4 Y rail feet are coplanar by running strings corner to corner and checking for a gap where they cross.
Even if you’re not chasing perfection having a reasonably well set up machine to start can reduce frustration with projects that are produced, for example if the lid doesn’t fit the box you made… Like a guitar, as a beginner you at least want it in tune - later you can worry about intonation, string height, action etc… Get the Onefinity square, parallel and coplanar and you’re 99% there.
You should be able to get things trammed close enough without going through all that. If after surfacing the wasteboard it’s clearly in need of changes, make the adjustments and try again. My machine didn’t require any tramming out of the box. There is zero noticeable deviation on the surface of the wasteboard. I’m sure a dial indicator would show some minute differences, but I’m not building anything for NASA… so it’s good to go. Save yourself the headache and enjoy the machine!
Which mounting holes do you have the Z using? I have a granite reference surface and did not have any issues using a dial indicator. Not sure if mine is an Edge though - can check tomorrow.
Note that there is nothing wrong with finishing with good, old-fashioned scraping cards.
I have trammed my 1F to deliver an acceptable surface but I don’t mind spending a few minutes to finish the parts. Regular glass was perfectly adequate for this result.
There might be good reasons for chasing the level of perfection you’re after, e.g. if you mill 1000’s of parts, just be aware that the same level of quality can be achieved by using traditional tools after the 1F.
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Aiph5u
(Aiph5u (not affiliated with Onefinity))
97
Hey Auntjemimma,
this is very simple:
Checking for perpendicularity between milling motor axis and (different areas of) worksurface
First, you make sure your Onefinity CNC is not twisted. That means all four feet must be in one plane. Since three points are always in one plane, it is enough to make sure that the fourth foot is also in this plane. Adjusting this can be done by placing a shim under one foot, where if the fourth foot is lower than the others, you place a shim under it, while if it is higher than the others, you place a shim on the next foot (in either direction). To perform the measurement to ensure a non-twisted machine, you can use one of the methods described here, the easiest way is the fishing line method, which is very reliable since it really measures on the rails (remember when using this method that in case the two fishing lines touch, you must first swap them over (the other one down) and there must not be a gap either, to finally be sure the four feet are in one plane). Another method used since ancient times to check for twisting are winding sticks.
If you have the QCW Frame which now includes the Any Surface Leveling System, or if you have height-adjustable feet or casters on your table, adjusting coplanarity can be done on the fly after having moved the table.
Then you surface process the wasteboard with a surfacing bit before the router is trimmed. I repeat: You surface it before the router is trimmed. You may then as result have nice even patterns on the wasteboard. But that doesn’t bother you, because:
You then place a glass plate on the wasteboard. A glass plate, not a block of granite. You take a block of granite if you want to bend your table top. Here you take a glass plate (the size of the glass plate should be twice the length of the swing arm you use in the next step). Since you made sure in steps 1 and 2 that your wasteboard is flat and not twisted, the glass pane lies flat everywhere without tilting or being twisted. The bumps that the untrimmed router left in the wasteboard are irrelevant, because the glass plate lies on the elevations of the pattern and they are the same height everywhere.
Now take your swing arm with one dial indicator and clamp it into the router’s collet. I repeat: A swing arm with one dial indicator, not two. Having two dial indicators means that the axis of the instrument has to be perpendicular to the leg with high precision and that is expensive. Spending money without having to is nonsense. With only one dial indicator, however, it doesn’t matter if your swing arm is perpendicular to the axis. Not at all. This is very inexpensive and perfectly accurate (as long as it doesn’t bend or wobble when measuring). You also might use the swing arm method with no dial indicator at all, just bend a steel rod into shape, or you can use the swing arm method with touch probe.
And now you place your glass plate anywhere you like on the wasteboard, you move the router (with CNC controller powered off) so that it is above the glass plate, and do: Swing dial indicator forwards, measure, backwards, measure, to the right, measure, to the left, measure, and then you have the four values you need to trim the router.
(How the trimming itself is performed is described in another posting.)
After finally having trimmed the router and checked that now the four measurements on your dial indicator are equal everywhere, you then repeat surfacing the wasteboard, and voilà, the nice even patterns are gone.
Hope this helps!
In fact you are able to surface it correctly. As long as the machine is not twisted (checked in step 1 above) you can surface it – if the machine is not twisted, the wasteboard will not be twisted either and thus be planar. And as for the even patterns that the untrimmed router left behind, you resurface again after the router is trimmed (step 6) and they are gone.
Notes
I have a block of granite like this, and do you know what its purpose is? Dress japanese waterstones and cast-iron hand plane soles with clinging wet sandpaper. For that they are excellent.
I have a 9.5x12.5x2" block. But my spoilboard is the standard 3/4" MDF on a QCW frame mounted on my plywood torsion box benchtop. I’m using the middle holes for mounting the Z.
Thanks for the co-planar tip. I ran a monofilament line diagonally on 4 points and at the center where they crossed I got a ~1/16" gap. I cannot imagine on a plywood table, across a >36" span getting any closer to co-planar than that. It was good to check, though.
