Lead Screw Inquiry

[C.I.S.]

We are using a screw drive on our robot to move a system of 3 pneumatic cylinders on a track. Does anybody know what size/kind of lead screw we need?

[tsaksa]

Your selection of a lead screw will be based on the parameters of your design such as. How far do you need for it to move back and forth? How much space might be taken up by a carriage. What precision will you need in your motion? How much force is this lead screw expected to encounter? How fast does the lead screw motion need to be? How are you planning to drive the screw? How will it be, or can it be supported at the ends? etc.

Many commercial lead screws are more precise and powerful than needed for many FIRST applications so you may be able to get by with a lower cost/grade of lead screw depending on your design. A low carbon steel screw with a plastic nut in 1/2 inch diameter or even smaller should work for a wide variety of applications. But if this is intended to do serious work such as lifting the robot, then you better research the answers to the above questions carefully before selecting a lead screw.

[Cecil]

I read the title as "Lead Screw Injury". I was extremely confused as to how someone got injured with one. I think I may finally need sleep after 3 weeks.

[tsaksa]

Originally Posted by Cecil

I read the title as "Lead Screw Injury". I was extremely confused as to how someone got injured with one. I think I may finally need sleep after 3 weeks.

Lead is a very heavy and toxic metal. It is also far to soft for reliable use in most mechanical applications. Why anyone thought it was a good idea to make screws out of the stuff is beyond me. It was only a matter of time before accidents started occurring.

[Ankit S.]

Originally Posted by Cecil

I read the title as "Lead Screw Injury". I was extremely confused as to how someone got injured with one. I think I may finally need sleep after 3 weeks.

I did the same
But theres atleast 3 more weeks without sleep left!

Originally Posted by tsaksa

Your selection of a lead screw will be based on the parameters of your design such as...

snip

Quoted for truth. It really depends on a lot of specifics. Ex: Different turns per inch result in differing amounts of speed and precision.
If you know how fast you want the stuff to move, you can do some calculations regarding rpm turns required to travel one inch.

[Justin Montois]

Originally Posted by BeltSanderRocks

I did the same
But theres atleast 3 more weeks without sleep left!

That makes 3. I also read it as injury. Kinda interesting.

[Kevin Sevcik]

If you're doing something serious with the screw like lifting your robot, get in touch with an applications engineer at Nook Industries. Tell them you're participating in a high school robot competition and what your parameters are and they can help you pick an appropriate lead screw or ball screw they have in stock. We used them for the leadscrew inside our telescoping arm in 2011 and they were extremely helpful.

[JamesCH95]

My limited experience:

-Precision grade lead screws/nuts from McMasters are only slightly more espensive than the junky stuff, worth it IMO.
-Make sure you're not going to exceed the critical rotational speed on your lead screw.

[Joe.Quirk]

Anyone know if the lead screws from Mcmaster are fully threaded? On a related note, does anyone know how, or the best way to make the ends into a regular round shaft to it can be applied to a motor or fit into a bearing?

[Kevin Sevcik]

Originally Posted by Joe.Quirk

Anyone know if the lead screws from Mcmaster are fully threaded? On a related note, does anyone know how, or the best way to make the ends into a regular round shaft to it can be applied to a motor or fit into a bearing?

Yes they are fully threaded. The best way to do the end-prep is on a lathe, obviously. If the screw is hardened and not cutting well, you can temper the end by heating it up to cherry red or orange with a torch and then letting it slowly cool.

[Jibri Wright]

Originally Posted by tsaksa

Lead is a very heavy and toxic metal. It is also far to soft for reliable use in most mechanical applications. Why anyone thought it was a good idea to make screws out of the stuff is beyond me. It was only a matter of time before accidents started occurring.

....... XD