need a reciprocating mechanism - Page 1
Forum section: electronics / general

author: engineheat
author_rank: Frequent Contributor
timestamp: May 17, 2021, 04:15:22 pm
content: Hi,I wonder if there are kits or toys that offers a reciprocating mechanism that converts rotary movement into linear? I need the linear movement to be about 1 - 2 cm, and the mechanism should be as small as possible. I wonder if there are kits or toys that you know of that have such a mechanism?Thanks

author: sandalcandal
author_rank: Unknown
timestamp: May 17, 2021, 04:28:53 pm
content: Lego?Kinda cheating considering you can build pretty much any basic mechanism but should work as long as you don't need too much load bearinghttp://www.technicopedia.com/fundamentals.htmlAttach a stub axel to one of the off-centre holes in a gear then you can make a crank like that.Edit: This has some exampleshttps://www.daslhub.org/unlv/courses/me425-625/lesson-B-simpleMachines1-leversShaftsAndCranks/lab/labLegoLeversShaftsAndCranks.pdf

author: andy3055
author_rank: Super Contributor
timestamp: May 17, 2021, 04:31:20 pm
content: With an old style mecano set (those metal stuff) you could make one easily. All you need is a circular piece with holes, a straight piece with holes, a tiny motor and a couple of nuts/bolts.

author: SeanB
author_rank: Super Contributor
timestamp: May 17, 2021, 06:31:47 pm
content: I know of one, though the mechanism is rather dodgy, along with the suppliers. They are common in toys, so look in the toy store for some with this motion.You have not mentioned volume, expected lifetime, number of cycles per minute, or voltage and current available for it.

author: ledtester
author_rank: Super Contributor
timestamp: May 17, 2021, 06:52:43 pm
content: I found some toys searching for "Tamiya" and reciprocating, such as:https://www.hobbylinc.com/htm/tam/tam71101.htmas well as the other Tamiya kits on that site.They're not going to be cheap.

author: jpanhalt
author_rank: Super Contributor
timestamp: May 17, 2021, 07:29:24 pm
content: Since you don't give any power requirements...Linear converters for model servos have been around for decades. There are also "linear servos" today. Check Google or Amazon.

author: james_s
author_rank: Super Contributor
timestamp: May 17, 2021, 07:31:26 pm
content: Is this for a one-off? All you need is a wheel or arm you can attach to a shaft and then drill a hole and attach an arm. You haven't really given enough information for anyone to make a specific recommendation.

author: Raj
author_rank: Frequent Contributor
timestamp: June 26, 2021, 12:10:24 pm
content: The smallest linear motion actuator I've ever seen are usually in camera lenses. A motor rotates a screw, which pushes on a nut. The nut can't rotate so it has to go up or down.There's also this-https://youtu.be/_UySbXafPyMAdafruit sells something similar.But do you know pcb way, I think, sells 3d printed parts now?

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 26, 2021, 01:02:17 pm
content: You didn't specify roughly how many turns for full travel, so if it's many, a screw and nut will do the trick. Grease them before assembly to reduce wear.

author: DrG
author_rank: Super Contributor
timestamp: June 26, 2021, 02:47:58 pm
content: Alibay has a load of micro steppers like this:search for "micro steppers"and here is an interesting toy mechanism:Search for "Reciprocating motion model Maker DIY electric motor drive toy crank linear motion model"When are you going to tell us what you are up to?

author: RJSV
author_rank: Super Contributor
timestamp: June 27, 2021, 02:36:53 am
content: I have a couple of greeting cards, specials with minor electronics, for Halloween 'monster cards', having blinking LED eyes in the special greeting card.Now, also the unit has a reciprocating mechanism, for producing 'eyeball' wiggles.The little mechanical box contains 10mm X 3mm motor, and a couple gears. I'm not sure if the little controller IC sends both directions polarity to the motor (IC is inside epoxy dot).The little gear box is 20mm by 20mm by 8mm thick.You'd have to check Hallmark Cards, and I will keep a look out, for that special Halloween card.

author: beanflying
author_rank: Super Contributor
timestamp: June 27, 2021, 02:53:33 am
content: While the OP hasn't been back with some required info the little indoor R/C linear servos are about the easiest to incorporate into a design with minimal mechanical engineering or hacks needed. Costs on them are sub $10USD and all you need to drive them is a 4-6VDC supply and a 1-2mS pulse from anything from a 555 timer hack to a PWM out of an arduino. Some of the other screw options from AliX or evilbay are a bit more robust but you would need to do the drive electronics and position sensing too if you need accurate control.