Lead screw Mounting

[jpike10]

I plan on using a 1/2-10 5 start lead screw found here CNC Machine Mechanical Parts

I have a question about mounting the screw to the end panel and was wondering what some methods used are?
In the dwg it shows two nuts on each side of the flange bearings.
I found some 1/2-10 5 start nuts but they are $44.00 each (ouch).
I have also seen them mounted just using collars instead of nuts.
and was wondering if that will work?
i thought there was supposed to be a certain amount of tension on the lead screw to keep it running true.
I run a cnc shop and mainly deal with large scale machines. but thought that this would be a great home project.
any help would be appreciated.

[TommieK]

I use 1/2" 8-2 Acme on my JGRO and I only use the collars to hold the screw in position, and while cutting I don't seem to experience any whipping. I do think that checking the screw for straightness (like rolling a pool cue) before installing could save a lot of problems. Probably not your problem, but have you ever seen an arrow straightener? Good luck on your build. Oh and by the way, beautiful drawings on the other thread concerning upgrades (I wish I could learn how to do that) and a very good looking way to solve the problem of sagging x-axis! Tom

[jpike10]

Thanks Tommie, i have been looking around and found that a few others are also using collars. which should be fine for the short distance of the lead screw.
usually when we install new ball screws in our machines (over 100" travel).
they need to be tension adjusted to get them to run true within .001 runout.
but , for this application it should be fine.
if needed i could go with a nut on each end to add tension and a collar on the inside.
I am still in the purchasing material stage and will cross that path when i get there.
solid works is a great program , luckily i have it at work. I could never afford it myself.

[kmacht]

I have 1/2 -10 single start on mine so nuts aren't that expensive. If you want to ajust tension but don't want to buy alot of expenisve nuts you can get away with buying just one. Put a collar on both ends of the shaft but only tighten down one collar. Put a nut on behind the loose collar and tighten it down until you have the pre-load on the screw you want. Tighten down the 2nd collar and remove the nut. Repeat for the other two axis.

You basicly use the nut to tighten the tension and then lock in the tension with the two collars.

Keith

[guerd87]

I had much the same problem when looking for threads. Ended up getting 1/2" 10TPI acme thread for $77AUD for 12 feet.

The nuts were going to be $10 EACH! No way.

After cutting to the right lengths took it down to a local machine shop and had them turn it on a lathe and thread it with a standard M10 thread on the ends. Added some thrust bearings and can adjust the tension fine.