Just as a follow up on the broken lead screw. after A2Z re cut the end I carefully assembled the Y axis and when I tightened the Y axis stepper mount the lead screw bound up and became very difficult to turn. Pulled everything apart and when I checked the stepper adapter plate from A2Z it was .017" thicker at the top.
After turning on a face plate to get the faces parallel all is well. also checked the X axis adapter plate and it had parallel faces. Just got a bum one, I guess.
The bad plate caused the lead screw to flex just outside the coupler and finally break.
GeneK
Originally Posted by GeneK
If anyone still has any doubts that properly sizing motors/gearing and matching the power supply and drives for a machine is the best way to go please see this thread: http://cnczone.com/forums/showthread.php?t=84700 .
There is a real crappy video of my Taig doing 250 IPM with my 'little' 166 oz-in motors. 250 IPM was scary but 100 IPM seemed very comfortable.
Jeff Birt
Dude, get real, that has nothing to do with you "properly sizing" and EVERYTHING to do with SMOOTHSTEPPER.
Search youtube for smoothstepper videos and you can see huge improvements on many machines.
It's nitrous oxide for CNC.
Hoss
Last edited by hoss2006; 07-03-2009 at 12:20 PM. Reason: added link
Gosh, you've... really got some nice toys here. - Roy Batty -- [URL]http://www.g0704.com[/URL]
First part
I've been playing with my new A2Z CNC Monster Mill for just over a week now. Yes, my 6-year-old son's CNC Etch-a-Sketch has been retired. I've been doing some simple engraving in scrap wood with a 1/4-inch router bit held in an end mill holder. Nothing serious, just trying to get a feel for how things go while I wait for the rest of my accessories and stock to arrive so I can start cutting metal. Right now it is set up for 150 IPM rapids and seems to be up to the task.
Friday night I made my first genuine part. It's nothing fancy, but it is my first part and it is functional. It is a 1/8 ply bracket so the emergency stop switch no longer dangles from its wiring.
I hand wrote the (very simple) G-code as I am still sorting out some software "features". I haven't set up any tool tables yet, so I had to reset the Z reference during my tool change from the drill bit to the router bit.
After zeroing on the back left corner of the stock I start the spindle and push the go button. The program starts by drilling the mounting holes, then pauses so I can change tools for the rest of the cutting.
Yeah, I could have cut it with the scroll saw and cleaned it up with the disk sander a lot faster, but that wasn't really the point, was it? Besides, I don't have a .870 drill bit for making the hole for the switch shaft. Yeah, I could have bought a 7/8 Forstner and used that, but then the hole would have been a bit sloppy.
Oh yeah, the screw heads. I installed this at about 2 am on Saturday, and didn't feel like forcing anything at that hour. The heads are now aligned.
Thayer
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A2Z CNC Monster Mill
Kerk Motion 4TPI lead screws
Sherline 2800 RPM spindle (for now)
Mach 3
Gecko G540
Keling 282 oz-in steppers w/36v power supply
Cool, thanks for the info.
Finally got this thing up and running. Ok well awhile ago......
I have the Mach 3 controller set to 140 IPM rapids. I did set it up to 240 IPM, but it seemed like it resonated and I have no need for speeds up that high anyways.
I am cutting mostly wood with this right now, and cutting feeds have been .050 in hard wood @ 60-100 IPM depending on what I cutter I am using.
2 flute 3/16 flat 90 ipm outside profile cut
2 flute 3/16 ball 100 ipm Surface profile cut
2 flute 3/16 flat 60 ipm circular interp ( counter bore holes )
No issues and the machine runs good. I did have a problem with the X axis bed and A2Z sent out a replacement to fix the problem. I just havent had time to install them yet.
But all in all I am happy with the machine. I kinda wish I would have built or bought something a little different for the amount of money I have in the machine, I could have spent a little more and got alot more. But live and learn. It does function the way it should.
Well another update on the machine. The rapids have been set to 160 ipm. No problems there. After running time checks on everything, I found that 90 ipm cuts vs 60 ipm cuts didn't make a noticeable difference unless I was standing there watching the machine. So I lowered alot of feed rates down and sped a couple up in other areas.
All in all it was running good till yesterday. The Y axis lead screw broke right at the preload nut. A2Z said they would recut my lead screw, but turn around time ( even though its fast they said about a week ) is too slow, so I am going to order a new one next day air, and then send in the broken one to be re-cut. The machine has only been cutting wood and not under any stress of cutting heavy hard items. So I am not sure why the screw broke.
