It’s a recommendation, not a rule.
It’s fine if you understand the drawbacks and it fits your use case, but a 24" beam is going to be much stiffer than a 48" beam…
So you are operating below what your machine “could” be capable of. That’s the important part.
Now, the beauty of building your own machine is that you can do what you want, but we have to make sure people understand why if the machine doesn’t perform as well as it should.
This will also make it more complicated to cut the strut plates, as they are longer than the x-axis travel distance
I cut them using tiling on the MPCNC Primo
Yep.
My 2’x4’ machine will be just as “stiff” as the 4’x8” machines that are already out there in the wild.
Yes it could be more stiff if I made the short dimension the beam but then I would need to Re-learn myself the x and y axis direction or more to the point I would need to “UN-LEARN” what is already in my brain as +x is to the right and +Y is to the back…
-or-
I would need to modify the config files to switch the x and y axis and do that each time I upgraded the config files.
So I chose the path of least resistance
and in general a 4’ beam on a Lowrider “should” be more “stiff” than a 4’ rail on the MPCNC Primo so in my mind this will be an upgrade from the Primo.
One other point is that this would give me the option in the future of moving the low rider to my 4’x8’ work table in my shop if a need arrives to CNC a full sheet
so I’m making an upgrade that will be beneficial in the sort term (more rigid than my current Primo) and may have a future benefit if converted to a full sheet CNC
you definitely don’t want to do that
That is definitely the case, and 4’ is way outside the bounds of recommendation for a Primo to run
Understood, and was not trying to convince you to the contrary. Just expanding on the Why is this advised against? question
Impressive!
The only concern I have is the bottleneck of suction right there “connecting” from the ring around the bit over to the tubing
I didn’t notice the video link before…
You also probably want to be very careful about the way this hose attachment point is so far up and out from the default one
Any drag or catching with that hose is going to have a bigger force than normal and can cause problems
Good catch. That tall “stack” becomes a “lever” with leverage that can throw off the motion of the machine.
I took another look, and noticed it looks like the bit is much further below the core than on my LR4. Is that correct? It looks like an elongated “stick-out” setup that will diminish performance rigidity (increase chances of runout)?
Yes, I agree, my preference is to minimize the size of the bristles touching the worksurface to focus the suction at the bit. I have something similiar on the Primo and so far no clogs and good chip evacuation.
The beauty of DIY is if something ain’t working, you can re-design it and make a version 2
the hose is mounted to a rail in the ceiling with roller bearings so the entire hose moves freely back and forth with the spindle.
I’m fairly confident this setup will be more rigid than the Primo and if I can get results like this on the Primo I should be able to get them on the LR4.
Doug, as designed, I have roughly 58mm from the bottom of the mounting bracket to the bottom of the ER-11 collet. How does this compare to your setup?
IMHO, that’s the correct comparison between machines. The length of the endmill will vary, and the depth of cut as well as the depth of the work material, will also vary.
As long as the distance between the bottom of the spindle mounting bracket and the bottom of the ER-11 collet is close to the setups using a router, we should be comparable in terms of rigidity.
This gives me roughly 95 mm of travel before the bottom of the ER-11 collet reaches the mounting height of the EMT brackets or the height of the surface the rollers run on.
I’m planning to set the right side EMT rail and The left side roller on a raised board to be able to put thicker workpieces but for comparison to other LR 4’s the dimensions above would be if the LR4 was directly mounted to a worksurface and the spoilboard was above the worksurface.
In my setup, my router mounts so that the collet is in line, or maybe 1mm below the core.
This maximizes the ability for the LowRider to get low… where it is best, and minimizes the lever arm created from the endmill pushing against the material.
You can 't go into the material with your collet, so what benefit do you have by extending it so far below the core?
Got it. I think the difference I was noticing, is your spindle seems to have more stick-out below the core, than my router does:
On mine, the collet is just barely below the core.
The best, most-rigid it can be, is to minimize the stick-out of both the spindle and the bit.
with a 65mm spindle I just set the bottom of the 65mm portion of the spindle at the bottom of the bottom mounting bracket. This way the bracket is fully engaged with the circumference of the 65mm spindle body.
The distance between the bottom of the 65mm diameter spindle body and the bottom of the ER-11 collet is likely slightly more than the distance between the bottom of the main body of the router and the bottom of the collet.
In general if I’m running the machine at feeds and speeds that case and issue then I’ll just back off until the Glowrider is not throwing a fit.
If need be I can just design a new custom bottom bracket and push the spindle up.
Yep. Pretty decent way to address the physical difference between a spindle and what the design targets, a trim router. That could bring benefit of added rigidity (resistance against runout) without any significant downside.
Hell yall,
I’m new to the forum and hope to receive some help. I have an old Langmuir CrossFire CNC table and need to upgrade it with better software, controllers, etc. Any advice?
Start your own thread. Someone else’s build thread isn’t the right place to ask for general help for your machine.
Start a thread, and ask specific questions about what you need help on
