[corgano]

So I recently bought a WT ZX45 and have pulled out the lead screws to replace them with ball screws. I've got a few questions as the threaded area on the X is a bit small given the table size and the Z axis is going to be a custom length as the Z is different than the Bolton and IH pics I've seen.

The table dimensions are 31-1/2" x 9-7/16".

The X screw has an overall length of 39-1/4" with only 31-3/8" of its length threaded. It is machined on both sides, one 4-1/8" and the other 3-3/4". The diameter of the machined ends is 5/8".

The Y screw has 15-3/4" threaded with one 4-1/8" machined end, again 5/8" diameter.

So I was thinking the following profiles for screws:

X with the same profile. Y will be 1/2" longer, with 14-3/4" threaded and 1-1/2" and 4-1/8" machined ends maintaining the 5/8" diameter. Z will be 36-1/2" threaded with 1-1/2" and 4-1/8" machined ends 5/8" diameter.

Does this match up approximately with what you guys have done in your RF45/ZX45 conversions?

Thanks in advance,
-Patrick

[gd.marsh]

Ballscrew lengths could be all over the place depending on what type of bearings you use & what type of bearing mounts you use. Diameters on the machined ends are determined by the bearings, retaining nuts & pulleys ..

If I were you I would try and read up on as many conversions as you can to first of all determine exactly what you plan to do & how .. then begin to approach everything from there ..

I know everyone does something a little different, but several of us are using 5/8" ballscrews on X & Y with 3/4" on Z .. figure out what diam. ballscrews first, then determine what bearings, nuts & pulleys will fit your ballscrews & THEN you can design your bearing mounts with that information. Ballscrew length will be determined by the type & size of your bearing mounts. It's all so inter-connected sometimes it seems like your chasing your tail. Educate yourself as much as you can by seeing how other guys have done it then either copy what someone else has done, or get creative!

This is my thread: http://www.cnczone.com/forums/bencht...onversion.html

You'll be able to find lots of help on the zone ..

[corgano]

Yeah, I've read through your thread, bob w.'s, felsner's, and eartaker's. I'm going to be ordering the 20mm screws from linearmotionbearings. I plan on using a pulley system for each axis with the standard keiling servo package. X and Y will have 1:2 ration and Z will have 1:3.

I was planning on using the original bearing blocks for the X and Y axis. I guess the primary intent of my questions was to see if the profiles I posted made sense given other people's conversions (didn't see profiles posted) and given screw expansion due to heat.

[eartaker]

I used the original housing like you are wanting to do but ended up boring them out and replacing the thrust bearings with AC's. the thrust bearings were junk compared to AC bearings.

[corgano]

I was debating doing 17mm diameter ends and going with 5203ZZ Bearing Angular Contact 17x40x17.5:Ball Bearings AC bearings.

Back to the original question and a more direct approach, how much space should I allot of profiled shaft between bearing blocks?

-Patrick

[eartaker]

around 2-3 inches, I also went with 17mm but used the 17X35X10 bearings.