But all in all , the machine is a decent machine. Alot better then the Sherline original setup. But for what I would to do is far from capable of being anything other then a real hobby toy.
I ordered a NM145 ( it will fit through my shop door since I don't have a bay door ) and have some plans for it. If I had a bay door, I would have been hunting the auctions for a real machine ( ATC etc ) to work with.
So if your looking for a good hobby toy, then the monster mill from A2Z is a good accurate machine from what I have experienced. Accuracy seems to be around .0005 when running good ( after running a few sets of parts ).
I realize that I originally was going to use this machine to crutch myself to a larger machine. And that the NM145 isnt going to be a Haas with 20 tool changer etc. But its all steps in that direction.
Don't expect industrial type performance from the A2Z , because its not designed to be an industrial type machine. But for the home hobbyist that wants to play around , its a good start.
g29cc, I had my Y axis break in just the same way. I found the c-shaped adapter plate between the stepper mount and the mill base was tapered by about 17 thousand's from top to bottom. I mounted the adapter on a face plate on my lathe and skimmed the back surface to make them parallel.
Before that I think the lead screw was not parallel to the mill base and the closer the saddle got to the stepper the more flex at the point where it broke.
At least that's my analysis of what I think happened.
GeneK
im going to veer slightly off topic here. for our purposes (benchtop cnc milling machines, not a haas), as long as you have the power to move... is there any disadvantage of running a low TPI screw to increase rapids? backlash is the same for any tpi screw, and the resolution of steppers is way higher then the accuracy of the machines (resolution != accuracy). just curious.
cheers
Teyber12, I had an e-mail discussion with Tim at A2Z about the 5 tpi vs 20 tpi, he assured me that the 5 tpi uses the higher torque of the lower step rate.
I have found that he was right, before my max traverse was 20 ipm, with the new lead screws I easily get 40 ipm. I had thought that losing the mechanical advantage of the finer pitch would marginalize or even over load the Sherline steppers. But I find the low TPI has improved performance of my mill, and the extra length on the x and y axes is great.
GeneK
I'll Check that out today when I get to the shop.
I also wanted to mention that Customer Service with A2Z is good.
This originally was supposed to be an table and base upgrade for my Sherline, but ended up as a complete new mill before I knew it. Now I look at upgrading my Sherline again ( because it needs a base and table ) and I am at the same idea of making another Monster Mill. But I have a new NM145 Novakon coming soon, so maybe I ll just leave the little Sherline alone and let it cut little parts and stuff. Its still good for some basic parts that are super tolerant.
I ll post what I find on the stepper mount plate.
Well still waiting on the return of my lead screw from A2Z. I am glad I went on my better judgment and bought a new screw. As its been 1 day shy 3 weeks of A2Z having my original broken lead screw with an original quote of 2-3 day turn around on machining ( figure 3 days return shipping so all in all about a week and a half turn around with shipping if everything was a perfect world ). I called today and the screw is supposed to be machined tomorrow and shipping. Maybe Cathleen meant 2-3 weeks on turn around for re-machining the screw.
I am just glad I ordered and bought a new one, or I would be sitting here with customers wondering whats going on. I ll have a spare lead screw I guess, so if another one breaks, I can atleast fix it while without waiting.
I don't think mine was that long, but I did have to call after about a week. Then it was about two or three days. Just as a thought, if it happens again I plan to simply cut off the rest of the 1/4" part and center drill and tap so I can insert a home made stud to replace it.
GeneK
I am not sure if I mentioned, but I have mine set to rapid at 160 ipm.
I have upgraded my X Y axis and lead screws and tuned it 120inch per minute rapids just until I reinstall limit switches. I have 200ounce inch steppers times 4 is 800oz inch. I don't understand the worry about loss of tourqe. A2z has great products.
Randall
I too have a Monster Mill. I noticed the wobbling of the X stepper mount when rapiding. I knew it was an alignment issue but have ignored it so far. Also I cant stop the Z carriage from moving just a little. I have adjusted the Gibs til the carriage wont move but the movement is still there. I really needed a bigger machine. I have made mine run in the 300ipm range. Here is a video running a 3D printing code as a test.
What size steppers are you running. That's blazing fast. I have not noticed any movement in X motor mount.
Randall
23-205-DS8 (3V 3A) steppers from the Hobby Cnc Pro kit.
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