Getting started with CNC routers with the OpenBuilds C-Beam machine?

[sky99]

Hello all!
I want to get started with CNC, and found the OpenBuild C-beam : OpenBuilds C-Beam Machine - OpenBuilds Part Store
It has a good price, is open source, good documentation and a good community, which are important aspects for me.

I wanted to build a CNC at first, but i obviously lack time, and don't know all that much about CNC (altough i did some research,
bought some HIWIN rails, i have a ballscrew rod, with some other CNC stuff. However, i'd like to get started fast, do some CNC routing projects,
get to know software a bit, etc...

I would like to drive it with a Smoothieboard (unless you guys have something bad to say about those boards, but i doubt it, knowing it's good reputation),
and external drivers for the NEMA23.

I want to get started with wood, and later on try aluminium, as it seems that users of this machine do aluminium with it.
Speed is not a too big deal either, and either this machine is fast enough for my use, or it will be a stepping stone towards buiding my own super rigid CNC (i plan a steel frame).

So what do you think about this CNC as a starter one? I'll probably run it on woods and plastics, and soft metals (i have very thin brass sheets that i want to use for faceplates on projects).
Do you think it'll do the trick as a learning tool, and for hobby use? Do you think i can get it to mill aluminium plates someday for a future CNC?

Do you think i can mod it with the things i already have to improve it if needs be?

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[sky99]

By the way, what do you think about driving it with a smoothieboard?

[TumbiUmbiTek]

If your building a C Beam for a controller you could probably get away with Arduino + CNC shield + 8825 drivers $30 on eBay. Flash with GRBL and use Easel or fusion 360 to create your code. Spend @ $130 at OMC Steppers online and you have 3 x nema23 2.8amp steppers and a 36v 10amp PSU and you've got all electronics for under $200 and software is free. This will easily drive your C Beam. I'm only a babe at this stuff but there's my two cents. Cheers

Sent from my LG-H870DS using Tapatalk

[fretman_2]

I agree...this is basically what I'm using...Arduino Uno running GRBL direct out to M542T drivers. I bought my motors and drivers from Steppermotoronline. It's a simple setup, but it works for everything I've done.

If your building a C Beam for a controller you could probably get away with Arduino + CNC shield + 8825 drivers $30 on eBay. Flash with GRBL and use Easel or fusion 360 to create your code. Spend @ $130 at OMC Steppers online and you have 3 x nema23 2.8amp steppers and a 36v 10amp PSU and you've got all electronics for under $200 and software is free. This will easily drive your C Beam. I'm only a babe at this stuff but there's my two cents. Cheers

Sent from my LG-H870DS using Tapatalk

[TumbiUmbiTek]

I agree...this is basically what I'm using...Arduino Uno running GRBL direct out to M542T drivers. I bought my motors and drivers from Steppermotoronline. It's a simple setup, but it works for everything I've done.

Ive just bought a 2nd hand pc to load linuxcnc onto, but am happy for this to be a long term learn. The smoothieboard does seem to have a following... and is the way Im thinking of going later on. Its hard to get advice on what software and controller card to buy because I suppose everyone does the hard yards with what they get and then become a devotee. I figure that choosing the C Beam style (I will use linear rails and ball screws and home made frame) I wont need to worry about flex in the gantry so much. Controller and software wise.. I figure with what I'll be able to do at first it wont matter what controller or software until my understanding/skill catches up with the hardware/software.

Sent from my LG-H870DS using Tapatalk

[wizard]

So what do you think about this CNC as a starter one? I'll probably run it on woods and plastics, and soft metals (i have very thin brass sheets that i want to use for faceplates on projects).
Do you think it'll do the trick as a learning tool, and for hobby use? Do you think i can get it to mill aluminium plates someday for a future CNC?

These are really hard questions to answer because much of it comes down to your expectations. So to your quoted questions:

1. Is it a good starter platform, hard for me to answer. I would tend to say no from personal experience in a wood working shop. Having purchased a few cheaper tools over the years and really learning to regret it, I would tend to argue going first with a machine that best fits your future needs. This can be likened to buying a crappy table saw and then 5 years down the road buying a more substantial unit. Generally going that route puts you behind in the pocket book and with respect to time. Oh and be careful about the term "soft metals" some of those reads alloys are anything but soft and some alloys of aluminum are really gummy and a pain to machine.

2. For learning almost anything will work if the goal is to master G-Code and the supporting CAD/CAM suites. Up to a certain extent anyways, at some point to increase your skills level you need to you need a machine that can do quality work. This implies a stiff machine with low backlash. As for hobby use against it comes back to what you expect. Some people build fine musical instruments for a hobby and as such have high expectations for precision and repeatability. Others are building boats! The tis a wide range of requirements and requires thought on your part as to what your expectations are.

