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I went a different route with my stiffness upgrades than most. First, my X-axis I completely replaced with a 40x40mm extrusion. I bought some V-rails from Openbuilds that bolt onto the the extrusion. When i did this, there is a 4mm difference from the standard makerslide setup. I used 4mm shims on the front 4 V-wheels to make up the difference. This has been a pretty solid upgrade!!
Next bought some 40x20x1000mm extrusions and bolted them to the Y-axis makerslides. I found without this, the Y-axis shakes a lot. This completely fixed this problem. I used self taping screws to attach the extrusion to the makerslides.
The next issue I had with the X-Carve, was there is nothing physically connecting the two Y-axis motors. I had a Romaxx CNC prior to this and one of the important features was it had both of the Y-axis pulleys connected with a rod. I designed and printed a bracket to house two bearings just below the X-Axis extrusion and connected the two pulleys with a 1/4" rod. This keeps the two sides square even if one of the motor misses a step.
I upgraded the belts to GT3 because the GT2’s kept skipping. So far I like the machine for the price, but it definitely needed some upgrades for it to be usable for me.
Great post James. I am planing to get myself an X-Carve in the next few weeks and am very interested in this style upgrades that help to make the machine work better. [quote=“JamesStehlin, post:1, topic:14244”]
First, my X-axis I completely replaced with a 40x40mm extrusion.
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Can you share the sources you used to find these extrusions?
Can you post some more detail on this mod. I really think this is one of the best ideas I have seen here that provides a very real and tangible benefit for the machine.
I am guessing you drilled new holes in the side plates to make up for the misalignment of the 40x40 mounting holes Vs the stock holes in the side plates due to the 4mm thickness difference? I have been meaning to mill new side plates VS drilling into the stock plates as I have this very same upgrade waiting to be done. I had just not decided between thicker aluminum tool plate or 11ga steel for the new side plates. Would be very interested in seeing what you did in this respect for the new holes.
Also been putting it off since my x carve is working almost daily to keep up with production and I hate to tear it down until I have everything 100% figured out and ready to mount on the spot so my downtime is reduced.
I’m happy to share my methods and any 3d files I’ve designed. Later tonight I will try to write a more detailed post with the attached stl files. Thanks for the feedback!
@CraigStueve1 I got the extrusions at openbuilds part store.
@Travelphotog I have not drilled new holes for the on the gantry plates yet. Right now the extrusion is screwed to the fixed holes on the gantry plates ant its pretty solid. I do plan to extend the other holes, so I have all 8 screws installed. For now this will do.
So, the pulley connector… I bought a .25" steel rod from Menards along the smallest diameter steel tube they had. I don’t remember the size off the top of my head, but the .25 inch rod didn’t fit snugly into the tube, so I had to print adapters that slide into the ends of the tube. Without the tube, the .25 bar flexes too much then the belts are tightened.
to hold the bar onto the gantry I designed a bearing holder that attaches to the stepper motor mounts and is supported the idler spacers. You will also need to buy some bearings, GT2 pulleys and idlers (I bought hem from inventables).
The bar gets cut to fit between the two gantrys and you have to take off one side to get the bar under the X-carriage. Then, in order to re-route the belt, you have to add an Idler to the rear V-wheel. You will need a longer screw.
Once you get it all together, Tighten one of the of the GT2 pulleys to the rod and make sure it id against the bearing. Next make sure both side of the gantry are square and tighten the other side. Now both sides are mechanically connected!
Thanks for the detailed instructions James. @JamesStehlin Based on your experience with the 40X40 extrusion for the X axis I am curious how you think a 1500mm one would do?
Great upgrades I like the idea of tying across gantry I might try with a bearing idler in middle since mine is 1500mm wide anybody tried swapping to rack with gear instead of belts?
I haven’t heard of switching to a gear set, but I’d be interested to see how it would work. I think that would work much better then belts but I think you might get more backlash.
If one wants to change to rack and pinion you have to use an anti back lash pinion. You also have to keep all chips out of the rack and pinion.
There are commercial routers, plasma cutters and oxy-act torch tables that use rack and pinion.
Finding rack and anti back lash pinions in the size you need for an XC at a price point that you can live with could be a problem.
Did a quick check. McMasterr-Carr sells 24pitch rack 4’ with mounting holes $55.52 each
Stock drive parts sells anti back lash pinions 24 pitch 30 tooth for 63.15 each
24 pitch is small and I’m not sure it would hold up to the job.
Now that you bring it up I have seen that set up before. They use a swing system and springs that hold the pinion tight into the rack to limit back lash.
With some engineering it could be made to work on the XC. Would the improvement be enough to cover the cost, I don’t know.
CNCRouterparts has a pretty good reputation overall, but I believe those are aluminum racks. So depending on use they could ware down over time. But I know there drive systems are considered very good, and last a long time. Moore gear makes some steel ones that I’ve heard good things about. I’ve read that https://www.finelineautomation.com/products/gear-rack?taxon_id=38 is also a Moore gear re branding, but I could not find that info on there web page.
There would have to be some pretty serious engineering to get the fixed motors in the Y and X to work with this. But there are several designs out in the world that already do this.
I have had a rack and pinion setup from CNC routerparts before and slippage can happen on those as well except when they slip they grind the aluminum pinion against a steel rack. If you ask me rack and pinion vs belt I would say both are good but different.
I have had a hobby cnc router with all major modes of travel acme, rack and pinion, ball screw and now belts. Hands down it is easier to work on the x carve (and cheaper) than anything I’ve had before. (changing a belt is much easier than changing a ball nut)
Beside the pulley and the belt and the grbl did you have to make any necessary changes to the setup? Are the idlers still good? Are the GT3 belts that much stronger? Did the pulley fit in the x-carriage easily?
Did you keep the stock idlers? Their groove is 1.75mm deep which is fine for the GT2 (1.34mm high), but looks kind of shallow for the GT3 (2.4mm high) according to this . Or did you upgrade to these? At 2.25mm, these cover most of the height of the GT3.
Does the extra 1.06mm (in belt height increase) clear ok between the idler and the MakerSlide? The CAD shows it might be too tight.
I did not change the idlers. It doesn’t interfere with makerslide or if it is close it might just be fitting into the groove. I never really paid attention.
