In trying to tram my X direction I found that the X Motor is torquing the entire X C-Beam. I get a ridge (in the z- direction) on the forward cut when moving in the X minus direction. When it moves in the X positive direction the cuts are flush. So I get this weird "wave" instead of a flat surface. Anyone else have this issue?
This probably has less to do with tramming and more to do with climb vs conventional cutting and overall torsional rigidity of the gantry vis-a-vis the leverage of your spindle arm. If your machine can't handle it, simply uncheck the "Both Ways" option in CAM and go with the method that provides the best finish- climb milling, in this case, which is normally the case in CNC. Both Ways is primarily a high-speed decking strategy, not a surface finish strategy. Add Stock To Leave (slightly larger than your ridge height) and then add a second facing op that's climb-milling only, if you like.
I'll give that a shot, thanks. Didn't think about the climb vs conventional, but then again I am only taking 0.01" off so didn't consider the bit would be "digging in" to cause any deflection.
In what material and cutter geometry? That doesn't seem like much... Maybe something's loose somewhere. If you have a dial indicator, try measuring different parts of the machine while it's cutting. It'll always dig in a little bit with conventional cutting and a spiral flute cutter, but that doesn't seem like enough DoC to cause a 30% dig-in problem.
It was doing this while surfacing a piece of HDPE so I decided to recheck everything and make sure all is square and flat. The Y direction is near perfect but I still get this goofy wave in the X direction. For testing I have been using the Pink insulation foam sheet, which is why I was thinking it might be a torquing action. I should be able to run more test this weekend, the dial indicator is a good idea. That should tell me if the C-Beam for the X is twisting.
When moving in the X-minus direction the tool is not 90 to the table, but when moving in the X-Positive direction the tool IS 90 to the table. It;s not a saw tooth pattern (see the red and blue lines above). I'm trying to figure out why it is not 90 in one direction and is 90 in the other.
That could happen if the Z axis is a bit loose between the wheels. I mean, its possible that with the lateral force on the cutter bit in one direction, the axis is "rotated" to say, 90 degrees (assuming it wasn't perfectly upright), but in the other direction it is rotated to less than 90 degrees. If the axis was perfectly perpendicular to the bed, but a tad sloppy then you would get the same problem in both directions.- hence the angular cut. With a perfectly trammed Z axis and firm wheel pressure it should be fine, unless you have some other mechanical problem I can't think of.
Don't know if this is related but I noticed today there is a "jitter" or "hesitation" when moving in the X positive (right) direction. It's not there when moving left (X negative). I can feel it with my hand on the Z axes. While moving right it jitters as if there is debris built up on the wheels, but I it's not there when moving left. None of the wheels are loose on the Z or X axes. What would make it hesitate in one direction but not the other? This is obviously causing my chatter on round cuts.
I would say it does sound like you're "digging" in when going one direction and not the other direction, as Rob suggested. I recently trammed my workbee, and did it by building a small rig for it: it helped be a lot getting things more level. (yes, there is room for another indicator, but i only have one) As you can see, i also have some issues with the flatness of my spoilboard (which was leveled before i made this device.) You can also buy them, but this was cheap as i had everything laying about. If you wish, i can share the fusion file.
I can't imagine my bit digging in on pink foam insulation at 0.01" deep. I think there is something else going on here, see my most previous post. The more I dig into this the more scratch my head moments I find. When moving right, I get a jitter. This really shows up when cutting a circle. The cut is smooth except for quadrants when the gantry is moving in the X positive direction on the curve. Regardless of climb cut or conventional. I believe this issue to be related. I also have measured a 0.0005 deflection in the X C-Beam, but only when moving the gantry to the right. I will admit that my waste board contributes to this as well, but I can only mitigate the issue and not eliminate the issue. Facing in the Y direction is near-perfect, both directions. Facing in the X direction is near-perfect when moving left, but canted when moving right - and here is another kicker - it's not uniform. Sometimes it will will skip a pass and be flush. And just to add another monkey wrench, the "jitter" happens ONLY on the left half of the X Beam and ONLY in the right direction (X positive), once it passes half way, no more jitter. I can not find anything loose, the wheels are tight and clean. The X beam is level and no twisted that I can see. Nothing appears to be in a bind. Threaded rod is clean. I'm going to check the motor connections as Gary suggested next (bad motor?). How tight should the wheels be? I should not be ale to rotate them with my fingers correct? Could they be too tight? Increase the current to the X motor maybe? I'll try to fiddle with it tonight. Thanks everyone for your suggestions.
