Hi, I want to start researching components for converting my new zay7045 to cnc and thought Id ask what you all have had the best luck with as far as the screws and ballnuts- Size and type, part numbers if possible, sources and prices. Those seem to me to be the most important part of the conversion. Also wanted to confirm whether the screws that came on my machine can be used with a better nut assembly or remove them completely and replace screws and ballnuts with new higher quality units. I have a good friend here that has converted his mini mill and he will help me some. Im not planning on buying a conversion kit for 3 or 4 grand, Im hoping to round up components and fab brackets myself and do this for $1500 or so myself. This sound do-able? Thanks, Dave

Anything is possible! If you have the resources to do all that you will be able to SAVE.
I don’t believe that the machine you have came with ball screws but I don’t know that. In any case, there are hundreds of suppliers just search for Ball Screws.
What you are looking for is the precision ground type of screw with anti backlash nuts (very expensive) they generally have an accuracy of .0005 per foot. They will be somewhere at 50 – 65 Rockwell make sure you can work with that!
If it was me I would not settle for less. Also read about the difference between steppers and servos(very important to know) I will give you a fair warning about most of the cheep steppers floating around on the web, don’t buy them!
Steppers will get hot!! Most manufacturers don’t recommend running them all day.

Are 5/8 ballscrews for x and y axis, and 3/4 for the z column the right sizes? Standard ballnuts good or do we need the double preloaded units? Thanks, Dave

If it was me I would match the size of the screw way past the capacity of the machine "My opinion" I think last time I checked a 5/8 screw would be good!
A single would do the job just make sure that it is a anti backlash preloaded nut. Remember! Lash & CNC Mill do NOT mix.
PS: Last I checked there were some companies that will make a custom screw for you. Without the proper tooling they can sometimes be a bugger to work with.

HomeshopCNC sells the 5/8" ballscrew at 1.25 per foot I believe. I would get two ballnuts to make it an anti-backlash setup, you might as well. You should easily be able to get this under 1500, especially since you are making some of the hardware yourself.

Steppers run hot, 50-90degrees C is perfectly normal. Keling offers some of the best deals on steppers in my opinion. Good place to look.

Have you ever designed a CNC? Look at the acuracy!
I was under the impression we are talking about Real CNC.

Have you tested a Keling motor, or any of these "cheap steppers"? I will test out my Z axis for repeatability tonight, as that one is being driven by a Keling motor.
Most steppers out there are made in China anyways

When you look at that, what matters most is repetability! Steppers don't have feedback. But a real Machinist will know how much load the machine can handle. I don't know if you guys do it just for hobby or for a living as well??
Anyway if you want to check something then I would suggest you set up a couple of dial indicators at the tables edges. and then move the table out both ways as much as posible, then tell the machine to return home you can do that on all three axis at the same time. Good Luck!

PS: do it more than once every now and then I check mine at least 10 times in a row with the Indicator returning to a perfect 0 every time.

What are you trying to say? A hobbyist machine won't have the same capabilities as a real, industrial CNC? I think everybody on this forum agrees with you. I think most everybody who is posting about their conversions for a benchtop mill is not looking for that performance either.
We all know steppers typically don't have feedback, but we put them on anyways because it is a simpler installation and cheaper.

I work at a machine shop, on machines you would call "real CNC". Yes it's nice, but it's not worth it for a hobbyist.

Look over the Industrial Hobbies web site carefully. You may or may not choose to buy their conversion kit, but you can see detailed instructions about how it is installed with lots of photos. I would think this would be extremely helpful to your design efforts.

IH uses Rockford ballscrews, but I confess i have forgotten what diameter they are.

Best,

BW

Thanks guys, Dave