Exploring the Design Changes of my PrintNC CNC Machine

[@sreed3819]

As a retired structural engineer, I compliment you on your design changes. I think you made many improvements.

[@T0tenkampf]

In general, would Rosette or Slot welds cause less distortion or at least a more balanced distortion on the gantry and gantry support junctions if you were able to design it that way?

[@eackerw85]

Any idea on when the print nc mini will be available?

[@BryanHoward]

Not sure but I think hoges is nearly finished with the design of it. It looks like an amazing little cnc and will probably be more popular than the bigger one. Because of its size, it should handle cutting small metal parts much better than the bigger one too.

[@pholos77]

hi there, nice mods, how do you plan to square everything after welding? i'm curently building one of those too and had an idea to prevent dirt from going onto the rails and ballscrew with bathroom ventilation pipes, surely not perfect but you can adapt it to your flavor, i can share the fusion file if you want

[@xConundrumx]

The immediate problem I see is racking for the Y axis, always a concern with 2 steppers on the Y. I would say add a crossmember at the bottom of the machine that is as wide as you can get away with and aligned endstops for both sides to 0 out the two ends. Downside here is that if you don't and racking does happen the stress can wear out the linear rails and ballscrews.

[@randyborders7855]

I'm not an expert and don't have much experience in cnc I think your build looks awesome and will work really well and be very stable for what your doing I'm not sure how the leverages and weights play into things but in my mind instead of building a complicated gantry riser like that you could get taller tubing or make risers to elevate the tube with short pieces of tubing spacers and weld or bolt it together so your weight is in the frame not adding to the gantry and it would reduce some of the leverage upon the gantry? Also finding coarser pitched ball screws so they don't have to rotate as fast for the travel speeds your after could reduce vibration and increase precision at higher speeds but it may reduce the torque it has also increasing the diameter of the ball screws could help with vibration in them I'm doing my homework now and wanting to build my own setup simular to yours I've built the root one cnc afew years ago but I'm not happy with allot of things with it I've looked into the root 4 cnc and this style design this one looks allot better to me not having plastic for structural pieces and knowing it can be welded after it's bolted and aligned for more strength is appealing also

[@efrencuadro2]

Just a Y axis holder redesigned, PrintNC becomes more powerful now. The 2 pieces Y axis holder can build itself, a must upgrade.

[@gizmobowen]

First of all, thank you for adding the voice annotation. It makes it much easier to understand what you're trying to do. I'm glad you said you have brakes on the Z-axis stepper motors to keep from moving the Z-axis too far. I actually have hard stops on the end of my rails to keep it from going to far. On the y-axis carriages, it isn't clear where you have access to bolt the carriage to the linear bearings. It looks like there's room on the outside but it will be hard to get inside to the screws. By widening so many parts of the Z-carriage and the gantry risers, you seem to be losing a lot of Y travel. Are you going to make the Y-axis parts longer to get the travel back or just live with the reduced working area? Where are all the parts coming from? Do you have access to a milling machine to make up the various components? Will there be any 3D printed parts or do you want to replace them all with machined aluminum parts? I like the idea of the longer rails on the Y-axis rails. I'd definitely do that from the beginning.

[@BryanHoward]

Yeah my machine currently is running servos so having a brake on the Z is an absolute must. Without it, the ball screw can be back spinned when the brake it let go. I’m actually gonna bring in the ball screw closer to the steel beam and flip the ball screw nut housing around. This would have the bolts more accessible than I’ve got in this video. I’ll have less travel in Y and also in X. X doesn’t bother me all that much because it’s the longest axis but Y is already short but it’s the cost of making it more rigid with dual bearings and I think it’d be worth it. I’ve got my printnc cnc machine fully functioning already with the standard 3d printed parts so all these parts would just be made on the machine itself. I’ve cut steel and aluminum and cast iron with good success already. Aluminum is no problem, steel I just make lighter cuts to not push the weak wood and 3d printed parts to breaking point. Alot of the parts to make the gantry risers need to be cut accurately but they don’t necessarily need to be cut on a cnc machine. What I’m thinking of doing is use the cnc machine as a big plotter to mark out accurate cuts and I’ll go back and use the circular saw, grinder, chop saw, etc (conventional tools) to do the actual cutting to save the endmills. I think if I were building a printnc from scratch and plan on doing dual bearing blocks soon after I have it working, I’d do a build with longer rails on the Y axis just because you lose a good deal of travel once you put another bearing block and a respectable amount of space between blocks for rigidity.