Maybe you answered before, so sorry if you have, but, chuck up a long endmill, hold the tip (power unplugged for router please) and give it a good wiggle... human touch can "feel" movements much smaller than the eye can see, and this tactile approach can be used to follow the "this feels a little loose" feeling all the way up the chain until you find something loose that shouldn't be / or locate something flexing within spec but now you know the source
Okie. That sounds weird. Have you checked your leadscrew? The fast That it’s only in one direction and only on part of the Travel suggests something that is not the same across the whole beam. as for electrical problems it’s very odd that I’d only be on one part of the travel across x. Do you have any way of measure the flex in the spindle? See if it’s changing as it travels across x axis?
I had a little bit of time this evening, 1. I was mistaken - the jitter does happen across the entire distance of the X. It's just not as noticeable. 2. I found that the Y axes does this also, in both directions. 3. Adjusting the current POTs didn't make a difference. 4. I believe this is an issue with the lead screws and threaded blocks. I loosened and re tightened the blocks on both Y leads and the jitter got a little better, I think. Or at least different. Is there a method to ensure these blocks are aligned properly and perpendicular to the lead and not binding it? 5. I checked every screw, nut, set screw, wheel, bracket I could find. nothing is loose. 6. Attached is a vid of me flexing the Z, I feel it has way to much movement in the front/back direction with very little pressure. This is why I am considering adding the High Z mod to stiffen the Z axes. There is very little movement side to side. The entire z flexes, nothing appeared loose.
Using the Interface, it is worse at 100%. Still there even at 50% but not near as noticeable. Haven't had time to run very many test yet but I'm not sure this jitter is present when cutting - and have suspicions that it is coming from poor communication between the Interface and Xbox. I have been having "anomalies" with the Interface. For example the X- button will sometimes move the machine in the Y- direction. the Y- button even lights up as if being pressed. The X+ button will sometimes start-stop-start-stop really fast without lifting my finger. I have had the X motor go into fault twice now, the "!" lights up red on the Xbox and the machine wont move in the X direction. That may have been due to the fact I turned the current limit up. I backed it off to where it was so we will see if it continues. Haven't had a chance yet to connect my laptop and see if that makes a difference. I think hard buttons would be more reliable. The Y direction jitters as well, but doesn't seem to translate into actual cutting. Cuts in the Y direction are fairly clean. the X direction however sucks and I believe this is due to the Z gantry not being very stable. In the picture this was cut with a 2 flute HSS, 12200 rpm 2169 mm/sec, 1.5875mm DOC climb cut. The top piece you can see the chatter, the bottom piece is the same cut but this time I was simply holding the front of the OpenBuilds Router bracket. Not a lot of pressure, just holding it steady. So, I need to either replace the X wheels with some linear rails, or try a second beam. I have also found 2 cracked wheels on the X gantry, pictured. Are these wheels molded or machined? the crack is so straight I wonder if they are cracking on the mold line. These wheels are the two forward wheels on the X, the ones that carry all the weight of the router and get all the force when pushing/pulling on the cutter. Early on I think I was running this machine too aggressive and the instabilities were too much for the wheels to handle. Not sure if this is what is causing the X jitter or not. But will replace them when and if I upgrade to a second beam on the X.
looks like a line (just a dent) that happens when I run the wheel into an end plate, does it go all the way through? 2169 is real fast! Gary
They are machined, but its possible the raw stock may be made using a float/mold (How acrylic plastic is made - material, making, used, processing, parts, Raw Materials) If they are new enough - http://support.openbuilds.com/support/home will be happy to help, if its been some time, consider it long term consumable
It sounds weird. I've had dents in my wheels (cause i ran over a wire) - without any issues. It seems that there are multiple issues to iron out. Electronics: - do you get the same issues if you use a pc and control the machine through usb from openbuilds control or something similar? - Does anything get hot when running? (i.e. controller, psu, motors?) Mechanics: - You could well go-ahead and replace the wheels with the cracks, though I'd be surprised if that makes the problem go away. - It does sound there is something loose. when you can put a hand on the clamp, and make the vibration go away, something is off - 2169 mm/min (i pressume it's not /sec?) - is a bit on the fast side, and if your bit is dull it means everything comes under heavy load. I usually run around 1800mm/min in plastic (POM) and most woods. though your dept of cut isn't too much. - what happens if you run the same program with around 1200mm/min? - it does sound like something is flexing too much. Are your leadscrews completely fixed and tensioned, so they can't move the least? (if they can move back and forth, it obviously creates a poor quality of cut. - last resort from me would be to take the Z and X axis apart, completely, and reassemble them, so that you can check that everything is tight. Sometimes when i take things apart, i realise that i've made a mistake, or discover something broken, that wasn't visible when it was assembled. it's not much help, but i hope you find something useful in there.
