fischertechnik community forum

Hello,

I am about to embark on my very first project using ft. So without wanting to give to much away I would be grateful if you could give me your thoughts on how I could do the following.

I want to use an XM Motor to push and pull a rectangular block across the surface of a base plate for a distance of about 90mm. I can easily take care of programming the motor, my problem lies in how to do it physically. To give you an idea of what I want imagine a croupier pushing chips across a gaming table to a winner and then pulling the empty rake back.

This all sounds simple in theory, but as I have never really built anything yet I am at a loss as to how to do it.

The front, sides and top of the rectangular block (rake) must be kept clear and will be made flush with appropriate pieces of ft. What I mean by this is that the block will be a rectangular box with 4 closed sides (front, top, left and right) and 2 open sides (underside and rear). So it is only though the rear opening that I can connect and drive my block. I would really appreciate your thoughts on this please or if you need more information then please ask.

Hello Mooki-Moo,

For that long dimension of 90 cm, I suggest using a fischertechnik chain. You can make this fit any length just by adding chain parts, and you can easily attach the chain into fischertechnik building blocks. So you need about 180 cm of chain, carried by a gear wheel at each end.

If you need a second dimension, I could imagine at least two solutions:

a) Make that 90 cm arm rotatable around one of its ends. At the other end, have a wheel or wheel pair that supports the arm above ground, and use a motor to drive this wheel so that the arm moves. This is kind of a polar coordinate system.

b) If you need rectangular coordinates, you could use one wheel (pair) at each end and drive both ends synchronously. This can easily be done by coupling both end wheels by long axles, so that all wheels turn in sync even if driven only from one side.

Good luck, and keep us updated! You might also whish to provide some photos of you plans or machine at www.ftcommunity.de and link them here to ease the discussion.

Best Regards,
Stefan

Hello steffalk,

In the original post I made an error, the distance to travel should in fact be 90mm, and I have since corrected the post. A chain is not an option as there is no tension on the block, the only way to drive it I think would be either by worm or track and this is where I get confused.

With the exception of the rear of the block all other sides must be clear. In addition to this the block's location and travel are fixed i.e. pushed out 90mm from its 'park' position and back again in a straight line. I hope this makes more sense.

Hello Mooki-Moo,

Ok then - why not use the worm gear? You would use some gear parts http://www.ft-datenbank.de/details.php? ... 5d093389f9, at the ends two http://www.ft-datenbank.de/details.php? ... 0c81b5020b, and one or more http://www.ft-datenbank.de/details.php? ... c882b11ea6.

Good luck,
Stefan

OK, I think I've worked it out. I got a big box of bits today and in it is a Schneckenmutter. This mounted at the rear of my rectangle will allow me to drive the block forward and back.

Hello steffalk,

I have just seen your reply and that is exactly what I was thinking.