[@gac231]

Very nice work and thank you for sharing. Could you get good results by 3d printing the gantry risers and filling them concrete or epoxy ?

[@BuildItAnyway]

yes you could see this article: cncrouterinfo.com/article/avoid-epoxy-granite-for-diy-cnc/

[@CunningLinguist01]

I would also like to know

[@nelsoncastano9779]

Thanks for sharing, how much does that CNC cost?

[@sergeb7945]

Love the overall improvement on rigidity, dual bearing on each rail, aso. My concern is about the welded gantry risers. They will most certainly require post machining due to the stress and warp induced by the welding operations. It would turn the project out of reach of lots of makers imho (plus you'd have to rename it from "PrintNC" to "WeldNC" 🤣)

[@BryanHoward]

This is my own machine and doesn't represent the PrintNC project. Welding always warps but I think the benefits will be worth the added effort to work around that.

[@keithwins]

@@BryanHoward I just found you, so maybe you've addressed this, but it seems to me welding or brazing the y-axis steel tubes to the cross-platform steel tubes would be helpful regarding rigidity: are you doing that?

[@BryanHoward]

@@keithwins TIG brazing silicon bronze is the plan for attaching the risers to the gantry. I've never done tig brazing before so will have to do some practice try's first. I think this would be a good application due to the distortion of welding.

[@pmsilvei]

I think you should mount the X axis ballscrew on the backside of the gantry, instead of being above the linear rail. That has some advantages, one of them is that it stays much more chip free. Also, it let's you upgrade and use stronger Z mounting brackets to the X axis. I did this on my design. BTW, My machine is not a PRINTNC I like your channel 😁

[@gizmobowen]

I agree that this seems like it could be an improvement. I like that it's away from the chips, but it also applies the forces to the gantry in between the linear rails instead of just on the top. That could limit the torque being applied to the ball screw due to the offset loading.

[@BryanHoward]

@@gizmobowen I light this idea too and was thinking about how I could pull it off after seeing them working well on the dual Y axis. Some things I'll run into doing it this way are I'll have to redo the cable chain because I won't be able to mount the rests on the back of the gantry without redoing alot of that work and If I mess with the cable chains I might have to recut/redo wiring with is gonna be a huge pain.

[@akka4751]

your design is great! would you share the cad file or keep it private? cheers

[@BryanHoward]

Thanks, I've put in the link in the description. I do have to make an update as its missing the new gantry risers.

[@MohamedSayed-vu1tm]

This is a good idea and I'm glad you like 👍

[@eldricliew6223]

Try a colder alternative to welding to avoid warping. Maybe brazing or metallised epoxy.

[@BryanHoward]

TIG welding the risers together and than TIG brazing silicon bronze the risers to the gantry tube might be a good way to get around warping. The heat will probably warp it alittle but not as much as straight welding them together.

[@davidpeterlin767]

The design changes are amazing! What kind of computer are you running this on?

[@BryanHoward]

The computer I'm doing cad design on is nothing special. It's something like a 6-year-old gaming PC. 1080 TI GPU. The CNC machine itself runs on linuxCNC.

[@davidpeterlin767]

Thanks for the answer!

[@AryaNakh]

This fantastic! Will you be making the files public? I would to integrate some of your changes in my PrintNC eventually!

[@BryanHoward]

I've got a repo of it here. Hasn't been updated with the new changes to the gantry risers though. I'll have to get around to pushing another update out: github.com/bhowiebkr/PrintNC_Pro_Solidworks

[@texasbowhunter2509]

