I've been reading for the the last 4 or 5 hours... This looks like the right spot.
C-Beam Sphinx seems to be robust enough for what I am trying to achieve (maybe?)

If my build was complete I could cut my own plate set... lol...
Bootstrapping has a price.

Questions to be asked before I start ordering the piece parts...

Will the Sphinx support a 1.5kw spindle? I'd like to do some small < 12" x 6, fairly shallow aluminum enclosures. < 2"
Will I be able to support 12x6" on the standard Build or will I need to go larger and if larger will I still have adequate rigidity for a 1.5kw spindle cutting aluminum?

Thanks,
Robert

 

Robert,

We seem to be in the exact same place! I am planning towards building a Sphinx. What about you? Andy with UGRACNC.COM helped me get focused that I would be running a CNC router, not a CDC mill. He said, "For your machine a 0.8kW or 1.5kW spindle feels right. 2.2kW looks to be an overkill. Your machine is not rigid enough." Will the Sphinx support a 1.5 KW or 2.2 KW spindle or not??? Does the Z axis need a brake to lock the z axis when not powered?

Refer to a post at: C-Beam cnc

I am drawn towards an ER20 collet. It seems to me that the ability to have a 1/2" end mill that has a 2" cutting length is just what I/we need to do the finish surface cut on small (2") parts. The bulk of the work would have to be done by smaller "bits". Say 1/4" OR 3/8".

I like the Onsrud web site. They have a lot of information about end mills and the feed and speed and depth of cut. the NYC CNC Youtube videos are excellent, too! I built a spreadsheet to work through the calcs and see approximately how much spindle HP is required for various end mills doing various cuts to aluminum. It was not uncommon to bump the sky for a 1.5KW spindle. I have attempted to upload the spread sheet. Please take a look and let me know if you think the model is valid or full of bull shavings! HOpe to hear back from you.

Sincerely,
Wayne B
Atlanta, GA

 

Hi @Kyo,

Great build !

I would like to build a Sphinx XL and I would like to know if it's possible to get the 3D parts files with the latest update (50 mm taller and correction for the nuts). I would like the same file as Chris Laidlaw use to sell on ebay..
I can produce the parts for my future machine at my work and I need the 3D files (STL,iges or step) to be able to do it.

Thanks for your help !
Jerome

 

I'm interested in this design, but I have a question about the z-axis. I've tried to read through the whole thread (whew!....) but I don't understand the point of the pulleys and belts at the top of the z-axis. Is that just to keep the lower center of gravity? It seems to add to the cost without the benefit of a reduction.

Thanks.

 

What is the z travel of this machine? Sorry if this question is already covered in the posts. I could not find it.
Thanks! I'm hoping to build one. Thanks for the great documentation!

 

I have been eying off the Plate maker because of the solid bridge instead of gantry, based off of people telling me that you need fixed bridge to make alloy plate parts. However in the description nd in comments you are talking of using this for cutting/milling alloy plates.

One thing I wanted was the plate maker, but just a bit bigger. My option was to have out riggers on the plate maker, then I saw your build. I love the way you have made it, it is sturdy looking for sure. Do you have any videos of you milling alloy plates to set me at rest to now decide on this build? If so I would love to know your thoughts on using this for milling alloy. This is the thing that has kept me from deciding which way to go.

 

No, sorry, no video. I have done a limited amount of aluminum milling and it seems good. Aluminum milling is a bit of a black art, but lots of people have done it successfully, even using machines like the OX. You need a lot of practice to get bit selection, cut depth, router speed, feed speeds, etc just right. Also requires some kind of lubrication, which makes a metal bed pretty much a necessity.

There should be lots of youtube videos out there of guys milling aluminum.

MG

 

Would you say as sturdy and good as the plate maker?

 

Don't know what you mean by "plate maker"... If you mean the original C-Beam Machine, then yes, its WAY better. Much simpler to build, MUCH stronger bed, stronger axes, 75% larger machining area, not much difference in price.

With a C-Beam, you can only get so much stiffness out of it, but this design, IMHO, beats the original hands down. One of the keys to getting a stiff machine is to keep it small. Machining aluminum with a 1000x1000mm machine would be poor at best.

MG

 

Hi MG,

Sorry I was referring to the CBM Plate maker.
C-Beam™ Machine - Plate Maker

Would you suggest the Plate maker over this Sphynx? Or did you mean above that the Sphynx is a better and stronger build? I have had people in the custom CNC group on Facebook last week telling me that I need to look for a machine with a rigid non moving gantry. They called it a bridge machine? Apologies, but I am so new to all this at the moment, and don't want to go down the wrong path for my first real CNC. At the moment all I have is an MPCNC for cutting foam and balsa. I am now wanting to cut alloy stuff.

I cannot imagine the need to go bigger than 500x500 for now on this build since I have the MPCNC to do long lengths of balsa and foam etc.

 

Alternatively I see you have built the upgraded CBM machine with outriggers. That was going to be my other choice of build if the Sphinx was not suggested by you.

