What a step up in performance, 400ipm rapids and cutting at 100ipm. I know it will cut much faster but I amd thrilled that I can now cut what used to be a 45 minute cut is now under 8 minutes.

Thank you Mark for the gears, belt and clamp thingy.

It is an upgrade that is much more inexpensive than acme rods and all that bushing work that you need to do, I did it and regretted not going with the belt mod first.

Here are some photos of where the stepper and idler pulleys are located, it took me 3 hours from start to finish with the junk I had around the house, I am not a woodworker nor do I have the tools to make it pretty but it works perfectly.

I used the bearings out of an old factory stepper motor for the idler shaft bearings so I didn't have to worry about bushings or wear on the 1/4-20 threaded rod that the gear rides on. Attached files

 

Yes, I have 7/16ths linear rods and bushings in the Y axis, so it glides like butter.
I now have my full 22 inch Y back as the acme rods and couplers took up some room inside the case, moving the stepper and idler cogs outside the case is really a no brainer as it makes adjustments/repairs much easier.
My Z axis is my slow part at 30ipm but I can live with that.

 

My belt is pretty tight. What stepper motor are you running?
When I first put it in I could stop the stepper with my finger, then I copied the settings for the axis off the MKII settings and it came to life, I did have to reverse the axis in mach3 though.

 

Ok, I kinda ran into a small problem, before the belt mod I had to run Mach3 in Sherline mode to stop my Z axis drift. Well, in Sherline mode my Y axis would drift, so I turned it off and Y axis is now perfect but the Z axis it drifting down thru the cut now.

Is there a way to tell it to just use the Z axis in Sherline mode?

 

Hi guys,

The belt mod is definitely worth the investment in time and outboarding the stepper and pulley is not all that difficult as you have discovered.

There was a time that I was running 1200ipm on my Y axis, but it was just way too fast. I ended up setting it 400ipm which works across nearly all materials.

I still limit the actual cutting speeds to 130ipm and let the rapids go at the higher 400ipm rate.

I don't think the Sherline mode can be set per axis, so you may want to consider investing some time in reworking of the Z axis gantry. With the help of my friend John, we put in oilite bearings, stainless steel 1/2" shafts, acme thread, and precision couplers so now the Z axis is rock solid and runs a smooth 40ipm.

Some of my liquid nail glue joints came apart about a month ago and required a little maintenace, but aside from that, my MK1 is going on 3 years now and is still a quality work horse that gets used frequently in my shop.

I would love to have an MKII, but considering my MK1 works so well, I really can't justify it.

 

Yes, I am running 1/2 linear rods with bushings in the Z along with endpoint washer thrust bearings and 3/8 acme rod with a lovejoy coupler.
I think I may have found my problem after doing hours of reading and playing with it.
I had to setup backlash. The problem that got me until I had my "DOH" moment was I was setting the backlash in positive number instead of negative since the Z is reversed adding to the problem.
There is no backlash in the Z axis except for the Vexta stepper motor that I had to tune out of the equation.
It seems to be feeling much better now that the dummy behind the keyboard figured it out.