Your design is very ambitious and admire you for the desire to run with it...However I feel that you are going to get yourself into a bit of trouble trying to weld the Gantry to the support...Personally I would not even dream especially with the time you have put into milling all as precise as you have... So let me offer a couple alternatives and after I hope it makes sense...NO WELD of Gantry to Supports with these 2 options... 1st method consider this...Your Rectangular tubes are 2x3 or 3x4 not that it really matters...Bore a HOLE say 2" diameter horizontally thru one side into the other...Then insert a 2" OD tube thru the hole...Now before you install the Gantry into the Support tack weld the tube in place...Just tack to keep the heat down to a minimum...Do this on each end keeping in mind that the 2" holes are going to be inside of the structure of the support...After you get the supports fabricated install your Gantry where you want it...put you epoxy granite in the hollow cavity filling up the hole that we just provided with epoxy granite and thoroughly fill the structure...What you have just done is locked the gantry in with the use of the epoxy granite as a hold down for your gantry... 2nd method would be instead of a large hole use multiple smaller holes with solid rod all the way thru and have the epoxy encapsulate the rods and hold your gantry in place... 3rd method which just came to mind would be to weld a plate inside the support where your Gantry would sit...perhaps a couple angles secured inside that are match drilled and tapped to holes that are inside Gantry...Now before you fill up with epoxy Granite secure the gantry to those plates/angles you supplied and attach your gantry to those points probably at least 4 points but 6 would be nicer...After secured and plumbed level the best you can fill the supports with the epoxy granite... Only this method will allow you to super fine tune the gantry if needed...remove the bolts and shim if necessary and then reinstall... If I had your skills and was going to build a support for my gantry like the one you designed the 3rd method would be the only option, I would use...just for the possibility and need to ship to make just as accurate as possible... If you use that method be sure to mold release the gantry so the epoxy doesn't bond permanently to the gantry sides, top and bottom FFT Best of LUCK which ever way you go Paul

[@BryanHoward]

These are a lot of interesting ideas. I’ll have to give this all some time to think over. I’ve changed a bit of the design of the risers due to the availability of flat bar steel. I couldn’t get the 3/16 material I was originally going to build the risers out of. Instead I got 1/4" for the same price. Because of the different material thickness 1/8 and 1/4 I’m not going to have a fun time welding and controlling the heat getting pumped into the thinner material. So I’ve changed it a bit to become a bolt on job with around 12 bolts. Because of the thicker material I simplified the risers to not have the inward angle as well. The 1/4" steel is going to be brutally strong anyway to not need such added complexities to be constrained by. In this design the 6 bolts closest to the gantry tube opening get threaded into the gantry risers from inside the tube. The 6 holes further to the inside get threaded past the risers and threaded into the gantry tube. Your suggestions with epoxy granite are compelling that I’ll have to take into consideration. I would like to have the machine functioning with the new risers before filling in the tubes and then at a later date fill them in. Here's a short video of what it has been looking like for the past couple weeks at: kzbin.info/www/bejne/qoClqqOcnb6NnMk Would be good to hear your thoughts about this approach. A limitation I already have is. The inside bolts that thread into the gantry. This whole tab+bolts will intersect with the back part of the Z assembly limiting its travel. It’s not a deal breaker but a design nuisance.

[@texasbowhunter2509]

@@BryanHoward I can see where the additional bolts on the outside of the riser would be a nascence...Move those bolts to the inside like the rear are located would be a better option...Or flip around where those bolt pattern on the outside of the support would be on the backside...But what ever you do you need to reduce as much welding as possible...adding all the extra material where the Gantry will sit is just undue heat added to the supports... Are you going to stress relieve the supports after you are finished welding up? Might want to address that... You know on the Gantry's out there are no vertical supports on the Gantry...It seems are the gantry's are bolted to the base...Just keep in mind that it is going to be a real challenge to align the vertical holes with the gantry if you have to tweak on the leveling of the Gantry...Then all bets are off...It would seem that the riser piece would have to be match drilled to the gantry 1st then tapped then installed and hitting all would be doable but very challenging... when I get into complicated designs, I often build what I envisioned out of cardboard or wood...get yourself a small sheet of 1/4" plywood from the big box store and cut out on the router...The using wood glue to hold all the corners together like the weld would use tape to hold corners in place while glue is setting up...This will help you get a better understanding of what you are envisioning and fine tune from there...As far as the additional attachment plates are I would NOT use them...If you want to absolutely use hardware on the sides of the Gantry as well as the bottom which I completely understand doing come up with something else to keep the heat down from the welding... With your skills could you design and create on the 3d printer? Then you can add all the design features for attachment of the base and sides in the build...Build the shell of the support just like the flat metal would be...After you get the support made put the gantry in place and pour your Epoxy Granite into the support you just made... This will not have any warpage from heat and be dead nut accurate...FFT With your skills on the CAD drawings sending the support to the printer would be a piece of cake Good Luck I know what ever route you go you will have weight at as many options as possible... You know after mentioning the last option of fabricating out of the 3d printer That appeals to me a whole lot more the welding and then after filling up with epoxy...I would think you would have a heck of a support and be just as ridged as hoped for...Not like steel but plenty strong... Paul