[lukewarm]

This is my second post here but I've browsed this forum quite a bit and learned a lot of great info from it. So this thread will detail my build as we progress and hopefully contribute a bit to this great forum and provide us with some invaluable feed back.

The stats on this machine so far are 10' by 5' rails and 14" of cutting depth. The x and y axis run on angle iron and sawmill carriage wheels. The z axis has yet to be determined but we're leaning toward a bearingless gib setup (sorry if I mix my terms please feel free to correct me). The x-axis (the long axis) will be driven by a cable drive setup and maybe one day in the future we might go to rack and pinion but for now our goals are low so we're going to try it. The building materials are mostly all scrounged bush metal we found and had donated so it has been built a bit excessively heavy, but bigger is better in my opinion.

Here's a few pictures. I'll try and answer any questions. Please note I'm not a machinist or a fabricator and we're learning as we go along so be gentle Cheers

[lukewarm]

Y-axis trucks. These are going to bolt to a piece of 6" x 10" x 1/2" plate with adjustment through shim stock and slots.

[lukewarm]

Hmmm, I suck at attaching files.

[lukewarm]

One more

[lukewarm]

I've been trying to size the motors for this project using software from Danaher Motion and I am led to believe that Nema 34 873 oz-in stepper motors would suffice for the long axis. My gantry weighs 200kg and is going to be driven by a chain drive setup. The chain is TSUBAKI RS40 with 1/2 inch pitch, the drive sprocket is a 10 tooth sprocket so 5" of travel per revolution and the sprocket will be driven by a 3:1 timing belt reduction. I believe this puts my resolution at 0.008" per step @ 1.8deg.

I'm not very confident that in the softwares results because I'm not 100% sure I put all the parameters in right so I'm hoping someone with real world experience can advise me if I'm on the right path with these motors. If I left out any important details please point them out, thanks in advance!

Also please feel free to criticize or question any aspect of my build. Any input is good input, I look forward to any response

EDIT: Also if someone can point me in the direction of information that would help me answer my own question I'd also appreciate that, I don't need to be spoon-fed the answer but my google-fu seems to be weak right now.

[lukewarm]

No replies yet but I thought I'd update anyway to let everyone know I'm pretty sure I've got my stepper motor issue figured out. Gearing only affects resolution as steppers are constant power not constant torque... Also have replaced the cross beam on the x-axis with a larger piece of I-Beam made of 1/2" material versus the 3/16" one we had originally. Just seemed out of place.


Anyway, the next purchase is 48" of 2" linear shaft and some 2" Rulon (awesome material) bearings for the Z-axis. Have decided the original metal-on-metal idea would be bad due to friction and resulting slip-stop chatter.

We're coming to realize that we've bitten off a lot with this project. What originally seems like a simple concept proves to be quite a challenge to implement. Every day is a learning curve with this project.


Thanks

[nofx]

I'm envious of those sawmill carriage wheels, Whats the diameter of them? The look tough as rocks. The thing with using a chain drive like your purposing is that u could in theory get 2 different ones one with say 2inch of travel and close up ur resolution and slow down ur speed a bit, if u want to do a more precise work and a large one for faster movement. Pop and tension. I'm interested in seeing more.

[lukewarm]

They have a 4" diameter and are built to last Got them from a somewhat local ebayer for a pretty good deal.


Yeah I'm looking forward to seeing how the chain drive works on the long axis. The idler sprockets we've ordered are good quality Martin brand with hardened teeth and good bearings. I'm confident we'll be able to put enough tension (500, 1000 pounds?) on the chain to take up any lash without distorting the frame or wearing out our parts. However I am apprehensive about the percent efficiency we'll get with chain as our stepper motors could be on the weak side. We may have to upgrade that axises motor. The other axises all going to be driven by rolled ball screws and nuts.

[voltsandbolts]

lukewarm,

I am working on my second router and am planning on trying chain drive on the X and Y. I will be interested in seeing how you implement your chain setup. I will be using #35 chain and 10 tooth drive sprockets, not sure if Ill need any reduction on the steppers.

I am building mostly from materials I had on hand or could scrounge easily.

Your build is looking good!

Rob

[jsheerin]

That gearing setup should work. I ran a simulation with a Keling 960oz*in N34 motor and that would give you above 100 lbf to cut with below ~850ipm going up to above 200 lbf at 0 ipm. This is with acceleration set at 50 in/s^2.

[lukewarm]

Thanks Jsheerin! Appreciate it

[lukewarm]

Finally had some time to do some work on the machine. Finished the y-axis carriage. It's two 1/2" plates sandwiched together to allow full adjustment of the trucks and fine tuning of the carriage. As it stands without the z-axiz assembly it weighs close to 100# I'd estimate.

[tommylight]

And i thought i was building something big !!!
That thing looks amazing, and definitely will take a lot of beating. As far as the steppers are concerned, i have some NEMA 34 that can pull an astonishing amount of weight on rails, so you should be good to go. Keep the good work and keep us posted.

Regards,
Tom, the other.

[lukewarm]

Thanks Tommy! This whole build has been subject to tons of changes. The turning point size-wise was when we decided to use the sawmill carriage wheels rather than a conventional linear guide setup. The frame and carriage had to be upgraded accordingly to fit the theme of the new wheels, I guess....

I'm happy to hear the feedback in regards to the Nema 34 steppers. Every time we add another 100 pounds of metal I cringe and fear for them. When we first got them they seemed like overkill, but our carriage wasn't as overweight back then


[b]A quick theoretical question: [\b]

Will milling steel be out of grasp for this machines rigidity? I'm fairly certain aluminum won't be a problem but I'd like to be able to mill steel. I'm looking at purchasing an X2 spindle to put on htis machine.

[lukewarm]

We've refocused a bit and decided to cut our long axis travel in half and dedicate this machine to aluminum and steel (hopefully) only. Yikes.

[lukewarm]

Been a while since I've posted any new photos, so here's a few to show our progress so far.

These pictures are of the Z assembly we devised. It's ugly but it works quite well, very little friction and quite solid feeling. The milling head is an X2 from littlemachineshop that will be powered by a 1.5HP motor and VFD combo.

I didn't take new pictures of the gantry yet, but the ball screw and motor are mounted on it. Next step is to mount limit switches, finish up a few loose ends and then get to the wiring nightmare.

[lukewarm]

Been doing a lot of electrical work. Our VFD logic board blew up so we made a replacement logic board but managed to let the smoke out of some IGBT packs by hooking up a connector wrong :nono: So here are some pictures of the replacements we built. Circuits, circuit boards and software are all of own design. Should do the job nicely =)

[lukewarm]

Random pictures

[lukewarm]

Again

[lukewarm]

The code for the VFD is still being written and tweaked so in the meantime I've been playing with the oxy-propane cutting attachment we made. Here are the results: