Building a Solsylva V-Bearing CNC - My first Foray

[manofmanyhats]

I put the gantry on the base. It runs reasonably well. I have some vibration at higher speeds that I suspect is due to wear on the pinions. I may replace them later on. I slowed the machine to rapid at 350 ipm. I'll likely cut at around 150 ipm. It seems extremely solid to me compared to the C-channel, but I won't really know until the z axis is on there. I need to figure out the length of belt I need to run the other axis, and still need to come up with a temporary z plate.

Notice the room left on top of the beam. If my single rail idea doesn't work, I'll put a 20mm rail on top and use a 3/4" thick aluminum angle to tie the 2 rails together.

[Devastator]

Very interested to hear how rigid it is with only one linear bearing. Seems underconstrained to me. Probably still better than pipe though. Makes for a nice and clean looking gantry for sure.

[jfong]

My CNC is the one that manofmanyhats was referring to regarding the use of a single heavy duty shs30 rail for the gantry axis.

80/20 extrusion router build
http://www.cnczone.com/forums/cnc-wo...86276-cnc.html

My machine has been running like that for the past 2.5 years. Rigid enough to cut any kind of material so far. The single rail idea was originally taken from a commercial ttech qc5000 pcb cutting system that I have. This is a 20k+ gantry style cutter that only has one thk sr20 rail on the gantry axis. I was able to find a 30" SHS30 rail on eBay for around $50 brand new. I couldn't find another one cheap so I ended up using just one rail. I figured since it worked well enough on the ttech, might as well try it. Fast forward 2 years, I found another 30" shs30 on eBay for cheap, again brand new. I still haven't installed it as per original plans for dual rail. The single rail is plenty rigid for what I use the machine for. One day I will eventually find some time to upgrade but it won't be soon.

[Devastator]

My CNC is the one that manofmanyhats was referring to regarding the use of a single heavy duty shs30 rail for the gantry axis.

I skimmed your build thread, thanks for sharing. Have you tried milling any metals with it? Sorry if that is mentioned in your thread and I skimmed over it.

[manofmanyhats]

My CNC is the one that manofmanyhats was referring to regarding the use of a single heavy duty shs30 rail for the gantry axis.

80/20 extrusion router build
http://www.cnczone.com/forums/cnc-wo...86276-cnc.html

My machine has been running like that for the past 2.5 years. Rigid enough to cut any kind of material so far. The single rail idea was originally taken from a commercial ttech qc5000 pcb cutting system that I have. This is a 20k+ gantry style cutter that only has one thk sr20 rail on the gantry axis. I was able to find a 30" SHS30 rail on eBay for around $50 brand new. I couldn't find another one cheap so I ended up using just one rail. I figured since it worked well enough on the ttech, might as well try it. Fast forward 2 years, I found another 30" shs30 on eBay for cheap, again brand new. I still haven't installed it as per original plans for dual rail. The single rail is plenty rigid for what I use the machine for. One day I will eventually find some time to upgrade but it won't be soon.

Cool to see you here as well. Thanks for answering so many of my questions.

[jfong]

I skimmed your build thread, thanks for sharing. Have you tried milling any metals with it? Sorry if that is mentioned in your thread and I skimmed over it.

No issues with milling aluminum at all. I don't do it to often since I have two CNC bench mills that I use instead. They have vices that hold the material easier.

The gantry CNC will do full depth 1/2" profile cuts in MDF with ease at 100ipm. It's loud and spits dust like crazy. I usually do it in 2 passes so the vacuum pick up will have a chance to keep up.

[jfong]

Cool to see you here as well. Thanks for answering so many of my questions.

Long time Cnczone member. Glad to be of help.

[Devastator]

No issues with milling aluminum at all.

That's good to hear, thanks!

[manofmanyhats]

A question about materials:

I designed another Z plate and will cut it out of scrap 1/4" 6061 or wood today to make sure I have the dimensions correct. It will be 7.5"x 6".

In thinking about the final Z plate, am I correct that for any given thickness 1018 steel will be 3 times as rigid (Modulus of elasticity is 205 GPa vs 68.9 GPa, shear modulus is 80.0 GPa vs 26 GPa) and 3 times the weight as 6061? I'd rather use thinner material for the z plate to keep the force acting on the gantry as close as possible to minimize the torque that it sees.

I'm waiting for the belt to arrive. I think I may have ordered a size too small. I also had to order the screws for the Z plate as I couldn't find any M10 flat socket head screws local to me. Finally, it seems like my delrin anti backlash nut has visible backlash in it. I guess it wore down after years of use. I'm waiting to order another to see if I need one for my Z axis as well.

