I’ve been kicking around some machine upgrades. All comments and input are welcome.
90% of what I do with it is machine polystyrene foam patterns for lost foam casting, so the machining loads are light and desired feed rates high. The machine is fairly lightweight so the smaller steppers do ok. It’s a relatively large work envelop but I need more Z travel (more on the z-design later) for pattern work and will be modifying that to 8”+ under spindle. To get the additional height I plan to just raise the entire gantry system and for work where I need more rigidity I’ll build a platform that minimizes Z extension and may build wet cutting fluid retention/return features into the platform for harder materials.
Here’s the machine as it stands. There are of course likes and dislikes about the machine but all things at a price point. IMO, It’s a decent hobby grade machine and at the time I bought I have about $2000 into it. It’s the larger XL model. There’s pictures at the link and you can take in whatever you have the appetite for.
https://millrightcnc.com/product/millright-cnc-mega-v-router-bundle/Some of my future pattern work may have very long run times. I need to get the machine to the point where it can reliably and at relatively low risk run unattended. I’m looking at replacing the POM rolling wheels with HGH linear track and SFU ball screws on all axis. Although I’ll likely pick up some accuracy, another major reason is debris tolerance. The v-grooves gather statically charged foam which can accumulate to the point to cause loss of steps. The rack and pinion has a similar issue to a lesser extent with foam but worse when collecting hard materials. The wipers on the linear rails and screws seem to do a good job, and as they collect a little foam dust even better. It may also reduce rolling and actuation friction a bit which can’t hurt with my smallish NEMA 23 steppers but may actually be needed with the increase Z-axis travel and weight due to not only the larger travel but also the possible addition of a spindle instead of the router.
The manufacturer of my machine more recently has offered what they call a “pro-version” that has similar linear rail approach but retains the rack and pinion drive. I’d replace the R&P with ball screws. Here is a link to that machine.
https://millrightcnc.com/product/mega-v-pro/I can buy import versions linear rail and ball screw the such to do the entire machine for about $350.
I’m also looking at upgrading from the smallish DeWalt 611 VS Router to a spindle. I don’t think I need a lot of power, but I do want the ability to handle ½” shank bits and ER20 collet spindles seem to be minimum 2.2kw or better and quieter running would certainly be welcome. There’s also the matter of air vs water cooled. Of course, I’m looking at the 4-bearing Chinese imports which can be had with VFD for under $300. I’m very leery of purchasing the Chinese sourced VFD without first seeing a manual first to make sure I can understand it. I seem to recall a thread somewhere (cnczone maybe?) that covers this very well. Any reference sources would be appreciated. Any opinion on water versus air cooled? Water is just more overhead but not that big of a deal to engineer.
While I had everything apart, for added rigidity I’d fill the gantry aluminum extrusions, at least the stationary two, and maybe the traveling one, I’d use the existing extrusions because they are very easy to retrofit. I could replace them with steel but at that point about the only thing I’m using from the original machine are the steppers and controller, which also could be better. I know the extrusions are not as straight/true as you’d want for linear rail but I see it done all over the place with apparent success.
On the z-axis, it seems the practice is to mount the rails on the stationary Z-plate and bearings on the travel portion. To get the under gantry clearance the router would have to be mounted significantly below the lower linear bearing packs. I was going to mount the rails on the traveling plate and make the traveling plate a stiff as possible, that way it would remain quite stiffer in the retracted position where heavier cutting could be done on platform. When extended, I’d probably only be cutting foam so the loads would be very low and inconsequential. Any other pros/cons to the two approaches?
In addition to my original purchase price, +$650 for ball screw and linear rail along with a spindle seems like good value for money, compared to $7.5-$15k to buy another more rigid machine with similar features……and yah I suppose the upper end of that could potentially buy a used (up?) real cnc machine, but I don’t have the space or appetite for that.
Best,
Kelly
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