 

No, I meant the Improved CBM, not the Sphinx. I have no experience with the Sphinx design, although Kyo seems to have done a great job... Seems that the Sphinx would be quite a bit more expensive to build, because of all the custom plates.

And yes, a "bridge" or moving table design should theoretically be stiffer than a design with a moving gantry. Assuming the table is properly supported, which was the major flaw in the original CBM design.

MG

 

I've gone ahead and built a "Sphinx". I might make some modifications later. I'm not sure why such limited Z is OK for many builders. I guess the difference is woodworking vs metal work.

Anyhow...

I am doing the wiring, and I am not sure how to attach a cable chain to the X axis gantry. With the trucks completely surrounding the C-Beam, I don't see where it can go and not interfere. I tried to read through the whole thread again, but only found reference to cable chain on the Y axis. I don't know if I'm just missing something obvious, but can anyone point me in the right direction?

Thanks.

 

@Rick 2.0 Thank you. I hadn't seen that. Lot's of pages on this build!

I wish I had seen that when I was ordering the v-slot. I'm reluctant to pay for shipping again. But it does give me ideas about where and how to mount the chain. Thanks!

 

You could just go to Home Depot and get a piece of 1x1" or 1.5x1.5" aluminum angle and just use that. Save having to ship v-slot...

MG

 

Here is my solution, based on a 0.5x0.75x0.0625 inch, aluminum angle from my local hardware store. There's a little sag. So, a wider or thicker extrusion might be better, but it's working just fine so far.

 

@Metalguru that was just what I was thinking. The thought of using the treaded holes for the motor mounts is appealing. I thought I could adapt that to just some aluminum angle.

@Tom C thanks for the STL! I'll print that up today and give it a try. PS, how are you attaching the spoilboard? T-Nuts? How do you keep from losing your mind trying to line them up to the holes in your spoilboard?

 

I usually use tee nuts and countersink the heads of the screws below the table surface by drilling about 5mm with a 1/2" forstner bit and then the rest of the way through with a 1/4" bit. This leaves the hole a bit sloppy so the screw is easier to line up. Pre measure the rail and position your tee nuts ahead of time. Use a small pick or scribe to line up the tee nuts with the hole when you put the spoil board on.

If you have access to the ends of the rails, I also use a piece ot TIG welding rod which is about a meter long x 1/16 diam, with a 1/4" rare earth magnet heatshrinked onto the end. Stick your tee nut to the magnet and you can easily slide it into the v-slot anywhere on the rail.

Lately, I have been using the 4 hole angle brackets a lot, I put them on the sides of the bed rails before assembly and then screw up into the bed through the angle brackets from underneath using a 5/8" screw. This securely fastens the bed and leaves most of your sanity and hair intact.

MG

 

I use drop in T-nuts (Drop In Tee Nuts) T-bolts with nylon insert locknuts (Nylon Insert Hex Locknut - M5). I countersink the spoil board similar to what @Metalguru descrlibed. I put the screws through the spoil board and get the treads started into the nylon insert before dropping the board onto the CNC frame. There's enough friction with the nylon that I can turn the T-nut into position to drop into the slot. As you tighten the locknut the T-nut will twist into place.

 

You completely lost me on that one... What is the purpose of the nylon nut? How do you have room for both a nylon nut and a tee nut in the slot? And how do you line up all 4 sides at once? And what's to stop the tee nut from jamming against the nylon nut before it's tight in the slot?

I find drop in tee nuts to be more of a pain than not, I use them only as a last resort, to avoid taking apart an assembly to put in pre-assembly tee nuts.

If you carefully measure your hole positions on the spoil board ( I use a compass to scribe a centerline down all 4 sides of the board), and then match the tee nut positions in the v-slot, it's pretty easy to line everything up. I only use tee nuts and through screws around the perimeter of the spoil board, on the center supports I use the angle brackets and screw the spoil board on from underneath. But then, I've built around 30 machines, it all gets easier with practice.

MG

 

My apologies for the confusion. I seem to have misspoke and pointed to the wrong link. I meant to say that I used T-bolts (https://www.amazon.com/gp/product/B072BFLLNJ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) with the nylon insert locknuts. So, the T-bolt is inserted through the bottom of the spoilboard, and a locknut (with washer) is started onto the threads of the bolt on the top side of the spoilboard. The nylon insert gets a good grip on the bolt threads and allows you to twist it into position.

Again, sorry for the confusion. I think I lost a couple more brain cells while I was writing that.

Tom

 

Ahhh, I get it now. Dang, those things ain't cheap.

MG

 

@Kyo
Nice build, I'm looking to build the same.

What kind of tolerance you can achieve with this machine?

Thanks!

 

I'm having a hard time finding M5 Low profile 27mm bolts. 30mm is too big for the c-frame and 25 seems too short to grab the nut enough. Where did you get your 27mm?

 

Once you hit 25mm in length, the lengths start going up in 5mm increments. Shorter than 25 they are usually avaialble in 2mm increments.

You could always use a belt sander to take off a couple of mm off a 30 screw.

MG