[manofmanyhats]

Finished temporary 1/4" Z plate:


I'm still not sure what I will use as the final version. I did not expect 1/4 to work as well as it does, so I may hold off on remaking it until I have a design for a different Z axis. I am not in a rush at this point to make more upgrades, because the machine is vastly more rigid as it is. I can't detect play when pushing on an endmill.

I have a loose pinion gear that I have to re- tap for a larger set screw. This is causing vibration and slight racking when it comes loose - as it is in the video. I have the rapids currently set to:

X - 400 ipm
Y - 600 ipm (the gear rack axis)
Z - 200 ipm.

These will all get slowed down since I have no need for it to be this fast. I'm still amazed that 1 nema 23 motor can move the whole gantry this quickly. The original c channel gantry was 6-8 lbs. The current one is around 35 without the z axis.

[jfong]

Looking good. What do you think about the linear rail so far? Post some video of the machine cutting when you get a chance.

[manofmanyhats]

Looking good. What do you think about the linear rail so far? Post some video of the machine cutting when you get a chance.

Thanks. The linear rail is very smooth and nice. I like not having to fiddle with adjusting V-bearings on that axis. Without knowing anything about profile rail, the machine really looks like the Z axis is a cantilever and should move all over the place. It is quite rigid, to the point that pulling and pushing on the Z axis is lifting the end of the machine off the table. I have some ideas for redoing the machine's wood table, but for now I'm quite happy.

The technical numbers for profile rails are staggering. It is hard to understand how something relatively small could be so strong.

I still have to take it apart to redo the pinion gear set screw. It is racking and stalling on that axis. I also have to resurface the bed. After that is done, I'll put up a video cutting something (probably next week).

I took off all of the limit switches on the machine while redoing it. I'm going to look into how to wire in hall effect sensors in place of the mechanical switches (I already broke a few).

[jfong]

Want to see something crazy! Here is a 50mm wide X 600mm rail I picked up on eBay sometime last year. I was the only bidder, $25 with free shipping. Brand new rail too. For comparison, the middle rail is a shs30. It's the same one you are using. The bottom rail is a sr15.

I haven't looked up the specs on the 50mm rail yet. It literally dwarfs the 30mm rail. I wasn't expecting to win the auction and not sure what I am going to use it for. Maybe retrofit the z axis on my bench mill.

[manofmanyhats]

That is gigantic. If you find a few more you could make a high level vertical machining center in your house.

[manofmanyhats]

Not really a fan of Mach 3's motion planner. I may try UCCNC soon.
I did a small stress test to see if everything holds together. Here is a simulated v carving done at 175ipm:

[Devastator]

Not really a fan of Mach 3's motion planner. I may try UCCNC soon.

Have you used your machine enough to make that determination? I'm looking at the UCCNC stuff and may go with that on my next build, but I'd like to hear from someone who can explain the difference between Mach 3 and UCCNC in laymen terms. I've put thousands of hours on my machine now and I'm wondering if I could tell the difference between the two. I think your CAM software makes a bigger difference.

[manofmanyhats]

Have you used your machine enough to make that determination? I'm looking at the UCCNC stuff and may go with that on my next build, but I'd like to hear from someone who can explain the difference between Mach 3 and UCCNC in laymen terms. I've put thousands of hours on my machine now and I'm wondering if I could tell the difference between the two. I think your CAM software makes a bigger difference.

I have over a thousand hours on this machine (with the old gantry) and have played with the look ahead and CV settings quite a bit. I do a fair bit of 3D work. I get decent results, but only if I have my accelerations turned up (currently 66 on x and y and 36 on Z). From what I've read, UCCNC has a smoother operation while also being more accurate. I'm already using a UC100.

Have you seen this video?

[Devastator]

Thanks for the info. I wonder why the video uses look ahead of 10 on mach, but 200 on UCCNC? So yeah, mach will create jerky movement at that setting. I did not know that look ahead settings affects accuracy. May explain my circles coming out ever so slightly ellipsed. Just doing some research, so thanks for the info and vid link!

[jfong]

I did a machine conversion for a friend and I had him buy a uc100/UCCNC because he wanted to use a laptop USB. While I had it in the shop, I installed it on my own gantry to play around with it. It's much smoother than my Mach3 setup. The motion planner really does work better. I should of took some video at the time. He has the machine now and as far as I know, he's happy.

I should purchase a uc100.

[Devastator]

I've been considering the UC400 with their HDBB2 BOB.