3. Mill aluminum? That is a hard question to answer, it certainly won't due in a production environment at least not for what I'd expect out of machining aluminum. There is also the question of how well you put it all together.


In any event a few comments on extruded T-slotted aluminum. What you can get varies widely in construing and quality. From my standpoint most of the stuff on the market is not really suitable for linear rail mounting. Further many underestimate the costs, which includes not only the extrusions but the hardware and gussets plates to hold it all together. Plus often it is a good idea to pay a fee to have the extrusion flattened.

If you are considering a more substantial Aluminum build, you really should be considering a build or partial build out of square or rectangular steel tubing. Using minimal effort you should be able to put together a gantry that is significantly stronger or stiff and still keep the prices reasonable. This usually pays off well for the gantry beam which are chronically under engineered on DIY machines.

In any event best of luck.

[Lucons]

Hi If you would like to build a Aluminum carving machine, you need to ensure high machine stiffness to avoid vibration during engraving Aluminum. This play a great role in cutting quality

[fretman_2]

I really like the C Beam machine concept, but I don't like the delhrin V wheels (or what every plastic they are). I had an aluminum extrusion Shapeoko 2 that wasn't very stiff. I do think that there will be some problems with stiffness with that aluminum extrusion/plastic V wheel combination. To the machine's credit...it's not a large machine so there aren't any large spans of extrusion. Still...the Shapeoko 2 I had started off as a 500mmX500mm machine and it was easily moved (torsion) by applying small amounts of pressure.

[wiremonkey]

Hey folks, I built the Kyo Sphinx with a bit wider X-axis and am struggling with rigidity. Fine for softer woods and acrylic and I can mill aluminum, but not well. I've started down the path of cost effectively upgrading my c-beam based machine if you care to take a peek at my trials and tribulations:
Cheers,
Tyler

[wizard]

Hey folks, I built the Kyo Sphinx with a bit wider X-axis and am struggling with rigidity. Fine for softer woods and acrylic and I can mill aluminum, but not well. I've started down the path of cost effectively upgrading my c-beam based machine if you care to take a peek at my trials and tribulations:
Cheers,
Tyler

Hi Tyler;

Sorry to hear about your rigidity problems. Unfortunately with machine tools there is no pill for that.

In any event your post reinforces in my mind the opinion I developed of this C Beam system from their web site. It really is a light duty solution really not up to the task of a general purpose router. In fact I suspect that some of the DIY roller skate bearing solutions I've seen on line result in stiffer machines.

By the way even though I usually dismiss extrusions due to cost do realize that there are far better extrusions to choose from. Expensive yes but you get what you pay for.

As for steel you should be able to find drops at a local steel supplier for around a $1 a pound ( the price has gone up, at one time it was as low as 60 cents a pound.). If not a steel supplier maybe a fab shop. By the way a combination of extrusions and steel tubing also is very viable.

I understand the cost issues but like I alluded to above my experience with buying wood working tools, based on cost, hasn't been good. Often you end up with tools barely up to the task they are sold for. This is why I haven't built a router yet because I have a good idea how it should perform and what the cost would be. The budget doesn't allow for it to be done out of pocket in one quick build. So I collect parts as time and the pocket book permits.

In any event a great video that highlights why one should avoid C-Beams for this sort of machine. I hope people thinking about going this route give it a view.

[wiremonkey]

Thanks for answering so quickly Mr. Wizard. Agreed, I think eventually I'll just go to steel. I'm trying to decide what thickness and size of x-axis to span about 750mm. I figure that 11 guage (1/8") will probably be thick enough on the walls if I go with 2" x 4" rectangular tube and attach my v track to it. I'd weld plates on the ends for mounting to my aluminum gantries. Yes, I'll probably end up going to steel eventually on the gantries too. You sir, are smarter than I! I just dove in head first. I'll say this though, it's great for cutting plywood, acrylic, even hard wood, but jumping to aluminum was the difficult move. I can do it, but it's not perfect and I have to go slow enough that the tool like probably won't be long. Let me add that the journey has been fantastic and I'm glad that I started and built a machine from scratch. Had I to do it again, I'd probably make a steel Z setup with aluminum X/Y table. The rigidity you can achieve is far greater in that configuration. Cheers and I hope some folks learn from my journey. Cheers.

[skrubol]

Seems like you've got a good idea of where your weak points are, but it might be good to quantify. If you don't have a dial indicator and indicator holder, get them, they're very useful. Mitutoyo indicators and noga holders are about the best value for good quality, but if the budget is really tight, Chinese variants can be had for much less.
Try measuring between the table and various places on the gantry and Z axis while pulling on the spindle in different directions with a fish/luggage scale. Also try with the Z up/down, carriage in the middle/ends of gantry, etc. If you can get repeatable measurements, then you will be able to better isolate where the biggest gains are able to be made from upgrades.

