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TchTchr
10-11-2009, 09:14 AM
Hey all,

Just now getting to do some cutting with the 06. Depth accuracy fluctuates from project to project. For example, when I mill some lettering, sometimes it turns out just right and the very next cutting the z-axis goes down about 3/16" deeper. Every now and again the cut starts out shallow and gets deeper with each letter. I have the 5 start thread on the z-axis. Could it be I'm losing steps because of the 5 start? The machine is at school so I don't have my settings handy.

Thanks in advance,
Brad

calgrdnr
10-11-2009, 12:13 PM
Hello Brad ,

I have the 5 start all around , no problems . I would say you are losing steps... now need to figure out why. If you are using Mach control I would start by tuning the motors. also make sure you are lubing the screws. I use a silicone spray seems to work well with the derlin leadnuts.

good luck keep use posted

Kent

TchTchr
10-12-2009, 09:16 AM
I just put a dry lube on last week. Here are my tuning specs:

hobbycnc pro board w/ 305oz motors

motor tuning on mach3:

steps per - 800

velocity - 30

acceleration - 2

step pulse - 0

dir pulse - 0

I need to dig deeper to find micro-stepping.

I believe I configured the board to 1/4 microsteps - it has been a couple of months since I did the configuration - microstepping is controlled by the jumpers - correct?

TchTchr
10-13-2009, 09:10 AM
I noticed yesterday while manually jogging the z-axis it hung up in a couple of spots. I guess it is binding up somehow. The z carriage seemed to travel freely before I hooked up the motor though. I have seen where others have installed springs to help the motor out when going up. Obviously I need to find out why it is not traveling smoothly the whole distance. If the hang up is not found, could single start acme overcome the couple of hang ups?

Thanks,
Brad

calgrdnr
10-13-2009, 09:35 AM
Hello Brad,

when I went to 5 start I only did the X and Y . but I kept haveing problems with the Z losing step everyone in a while so I changed to 5 start on the Z havn't had the problem since.

I see you are using dry lupe. I tried that when first built my machine and didn't get good results, went to white lithium grease and all was good. switched to silicone after swap to 5 start and derlin nuts.

also check alignment of the screw mine was off in the begining so I oversized the holes in used to mount the bearing plates and readjusted alignment .

Good luck hope you get it figured out soon

Kent

ger21
10-13-2009, 11:20 AM
If the board is set to 1/4 step, the steps/unit should be 1600. Change the step and dir pulse width to 2 or 3.

I use a light oil (air tool oil) to lube my screws.

pminmo
10-13-2009, 05:09 PM
I just put a dry lube on last week. Here are my tuning specs:

hobbycnc pro board w/ 305oz motors

step pulse - 0

dir pulse - 0



The 0 pulse widths are a problem. If your kernel speed will accept 5us then use 5us, if not use 4us.

TchTchr
10-16-2009, 11:34 AM
Thanks for the replies! I think we're getting there. I was wrong on my microsteps - I had the controller configured to 1/2 microsteps. I switched all axis to 1/4 steps. This made the x and y considerably quieter and smoother, but it really made the z hang up when taking off - otherwise it is smooth the rest of the travel. Probably a dumb question, but I want to make sure - is it alright to have one axis at 1/2 step and the other two at 1/4 step?

pminmo
10-16-2009, 11:55 AM
yes

Serb
10-17-2009, 11:53 PM
No matter what screw you have you should not be loosing steps unless you used the unshielded cable provided by hobbyCNC (so nice of Dave) and are running it next to your router power cable, or you are binding the travel on the Z. If everything is lined up the only reason for oil would be to stop corrosion, and a little bit of lubrication of course.

Best lubricant to use is stuff called Chain Wax, sticks and stays on forever. It's designed for racing bike chains and if it doesn't fling off from a chain doing 100+ mph it'll probably stay on the screw. You can find it where they sell those plastic looking bikes.

BobF
11-27-2009, 10:57 AM
Make sure your motor couplers are not slipping. That was the problem on mine. Just slipped sometimes, so appeared to be loosing steps.