I am on a very tight budget and so I need the most inexpensive lead screw I can find. Not only that, but I only need the screw to bear a load of at most 15 pounds. I have done considerable searching, but cannot find any suited for my very small scale project at a reasonable price. The following link is for the least expensive I have found so far, but it still has a capacity of 240 pounds for a plastic nut:
========= Much depends on what you are using it for and how durable it must be [and under what conditions]. More info = better advice.
4 lead anything will be expensive.Can you use a larger piece of allthread with a coarse pitch, and a nut clamped in place? If back lash is excessive, you could use two nuts with a spring between them clamped against the slide. This will reduce backlash and allow adjustment for wear. Stronger spring = less backlash but harder to turn.
See
Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains.
Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814.
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This is for a rather ambitious robotics project. I need the lead screw to lift a small platform about 4 inches, weighing no more than
10 or 15 pounds. I also need a lead screw mechanism to slide a platform in a horizontal direction mounted on a rail or track. That platform would also be about 10 pounds, and I need it to slide at least 3 feet. Both of these would be connected to rotary motors. According to my research, it seemed like a lead screw was the least expensive screw mechanism available. If there is something less expensive, I would much rather use that. Also I need a moderate degree of precision so I can move the platforms in increments of a millimeter at a time, and it must be able to hold its position and not "drift" when the motor is not pushing it along..5 in / .25 in threaded rod from the local hardware store. Chuck it in a drill press at a low speed and gently sand the sharp apex from the threads. Even cheaper?... steal the rod.
Hul
snipped-for-privacy@keenebroadband.com wrote:
see
I think it's worth asking - what is the actual purpose for the lead screw? Often, I've found that if something I want isn't available, it's because I'm trying to do something the hard way, and something better/easier exists.
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===== Sounds like a natural for allthread and some nuts.
Unless you have space/weight limitations use 1/2X20 or 7/16 X20. Given your accuracy requirements, you can simply tap a hole to the same thread size. 1/4X20 should be adequate is you can keep the screws under tension.
These will wear out in fairly short order (a few thousand to 10s of thousands of cycles depending on lube and nut material], but should be adequate for your needs, i.e. proof of concept. Self lubricating material such as nylon, delrin and HDPE with relatively long threads [c. 1 inch] will last longer. A one inch [2X] "depth of thread" in a polymer should eliminate any backlash until wear become evident.
FWIW -- with a depth of thread engagement equal to the major diameter, most screw materials will fail before the threads strip. With a 1 inch depth of thread [2X diameter], a 7/16 or
1/2 screw *WILL* fail before the threads do until the wear becomes totally excessive.Allthread [or Redithread] typically comes in 2, 3, and 6 foot lengths in the US. For example click on
and you get to pick any *TWO*
******************Good luck on your project, and please feel free to ask if you have more questions.
Where are you located? Your use of "millimeter at a time" indicates you may not be a US resident.
Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains.
Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814.
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All thread and a do it yourself split nut.
Gunner
snipped-for-privacy@keenebroadband.com wrote in news:1185745677.335030.119980 @g4g2000hsf.googlegroups.com:
Acme screw and nut from McMaster-Carr would be my suggestion.
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