[infamous_panda]

Gents,

Never gave rigidity much thought until now that I have been cutting more aluminum. I came with a concept of having a metal cutting compartment underneath a section of removable spoilboard. This way I can place a tray to capture chips and coolant underneath and then cover up when not in use. After cutting some parts I think I am running into an issue of rigidity due to the Z axis having to dive down deeper. My straight cuts that are parallel to the gantry seem to chatter like crazy. So I don't want to give up on this concept just yet.

I got a quote from CNCRP to upgrade my V-con to Linear rails for $1600 and I am wondering if it is worthwhile.

Does anyone have any first hand experience with both systems? I have seen threads with people deciding to upgrade but not any comparison.

Would moving my Z-axis mounting plate further down the carrier help? How about adding more V-bearings.

[PapaLima]

I have the newer Pro version 4824 with the linear rails but I haven't cut aluminum yet. It hasn't even blinked at anything I have thrown at it, but I have noticed a dependency on good bits.

Could you describe how you set up your "concept of having a metal cutting compartment underneath a section of removable spoilboard"? I've been thinking about how I can set up to occasionally cut aluminum and still be able to cut wood and contain the mess.

[infamous_panda]

I have the newer Pro version 4824 with the linear rails but I haven't cut aluminum yet. It hasn't even blinked at anything I have thrown at it, but I have noticed a dependency on good bits.

Could you describe how you set up your "concept of having a metal cutting compartment underneath a section of removable spoilboard"? I've been thinking about how I can set up to occasionally cut aluminum and still be able to cut wood and contain the mess.

Yeah finding someone who can compare the two (that is not interested in selling) is hard.

If you look closely at the image. I have a 3 8040 extrusions running perpendicular to the beds crossmembers. These are mounted below the spoil board with enough clearance for my milling vices to stay permanently mounted. I have a tray below that which catches the coolant.

[Kosh]

Gents,

Never gave rigidity much thought until now that I have been cutting more aluminum. I came with a concept of having a metal cutting compartment underneath a section of removable spoilboard. This way I can place a tray to capture chips and coolant underneath and then cover up when not in use. After cutting some parts I think I am running into an issue of rigidity due to the Z axis having to dive down deeper. My straight cuts that are parallel to the gantry seem to chatter like crazy. So I don't want to give up on this concept just yet.

I got a quote from CNCRP to upgrade my V-con to Linear rails for $1600 and I am wondering if it is worthwhile.

Does anyone have any first hand experience with both systems? I have seen threads with people deciding to upgrade but not any comparison.

Would moving my Z-axis mounting plate further down the carrier help? How about adding more V-bearings.

It is well worth the money. I started with the V-con design and upgraded to the linear bearings. The issue I was having was getting the v-con rails perfectly flat. If they aren't your z-axis can tilt side to side and it translates over the length of the spindle to the end of the bit. As I am doing highly accurate guitar inlay work, it was significant enough to be a problem.

One solution is to install more v-rail holders for more frequent support, but I opted to upgrade and have not regretted it one bit. The machine is SUPER accurate not.

Here's my thread trying to figure out what was going on:

https://www.cnczone.com/forums/cnc-r...is-travel.html

I should clarify on the issue: It was mostly noticeable when matching parts (the inlay and the pocket for the inlay) , and large parts, were done on different parts of the table, as you can see in that thread.

[infamous_panda]

Thanks for the input!

My accuracy is actually quite good and better than I would expect. As I am mostly cutting aluminum now I am wondering if upgrading to linear rails will allow me to move a lot faster and deeper or if I really should be looking at a different kind of machine. Right now it seems like rigidity is my biggest bottleneck.

[GME]

Thanks for the input!

My accuracy is actually quite good and better than I would expect. As I am mostly cutting aluminum now I am wondering if upgrading to linear rails will allow me to move a lot faster and deeper or if I really should be looking at a different kind of machine. Right now it seems like rigidity is my biggest bottleneck.

You've identified the underlying issue - machines like yours are not super rigid. All you can do is try to accommodate the lack of rigidity. These machines are not metal mills and will never perform like a mill.

What are your cut depths? Could be that you are trying to take too big of bite per pass. Machines like yours require very light cuts per pass. Finding the right depth of cut is a matter of trial and error & observing what works for your rig.

What type of bit/end mills are you using. On a CNC router, O-Flutes tend to work best. Finding the right feed rate is important.

I cannot directly answer your question regarding linear rails. I don't have "before and after" experience you are looking for. I can safely say that linear rails are significantly better than V-Cons. Apparently, CNCRP agrees, given that they've dropped V-Cons in favor of linear rails.

You may be onto something suspecting the problem may be, at least in part, related to your Z axis. Going more than 3" deeper than when cutting wood could be causing more flex. However, I would tend to associate a taller gantry height to loss of rigidity more than running the Z axis deeper.

I guess I'd look at cut depth, feeds & speeds and bit type and tune, tune, tune, before spending bucks on an upgrade (assuming your good with the V-Con rails). If you need to upgrade, you may want to consider the CNCRP ball screw Z-axis as a first step. Looking at your drawing, there is a whole lot more metal in the ball screw axis than in yours. I should think the ball screw axis would be more rigid. If you have CAD that will open a .step file, here is the file from the CNCRP site for it. With CAD like Fusion 360, you can deconstruct the axis and see how it's put together.

http://www.cncrouterparts.com/dl/cad...40-00-300.STEP

Gary

[wmgeorge]

Bottom line, if you need a milling machine, don't use a cnc router.