Hey there every one.

I am trying to find the best design for a small but strong Grab / Claw / Gripper to use with my Lego robotic arm project. I have found three suitable designs and I have built and pictured them.

This grab was designed by Leo Dorst this design is very special as it is symmetrical both sides of the grab open and close the exact same way (Taking in to account the play between the gears) . I have made minimal changes to this design just changed the size for the grab arms and added rubber tips to them. This design is also not centred around the drive axle and would not be easily connected to a turntable.

This grab was designed by Leo Dorst this design is very special as it is symmetrical both sides of the grab open and close the exact same way (Taking in to account the play between the gears) . I have made minimal changes to this design just changed the size for the grab arms and added rubber tips to them. This design can easily be connected to a large turntable.

This design is very closely based on a grabber made By Eric Sophie over at MOCpages.com. I have just fine tuned the design removing some unnecessary parts as well as replacing larger parts with smaller ones. The grab its now suited to fit with the new small lego turntable. This design does not open or close symmetrically.

I am very interested in your idea's and your comments.

Thanks

Firky.

Great designs!.

nice designs, i will definitely bookmark this. Those claws could be very useful!

tim

Yeah, the third one is my fav.

@ Firky: All of your designs look very useful. Are you planning on mating the claws onto a Lego 99009 + 99010 mini Technic Turntable, to enable it to rotate on the end of a robotic arm?

Thanks for your kind words however,

I'm not really sure how or when you can claim a design as your own. I just wanted to be clear that these designs were originally designed by Eric Sophie and Leo Dorst and then modified by me to suit my needs. If the changes made now make this version my design then so be it.

@ DLuders: Indeed I do its suited to fit perfectly with a mini Lego technic turntable. The drive axle is dead centre and will fit though the middle of the turntable two 4L axles will hold the turntable in place. I currently don't have a Mini turntable but its in the post on its way here.

I dont think that will fit into the turntable because the turntable's holes that the beems go in would hit the gear .

tim

@ Tim: Hi Tim Thanks for concern. I have taken a number of pictures to help show how the mini turntable will fit using parts that are the close match to the turntable its self.

This picture hows how the two connecting 1L lift arms on the turntable will connect to the grab. (grab is in open position)

This picture hows how the two connecting 1L lift arms on the turntable will connect to the grab. (grab is in closed position)

This picture hows how the two connecting 1L lift arms on the turntable allowing enough room for the Axle to fit through.

This picture hows how the 28 tooth gear (I only have a 24 tooth gear in the picture) on the turntable fit against to the grab. (grab is in closed position)

This picture hows how the 28 tooth gear (I only have a 24 tooth gear in the picture) on the turntable fit against to the grab. (grab is in open position)

This picture hows how the 28 tooth gear (I only have a 24 tooth gear in the picture) on the turntable fit against the grab. (grab is in open position)

I hope these pictures clear things up.

Firky

Ohh okay. I though that the yellow connector would hit the gear.

tim

I am still awaiting the arrival of the Mini lego turntable so I decided to work with one of the other grabs in the mean time.

Nice Work

Fantastic work on these claws

Now this is an interesting topic, some great designs and 1 area I need to improve on!

Thanks Guys. I really wish the micro motor was easier to mount. by they time I've built a mount to secure the motor in place the M motor is smaller and much stronger.

Hey guys,

Its been a while. So since my last posts I did receive my 28 tooth mini turntable and I have fitted it to the grab.

How ever since its a 28 tooth and not a 24 tooth mounting gears for the rotation of the turntable isn't easy. The only gears that fit are the double bevelled gears as shown below, and with the orataition shown below the axle from the double bevelled gear blocks the thought hole in the trun table that would be used for the grab drive.

Here you can see where the grab drive would go

Here you can see that the axle used for the double bevelled gear blocks the hole.

So guys Im after your help? whats the best way to work with the mini turn table?

Thanks

Firky

Couldn't you just align the bewel gear with the turntable so that you have 2 protruding axles from the grabber?

Sadly the 28 tooth turntable does not fit with the gears as easily as the 20 tooth and the 12 tooth.

Sadly the 28 tooth turntable does not fit with the gears as easily as the 20 tooth and the 12 tooth.

That could be solved with half a stud offset.

Edited September 22, 201212 yr by Carsten Svendsen

Im sure I tried that before. maybe i didn't off set it tho. ill try it again and see how it goes.

Thanks Firky

Two min's while I make something............

Edited September 22, 201212 yr by Alasdair Ryan

waits intently :)

Will this help you?

Edited September 22, 201212 yr by Alasdair Ryan

It would most definitely work. However it's on the big side. Using the 20 tooth gear with the small turn table kinda defects the purpose of using the small turntable as its almost as big as the standard turntable. Sadly I don't have enough parts today to try the offsetting. Using the 12 tooth gear with an offset seems to be the best choice so far.

Thanks for trying :)

Firky

Edited September 22, 201212 yr by Firky

The problem with having a 1/2 stud off set is that is not very easy to brace.

Guys, do it like this:

Also its a higher gear ratio this way.