@Gary I haven't ran my X into the end plat yet - I have however ran the Y into end plates, no mark on those wheels however. The Speeds I am using are from sources of Speeds and Feeds I have been reading about but I for get that info is for machines that can handle those speeds. Most sites I look on have the surface speed at 400 - 600 ft/min and a chip load of 0.003 to 0.006 for HDPE. but I see I am going to have to slow things down a bit. @Peter Thanks, I purchased the LEAD 1010 in November, but like I said, I think I have been too aggressive with it. I'll order extra wheels with the High Z mod kit. @Kristoffer I'll be able to connect my laptop this weekend to it and see if I get the same results. Nothing gets hot that I can tell. I've slowed it down to around 1700 mm/min without much difference. If you watch the video I posted above on a different reply you can see how much flex there is in the forward/back direction of the Z axes. I'll see if I can find a speed that gives me a clean cut this weekend. Like I said, i may be just to aggressive with it. I think adding a second beam on the X will help reduce that Z flex. I'll check my lead screws and make sure they are tight and not moving end to end. I know they flex but I don't think they move end to end. I'll do more testing and see if I can figure anything else this weekend, I'll keep you all posted. Thanks everyone.
I would say stiffening the x axis and z axis could help. One more thing after rewatching your video: - is that test done with the carriage in roughly the middle of the x axis, or is it at the end? - and do you need all that Z-travel? it looks to me like the X axis could be moved up or down on the vertical beams it's mounted to? and by doing so, you could perhaps have less z-travel and gain a lot more rigidity?
Could the jitter be whip in the lead screw? Kirstoffer asked if the lead screw is under tension since tension will reduce/eliminate the whip.
That's what I'm going to check this weekend. I don't think they whip but I haven't checked to make sure.
Yes, the router is about center on the X beam, and I am planing on using this to flatten spalted wood logs and such, so I need about 3" to 4". However I am thinking about making a new table so I can remove the waste board and supports and I can mount logs from underneath. That way they can be any thickness I need. I'll just be flattening the surface, not carving anything. But you and @JustinTime hit the nail on the head. I re tension the lead screws and happy days - the jitter was gone, both the X and Y. (knock on wood) I then did testing with my feeds and speeds and I get a acceptable cut at around 1500 mm/min. However the Z still has a lot of play to and fro, I would be able to go faster. So I will probably be adding the High Z mod to get a second beam. I'll cut down the Z and the two vertical pieces for a standard height like the LEAD 1515. Tomorrow I will run my tramming test again and see how that pans out. I got side tracked today and forgot what started all this lol. Thanks!!
Brilliant news! Thanks for the update, and fantastic what a little bit of play can do. I'm using a workbee (not too far from a LEAD), and was rough-cutting aluminum yesterday at 2400mm/min, so it is possible that you can get more speed, depending on depth of cut ofcourse. I'm working on a new X and Z axis for it, as i feel it has too much flex as it is today. C-beam aluminum is not the stiffest material on the planet. I'm trying my luck with some liniear rails. You could look into that to stiffen things up. - But no doubt, running Z as close to the "X-Beam" as possible, will take out a lot of flex. Happy routing!
Thanks again everyone, As for Tramming issue, I realized I drew my original image backwards, it leave the forward edge on the X+ direction and flat on the X-, But anyways. after all this I have gotten that ridge down to less than 0.001. So the issues is still there but far less than previously. As I mentioned before, I can see about a 0.001 deflection in the beam when moving back and forth so some if not all of this is due to the X motor torquing the beam. I've resolved to surfacing in one direction for the best cut. These are my chips for 1500mm/min single flute, 1.5875mm doc. No chatter and very little deflection on a 1" thick part.
