I'm in the beginning stages of planning for a new CNC. I'm thinking of something like a LEAD CNC, maybe with a different aspect ratio. My application is bass/guitar construction, using a lot of hard maple. My current setup uses belts, so I'm well acquainted with the advantages of disadvantages of belts, but have zero experience with ACME or ball screws. My concerns about ACME or ball screws come down to those in the title. First, dust. I don't use a dust collection boot. I've looked a different designs and it just isn't for me, for various reasons. I use an enclosure and vacuum out after cuts. My current machine very forgiving with dust, and belt drive may be one reason. I avoid cutting MDF, but occasionally I need to, mostly for spoilboards and jigs. I've been warned about ball screws and dust. I would think ACME screws would be a little less problematic. Second, backlash. Belt drive has no backlash, so I've not deal with it. How much of a problem is this cutting hard maple in real life with an ACME screw? Third, and this is sort of newbie question - what happens when something goes very wrong like driving your collet into a vise or such? This does not happen often, but the belt drive is forgiving, it just starts "slipping" the toothed belt. What happens with a screw drive when the irresistible force meets the immovable object?
I'm considering an upgrade to a new CNC, probably something like a LEAD CNC. A friend has a little Shapeoko, and he mentioned to me that if dust or chips get on top of the lower carriage rails where v wheels roll, it can be a real problem. I use and enclosure instead of a dust boot, so this raised a red flag for me. So I looked at the design of the LEAD CNC, and offhand, it doesn't look like a problem to me, because the design of the extrusion has a pretty deep cavity below where the wheels roll. I would think that any chips that end up flying that direction would simply fall down into the cavity, and then I can vacuum it out after the cut. Is this correct? Thanks for any help..
1) Dust: No real impact. The leadnuts prevent the dust from entering. Occational cleaning will be in order. We also have a really great dust shoe if you later on want to do something better: Dust Shoe for Routers (your lungs will still thank you, even with an enclosure) 2) Dust can accumalate in the slots under the wheels yes if left for a long long time, but the V-shaped profile is pretty much self-cleaning (the part where the wheels roll, ie the important part of the profile) 3) Leadscrews are superior to belts in just about every way... No worries there. More torque, more precision, no backlash as we use anti-backlash nuts (nothing worse than belt stretch issues, constantly going less aggressive for fear of belt slipping on pulley etc) 4) in the event of a hard crash they still just skip the motors - no real chance of permanent damage (motors are appropriately rated)
OK, that's great news. And it just so happens that I'm right now dealing with what looks like a belt stretch issue, though in this case it looks like loss of accuracy. So I'm losing patience with my router. So let me ask another question. If this isn't the right forum or I should change the topic, let me know and I'll repost. I have two choices in replacing my current router. I can try to sell it and start anew - I've been told these Zenbot 24X48 routers can actually get some money even though it's not a good match for me anymore. We'll see. Or I can use the components I've got, and that leads to the question, which is basically "can I start with a standard Openbuilds model like the LEAD CNC and subtract parts to bring down the price, and if so, do I lose anything in terms of package pricing?" Reusable components would be: Four NEMA 23 motors. Gecko stepper motor driver. UCCNC software and USB motion controller Router Final question. My application only requires about 16 in of cutting area in one dimension, but I'd like 48 in the other direction for neck through bass guitar. The openbuilds system is attractive that way because it's modular. So it's similar to the question above - does buying all the individual parts have a cost penalty compared to a package? OK, I forgot, one more question. When building a system with a high aspect ratio table such as above, I've noticed that some design make the gantry the long dimension. This doesn't seem to make sense from a stiffness point of view. It seems like torsional flex in the gantry would be an issue which this design as opposed to having two long rails and a short gantry. Thanks for all your help.
You can re-use some of your components yes. The kits has motors, electronics, etc as optional extras during checkout - just leave it unticked. A customised size is possible yes, but not a significant saving. Leadscrews and extrusions are relatively cheap, so chopping them shorter is hardly ever worth it (unless your workshop really cannot fit the full size). You will always find bigger jobs to do with a bigger machine. Ordering is easier as kit too. Custom requires you to dig through the parts list and checkout individual items. Easier to grab the kit If you do decide to go custom, your instincts are correct - shorter gantry and longer base is stiffer.
More convenient from a loading perspective, and more like a traditional manual mill layout. Your concern about torsional rigidity is spot-on, though; I'd argue it's better to make a long-gantry machine a moving-bed system so you can really massively over-build the gantry and columns with a lesser motor power penalty (it's hard to sling a table, but it's a lot harder to throw a 100lb gantry around). It's easier, build-wise, to make the gantry as narrow as possible, but loading will be slightly less convenient and "table-like". But even that would be significantly reduced if you simply raised the bed up to the height of the side rails and made the long axis a little bit longer to give the gantry room to home out of the way of loading.
Hi, I'm looking at picking up a LEAD CNC, and was pricing things out, and noticed a pretty sizable price difference between the 1010 and the 1515, and then noticed the 1515 has a sort of double gantry. I wonder is that is because the gantry is longer than the 1010 and therefore needs to be stiffer. Here is why I ask. I do need a 48" cutting area in one dimension, future proofing for building neck through bass guitars (I will be building bolt ons for while, until I'm really happy with final designs). But I only need about 16" of cutting area in the other dimension - far less than even the 1010. My current router I'll be upgrading from has a cutting area of 24x48. If the reason for the double gantry on the 1515 is the gantry length, then it would seem I could customize the 1010 by lengthening the rails the gantry rests on, and save some dough. In addition, I could save space in the shop by shortening the gantry. 24x48 is a good fit for both the space I have and the needs I have. I know the machine would be a "side loader", but I already deal with that. Given my needs, would a modified 1010 be a reasonable choice, and if so, what would I do to change the order so I would end up with the right parts? And would doing it custom like this add cost? I'm willing to do the detailed work of modifying a parts list if that is all that is involved. Thanks for any help!
Also bring in the tensioned leadscrew design from the LEAD1515 (going over 1000mm needs the tensioned setup) Pull up Sketchup Make Index of /mirror/sketchup - import the LEAD1515 and LEAD1010 models. Spends some time designing your own machine - draw up a BOM from that and check out the individual parts from the store at openbuildspartstore.com
If you would like a different configuration than is shown in the shop, please contact the shop for a custom quote. Taking the Y-axis up to 1500mm on a LEAD 1010 is a fairly simple trade out for them. As far as flex in the gantry beam, if you're using a normal weight router and only cutting hardwoods with system you shouldn't have issues with flex. And should you desire more stiffness in the gantry at a future date the upgrade is fairly simple and has no backtracking (waste) on parts. As far as the side loader comment, I didn't follow what you're asking. Please provide a sketch of what you had in mind.
Thanks so much for the help. This exchange has convinced me that my initial inclination to go with Openbuilds for a new machine was exactly right. Embracing the maker culture with modular machines is exactly the right note. As far as what I meant by "sideloader", I was referring to a machine where the side rails are considerably longer than the gantry, like my present machine, so you are loading from the "side". I actually think of the X axis of such a machine as being the axis of the side rails, and the Y axis as being the gantry axis.
You will find that very confusing - almost everyone is going to refer to the moving gantry as X (left - right) and the side rails (back - front) as Y. So you are wanting a front loading machine. Alex.
Fair enough. I've been working with the other axis system for a few years now, but I'm very adaptable.