[wiremonkey]

Hello skrubol,
Yes! I'm on it. I have a few dial indicators and use them to calibrate the machine in other ways, but it hadn't occurred to me to use them for this purpose. I have a sweet Federal digital that is accurate to .001mm and just picked up a Mitutoyo dial off off eBay with a 10cm range. Ha! It's a learning curve. I'm in the process now of making that video where I see just where the faults are. I'll post here and please watch and maybe you can lend some input on interpreting the results.
I'll setup the CNC with the router end placed on a hard wood and use the powered CNC to drop the Z a set amount, say 2mm and then I'll take measurements all over the machine, all across the X travel. As I've found out, the X c-beam is the largest offender, but I imagine there are smaller rigidity issues introduced wherever there is a poly carb wheel in my setup.
In the longer run, I'm trying to decide about my future options, should I:
A. Slowly replace my machine with steel components, starting with the X axis beam.
B. Move to an X/Y table design, or at the least, switch the Y travel to table instead of moving gantry and beam. This way I could at least make "steel up" the X and Z.
C. Take the reusable parts in this machine and move to full X/Y table design, all steel. I know I'll give up lots of working area.
Hmmmmmm. So many options and I don't have the space in my tiny shops for two machines or I'd probably head down the path of making a hard core metal only milling machine.
I love the journey!
Thanks for helping out.

[skrubol]

You'll want to measure the force you apply even if you're applying a known displacement. If you don't, as you upgrade components, you may see the areas of deflection change, but you won't be able to measure the improvement.
I don't think C will be worthwhile. If you go that far, might as well go to a C column mill rather than gantry, which would probably have very little part reuse from a router. There's nothing wrong with a router/gantry mill. If you want more Y than Z and don't mind the form factor (column mills are a little easier to load/unload maybe?) a gantry is probably stiffer than a column. After all, the gantry is supported at both ends, whereas a mill head is cantilevered. (about 8x as strong for the same beam, length and load I think.)

[wiremonkey]

It's not a good idea to make an aluminum cutting mill out of aluminum. It's the same reason we don't feed chickens to chickens.

[wiremonkey]

Hmmm, skrubol, how would you measure force? I have a small gram scale (don't get any ideas) but I don't think the range is high enough. A bathroom scale maybe, but that would not be very accurate. What about a torque wrench rigged with an extension arm, I send the Z down until it clicks. Ha! I'll try the bathroom scale and see where things start to move and if it's repeatable.

[skrubol]

It's not a good idea to make an aluminum cutting mill out of aluminum. It's the same reason we don't feed chickens to chickens.

What do you make a mill to cut cast iron or steel out of?
Does Aluminum carry viruses or bacteria I don't know about?

Hmmm, skrubol, how would you measure force? I have a small gram scale (don't get any ideas) but I don't think the range is high enough. A bathroom scale maybe, but that would not be very accurate. What about a torque wrench rigged with an extension arm, I send the Z down until it clicks. Ha! I'll try the bathroom scale and see where things start to move and if it's repeatable.

Fish scale or luggage scale.. They aren't too accurate, but should be decently repeatable and good enough to measure the big gains (you aren't trying to tweak a few percent out, you are looking for several X increase in stiffness it seems,) and they're tension scales so easy to rig. Oh, and dirt cheap.
Something like this https://www.amazon.com/gp/product/B0...d_i=2477391011

[wizard]

Fish scales, assuming they go high enough, are very useful for appling a measured force to a machine. When looking for gross errors you dont need a lot of precision.

If you work on a specific machine type long enough you dont even need a scale. I use to work on a series of lathes and could detect lose mechanical systems with out the aid of a scale. You get to the point that you know how much force is suitable for each axis. The idea behind using a scale is to help people new to machinery realize just how much force they are applying. In these light weight machines it is pretty easy to apply more force than required.

[fretman_2]

Put a dial indicator on your spindle so it will measure sideways...zero it out, then push sideways or laterally on your gantry. You'll get a rough idea of just how stiff it is from doing that...

[wiremonkey]

OK folks, table top 70lb postage scale in hand. Watch me now! Thanks for the hot tips. I'm just doing one little upgrade, a 1/4" steel plate on top of my bed aluminum (al-yoo-minee-um for you UK'ers) extrusion. Meant to beef up the Z to machine rigidity in general and increase mass (about 40lbs) since I'm adding more weight to my moving parts on this thing. I've added the stainless 2mm wall channel to the c-beam X and there is no doubt that it helped, but by how much is the question at hand. I'll post a video about my findings in the next day or so.
Pip, pip...