Seen a similar challenge last year.

Check your local hobby shops, especially those that build model trains or remote controlled cars/boats/planes.

They usually have a selection of relatively small metal sections to be used for driveshafts and so on.

If you are having that trouble with the axles, then maybe your load bearing gears will also need to be metalic to accomodate the torque necessary. You can pick them up at the same places.

Most hobby shops will have a "gearbox fun kit" that will include a series of shafts, worm gears, normal gears and such in a selection of metal and plastic.

Helped build a small "robot" (Fitted inside 40cm cube) powered by two AA batteries. Tried plastic shafts and gears initially, but migrated to metal forthe high torque components.

Hello Just an Engineer,

I am jfmfit who's first asked about a machine to strip tablets from the foil they are packed in.

I had figured to use all lego bits including axles. Problem is there is more strength in a stick of liquorice than lego axles.

I am about to move so it has come to a stop for the moment. But, if it was possible to get a metal lego axle of say 400 mm I can cut it off to length as required.

I hope to build a wooden or metal machine if I can set up a small workshop where ever I end up. But if I was able to put something together before I moved it would be great.

As you may know lego axles are cross shaped with a central core of 3 mm. I have not been able to get out to any local model shops, but I am going out next Tuesday so will see how helpful the local peeps are! Wish me luck..........

Many thanks for your help.

jfmfit

Hi again Just an Engineer:,

We had 'Robot Wars' programs on out televisions for about three years.

After the first six programs the Robots sorted themselves into about four types. There was the 'brute force', 'lift and flip', saw or cut to stop movement, and wedge shapes were were all flip machines. There was also 'mini-bots' which were less than 100 mm square.

Do you put your Robot into competition? It was on out telly as Dads workshop's roof started to leak. I was not well enough to mend it but, I never lost my interest in Robots and machines in general.

Actually having a 'picture' of what I wanted in my mind and, then being able to build the machine as near as I can with what I have to build it with, including tools, it brilliant! The mistake I made was to choose Lego. Lego is fine and I can build strength into my machine. The problem is I had no idea hos soft and flexible the axles were. They were also quite short, with the longest about 125 mm, so I had to have a joint in the roller, which is the main drive mechanism. I did not know of any other engineering sets. If I had of I would have chosen one which uses round axles at least 10" long.

I am disappointed and annoyed but feel I can perhaps save what I am designing by using maybe brass or white metal bar? Of course as I have said, I will need to get thicker gears able to fit round bars. I searched for and found some gears about a year ago. I have to find other ones which are all metal.

As you say the torque is just too much for the thin, plastic flat gears Lego uses. I need wider gears at least 10 mm thick to help them stay in mesh?

I think 2-1 ratio is what I need, the difficulty bit is finding gear 'centres' that work with Lego. At least, for the moment. I do not have tools and a bench etc to fettle a machine from scratch made from flat stainless or aluminium sheet. After I move I may use part of my flat or house as a workshop. But, it all boils down to space, you know?

Several years ago I built a diamond cutting saw to slice pretty stone. The place a got the drive from is still there so I know of it and at least three or four other similar places apart from any model car and train builders shops. There is maybe six shops I know of. I just have not got around to checking them out, as, I assumed wrongly Lego axles would be strong enough. I made that design decision before I got any Lego! Stupid I know, but it is the route I took. I think as I have said I am still able to use Lego bricks as a base. I am going to try and find some drive and axles to allow it.

jfmfit.

Problem is you are talking small numbers.
I don't see an efficient way to make small quantities...

Extrusion (aluminium) would be fine for a production run... but would cost a bit for tooling....maybe worth checking aluminium extrusions in case it's been done before.

I think you'll just have to move up to a more rugged system.

There are companies who sell all sorts of cogs, sprockets mechanical doodabs...look in the engineering journals (must be a pun there). I'd point you somewhere but I'm not in work today.

Good luck
Del

Hi Del the cat,

thank for replying since you are not in work. You are a kind man you know!

That is the problem. I need at most maybe a metre. I think I will have to go the route of using smooth 5 mm axle and file a flat on one side along its length to tight the screws to as I will probably find it easier to use hubs or flat gears pushed together to make the thicker bit of the top roller and then the sharp gears with give a 'key' to grip the polyurethane non slip sheet I have and will use as a soft way to squeeze the tabs out through the foil.

I really want to make the machine as small as I can but, large enough to allow me to add a little bulk to make the whole thing stronger. After knocking up a mini prototype I found there is an awful lot of torque going through the top roller. So much in fact the roller will not turn, instead it twists. I will need to find some thicker gears which fit the axle. But it should be no problem. I looked for some a year or so back but the short-cut is out of date now. I think I will go for all brass. Maybe I can find some that have grub screws to tighten them on the main top roller. The drive gears at the end I can bolt on.

Bye the way, thanks for your continued help OK?

jfmfit

Hello Del the cat,

hope you are fine.

I have come back to this post in case there was any other posts of interest.

Have or do you have time to let me know about the companies you mention which, could possibly supply me with axles and the like.

I have advice from (I think) 'Just an Engineer'. He has some Lego and said he figured and axle of 4.75mm x 1.8mm was a tight fit and could do the job.

I have not been able to get out but if I had an address you know is good, I could try them? We do have quite a lot of model shops, its just getting there. I need someone to 'escort' me because of the fits, you know?.

I will also need a thick axle to support the strippers underneath the roller which draws the foil packs into the mechanism.

Unfortunately, as you may already know I have just bought quite a lot of Lego. I bought it before I found the axles were crap? I will do some more searches and maybe will find something.

I am going through a move at the moment so am busy packing and viewing places. Once I get settled into my new place, and perhaps set up a small bench to do small work on things will come together.

Take care...........

John aka (jfmfit)